HDFS-14304: High lock contention on hdfsHashMutex in libhdfs

This closes #595

Signed-off-by: Todd Lipcon <todd@apache.org>

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfs-tests/CMakeLists.txt

@@ -29,8 +29,8 @@ include_directories(
 
 add_library(native_mini_dfs
     native_mini_dfs.c
-    ../libhdfs/common/htable.c
     ../libhdfs/exception.c
+    ../libhdfs/jclasses.c
     ../libhdfs/jni_helper.c
     ${OS_DIR}/mutexes.c
     ${OS_DIR}/thread_local_storage.c
@@ -39,6 +39,3 @@ add_library(native_mini_dfs
 add_executable(test_native_mini_dfs test_native_mini_dfs.c)
 target_link_libraries(test_native_mini_dfs native_mini_dfs ${JAVA_JVM_LIBRARY})
 add_test(test_test_native_mini_dfs test_native_mini_dfs)
-
-add_executable(test_htable ../libhdfs/common/htable.c test_htable.c)
-target_link_libraries(test_htable ${OS_LINK_LIBRARIES})

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfs-tests/native_mini_dfs.c

@@ -17,6 +17,7 @@
  */
 
 #include "exception.h"
+#include "jclasses.h"
 #include "jni_helper.h"
 #include "native_mini_dfs.h"
 #include "platform.h"
@@ -36,9 +37,7 @@
 
 #define MINIDFS_CLUSTER_BUILDER "org/apache/hadoop/hdfs/MiniDFSCluster$Builder"
 #define MINIDFS_CLUSTER "org/apache/hadoop/hdfs/MiniDFSCluster"
-#define HADOOP_CONF     "org/apache/hadoop/conf/Configuration"
 #define HADOOP_NAMENODE "org/apache/hadoop/hdfs/server/namenode/NameNode"
-#define JAVA_INETSOCKETADDRESS "java/net/InetSocketAddress"
 
 struct NativeMiniDfsCluster {
     /**
@@ -60,8 +59,7 @@ static int hdfsDisableDomainSocketSecurity(void)
       errno = EINTERNAL;
       return -1;
     }
-    jthr = invokeMethod(env, NULL, STATIC, NULL,
+    jthr = invokeMethod(env, NULL, STATIC, NULL, JC_DOMAIN_SOCKET,
-            "org/apache/hadoop/net/unix/DomainSocket",
             "disableBindPathValidation", "()V");
     if (jthr) {
         errno = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -126,11 +124,6 @@ struct NativeMiniDfsCluster* nmdCreate(struct NativeMiniDfsConf *conf)
             "nmdCreate: new Configuration");
         goto error;
     }
-    if (jthr) {
-        printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
-                              "nmdCreate: Configuration::setBoolean");
-        goto error;
-    }
     // Disable 'minimum block size' -- it's annoying in tests.
     (*env)->DeleteLocalRef(env, jconfStr);
     jconfStr = NULL;
@@ -140,8 +133,9 @@ struct NativeMiniDfsCluster* nmdCreate(struct NativeMiniDfsConf *conf)
                               "nmdCreate: new String");
         goto error;
     }
-    jthr = invokeMethod(env, NULL, INSTANCE, cobj, HADOOP_CONF,
+    jthr = invokeMethod(env, NULL, INSTANCE, cobj,
-                        "setLong", "(Ljava/lang/String;J)V", jconfStr, 0LL);
+            JC_CONFIGURATION, "setLong", "(Ljava/lang/String;J)V", jconfStr,
+            0LL);
     if (jthr) {
         printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
                               "nmdCreate: Configuration::setLong");
@@ -163,7 +157,7 @@ struct NativeMiniDfsCluster* nmdCreate(struct NativeMiniDfsConf *conf)
             goto error;
         }
     }
-    jthr = invokeMethod(env, &val, INSTANCE, bld, MINIDFS_CLUSTER_BUILDER,
+    jthr = findClassAndInvokeMethod(env, &val, INSTANCE, bld, MINIDFS_CLUSTER_BUILDER,
             "format", "(Z)L" MINIDFS_CLUSTER_BUILDER ";", conf->doFormat);
     if (jthr) {
         printExceptionAndFree(env, jthr, PRINT_EXC_ALL, "nmdCreate: "
@@ -172,7 +166,7 @@ struct NativeMiniDfsCluster* nmdCreate(struct NativeMiniDfsConf *conf)
     }
     (*env)->DeleteLocalRef(env, val.l);
     if (conf->webhdfsEnabled) {
-        jthr = invokeMethod(env, &val, INSTANCE, bld, MINIDFS_CLUSTER_BUILDER,
+        jthr = findClassAndInvokeMethod(env, &val, INSTANCE, bld, MINIDFS_CLUSTER_BUILDER,
                         "nameNodeHttpPort", "(I)L" MINIDFS_CLUSTER_BUILDER ";",
                         conf->namenodeHttpPort);
         if (jthr) {
@@ -183,7 +177,7 @@ struct NativeMiniDfsCluster* nmdCreate(struct NativeMiniDfsConf *conf)
         (*env)->DeleteLocalRef(env, val.l);
     }
     if (conf->numDataNodes) {
-        jthr = invokeMethod(env, &val, INSTANCE, bld, MINIDFS_CLUSTER_BUILDER,
+        jthr = findClassAndInvokeMethod(env, &val, INSTANCE, bld, MINIDFS_CLUSTER_BUILDER,
                 "numDataNodes", "(I)L" MINIDFS_CLUSTER_BUILDER ";", conf->numDataNodes);
         if (jthr) {
             printExceptionAndFree(env, jthr, PRINT_EXC_ALL, "nmdCreate: "
@@ -192,7 +186,7 @@ struct NativeMiniDfsCluster* nmdCreate(struct NativeMiniDfsConf *conf)
         }
     }
     (*env)->DeleteLocalRef(env, val.l);
-    jthr = invokeMethod(env, &val, INSTANCE, bld, MINIDFS_CLUSTER_BUILDER,
+    jthr = findClassAndInvokeMethod(env, &val, INSTANCE, bld, MINIDFS_CLUSTER_BUILDER,
             "build", "()L" MINIDFS_CLUSTER ";");
     if (jthr) {
         printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -242,7 +236,7 @@ int nmdShutdown(struct NativeMiniDfsCluster* cl)
         fprintf(stderr, "nmdShutdown: getJNIEnv failed\n");
         return -EIO;
     }
-    jthr = invokeMethod(env, NULL, INSTANCE, cl->obj,
+    jthr = findClassAndInvokeMethod(env, NULL, INSTANCE, cl->obj,
             MINIDFS_CLUSTER, "shutdown", "()V");
     if (jthr) {
         printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -260,7 +254,7 @@ int nmdWaitClusterUp(struct NativeMiniDfsCluster *cl)
         fprintf(stderr, "nmdWaitClusterUp: getJNIEnv failed\n");
         return -EIO;
     }
-    jthr = invokeMethod(env, NULL, INSTANCE, cl->obj,
+    jthr = findClassAndInvokeMethod(env, NULL, INSTANCE, cl->obj,
             MINIDFS_CLUSTER, "waitClusterUp", "()V");
     if (jthr) {
         printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -282,7 +276,7 @@ int nmdGetNameNodePort(const struct NativeMiniDfsCluster *cl)
     }
     // Note: this will have to be updated when HA nativeMiniDfs clusters are
     // supported
-    jthr = invokeMethod(env, &jVal, INSTANCE, cl->obj,
+    jthr = findClassAndInvokeMethod(env, &jVal, INSTANCE, cl->obj,
             MINIDFS_CLUSTER, "getNameNodePort", "()I");
     if (jthr) {
         printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -307,7 +301,7 @@ int nmdGetNameNodeHttpAddress(const struct NativeMiniDfsCluster *cl,
         return -EIO;
     }
     // First get the (first) NameNode of the cluster
-    jthr = invokeMethod(env, &jVal, INSTANCE, cl->obj, MINIDFS_CLUSTER,
+    jthr = findClassAndInvokeMethod(env, &jVal, INSTANCE, cl->obj, MINIDFS_CLUSTER,
                         "getNameNode", "()L" HADOOP_NAMENODE ";");
     if (jthr) {
         printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -318,8 +312,8 @@ int nmdGetNameNodeHttpAddress(const struct NativeMiniDfsCluster *cl,
     jNameNode = jVal.l;
 
     // Then get the http address (InetSocketAddress) of the NameNode
-    jthr = invokeMethod(env, &jVal, INSTANCE, jNameNode, HADOOP_NAMENODE,
+    jthr = findClassAndInvokeMethod(env, &jVal, INSTANCE, jNameNode, HADOOP_NAMENODE,
-                        "getHttpAddress", "()L" JAVA_INETSOCKETADDRESS ";");
+                        "getHttpAddress", "()L" JAVA_NET_ISA ";");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
                                     "nmdGetNameNodeHttpAddress: "
@@ -328,8 +322,8 @@ int nmdGetNameNodeHttpAddress(const struct NativeMiniDfsCluster *cl,
     }
     jAddress = jVal.l;
 
-    jthr = invokeMethod(env, &jVal, INSTANCE, jAddress,
+    jthr = findClassAndInvokeMethod(env, &jVal, INSTANCE, jAddress,
-                        JAVA_INETSOCKETADDRESS, "getPort", "()I");
+                        JAVA_NET_ISA, "getPort", "()I");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
                                     "nmdGetNameNodeHttpAddress: "
@@ -338,7 +332,7 @@ int nmdGetNameNodeHttpAddress(const struct NativeMiniDfsCluster *cl,
     }
     *port = jVal.i;
 
-    jthr = invokeMethod(env, &jVal, INSTANCE, jAddress, JAVA_INETSOCKETADDRESS,
+    jthr = findClassAndInvokeMethod(env, &jVal, INSTANCE, jAddress, JAVA_NET_ISA,
                         "getHostName", "()Ljava/lang/String;");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfs-tests/test_htable.c

@@ -1,100 +0,0 @@
-/**
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements.  See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership.  The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License.  You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "common/htable.h"
-#include "expect.h"
-#include "hdfs_test.h"
-
-#include <errno.h>
-#include <inttypes.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-
-// Disable type cast and loss of precision warnings, because the test
-// manipulates void* values manually on purpose.
-#ifdef WIN32
-#pragma warning(disable: 4244 4306)
-#endif
-
-static uint32_t simple_hash(const void *key, uint32_t size)
-{
-    uintptr_t k = (uintptr_t)key;
-    return ((13 + k) * 6367) % size;
-}
-
-static int simple_compare(const void *a, const void *b)
-{
-    return a == b;
-}
-
-static void expect_102(void *f, void *k, void *v)
-{
-    int *found_102 = f;
-    uintptr_t key = (uintptr_t)k;
-    uintptr_t val = (uintptr_t)v;
-
-    if ((key == 2) && (val == 102)) {
-        *found_102 = 1;
-    } else {
-        abort();
-    }
-}
-
-static void *htable_pop_val(struct htable *ht, void *key)
-{
-    void *old_key, *old_val;
-
-    htable_pop(ht, key, &old_key, &old_val);
-    return old_val;
-}
-
-int main(void)
-{
-    struct htable *ht;
-    int found_102 = 0;
-
-    ht = htable_alloc(4, simple_hash, simple_compare);
-    EXPECT_INT_EQ(0, htable_used(ht));
-    EXPECT_INT_EQ(4, htable_capacity(ht));
-    EXPECT_NULL(htable_get(ht, (void*)123));
-    EXPECT_NULL(htable_pop_val(ht, (void*)123));
-    EXPECT_ZERO(htable_put(ht, (void*)123, (void*)456));
-    EXPECT_INT_EQ(456, (uintptr_t)htable_get(ht, (void*)123));
-    EXPECT_INT_EQ(456, (uintptr_t)htable_pop_val(ht, (void*)123));
-    EXPECT_NULL(htable_pop_val(ht, (void*)123));
-
-    // Enlarge the hash table
-    EXPECT_ZERO(htable_put(ht, (void*)1, (void*)101));
-    EXPECT_ZERO(htable_put(ht, (void*)2, (void*)102));
-    EXPECT_ZERO(htable_put(ht, (void*)3, (void*)103));
-    EXPECT_INT_EQ(3, htable_used(ht));
-    EXPECT_INT_EQ(8, htable_capacity(ht));
-    EXPECT_INT_EQ(102, (uintptr_t)htable_get(ht, (void*)2));
-    EXPECT_INT_EQ(101, (uintptr_t)htable_pop_val(ht, (void*)1));
-    EXPECT_INT_EQ(103, (uintptr_t)htable_pop_val(ht, (void*)3));
-    EXPECT_INT_EQ(1, htable_used(ht));
-    htable_visit(ht, expect_102, &found_102);
-    EXPECT_INT_EQ(1, found_102);
-    htable_free(ht);
-
-    fprintf(stderr, "SUCCESS.\n");
-    return EXIT_SUCCESS;
-}
-
-// vim: ts=4:sw=4:tw=79:et

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfs/CMakeLists.txt

@@ -35,7 +35,7 @@ hadoop_add_dual_library(hdfs
     exception.c
     jni_helper.c
     hdfs.c
-    common/htable.c
+    jclasses.c
     ${OS_DIR}/mutexes.c
     ${OS_DIR}/thread_local_storage.c
 )

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfs/common/htable.c

@@ -1,287 +0,0 @@
-/**
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements.  See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership.  The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License.  You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "common/htable.h"
-
-#include <errno.h>
-#include <inttypes.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
-
-struct htable_pair {
-    void *key;
-    void *val;
-};
-
-/**
- * A hash table which uses linear probing.
- */
-struct htable {
-    uint32_t capacity;
-    uint32_t used;
-    htable_hash_fn_t hash_fun;
-    htable_eq_fn_t eq_fun;
-    struct htable_pair *elem;
-};
-
-/**
- * An internal function for inserting a value into the hash table.
- *
- * Note: this function assumes that you have made enough space in the table.
- *
- * @param nelem         The new element to insert.
- * @param capacity      The capacity of the hash table.
- * @param hash_fun      The hash function to use.
- * @param key           The key to insert.
- * @param val           The value to insert.
- */
-static void htable_insert_internal(struct htable_pair *nelem, 
-        uint32_t capacity, htable_hash_fn_t hash_fun, void *key,
-        void *val)
-{
-    uint32_t i;
-
-    i = hash_fun(key, capacity);
-    while (1) {
-        if (!nelem[i].key) {
-            nelem[i].key = key;
-            nelem[i].val = val;
-            return;
-        }
-        i++;
-        if (i == capacity) {
-            i = 0;
-        }
-    }
-}
-
-static int htable_realloc(struct htable *htable, uint32_t new_capacity)
-{
-    struct htable_pair *nelem;
-    uint32_t i, old_capacity = htable->capacity;
-    htable_hash_fn_t hash_fun = htable->hash_fun;
-
-    nelem = calloc(new_capacity, sizeof(struct htable_pair));
-    if (!nelem) {
-        return ENOMEM;
-    }
-    for (i = 0; i < old_capacity; i++) {
-        struct htable_pair *pair = htable->elem + i;
-        if (pair->key) {
-            htable_insert_internal(nelem, new_capacity, hash_fun,
-                                   pair->key, pair->val);
-        }
-    }
-    free(htable->elem);
-    htable->elem = nelem;
-    htable->capacity = new_capacity;
-    return 0;
-}
-
-static uint32_t round_up_to_power_of_2(uint32_t i)
-{
-    if (i == 0) {
-        return 1;
-    }
-    i--;
-    i |= i >> 1;
-    i |= i >> 2;
-    i |= i >> 4;
-    i |= i >> 8;
-    i |= i >> 16;
-    i++;
-    return i;
-}
-
-struct htable *htable_alloc(uint32_t size,
-                htable_hash_fn_t hash_fun, htable_eq_fn_t eq_fun)
-{
-    struct htable *htable;
-
-    htable = calloc(1, sizeof(*htable));
-    if (!htable) {
-        return NULL;
-    }
-    size = round_up_to_power_of_2(size);
-    if (size < HTABLE_MIN_SIZE) {
-        size = HTABLE_MIN_SIZE;
-    }
-    htable->hash_fun = hash_fun;
-    htable->eq_fun = eq_fun;
-    htable->used = 0;
-    if (htable_realloc(htable, size)) {
-        free(htable);
-        return NULL;
-    }
-    return htable;
-}
-
-void htable_visit(struct htable *htable, visitor_fn_t fun, void *ctx)
-{
-    uint32_t i;
-
-    for (i = 0; i != htable->capacity; ++i) {
-        struct htable_pair *elem = htable->elem + i;
-        if (elem->key) {
-            fun(ctx, elem->key, elem->val);
-        }
-    }
-}
-
-void htable_free(struct htable *htable)
-{
-    if (htable) {
-        free(htable->elem);
-        free(htable);
-    }
-}
-
-int htable_put(struct htable *htable, void *key, void *val)
-{
-    int ret;
-    uint32_t nused;
-
-    // NULL is not a valid key value.
-    // This helps us implement htable_get_internal efficiently, since we know
-    // that we can stop when we encounter the first NULL key.
-    if (!key) {
-        return EINVAL;
-    }
-    // NULL is not a valid value.  Otherwise the results of htable_get would
-    // be confusing (does a NULL return mean entry not found, or that the
-    // entry was found and was NULL?) 
-    if (!val) {
-        return EINVAL;
-    }
-    // Re-hash if we have used more than half of the hash table
-    nused = htable->used + 1;
-    if (nused >= (htable->capacity / 2)) {
-        ret = htable_realloc(htable, htable->capacity * 2);
-        if (ret)
-            return ret;
-    }
-    htable_insert_internal(htable->elem, htable->capacity,
-                                htable->hash_fun, key, val);
-    htable->used++;
-    return 0;
-}
-
-static int htable_get_internal(const struct htable *htable,
-                               const void *key, uint32_t *out)
-{
-    uint32_t start_idx, idx;
-
-    start_idx = htable->hash_fun(key, htable->capacity);
-    idx = start_idx;
-    while (1) {
-        struct htable_pair *pair = htable->elem + idx;
-        if (!pair->key) {
-            // We always maintain the invariant that the entries corresponding
-            // to a given key are stored in a contiguous block, not separated
-            // by any NULLs.  So if we encounter a NULL, our search is over.
-            return ENOENT;
-        } else if (htable->eq_fun(pair->key, key)) {
-            *out = idx;
-            return 0;
-        }
-        idx++;
-        if (idx == htable->capacity) {
-            idx = 0;
-        }
-        if (idx == start_idx) {
-            return ENOENT;
-        }
-    }
-}
-
-void *htable_get(const struct htable *htable, const void *key)
-{
-    uint32_t idx;
-
-    if (htable_get_internal(htable, key, &idx)) {
-        return NULL;
-    }
-    return htable->elem[idx].val;
-}
-
-void htable_pop(struct htable *htable, const void *key,
-                void **found_key, void **found_val)
-{
-    uint32_t hole, i;
-    const void *nkey;
-
-    if (htable_get_internal(htable, key, &hole)) {
-        *found_key = NULL;
-        *found_val = NULL;
-        return;
-    }
-    i = hole;
-    htable->used--;
-    // We need to maintain the compactness invariant used in
-    // htable_get_internal.  This invariant specifies that the entries for any
-    // given key are never separated by NULLs (although they may be separated
-    // by entries for other keys.)
-    while (1) {
-        i++;
-        if (i == htable->capacity) {
-            i = 0;
-        }
-        nkey = htable->elem[i].key;
-        if (!nkey) {
-            *found_key = htable->elem[hole].key;
-            *found_val = htable->elem[hole].val;
-            htable->elem[hole].key = NULL;
-            htable->elem[hole].val = NULL;
-            return;
-        } else if (htable->eq_fun(key, nkey)) {
-            htable->elem[hole].key = htable->elem[i].key;
-            htable->elem[hole].val = htable->elem[i].val;
-            hole = i;
-        }
-    }
-}
-
-uint32_t htable_used(const struct htable *htable)
-{
-    return htable->used;
-}
-
-uint32_t htable_capacity(const struct htable *htable)
-{
-    return htable->capacity;
-}
-
-uint32_t ht_hash_string(const void *str, uint32_t max)
-{
-    const char *s = str;
-    uint32_t hash = 0;
-
-    while (*s) {
-        hash = (hash * 31) + *s;
-        s++;
-    }
-    return hash % max;
-}
-
-int ht_compare_string(const void *a, const void *b)
-{
-    return strcmp(a, b) == 0;
-}
-
-// vim: ts=4:sw=4:tw=79:et

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfs/common/htable.h

@@ -1,161 +0,0 @@
-/**
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements.  See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership.  The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License.  You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef HADOOP_CORE_COMMON_HASH_TABLE
-#define HADOOP_CORE_COMMON_HASH_TABLE
-
-#include <inttypes.h>
-#include <stdio.h>
-#include <stdint.h>
-
-#define HTABLE_MIN_SIZE 4
-
-struct htable;
-
-/**
- * An HTable hash function.
- *
- * @param key       The key.
- * @param capacity  The total capacity.
- *
- * @return          The hash slot.  Must be less than the capacity.
- */
-typedef uint32_t (*htable_hash_fn_t)(const void *key, uint32_t capacity);
-
-/**
- * An HTable equality function.  Compares two keys.
- *
- * @param a         First key.
- * @param b         Second key.
- *
- * @return          nonzero if the keys are equal.
- */
-typedef int (*htable_eq_fn_t)(const void *a, const void *b);
-
-/**
- * Allocate a new hash table.
- *
- * @param capacity  The minimum suggested starting capacity.
- * @param hash_fun  The hash function to use in this hash table.
- * @param eq_fun    The equals function to use in this hash table.
- *
- * @return          The new hash table on success; NULL on OOM.
- */
-struct htable *htable_alloc(uint32_t capacity, htable_hash_fn_t hash_fun,
-                            htable_eq_fn_t eq_fun);
-
-typedef void (*visitor_fn_t)(void *ctx, void *key, void *val);
-
-/**
- * Visit all of the entries in the hash table.
- *
- * @param htable    The hash table.
- * @param fun       The callback function to invoke on each key and value.
- * @param ctx       Context pointer to pass to the callback.
- */
-void htable_visit(struct htable *htable, visitor_fn_t fun, void *ctx);
-
-/**
- * Free the hash table.
- *
- * It is up the calling code to ensure that the keys and values inside the
- * table are de-allocated, if that is necessary.
- *
- * @param htable    The hash table.
- */
-void htable_free(struct htable *htable);
-
-/**
- * Add an entry to the hash table.
- *
- * @param htable    The hash table.
- * @param key       The key to add.  This cannot be NULL.
- * @param fun       The value to add.  This cannot be NULL.
- *
- * @return          0 on success;
- *                  EEXIST if the value already exists in the table;
- *                  ENOMEM if there is not enough memory to add the element.
- *                  EFBIG if the hash table has too many entries to fit in 32
- *                      bits.
- */
-int htable_put(struct htable *htable, void *key, void *val);
-
-/**
- * Get an entry from the hash table.
- *
- * @param htable    The hash table.
- * @param key       The key to find.
- *
- * @return          NULL if there is no such entry; the entry otherwise.
- */
-void *htable_get(const struct htable *htable, const void *key);
-
-/**
- * Get an entry from the hash table and remove it.
- *
- * @param htable    The hash table.
- * @param key       The key for the entry find and remove.
- * @param found_key (out param) NULL if the entry was not found; the found key
- *                      otherwise.
- * @param found_val (out param) NULL if the entry was not found; the found
- *                      value otherwise.
- */
-void htable_pop(struct htable *htable, const void *key,
-                void **found_key, void **found_val);
-
-/**
- * Get the number of entries used in the hash table.
- *
- * @param htable    The hash table.
- *
- * @return          The number of entries used in the hash table.
- */
-uint32_t htable_used(const struct htable *htable);
-
-/**
- * Get the capacity of the hash table.
- *
- * @param htable    The hash table.
- *
- * @return          The capacity of the hash table.
- */
-uint32_t htable_capacity(const struct htable *htable);
-
-/**
- * Hash a string.
- *
- * @param str       The string.
- * @param max       Maximum hash value
- *
- * @return          A number less than max.
- */
-uint32_t ht_hash_string(const void *str, uint32_t max);
-
-/**
- * Compare two strings.
- *
- * @param a         The first string.
- * @param b         The second string.
- *
- * @return          1 if the strings are identical; 0 otherwise.
- */
-int ht_compare_string(const void *a, const void *b);
-
-#endif
-
-// vim: ts=4:sw=4:tw=79:et

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfs/exception.c

@@ -18,6 +18,7 @@
 
 #include "exception.h"
 #include "hdfs/hdfs.h"
+#include "jclasses.h"
 #include "jni_helper.h"
 #include "platform.h"
 
@@ -129,8 +130,7 @@ static char* getExceptionUtilString(JNIEnv *env, jthrowable exc, char *methodNam
     jvalue jVal;
     jstring jStr = NULL;
     char *excString = NULL;
-    jthr = invokeMethod(env, &jVal, STATIC, NULL,
+    jthr = invokeMethod(env, &jVal, STATIC, NULL, JC_EXCEPTION_UTILS,
-        "org/apache/commons/lang3/exception/ExceptionUtils",
             methodName, "(Ljava/lang/Throwable;)Ljava/lang/String;", exc);
     if (jthr) {
         destroyLocalReference(env, jthr);

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfs/hdfs.c

@@ -18,6 +18,7 @@
 
 #include "exception.h"
 #include "hdfs/hdfs.h"
+#include "jclasses.h"
 #include "jni_helper.h"
 #include "platform.h"
 
@@ -26,23 +27,6 @@
 #include <stdio.h>
 #include <string.h>
 
-/* Some frequently used Java paths */
-#define HADOOP_CONF     "org/apache/hadoop/conf/Configuration"
-#define HADOOP_PATH     "org/apache/hadoop/fs/Path"
-#define HADOOP_LOCALFS  "org/apache/hadoop/fs/LocalFileSystem"
-#define HADOOP_FS       "org/apache/hadoop/fs/FileSystem"
-#define HADOOP_FSSTATUS "org/apache/hadoop/fs/FsStatus"
-#define HADOOP_BLK_LOC  "org/apache/hadoop/fs/BlockLocation"
-#define HADOOP_DFS      "org/apache/hadoop/hdfs/DistributedFileSystem"
-#define HADOOP_ISTRM    "org/apache/hadoop/fs/FSDataInputStream"
-#define HADOOP_OSTRM    "org/apache/hadoop/fs/FSDataOutputStream"
-#define HADOOP_STAT     "org/apache/hadoop/fs/FileStatus"
-#define HADOOP_FSPERM   "org/apache/hadoop/fs/permission/FsPermission"
-#define JAVA_NET_ISA    "java/net/InetSocketAddress"
-#define JAVA_NET_URI    "java/net/URI"
-#define JAVA_STRING     "java/lang/String"
-#define READ_OPTION     "org/apache/hadoop/fs/ReadOption"
-
 #define JAVA_VOID       "V"
 
 /* Macros for constructing method signatures */
@@ -109,8 +93,7 @@ int hdfsGetHedgedReadMetrics(hdfsFS fs, struct hdfsHedgedReadMetrics **metrics)
     }
 
     jthr = invokeMethod(env, &jVal, INSTANCE, jFS,
-                  HADOOP_DFS,
+            JC_DISTRIBUTED_FILE_SYSTEM, "getHedgedReadMetrics",
-                  "getHedgedReadMetrics",
             "()Lorg/apache/hadoop/hdfs/DFSHedgedReadMetrics;");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -126,8 +109,7 @@ int hdfsGetHedgedReadMetrics(hdfsFS fs, struct hdfsHedgedReadMetrics **metrics)
     }
 
     jthr = invokeMethod(env, &jVal, INSTANCE, hedgedReadMetrics,
-                  "org/apache/hadoop/hdfs/DFSHedgedReadMetrics",
+            JC_DFS_HEDGED_READ_METRICS, "getHedgedReadOps", "()J");
-                  "getHedgedReadOps", "()J");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
             "hdfsGetHedgedReadStatistics: getHedgedReadOps failed");
@@ -136,8 +118,7 @@ int hdfsGetHedgedReadMetrics(hdfsFS fs, struct hdfsHedgedReadMetrics **metrics)
     m->hedgedReadOps = jVal.j;
 
     jthr = invokeMethod(env, &jVal, INSTANCE, hedgedReadMetrics,
-                  "org/apache/hadoop/hdfs/DFSHedgedReadMetrics",
+            JC_DFS_HEDGED_READ_METRICS, "getHedgedReadWins", "()J");
-                  "getHedgedReadWins", "()J");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
             "hdfsGetHedgedReadStatistics: getHedgedReadWins failed");
@@ -146,8 +127,7 @@ int hdfsGetHedgedReadMetrics(hdfsFS fs, struct hdfsHedgedReadMetrics **metrics)
     m->hedgedReadOpsWin = jVal.j;
 
     jthr = invokeMethod(env, &jVal, INSTANCE, hedgedReadMetrics,
-                  "org/apache/hadoop/hdfs/DFSHedgedReadMetrics",
+            JC_DFS_HEDGED_READ_METRICS, "getHedgedReadOpsInCurThread", "()J");
-                  "getHedgedReadOpsInCurThread", "()J");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
             "hdfsGetHedgedReadStatistics: getHedgedReadOpsInCurThread failed");
@@ -193,8 +173,7 @@ int hdfsFileGetReadStatistics(hdfsFile file,
         goto done;
     }
     jthr = invokeMethod(env, &jVal, INSTANCE, file->file,
-                  "org/apache/hadoop/hdfs/client/HdfsDataInputStream",
+            JC_HDFS_DATA_INPUT_STREAM, "getReadStatistics",
-                  "getReadStatistics",
             "()Lorg/apache/hadoop/hdfs/ReadStatistics;");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -208,8 +187,7 @@ int hdfsFileGetReadStatistics(hdfsFile file,
         goto done;
     }
     jthr = invokeMethod(env, &jVal, INSTANCE, readStats,
-                  "org/apache/hadoop/hdfs/ReadStatistics",
+            JC_READ_STATISTICS, "getTotalBytesRead", "()J");
-                  "getTotalBytesRead", "()J");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
             "hdfsFileGetReadStatistics: getTotalBytesRead failed");
@@ -218,8 +196,7 @@ int hdfsFileGetReadStatistics(hdfsFile file,
     s->totalBytesRead = jVal.j;
 
     jthr = invokeMethod(env, &jVal, INSTANCE, readStats,
-                  "org/apache/hadoop/hdfs/ReadStatistics",
+            JC_READ_STATISTICS, "getTotalLocalBytesRead", "()J");
-                  "getTotalLocalBytesRead", "()J");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
             "hdfsFileGetReadStatistics: getTotalLocalBytesRead failed");
@@ -228,8 +205,8 @@ int hdfsFileGetReadStatistics(hdfsFile file,
     s->totalLocalBytesRead = jVal.j;
 
     jthr = invokeMethod(env, &jVal, INSTANCE, readStats,
-                  "org/apache/hadoop/hdfs/ReadStatistics",
+            JC_READ_STATISTICS, "getTotalShortCircuitBytesRead",
-                  "getTotalShortCircuitBytesRead", "()J");
+            "()J");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
             "hdfsFileGetReadStatistics: getTotalShortCircuitBytesRead failed");
@@ -237,8 +214,8 @@ int hdfsFileGetReadStatistics(hdfsFile file,
     }
     s->totalShortCircuitBytesRead = jVal.j;
     jthr = invokeMethod(env, &jVal, INSTANCE, readStats,
-                  "org/apache/hadoop/hdfs/ReadStatistics",
+            JC_READ_STATISTICS, "getTotalZeroCopyBytesRead",
-                  "getTotalZeroCopyBytesRead", "()J");
+            "()J");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
             "hdfsFileGetReadStatistics: getTotalZeroCopyBytesRead failed");
@@ -280,8 +257,8 @@ int hdfsFileClearReadStatistics(hdfsFile file)
         goto done;
     }
     jthr = invokeMethod(env, NULL, INSTANCE, file->file,
-                  "org/apache/hadoop/hdfs/client/HdfsDataInputStream",
+            JC_HDFS_DATA_INPUT_STREAM, "clearReadStatistics",
-                  "clearReadStatistics", "()V");
+            "()V");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
             "hdfsFileClearReadStatistics: clearReadStatistics failed");
@@ -324,8 +301,7 @@ int hdfsDisableDomainSocketSecurity(void)
       errno = EINTERNAL;
       return -1;
     }
-    jthr = invokeMethod(env, NULL, STATIC, NULL,
+    jthr = invokeMethod(env, NULL, STATIC, NULL, JC_DOMAIN_SOCKET,
-            "org/apache/hadoop/net/unix/DomainSocket",
             "disableBindPathValidation", "()V");
     if (jthr) {
         errno = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -363,7 +339,7 @@ static jthrowable constructNewObjectOfPath(JNIEnv *env, const char *path,
     if (jthr)
         return jthr;
     //Construct the org.apache.hadoop.fs.Path object
-    jthr = constructNewObjectOfClass(env, &jPath, "org/apache/hadoop/fs/Path",
+    jthr = constructNewObjectOfCachedClass(env, &jPath, JC_PATH,
             "(Ljava/lang/String;)V", jPathString);
     destroyLocalReference(env, jPathString);
     if (jthr)
@@ -383,7 +359,7 @@ static jthrowable hadoopConfGetStr(JNIEnv *env, jobject jConfiguration,
     if (jthr)
         goto done;
     jthr = invokeMethod(env, &jVal, INSTANCE, jConfiguration,
-            HADOOP_CONF, "get", JMETHOD1(JPARAM(JAVA_STRING),
+            JC_CONFIGURATION, "get", JMETHOD1(JPARAM(JAVA_STRING),
                     JPARAM(JAVA_STRING)), jkey);
     if (jthr)
         goto done;
@@ -407,7 +383,8 @@ int hdfsConfGetStr(const char *key, char **val)
         ret = EINTERNAL;
         goto done;
     }
-    jthr = constructNewObjectOfClass(env, &jConfiguration, HADOOP_CONF, "()V");
+    jthr = constructNewObjectOfCachedClass(env, &jConfiguration,
+            JC_CONFIGURATION, "()V");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
             "hdfsConfGetStr(%s): new Configuration", key);
@@ -443,8 +420,8 @@ static jthrowable hadoopConfGetInt(JNIEnv *env, jobject jConfiguration,
     if (jthr)
         return jthr;
     jthr = invokeMethod(env, &jVal, INSTANCE, jConfiguration,
-            HADOOP_CONF, "getInt", JMETHOD2(JPARAM(JAVA_STRING), "I", "I"),
+            JC_CONFIGURATION, "getInt",
-            jkey, (jint)(*val));
+            JMETHOD2(JPARAM(JAVA_STRING), "I", "I"), jkey, (jint)(*val));
     destroyLocalReference(env, jkey);
     if (jthr)
         return jthr;
@@ -464,7 +441,8 @@ int hdfsConfGetInt(const char *key, int32_t *val)
       ret = EINTERNAL;
       goto done;
     }
-    jthr = constructNewObjectOfClass(env, &jConfiguration, HADOOP_CONF, "()V");
+    jthr = constructNewObjectOfCachedClass(env, &jConfiguration,
+            JC_CONFIGURATION, "()V");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
             "hdfsConfGetInt(%s): new Configuration", key);
@@ -697,7 +675,8 @@ hdfsFS hdfsBuilderConnect(struct hdfsBuilder *bld)
     }
 
     //  jConfiguration = new Configuration();
-    jthr = constructNewObjectOfClass(env, &jConfiguration, HADOOP_CONF, "()V");
+    jthr = constructNewObjectOfCachedClass(env, &jConfiguration,
+            JC_CONFIGURATION, "()V");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
             "hdfsBuilderConnect(%s)", hdfsBuilderToStr(bld, buf, sizeof(buf)));
@@ -719,9 +698,10 @@ hdfsFS hdfsBuilderConnect(struct hdfsBuilder *bld)
         // Get a local filesystem.
         if (bld->forceNewInstance) {
             // fs = FileSytem#newInstanceLocal(conf);
-            jthr = invokeMethod(env, &jVal, STATIC, NULL, HADOOP_FS,
+            jthr = invokeMethod(env, &jVal, STATIC, NULL,
-                    "newInstanceLocal", JMETHOD1(JPARAM(HADOOP_CONF),
+                    JC_FILE_SYSTEM, "newInstanceLocal",
-                    JPARAM(HADOOP_LOCALFS)), jConfiguration);
+                    JMETHOD1(JPARAM(HADOOP_CONF), JPARAM(HADOOP_LOCALFS)),
+                    jConfiguration);
             if (jthr) {
                 ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
                     "hdfsBuilderConnect(%s)",
@@ -731,9 +711,9 @@ hdfsFS hdfsBuilderConnect(struct hdfsBuilder *bld)
             jFS = jVal.l;
         } else {
             // fs = FileSytem#getLocal(conf);
-            jthr = invokeMethod(env, &jVal, STATIC, NULL, HADOOP_FS, "getLocal",
+            jthr = invokeMethod(env, &jVal, STATIC, NULL,
-                             JMETHOD1(JPARAM(HADOOP_CONF),
+                    JC_FILE_SYSTEM, "getLocal",
-                                      JPARAM(HADOOP_LOCALFS)),
+                    JMETHOD1(JPARAM(HADOOP_CONF), JPARAM(HADOOP_LOCALFS)),
                     jConfiguration);
             if (jthr) {
                 ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -746,8 +726,8 @@ hdfsFS hdfsBuilderConnect(struct hdfsBuilder *bld)
     } else {
         if (!strcmp(bld->nn, "default")) {
             // jURI = FileSystem.getDefaultUri(conf)
-            jthr = invokeMethod(env, &jVal, STATIC, NULL, HADOOP_FS,
+            jthr = invokeMethod(env, &jVal, STATIC, NULL,
-                          "getDefaultUri",
+                    JC_FILE_SYSTEM, "getDefaultUri",
                     "(Lorg/apache/hadoop/conf/Configuration;)Ljava/net/URI;",
                     jConfiguration);
             if (jthr) {
@@ -769,9 +749,9 @@ hdfsFS hdfsBuilderConnect(struct hdfsBuilder *bld)
                     hdfsBuilderToStr(bld, buf, sizeof(buf)));
                 goto done;
             }
-            jthr = invokeMethod(env, &jVal, STATIC, NULL, JAVA_NET_URI,
+            jthr = invokeMethod(env, &jVal, STATIC, NULL,
-                             "create", "(Ljava/lang/String;)Ljava/net/URI;",
+                    JC_URI, "create",
-                             jURIString);
+                    "(Ljava/lang/String;)Ljava/net/URI;", jURIString);
             if (jthr) {
                 ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
                     "hdfsBuilderConnect(%s)",
@@ -799,11 +779,11 @@ hdfsFS hdfsBuilderConnect(struct hdfsBuilder *bld)
             goto done;
         }
         if (bld->forceNewInstance) {
-            jthr = invokeMethod(env, &jVal, STATIC, NULL, HADOOP_FS,
+            jthr = invokeMethod(env, &jVal, STATIC, NULL,
-                    "newInstance", JMETHOD3(JPARAM(JAVA_NET_URI), 
+                    JC_FILE_SYSTEM, "newInstance",
-                        JPARAM(HADOOP_CONF), JPARAM(JAVA_STRING),
+                    JMETHOD3(JPARAM(JAVA_NET_URI), JPARAM(HADOOP_CONF),
-                        JPARAM(HADOOP_FS)),
+                             JPARAM(JAVA_STRING), JPARAM(HADOOP_FS)), jURI,
-                    jURI, jConfiguration, jUserString);
+                    jConfiguration, jUserString);
             if (jthr) {
                 ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
                     "hdfsBuilderConnect(%s)",
@@ -812,10 +792,11 @@ hdfsFS hdfsBuilderConnect(struct hdfsBuilder *bld)
             }
             jFS = jVal.l;
         } else {
-            jthr = invokeMethod(env, &jVal, STATIC, NULL, HADOOP_FS, "get",
+            jthr = invokeMethod(env, &jVal, STATIC, NULL,
+                    JC_FILE_SYSTEM, "get",
                     JMETHOD3(JPARAM(JAVA_NET_URI), JPARAM(HADOOP_CONF),
-                        JPARAM(JAVA_STRING), JPARAM(HADOOP_FS)),
+                            JPARAM(JAVA_STRING), JPARAM(HADOOP_FS)), jURI,
-                        jURI, jConfiguration, jUserString);
+                            jConfiguration, jUserString);
             if (jthr) {
                 ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
                     "hdfsBuilderConnect(%s)",
@@ -877,7 +858,7 @@ int hdfsDisconnect(hdfsFS fs)
         return -1;
     }
 
-    jthr = invokeMethod(env, NULL, INSTANCE, jFS, HADOOP_FS,
+    jthr = invokeMethod(env, NULL, INSTANCE, jFS, JC_FILE_SYSTEM,
             "close", "()V");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -909,8 +890,9 @@ static jthrowable getDefaultBlockSize(JNIEnv *env, jobject jFS,
     jthrowable jthr;
     jvalue jVal;
 
-    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, HADOOP_FS,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, JC_FILE_SYSTEM,
-                 "getDefaultBlockSize", JMETHOD1(JPARAM(HADOOP_PATH), "J"), jPath);
+            "getDefaultBlockSize", JMETHOD1(JPARAM(HADOOP_PATH),
+                    "J"), jPath);
     if (jthr)
         return jthr;
     *out = jVal.j;
@@ -1053,13 +1035,13 @@ static hdfsFile hdfsOpenFileImpl(hdfsFS fs, const char *path, int flags,
 
     if (accmode == O_RDONLY) {
         method = "open";
-        signature = JMETHOD2(JPARAM(HADOOP_PATH), "I", JPARAM(HADOOP_ISTRM));
+        signature = JMETHOD2(JPARAM(HADOOP_PATH), "I", JPARAM(HADOOP_FSDISTRM));
     } else if (flags & O_APPEND) {
         method = "append";
-	signature = JMETHOD1(JPARAM(HADOOP_PATH), JPARAM(HADOOP_OSTRM));
+        signature = JMETHOD1(JPARAM(HADOOP_PATH), JPARAM(HADOOP_FSDOSTRM));
     } else {
         method = "create";
-	signature = JMETHOD2(JPARAM(HADOOP_PATH), "ZISJ", JPARAM(HADOOP_OSTRM));
+        signature = JMETHOD2(JPARAM(HADOOP_PATH), "ZISJ", JPARAM(HADOOP_FSDOSTRM));
     }
 
     /* Create an object of org.apache.hadoop.fs.Path */
@@ -1071,7 +1053,7 @@ static hdfsFile hdfsOpenFileImpl(hdfsFS fs, const char *path, int flags,
     }
 
     /* Get the Configuration object from the FileSystem object */
-    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, HADOOP_FS,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, JC_FILE_SYSTEM,
             "getConf", JMETHOD1("", JPARAM(HADOOP_CONF)));
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -1093,8 +1075,8 @@ static hdfsFile hdfsOpenFileImpl(hdfsFS fs, const char *path, int flags,
 
     if (!bufferSize) {
         jthr = invokeMethod(env, &jVal, INSTANCE, jConfiguration,
-                         HADOOP_CONF, "getInt", "(Ljava/lang/String;I)I",
+                JC_CONFIGURATION, "getInt",
-                         jStrBufferSize, 4096);
+                "(Ljava/lang/String;I)I", jStrBufferSize, 4096);
         if (jthr) {
             ret = printExceptionAndFree(env, jthr, NOPRINT_EXC_FILE_NOT_FOUND |
                 NOPRINT_EXC_ACCESS_CONTROL | NOPRINT_EXC_UNRESOLVED_LINK,
@@ -1108,8 +1090,8 @@ static hdfsFile hdfsOpenFileImpl(hdfsFS fs, const char *path, int flags,
     if ((accmode == O_WRONLY) && (flags & O_APPEND) == 0) {
         if (!replication) {
             jthr = invokeMethod(env, &jVal, INSTANCE, jConfiguration,
-                             HADOOP_CONF, "getInt", "(Ljava/lang/String;I)I",
+                             JC_CONFIGURATION, "getInt",
-                             jStrReplication, 1);
+                             "(Ljava/lang/String;I)I", jStrReplication, 1);
             if (jthr) {
                 ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
                     "hdfsOpenFile(%s): Configuration#getInt(dfs.replication)",
@@ -1125,11 +1107,11 @@ static hdfsFile hdfsOpenFileImpl(hdfsFS fs, const char *path, int flags,
 
     // READ?
     if (accmode == O_RDONLY) {
-        jthr = invokeMethod(env, &jVal, INSTANCE, jFS, HADOOP_FS,
+        jthr = invokeMethod(env, &jVal, INSTANCE, jFS, JC_FILE_SYSTEM,
                 method, signature, jPath, jBufferSize);
     }  else if ((accmode == O_WRONLY) && (flags & O_APPEND)) {
         // WRITE/APPEND?
-       jthr = invokeMethod(env, &jVal, INSTANCE, jFS, HADOOP_FS,
+       jthr = invokeMethod(env, &jVal, INSTANCE, jFS, JC_FILE_SYSTEM,
                method, signature, jPath);
     } else {
         // WRITE/CREATE
@@ -1143,9 +1125,9 @@ static hdfsFile hdfsOpenFileImpl(hdfsFS fs, const char *path, int flags,
                 goto done;
             }
         }
-        jthr = invokeMethod(env, &jVal, INSTANCE, jFS, HADOOP_FS,
+        jthr = invokeMethod(env, &jVal, INSTANCE, jFS, JC_FILE_SYSTEM,
-                         method, signature, jPath, jOverWrite,
+                method, signature, jPath, jOverWrite, jBufferSize,
-                         jBufferSize, jReplication, jBlockSize);
+                jReplication, jBlockSize);
     }
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -1178,8 +1160,9 @@ static hdfsFile hdfsOpenFileImpl(hdfsFS fs, const char *path, int flags,
                                         "hdfsOpenFile(%s): newJavaStr", path);
             goto done;
         }
-        jthr = invokeMethod(env, &jVal, INSTANCE, jFile, HADOOP_ISTRM,
+        jthr = invokeMethod(env, &jVal, INSTANCE, jFile,
-                            "hasCapability", "(Ljava/lang/String;)Z", jCapabilityString);
+                JC_FS_DATA_INPUT_STREAM, "hasCapability",
+                "(Ljava/lang/String;)Z", jCapabilityString);
         if (jthr) {
             ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
                     "hdfsOpenFile(%s): FSDataInputStream#hasCapability", path);
@@ -1243,7 +1226,7 @@ int hdfsTruncateFile(hdfsFS fs, const char* path, tOffset newlength)
         return -1;
     }
 
-    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, HADOOP_FS,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, JC_FILE_SYSTEM,
             "truncate", JMETHOD2(JPARAM(HADOOP_PATH), "J", "Z"),
             jPath, newlength);
     destroyLocalReference(env, jPath);
@@ -1272,11 +1255,11 @@ int hdfsUnbufferFile(hdfsFile file)
         ret = ENOTSUP;
         goto done;
     }
-    jthr = invokeMethod(env, NULL, INSTANCE, file->file, HADOOP_ISTRM,
+    jthr = invokeMethod(env, NULL, INSTANCE, file->file,
-                     "unbuffer", "()V");
+            JC_FS_DATA_INPUT_STREAM, "unbuffer", "()V");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
-                HADOOP_ISTRM "#unbuffer failed:");
+                HADOOP_FSDISTRM "#unbuffer failed:");
         goto done;
     }
     ret = 0;
@@ -1293,7 +1276,7 @@ int hdfsCloseFile(hdfsFS fs, hdfsFile file)
     //  file.close 
 
     //The interface whose 'close' method to be called
-    const char *interface;
+    CachedJavaClass cachedJavaClass;
     const char *interfaceShortName;
 
     //Caught exception
@@ -1312,11 +1295,14 @@ int hdfsCloseFile(hdfsFS fs, hdfsFile file)
         return -1;
     }
 
-    interface = (file->type == HDFS_STREAM_INPUT) ?
+    if (file->type == HDFS_STREAM_INPUT) {
-        HADOOP_ISTRM : HADOOP_OSTRM;
+        cachedJavaClass = JC_FS_DATA_INPUT_STREAM;
+    } else {
+        cachedJavaClass = JC_FS_DATA_OUTPUT_STREAM;
+    }
   
-    jthr = invokeMethod(env, NULL, INSTANCE, file->file, interface,
+    jthr = invokeMethod(env, NULL, INSTANCE, file->file,
-                     "close", "()V");
+            cachedJavaClass, "close", "()V");
     if (jthr) {
         interfaceShortName = (file->type == HDFS_STREAM_INPUT) ? 
             "FSDataInputStream" : "FSDataOutputStream";
@@ -1360,7 +1346,7 @@ int hdfsExists(hdfsFS fs, const char *path)
             "hdfsExists: constructNewObjectOfPath");
         return -1;
     }
-    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, HADOOP_FS,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, JC_FILE_SYSTEM,
             "exists", JMETHOD1(JPARAM(HADOOP_PATH), "Z"), jPath);
     destroyLocalReference(env, jPath);
     if (jthr) {
@@ -1441,8 +1427,8 @@ tSize hdfsRead(hdfsFS fs, hdfsFile f, void* buffer, tSize length)
         return -1;
     }
 
-    jthr = invokeMethod(env, &jVal, INSTANCE, jInputStream, HADOOP_ISTRM,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jInputStream,
-                               "read", "([B)I", jbRarray);
+            JC_FS_DATA_INPUT_STREAM, "read", "([B)I", jbRarray);
     if (jthr) {
         destroyLocalReference(env, jbRarray);
         errno = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -1505,7 +1491,8 @@ tSize readDirect(hdfsFS fs, hdfsFile f, void* buffer, tSize length)
     }
 
     jthr = invokeMethod(env, &jVal, INSTANCE, jInputStream,
-        HADOOP_ISTRM, "read", "(Ljava/nio/ByteBuffer;)I", bb);
+            JC_FS_DATA_INPUT_STREAM, "read",
+            "(Ljava/nio/ByteBuffer;)I", bb);
     destroyLocalReference(env, bb);
     if (jthr) {
         errno = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -1556,8 +1543,9 @@ tSize hdfsPread(hdfsFS fs, hdfsFile f, tOffset position,
             "hdfsPread: NewByteArray");
         return -1;
     }
-    jthr = invokeMethod(env, &jVal, INSTANCE, f->file, HADOOP_ISTRM,
+    jthr = invokeMethod(env, &jVal, INSTANCE, f->file,
-                     "read", "(J[BII)I", position, jbRarray, 0, length);
+            JC_FS_DATA_INPUT_STREAM, "read", "(J[BII)I", position,
+            jbRarray, 0, length);
     if (jthr) {
         destroyLocalReference(env, jbRarray);
         errno = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -1642,7 +1630,8 @@ tSize hdfsWrite(hdfsFS fs, hdfsFile f, const void* buffer, tSize length)
         return -1;
     }
     jthr = invokeMethod(env, NULL, INSTANCE, jOutputStream,
-            HADOOP_OSTRM, "write", "([B)V", jbWarray);
+            JC_FS_DATA_OUTPUT_STREAM, "write", "([B)V",
+            jbWarray);
     destroyLocalReference(env, jbWarray);
     if (jthr) {
         errno = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -1677,7 +1666,7 @@ int hdfsSeek(hdfsFS fs, hdfsFile f, tOffset desiredPos)
 
     jInputStream = f->file;
     jthr = invokeMethod(env, NULL, INSTANCE, jInputStream,
-            HADOOP_ISTRM, "seek", "(J)V", desiredPos);
+            JC_FS_DATA_INPUT_STREAM, "seek", "(J)V", desiredPos);
     if (jthr) {
         errno = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
             "hdfsSeek(desiredPos=%" PRId64 ")"
@@ -1687,15 +1676,13 @@ int hdfsSeek(hdfsFS fs, hdfsFile f, tOffset desiredPos)
     return 0;
 }
 
-
-
 tOffset hdfsTell(hdfsFS fs, hdfsFile f)
 {
     // JAVA EQUIVALENT
     //  pos = f.getPos();
 
     jobject jStream;
-    const char *interface;
+    CachedJavaClass cachedJavaClass;
     jvalue jVal;
     jthrowable jthr;
 
@@ -1714,10 +1701,13 @@ tOffset hdfsTell(hdfsFS fs, hdfsFile f)
 
     //Parameters
     jStream = f->file;
-    interface = (f->type == HDFS_STREAM_INPUT) ?
+    if (f->type == HDFS_STREAM_INPUT) {
-        HADOOP_ISTRM : HADOOP_OSTRM;
+        cachedJavaClass = JC_FS_DATA_INPUT_STREAM;
+    } else {
+        cachedJavaClass = JC_FS_DATA_OUTPUT_STREAM;
+    }
     jthr = invokeMethod(env, &jVal, INSTANCE, jStream,
-                     interface, "getPos", "()J");
+            cachedJavaClass, "getPos", "()J");
     if (jthr) {
         errno = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
             "hdfsTell: %s#getPos",
@@ -1748,7 +1738,7 @@ int hdfsFlush(hdfsFS fs, hdfsFile f)
         return -1;
     }
     jthr = invokeMethod(env, NULL, INSTANCE, f->file,
-                     HADOOP_OSTRM, "flush", "()V");
+            JC_FS_DATA_OUTPUT_STREAM, "flush", "()V");
     if (jthr) {
         errno = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
             "hdfsFlush: FSDataInputStream#flush");
@@ -1777,7 +1767,7 @@ int hdfsHFlush(hdfsFS fs, hdfsFile f)
 
     jOutputStream = f->file;
     jthr = invokeMethod(env, NULL, INSTANCE, jOutputStream,
-                     HADOOP_OSTRM, "hflush", "()V");
+            JC_FS_DATA_OUTPUT_STREAM, "hflush", "()V");
     if (jthr) {
         errno = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
             "hdfsHFlush: FSDataOutputStream#hflush");
@@ -1806,7 +1796,7 @@ int hdfsHSync(hdfsFS fs, hdfsFile f)
 
     jOutputStream = f->file;
     jthr = invokeMethod(env, NULL, INSTANCE, jOutputStream,
-                     HADOOP_OSTRM, "hsync", "()V");
+            JC_FS_DATA_OUTPUT_STREAM, "hsync", "()V");
     if (jthr) {
         errno = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
             "hdfsHSync: FSDataOutputStream#hsync");
@@ -1840,7 +1830,7 @@ int hdfsAvailable(hdfsFS fs, hdfsFile f)
     //Parameters
     jInputStream = f->file;
     jthr = invokeMethod(env, &jVal, INSTANCE, jInputStream,
-                     HADOOP_ISTRM, "available", "()I");
+            JC_FS_DATA_INPUT_STREAM, "available", "()I");
     if (jthr) {
         errno = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
             "hdfsAvailable: FSDataInputStream#available");
@@ -1885,8 +1875,8 @@ static int hdfsCopyImpl(hdfsFS srcFS, const char *src, hdfsFS dstFS,
     }
 
     //Create the org.apache.hadoop.conf.Configuration object
-    jthr = constructNewObjectOfClass(env, &jConfiguration,
+    jthr = constructNewObjectOfCachedClass(env, &jConfiguration,
-                                     HADOOP_CONF, "()V");
+            JC_CONFIGURATION, "()V");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
             "hdfsCopyImpl: Configuration constructor");
@@ -1894,8 +1884,8 @@ static int hdfsCopyImpl(hdfsFS srcFS, const char *src, hdfsFS dstFS,
     }
 
     //FileUtil#copy
-    jthr = invokeMethod(env, &jVal, STATIC,
+    jthr = invokeMethod(env, &jVal, STATIC, NULL, JC_FILE_UTIL,
-            NULL, "org/apache/hadoop/fs/FileUtil", "copy",
+            "copy",
             "(Lorg/apache/hadoop/fs/FileSystem;Lorg/apache/hadoop/fs/Path;"
             "Lorg/apache/hadoop/fs/FileSystem;Lorg/apache/hadoop/fs/Path;"
             "ZLorg/apache/hadoop/conf/Configuration;)Z",
@@ -1961,9 +1951,9 @@ int hdfsDelete(hdfsFS fs, const char *path, int recursive)
         return -1;
     }
     jRecursive = recursive ? JNI_TRUE : JNI_FALSE;
-    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, HADOOP_FS,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, JC_FILE_SYSTEM,
-                     "delete", "(Lorg/apache/hadoop/fs/Path;Z)Z",
+            "delete", "(Lorg/apache/hadoop/fs/Path;Z)Z", jPath,
-                     jPath, jRecursive);
+            jRecursive);
     destroyLocalReference(env, jPath);
     if (jthr) {
         errno = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -2015,9 +2005,9 @@ int hdfsRename(hdfsFS fs, const char *oldPath, const char *newPath)
 
     // Rename the file
     // TODO: use rename2 here?  (See HDFS-3592)
-    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, HADOOP_FS, "rename",
+    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, JC_FILE_SYSTEM,
-                     JMETHOD2(JPARAM(HADOOP_PATH), JPARAM(HADOOP_PATH), "Z"),
+            "rename", JMETHOD2(JPARAM(HADOOP_PATH), JPARAM
-                     jOldPath, jNewPath);
+            (HADOOP_PATH), "Z"), jOldPath, jNewPath);
     if (jthr) {
         errno = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
             "hdfsRename(oldPath=%s, newPath=%s): FileSystem#rename",
@@ -2060,9 +2050,8 @@ char* hdfsGetWorkingDirectory(hdfsFS fs, char* buffer, size_t bufferSize)
     }
 
     //FileSystem#getWorkingDirectory()
-    jthr = invokeMethod(env, &jVal, INSTANCE, jFS,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, JC_FILE_SYSTEM,
-                     HADOOP_FS, "getWorkingDirectory",
+            "getWorkingDirectory", "()Lorg/apache/hadoop/fs/Path;");
-                     "()Lorg/apache/hadoop/fs/Path;");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
             "hdfsGetWorkingDirectory: FileSystem#getWorkingDirectory");
@@ -2077,8 +2066,7 @@ char* hdfsGetWorkingDirectory(hdfsFS fs, char* buffer, size_t bufferSize)
     }
 
     //Path#toString()
-    jthr = invokeMethod(env, &jVal, INSTANCE, jPath, 
+    jthr = invokeMethod(env, &jVal, INSTANCE, jPath, JC_PATH, "toString",
-                     "org/apache/hadoop/fs/Path", "toString",
             "()Ljava/lang/String;");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -2143,9 +2131,9 @@ int hdfsSetWorkingDirectory(hdfsFS fs, const char *path)
     }
 
     //FileSystem#setWorkingDirectory()
-    jthr = invokeMethod(env, NULL, INSTANCE, jFS, HADOOP_FS,
+    jthr = invokeMethod(env, NULL, INSTANCE, jFS, JC_FILE_SYSTEM,
-                     "setWorkingDirectory", 
+            "setWorkingDirectory", "(Lorg/apache/hadoop/fs/Path;)V",
-                     "(Lorg/apache/hadoop/fs/Path;)V", jPath);
+            jPath);
     destroyLocalReference(env, jPath);
     if (jthr) {
         errno = printExceptionAndFree(env, jthr, NOPRINT_EXC_ILLEGAL_ARGUMENT,
@@ -2185,9 +2173,8 @@ int hdfsCreateDirectory(hdfsFS fs, const char *path)
 
     //Create the directory
     jVal.z = 0;
-    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, HADOOP_FS,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, JC_FILE_SYSTEM,
-                     "mkdirs", "(Lorg/apache/hadoop/fs/Path;)Z",
+            "mkdirs", "(Lorg/apache/hadoop/fs/Path;)Z", jPath);
-                     jPath);
     destroyLocalReference(env, jPath);
     if (jthr) {
         errno = printExceptionAndFree(env, jthr,
@@ -2235,7 +2222,7 @@ int hdfsSetReplication(hdfsFS fs, const char *path, int16_t replication)
     }
 
     //Create the directory
-    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, HADOOP_FS,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, JC_FILE_SYSTEM,
             "setReplication", "(Lorg/apache/hadoop/fs/Path;S)Z",
             jPath, replication);
     destroyLocalReference(env, jPath);
@@ -2298,7 +2285,7 @@ int hdfsChown(hdfsFS fs, const char *path, const char *owner, const char *group)
     }
 
     //Create the directory
-    jthr = invokeMethod(env, NULL, INSTANCE, jFS, HADOOP_FS,
+    jthr = invokeMethod(env, NULL, INSTANCE, jFS, JC_FILE_SYSTEM,
             "setOwner", JMETHOD3(JPARAM(HADOOP_PATH),
                     JPARAM(JAVA_STRING), JPARAM(JAVA_STRING), JAVA_VOID),
             jPath, jOwner, jGroup);
@@ -2343,12 +2330,12 @@ int hdfsChmod(hdfsFS fs, const char *path, short mode)
     }
 
     // construct jPerm = FsPermission.createImmutable(short mode);
-    jthr = constructNewObjectOfClass(env, &jPermObj,
+    jthr = constructNewObjectOfCachedClass(env, &jPermObj, JC_FS_PERMISSION,
-                HADOOP_FSPERM,"(S)V",jmode);
+            "(S)V",jmode);
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
-            "constructNewObjectOfClass(%s)", HADOOP_FSPERM);
+            "constructNewObjectOfCachedClass(%s)", HADOOP_FSPERM);
-        return -1;
+        goto done;
     }
 
     //Create an object of org.apache.hadoop.fs.Path
@@ -2360,10 +2347,9 @@ int hdfsChmod(hdfsFS fs, const char *path, short mode)
     }
 
     //Create the directory
-    jthr = invokeMethod(env, NULL, INSTANCE, jFS, HADOOP_FS,
+    jthr = invokeMethod(env, NULL, INSTANCE, jFS, JC_FILE_SYSTEM,
-            "setPermission",
+            "setPermission", JMETHOD2(JPARAM(HADOOP_PATH),
-            JMETHOD2(JPARAM(HADOOP_PATH), JPARAM(HADOOP_FSPERM), JAVA_VOID),
+                    JPARAM(HADOOP_FSPERM), JAVA_VOID), jPath, jPermObj);
-            jPath, jPermObj);
     if (jthr) {
         ret = printExceptionAndFree(env, jthr,
             NOPRINT_EXC_ACCESS_CONTROL | NOPRINT_EXC_FILE_NOT_FOUND |
@@ -2413,9 +2399,9 @@ int hdfsUtime(hdfsFS fs, const char *path, tTime mtime, tTime atime)
     jmtime = (mtime == NO_CHANGE) ? -1 : (mtime * (jlong)1000);
     jatime = (atime == NO_CHANGE) ? -1 : (atime * (jlong)1000);
 
-    jthr = invokeMethod(env, NULL, INSTANCE, jFS, HADOOP_FS,
+    jthr = invokeMethod(env, NULL, INSTANCE, jFS, JC_FILE_SYSTEM,
-            "setTimes", JMETHOD3(JPARAM(HADOOP_PATH), "J", "J", JAVA_VOID),
+            "setTimes", JMETHOD3(JPARAM(HADOOP_PATH), "J", "J",
-            jPath, jmtime, jatime);
+                    JAVA_VOID), jPath, jmtime, jatime);
     destroyLocalReference(env, jPath);
     if (jthr) {
         errno = printExceptionAndFree(env, jthr,
@@ -2579,27 +2565,28 @@ static jthrowable hadoopRzOptionsGetEnumSet(JNIEnv *env,
         goto done;
     }
     if (opts->skipChecksums) {
-        jthr = fetchEnumInstance(env, READ_OPTION,
+        jthr = fetchEnumInstance(env, HADOOP_RO,
                   "SKIP_CHECKSUMS", &enumInst);
         if (jthr) {
             goto done;
         }
-        jthr = invokeMethod(env, &jVal, STATIC, NULL,
+        jthr = invokeMethod(env, &jVal, STATIC, NULL, JC_ENUM_SET,
-                "java/util/EnumSet", "of",
+                "of", "(Ljava/lang/Enum;)Ljava/util/EnumSet;", enumInst);
-                "(Ljava/lang/Enum;)Ljava/util/EnumSet;", enumInst);
         if (jthr) {
             goto done;
         }
         enumSetObj = jVal.l;
     } else {
-        jclass clazz = (*env)->FindClass(env, READ_OPTION);
+        jclass clazz = (*env)->FindClass(env, HADOOP_RO);
         if (!clazz) {
             jthr = getPendingExceptionAndClear(env);
             goto done;
         }
-        jthr = invokeMethod(env, &jVal, STATIC, NULL,
+        jthr = invokeMethod(env, &jVal, STATIC, NULL, JC_ENUM_SET,
-                "java/util/EnumSet", "noneOf",
+                "noneOf", "(Ljava/lang/Class;)Ljava/util/EnumSet;", clazz);
-                "(Ljava/lang/Class;)Ljava/util/EnumSet;", clazz);
+        if (jthr) {
+            goto done;
+        }
         enumSetObj = jVal.l;
     }
     // create global ref
@@ -2628,7 +2615,7 @@ static int hadoopReadZeroExtractBuffer(JNIEnv *env,
     jarray array = NULL;
 
     jthr = invokeMethod(env, &jVal, INSTANCE, buffer->byteBuffer,
-                     "java/nio/ByteBuffer", "remaining", "()I");
+            JC_BYTE_BUFFER, "remaining", "()I");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
                 "hadoopReadZeroExtractBuffer: ByteBuffer#remaining failed: ");
@@ -2636,7 +2623,7 @@ static int hadoopReadZeroExtractBuffer(JNIEnv *env,
     }
     buffer->length = jVal.i;
     jthr = invokeMethod(env, &jVal, INSTANCE, buffer->byteBuffer,
-                     "java/nio/ByteBuffer", "position", "()I");
+            JC_BYTE_BUFFER, "position", "()I");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
                 "hadoopReadZeroExtractBuffer: ByteBuffer#position failed: ");
@@ -2667,7 +2654,7 @@ static int hadoopReadZeroExtractBuffer(JNIEnv *env,
     }
     // Get the backing array object of this buffer.
     jthr = invokeMethod(env, &jVal, INSTANCE, buffer->byteBuffer,
-                     "java/nio/ByteBuffer", "array", "()[B");
+            JC_BYTE_BUFFER, "array", "()[B");
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
                 "hadoopReadZeroExtractBuffer: ByteBuffer#array failed: ");
@@ -2761,7 +2748,8 @@ struct hadoopRzBuffer* hadoopReadZero(hdfsFile file,
                 "hadoopReadZero: hadoopRzOptionsGetEnumSet failed: ");
         goto done;
     }
-    jthr = invokeMethod(env, &jVal, INSTANCE, file->file, HADOOP_ISTRM, "read",
+    jthr = invokeMethod(env, &jVal, INSTANCE, file->file,
+            JC_FS_DATA_INPUT_STREAM, "read",
             "(Lorg/apache/hadoop/io/ByteBufferPool;ILjava/util/EnumSet;)"
             "Ljava/nio/ByteBuffer;", opts->byteBufferPool, maxLength, enumSet);
     if (jthr) {
@@ -2826,7 +2814,7 @@ void hadoopRzBufferFree(hdfsFile file, struct hadoopRzBuffer *buffer)
     }
     if (buffer->byteBuffer) {
         jthr = invokeMethod(env, &jVal, INSTANCE, file->file,
-                    HADOOP_ISTRM, "releaseBuffer",
+                JC_FS_DATA_INPUT_STREAM, "releaseBuffer",
                 "(Ljava/nio/ByteBuffer;)V", buffer->byteBuffer);
         if (jthr) {
             printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -2876,8 +2864,8 @@ hdfsGetHosts(hdfsFS fs, const char *path, tOffset start, tOffset length)
             "hdfsGetHosts(path=%s): constructNewObjectOfPath", path);
         goto done;
     }
-    jthr = invokeMethod(env, &jFSVal, INSTANCE, jFS,
+    jthr = invokeMethod(env, &jFSVal, INSTANCE, jFS, JC_FILE_SYSTEM,
-            HADOOP_FS, "getFileStatus", "(Lorg/apache/hadoop/fs/Path;)"
+            "getFileStatus", "(Lorg/apache/hadoop/fs/Path;)"
             "Lorg/apache/hadoop/fs/FileStatus;", jPath);
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, NOPRINT_EXC_FILE_NOT_FOUND,
@@ -2889,11 +2877,11 @@ hdfsGetHosts(hdfsFS fs, const char *path, tOffset start, tOffset length)
     jFileStatus = jFSVal.l;
 
     //org.apache.hadoop.fs.FileSystem#getFileBlockLocations
-    jthr = invokeMethod(env, &jVal, INSTANCE, jFS,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, JC_FILE_SYSTEM,
-                     HADOOP_FS, "getFileBlockLocations", 
+            "getFileBlockLocations",
             "(Lorg/apache/hadoop/fs/FileStatus;JJ)"
-                     "[Lorg/apache/hadoop/fs/BlockLocation;",
+            "[Lorg/apache/hadoop/fs/BlockLocation;", jFileStatus, start,
-                     jFileStatus, start, length);
+            length);
     if (jthr) {
         ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
                 "hdfsGetHosts(path=%s, start=%"PRId64", length=%"PRId64"):"
@@ -2928,8 +2916,9 @@ hdfsGetHosts(hdfsFS fs, const char *path, tOffset start, tOffset length)
             goto done;
         }
         
-        jthr = invokeMethod(env, &jVal, INSTANCE, jFileBlock, HADOOP_BLK_LOC,
+        jthr = invokeMethod(env, &jVal, INSTANCE, jFileBlock,
-                         "getHosts", "()[Ljava/lang/String;");
+                JC_BLOCK_LOCATION, "getHosts",
+                "()[Ljava/lang/String;");
         if (jthr) {
             ret = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
                 "hdfsGetHosts(path=%s, start=%"PRId64", length=%"PRId64"):"
@@ -3034,7 +3023,7 @@ tOffset hdfsGetDefaultBlockSize(hdfsFS fs)
     }
 
     //FileSystem#getDefaultBlockSize()
-    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, HADOOP_FS,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, JC_FILE_SYSTEM,
             "getDefaultBlockSize", "()J");
     if (jthr) {
         errno = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -3098,7 +3087,7 @@ tOffset hdfsGetCapacity(hdfsFS fs)
     }
 
     //FileSystem#getStatus
-    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, HADOOP_FS,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, JC_FILE_SYSTEM,
             "getStatus", "()Lorg/apache/hadoop/fs/FsStatus;");
     if (jthr) {
         errno = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -3106,8 +3095,8 @@ tOffset hdfsGetCapacity(hdfsFS fs)
         return -1;
     }
     fss = (jobject)jVal.l;
-    jthr = invokeMethod(env, &jVal, INSTANCE, fss, HADOOP_FSSTATUS,
+    jthr = invokeMethod(env, &jVal, INSTANCE, fss,
-                     "getCapacity", "()J");
+            JC_FS_STATUS, "getCapacity", "()J");
     destroyLocalReference(env, fss);
     if (jthr) {
         errno = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -3138,7 +3127,7 @@ tOffset hdfsGetUsed(hdfsFS fs)
     }
 
     //FileSystem#getStatus
-    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, HADOOP_FS,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, JC_FILE_SYSTEM,
             "getStatus", "()Lorg/apache/hadoop/fs/FsStatus;");
     if (jthr) {
         errno = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -3146,8 +3135,8 @@ tOffset hdfsGetUsed(hdfsFS fs)
         return -1;
     }
     fss = (jobject)jVal.l;
-    jthr = invokeMethod(env, &jVal, INSTANCE, fss, HADOOP_FSSTATUS,
+    jthr = invokeMethod(env, &jVal, INSTANCE, fss, JC_FS_STATUS,
-                     "getUsed", "()J");
+            HADOOP_FSSTATUS,"getUsed", "()J");
     destroyLocalReference(env, fss);
     if (jthr) {
         errno = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -3205,45 +3194,45 @@ getFileInfoFromStat(JNIEnv *env, jobject jStat, hdfsFileInfo *fileInfo)
     struct hdfsExtendedFileInfo *extInfo;
     size_t extOffset;
 
-    jthr = invokeMethod(env, &jVal, INSTANCE, jStat,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jStat, JC_FILE_STATUS, "isDir",
-                     HADOOP_STAT, "isDir", "()Z");
+            "()Z");
     if (jthr)
         goto done;
     fileInfo->mKind = jVal.z ? kObjectKindDirectory : kObjectKindFile;
 
-    jthr = invokeMethod(env, &jVal, INSTANCE, jStat,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jStat, JC_FILE_STATUS,
-                     HADOOP_STAT, "getReplication", "()S");
+            "getReplication", "()S");
     if (jthr)
         goto done;
     fileInfo->mReplication = jVal.s;
 
-    jthr = invokeMethod(env, &jVal, INSTANCE, jStat,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jStat, JC_FILE_STATUS,
-                     HADOOP_STAT, "getBlockSize", "()J");
+            "getBlockSize", "()J");
     if (jthr)
         goto done;
     fileInfo->mBlockSize = jVal.j;
 
-    jthr = invokeMethod(env, &jVal, INSTANCE, jStat,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jStat, JC_FILE_STATUS,
-                     HADOOP_STAT, "getModificationTime", "()J");
+            "getModificationTime", "()J");
     if (jthr)
         goto done;
     fileInfo->mLastMod = jVal.j / 1000;
 
-    jthr = invokeMethod(env, &jVal, INSTANCE, jStat,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jStat, JC_FILE_STATUS,
-                     HADOOP_STAT, "getAccessTime", "()J");
+            "getAccessTime", "()J");
     if (jthr)
         goto done;
     fileInfo->mLastAccess = (tTime) (jVal.j / 1000);
 
     if (fileInfo->mKind == kObjectKindFile) {
-        jthr = invokeMethod(env, &jVal, INSTANCE, jStat,
+        jthr = invokeMethod(env, &jVal, INSTANCE, jStat, JC_FILE_STATUS,
-                         HADOOP_STAT, "getLen", "()J");
+                "getLen", "()J");
         if (jthr)
             goto done;
         fileInfo->mSize = jVal.j;
     }
 
-    jthr = invokeMethod(env, &jVal, INSTANCE, jStat, HADOOP_STAT,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jStat,  JC_FILE_STATUS,
             "getPath", "()Lorg/apache/hadoop/fs/Path;");
     if (jthr)
         goto done;
@@ -3254,8 +3243,8 @@ getFileInfoFromStat(JNIEnv *env, jobject jStat, hdfsFileInfo *fileInfo)
         goto done;
     }
 
-    jthr = invokeMethod(env, &jVal, INSTANCE, jPath, HADOOP_PATH,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jPath, JC_PATH, "toString",
-                     "toString", "()Ljava/lang/String;");
+            "()Ljava/lang/String;");
     if (jthr)
         goto done;
     jPathName = jVal.l;
@@ -3267,8 +3256,8 @@ getFileInfoFromStat(JNIEnv *env, jobject jStat, hdfsFileInfo *fileInfo)
     }
     fileInfo->mName = strdup(cPathName);
     (*env)->ReleaseStringUTFChars(env, jPathName, cPathName);
-    jthr = invokeMethod(env, &jVal, INSTANCE, jStat, HADOOP_STAT,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jStat, JC_FILE_STATUS, "getOwner",
-                    "getOwner", "()Ljava/lang/String;");
+            "()Ljava/lang/String;");
     if (jthr)
         goto done;
     jUserName = jVal.l;
@@ -3288,15 +3277,15 @@ getFileInfoFromStat(JNIEnv *env, jobject jStat, hdfsFileInfo *fileInfo)
     (*env)->ReleaseStringUTFChars(env, jUserName, cUserName);
     extInfo = getExtendedFileInfo(fileInfo);
     memset(extInfo, 0, sizeof(*extInfo));
-    jthr = invokeMethod(env, &jVal, INSTANCE, jStat,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jStat, JC_FILE_STATUS,
-                    HADOOP_STAT, "isEncrypted", "()Z");
+            "isEncrypted", "()Z");
     if (jthr) {
         goto done;
     }
     if (jVal.z == JNI_TRUE) {
         extInfo->flags |= HDFS_EXTENDED_FILE_INFO_ENCRYPTED;
     }
-    jthr = invokeMethod(env, &jVal, INSTANCE, jStat, HADOOP_STAT,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jStat, JC_FILE_STATUS,
             "getGroup", "()Ljava/lang/String;");
     if (jthr)
         goto done;
@@ -3309,19 +3298,19 @@ getFileInfoFromStat(JNIEnv *env, jobject jStat, hdfsFileInfo *fileInfo)
     fileInfo->mGroup = strdup(cGroupName);
     (*env)->ReleaseStringUTFChars(env, jGroupName, cGroupName);
 
-    jthr = invokeMethod(env, &jVal, INSTANCE, jStat, HADOOP_STAT,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jStat, JC_FILE_STATUS,
             "getPermission",
             "()Lorg/apache/hadoop/fs/permission/FsPermission;");
     if (jthr)
         goto done;
     if (jVal.l == NULL) {
         jthr = newRuntimeError(env, "%s#getPermission returned NULL!",
-            HADOOP_STAT);
+            HADOOP_FILESTAT);
         goto done;
     }
     jPermission = jVal.l;
-    jthr = invokeMethod(env, &jVal, INSTANCE, jPermission, HADOOP_FSPERM,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jPermission,
-                         "toShort", "()S");
+            JC_FS_PERMISSION, "toShort", "()S");
     if (jthr)
         goto done;
     fileInfo->mPermissions = jVal.s;
@@ -3355,18 +3344,17 @@ getFileInfo(JNIEnv *env, jobject jFS, jobject jPath, hdfsFileInfo **fileInfo)
     jvalue  jVal;
     jthrowable jthr;
 
-    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, HADOOP_FS,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, JC_FILE_SYSTEM, "exists",
-                     "exists", JMETHOD1(JPARAM(HADOOP_PATH), "Z"),
+            JMETHOD1(JPARAM(HADOOP_PATH), "Z"), jPath);
-                     jPath);
     if (jthr)
         return jthr;
     if (jVal.z == 0) {
         *fileInfo = NULL;
         return NULL;
     }
-    jthr = invokeMethod(env, &jVal, INSTANCE, jFS,
+    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, JC_FILE_SYSTEM,
-            HADOOP_FS, "getFileStatus",
+            "getFileStatus", JMETHOD1(JPARAM(HADOOP_PATH), JPARAM
-            JMETHOD1(JPARAM(HADOOP_PATH), JPARAM(HADOOP_STAT)), jPath);
+            (HADOOP_FILESTAT)), jPath);
     if (jthr)
         return jthr;
     jStat = jVal.l;
@@ -3416,9 +3404,9 @@ hdfsFileInfo* hdfsListDirectory(hdfsFS fs, const char *path, int *numEntries)
         goto done;
     }
 
-    jthr = invokeMethod(env, &jVal, INSTANCE, jFS, HADOOP_DFS, "listStatus",
+    jthr = invokeMethod(env, &jVal, INSTANCE, jFS,
-                     JMETHOD1(JPARAM(HADOOP_PATH), JARRPARAM(HADOOP_STAT)),
+            JC_DISTRIBUTED_FILE_SYSTEM, "listStatus",
-                     jPath);
+            JMETHOD1(JPARAM(HADOOP_PATH), JARRPARAM(HADOOP_FILESTAT)), jPath);
     if (jthr) {
         ret = printExceptionAndFree(env, jthr,
             NOPRINT_EXC_ACCESS_CONTROL | NOPRINT_EXC_FILE_NOT_FOUND |

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfs/jclasses.c

@@ -0,0 +1,136 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "exception.h"
+#include "jclasses.h"
+#include "jni_helper.h"
+#include "os/mutexes.h"
+
+#include <assert.h>
+
+/**
+ * Whether initCachedClasses has been called or not. Protected by the mutex
+ * jclassInitMutex.
+ */
+static int jclassesInitialized = 0;
+
+typedef struct {
+    jclass javaClass;
+    const char *className;
+} javaClassAndName;
+
+/**
+ * A collection of commonly used jclass objects that are used throughout
+ * libhdfs. The jclasses are loaded immediately after the JVM is created (see
+ * initCachedClasses). The array is indexed using CachedJavaClass.
+ */
+javaClassAndName cachedJavaClasses[NUM_CACHED_CLASSES];
+
+/**
+ * Helper method that creates and sets a jclass object given a class name.
+ * Returns a jthrowable on error, NULL otherwise.
+ */
+static jthrowable initCachedClass(JNIEnv *env, const char *className,
+        jclass *cachedJclass) {
+    assert(className != NULL && "Found a CachedJavaClass without a class "
+                                "name");
+    jthrowable jthr = NULL;
+    jclass tempLocalClassRef;
+    tempLocalClassRef = (*env)->FindClass(env, className);
+    if (!tempLocalClassRef) {
+        jthr = getPendingExceptionAndClear(env);
+        goto done;
+    }
+    *cachedJclass = (jclass) (*env)->NewGlobalRef(env, tempLocalClassRef);
+    if (!*cachedJclass) {
+        jthr = getPendingExceptionAndClear(env);
+        goto done;
+    }
+done:
+    destroyLocalReference(env, tempLocalClassRef);
+    return jthr;
+}
+
+jthrowable initCachedClasses(JNIEnv* env) {
+    mutexLock(&jclassInitMutex);
+    if (!jclassesInitialized) {
+        // Set all the class names
+        cachedJavaClasses[JC_CONFIGURATION].className =
+                "org/apache/hadoop/conf/Configuration";
+        cachedJavaClasses[JC_PATH].className =
+                "org/apache/hadoop/fs/Path";
+        cachedJavaClasses[JC_FILE_SYSTEM].className =
+                "org/apache/hadoop/fs/FileSystem";
+        cachedJavaClasses[JC_FS_STATUS].className =
+                "org/apache/hadoop/fs/FsStatus";
+        cachedJavaClasses[JC_FILE_UTIL].className =
+                "org/apache/hadoop/fs/FileUtil";
+        cachedJavaClasses[JC_BLOCK_LOCATION].className =
+                "org/apache/hadoop/fs/BlockLocation";
+        cachedJavaClasses[JC_DFS_HEDGED_READ_METRICS].className =
+                "org/apache/hadoop/hdfs/DFSHedgedReadMetrics";
+        cachedJavaClasses[JC_DISTRIBUTED_FILE_SYSTEM].className =
+                "org/apache/hadoop/hdfs/DistributedFileSystem";
+        cachedJavaClasses[JC_FS_DATA_INPUT_STREAM].className =
+                "org/apache/hadoop/fs/FSDataInputStream";
+        cachedJavaClasses[JC_FS_DATA_OUTPUT_STREAM].className =
+                "org/apache/hadoop/fs/FSDataOutputStream";
+        cachedJavaClasses[JC_FILE_STATUS].className =
+                "org/apache/hadoop/fs/FileStatus";
+        cachedJavaClasses[JC_FS_PERMISSION].className =
+                "org/apache/hadoop/fs/permission/FsPermission";
+        cachedJavaClasses[JC_READ_STATISTICS].className =
+                "org/apache/hadoop/hdfs/ReadStatistics";
+        cachedJavaClasses[JC_HDFS_DATA_INPUT_STREAM].className =
+                "org/apache/hadoop/hdfs/client/HdfsDataInputStream";
+        cachedJavaClasses[JC_DOMAIN_SOCKET].className =
+                "org/apache/hadoop/net/unix/DomainSocket";
+        cachedJavaClasses[JC_URI].className =
+                "java/net/URI";
+        cachedJavaClasses[JC_BYTE_BUFFER].className =
+                "java/nio/ByteBuffer";
+        cachedJavaClasses[JC_ENUM_SET].className =
+                "java/util/EnumSet";
+        cachedJavaClasses[JC_EXCEPTION_UTILS].className =
+                "org/apache/commons/lang3/exception/ExceptionUtils";
+
+        // Create and set the jclass objects based on the class names set above
+        jthrowable jthr;
+        int numCachedClasses =
+                sizeof(cachedJavaClasses) / sizeof(javaClassAndName);
+        for (int i = 0; i < numCachedClasses; i++) {
+            jthr = initCachedClass(env, cachedJavaClasses[i].className,
+                                   &cachedJavaClasses[i].javaClass);
+            if (jthr) {
+                mutexUnlock(&jclassInitMutex);
+                return jthr;
+            }
+        }
+        jclassesInitialized = 1;
+    }
+    mutexUnlock(&jclassInitMutex);
+    return NULL;
+}
+
+jclass getJclass(CachedJavaClass cachedJavaClass) {
+    return cachedJavaClasses[cachedJavaClass].javaClass;
+}
+
+const char *getClassName(CachedJavaClass cachedJavaClass) {
+    return cachedJavaClasses[cachedJavaClass].className;
+}

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfs/jclasses.h

@@ -0,0 +1,112 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef LIBHDFS_JCLASSES_H
+#define LIBHDFS_JCLASSES_H
+
+#include <jni.h>
+
+/**
+ * Encapsulates logic to cache jclass objects so they can re-used across
+ * calls to FindClass. Creating jclass objects every time libhdfs has to
+ * invoke a method can hurt performance. By cacheing jclass objects we avoid
+ * this overhead.
+ *
+ * We use the term "cached" here loosely; jclasses are not truly cached,
+ * instead they are created once during JVM load and are kept alive until the
+ * process shutdowns. There is no eviction of jclass objects.
+ *
+ * @see https://www.ibm.com/developerworks/library/j-jni/index.html#notc
+ */
+
+/**
+ * Each enum value represents one jclass that is cached. Enum values should
+ * be passed to getJclass or getName to get the jclass object or class name
+ * represented by the enum value.
+ */
+typedef enum {
+    JC_CONFIGURATION,
+    JC_PATH,
+    JC_FILE_SYSTEM,
+    JC_FS_STATUS,
+    JC_FILE_UTIL,
+    JC_BLOCK_LOCATION,
+    JC_DFS_HEDGED_READ_METRICS,
+    JC_DISTRIBUTED_FILE_SYSTEM,
+    JC_FS_DATA_INPUT_STREAM,
+    JC_FS_DATA_OUTPUT_STREAM,
+    JC_FILE_STATUS,
+    JC_FS_PERMISSION,
+    JC_READ_STATISTICS,
+    JC_HDFS_DATA_INPUT_STREAM,
+    JC_DOMAIN_SOCKET,
+    JC_URI,
+    JC_BYTE_BUFFER,
+    JC_ENUM_SET,
+    JC_EXCEPTION_UTILS,
+    // A special marker enum that counts the number of cached jclasses
+    NUM_CACHED_CLASSES
+} CachedJavaClass;
+
+/**
+ * Internally initializes all jclass objects listed in the CachedJavaClass
+ * enum. This method is idempotent and thread-safe.
+ */
+jthrowable initCachedClasses(JNIEnv* env);
+
+/**
+ * Return the jclass object represented by the given CachedJavaClass
+ */
+jclass getJclass(CachedJavaClass cachedJavaClass);
+
+/**
+ * Return the class name represented by the given CachedJavaClass
+ */
+const char *getClassName(CachedJavaClass cachedJavaClass);
+
+/* Some frequently used HDFS class names */
+#define HADOOP_CONF     "org/apache/hadoop/conf/Configuration"
+#define HADOOP_PATH     "org/apache/hadoop/fs/Path"
+#define HADOOP_LOCALFS  "org/apache/hadoop/fs/LocalFileSystem"
+#define HADOOP_FS       "org/apache/hadoop/fs/FileSystem"
+#define HADOOP_FSSTATUS "org/apache/hadoop/fs/FsStatus"
+#define HADOOP_FILEUTIL "org/apache/hadoop/fs/FileUtil"
+#define HADOOP_BLK_LOC  "org/apache/hadoop/fs/BlockLocation"
+#define HADOOP_DFS_HRM  "org/apache/hadoop/hdfs/DFSHedgedReadMetrics"
+#define HADOOP_DFS      "org/apache/hadoop/hdfs/DistributedFileSystem"
+#define HADOOP_FSDISTRM "org/apache/hadoop/fs/FSDataInputStream"
+#define HADOOP_FSDOSTRM "org/apache/hadoop/fs/FSDataOutputStream"
+#define HADOOP_FILESTAT "org/apache/hadoop/fs/FileStatus"
+#define HADOOP_FSPERM   "org/apache/hadoop/fs/permission/FsPermission"
+#define HADOOP_RSTAT    "org/apache/hadoop/hdfs/ReadStatistics"
+#define HADOOP_HDISTRM  "org/apache/hadoop/hdfs/client/HdfsDataInputStream"
+#define HADOOP_RO       "org/apache/hadoop/fs/ReadOption"
+#define HADOOP_DS       "org/apache/hadoop/net/unix/DomainSocket"
+
+/* Some frequently used Java class names */
+#define JAVA_NET_ISA    "java/net/InetSocketAddress"
+#define JAVA_NET_URI    "java/net/URI"
+#define JAVA_BYTEBUFFER "java/nio/ByteBuffer"
+#define JAVA_STRING     "java/lang/String"
+#define JAVA_ENUMSET    "java/util/EnumSet"
+
+/* Some frequently used third-party class names */
+
+#define EXCEPTION_UTILS "org/apache/commons/lang3/exception/ExceptionUtils"
+
+#endif /*LIBHDFS_JCLASSES_H*/

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfs/jni_helper.c

@@ -18,17 +18,15 @@
 
 #include "config.h"
 #include "exception.h"
+#include "jclasses.h"
 #include "jni_helper.h"
 #include "platform.h"
-#include "common/htable.h"
 #include "os/mutexes.h"
 #include "os/thread_local_storage.h"
 
 #include <stdio.h> 
 #include <string.h> 
 
-static struct htable *gClassRefHTable = NULL;
-
 /** The Native return types that methods could return */
 #define JVOID         'V'
 #define JOBJECT       'L'
@@ -42,13 +40,6 @@ static struct htable *gClassRefHTable = NULL;
 #define JFLOAT        'F'
 #define JDOUBLE       'D'
 
-
-/**
- * MAX_HASH_TABLE_ELEM: The maximum no. of entries in the hashtable.
- * It's set to 4096 to account for (classNames + No. of threads)
- */
-#define MAX_HASH_TABLE_ELEM 4096
-
 /**
  * Length of buffer for retrieving created JVMs.  (We only ever create one.)
  */
@@ -106,32 +97,27 @@ jthrowable newCStr(JNIEnv *env, jstring jstr, char **out)
     return NULL;
 }
 
-jthrowable invokeMethod(JNIEnv *env, jvalue *retval, MethType methType,
+/**
-                 jobject instObj, const char *className,
+ * Does the work to actually execute a Java method. Takes in an existing jclass
-                 const char *methName, const char *methSignature, ...)
+ * object and a va_list of arguments for the Java method to be invoked.
+ */
+static jthrowable invokeMethodOnJclass(JNIEnv *env, jvalue *retval,
+        MethType methType, jobject instObj, jclass cls, const char *className,
+        const char *methName, const char *methSignature, va_list args)
 {
-    va_list args;
-    jclass cls;
     jmethodID mid;
     jthrowable jthr;
     const char *str;
     char returnType;
 
-    jthr = validateMethodType(env, methType);
+    jthr = methodIdFromClass(cls, className, methName, methSignature, methType,
-    if (jthr)
+                             env, &mid);
-        return jthr;
-    jthr = globalClassReference(className, env, &cls);
-    if (jthr)
-        return jthr;
-    jthr = methodIdFromClass(className, methName, methSignature, 
-                            methType, env, &mid);
     if (jthr)
         return jthr;
     str = methSignature;
     while (*str != ')') str++;
     str++;
     returnType = *str;
-    va_start(args, methSignature);
     if (returnType == JOBJECT || returnType == JARRAYOBJECT) {
         jobject jobj = NULL;
         if (methType == STATIC) {
@@ -190,7 +176,6 @@ jthrowable invokeMethod(JNIEnv *env, jvalue *retval, MethType methType,
         }
         retval->i = ji;
     }
-    va_end(args);
 
     jthr = (*env)->ExceptionOccurred(env);
     if (jthr) {
@@ -200,43 +185,115 @@ jthrowable invokeMethod(JNIEnv *env, jvalue *retval, MethType methType,
     return NULL;
 }
 
-jthrowable constructNewObjectOfClass(JNIEnv *env, jobject *out, const char *className, 
+jthrowable findClassAndInvokeMethod(JNIEnv *env, jvalue *retval,
-                                  const char *ctorSignature, ...)
+        MethType methType, jobject instObj, const char *className,
+        const char *methName, const char *methSignature, ...)
 {
+    jclass cls = NULL;
+    jthrowable jthr = NULL;
+
     va_list args;
-    jclass cls;
+    va_start(args, methSignature);
+
+    jthr = validateMethodType(env, methType);
+    if (jthr) {
+        goto done;
+    }
+
+    cls = (*env)->FindClass(env, className);
+    if (!cls) {
+        jthr = getPendingExceptionAndClear(env);
+        goto done;
+    }
+
+    jthr = invokeMethodOnJclass(env, retval, methType, instObj, cls,
+            className, methName, methSignature, args);
+
+done:
+    va_end(args);
+    destroyLocalReference(env, cls);
+    return jthr;
+}
+
+jthrowable invokeMethod(JNIEnv *env, jvalue *retval, MethType methType,
+        jobject instObj, CachedJavaClass class,
+        const char *methName, const char *methSignature, ...)
+{
+    jthrowable jthr;
+
+    va_list args;
+    va_start(args, methSignature);
+
+    jthr = invokeMethodOnJclass(env, retval, methType, instObj,
+            getJclass(class), getClassName(class), methName, methSignature,
+            args);
+
+    va_end(args);
+    return jthr;
+}
+
+static jthrowable constructNewObjectOfJclass(JNIEnv *env,
+        jobject *out, jclass cls, const char *className,
+                const char *ctorSignature, va_list args) {
     jmethodID mid;
     jobject jobj;
     jthrowable jthr;
 
-    jthr = globalClassReference(className, env, &cls);
+    jthr = methodIdFromClass(cls, className, "<init>", ctorSignature, INSTANCE,
+            env, &mid);
     if (jthr)
         return jthr;
-    jthr = methodIdFromClass(className, "<init>", ctorSignature, 
-                            INSTANCE, env, &mid);
-    if (jthr)
-        return jthr;
-    va_start(args, ctorSignature);
     jobj = (*env)->NewObjectV(env, cls, mid, args);
-    va_end(args);
     if (!jobj)
         return getPendingExceptionAndClear(env);
     *out = jobj;
     return NULL;
 }
 
+jthrowable constructNewObjectOfClass(JNIEnv *env, jobject *out,
+        const char *className, const char *ctorSignature, ...)
+{
+    va_list args;
+    jclass cls;
+    jthrowable jthr = NULL;
 
-jthrowable methodIdFromClass(const char *className, const char *methName, 
+    cls = (*env)->FindClass(env, className);
-                            const char *methSignature, MethType methType, 
+    if (!cls) {
+        jthr = getPendingExceptionAndClear(env);
+        goto done;
+    }
+
+    va_start(args, ctorSignature);
+    jthr = constructNewObjectOfJclass(env, out, cls, className,
+            ctorSignature, args);
+    va_end(args);
+done:
+    destroyLocalReference(env, cls);
+    return jthr;
+}
+
+jthrowable constructNewObjectOfCachedClass(JNIEnv *env, jobject *out,
+        CachedJavaClass cachedJavaClass, const char *ctorSignature, ...)
+{
+    jthrowable jthr = NULL;
+    va_list args;
+    va_start(args, ctorSignature);
+
+    jthr = constructNewObjectOfJclass(env, out,
+            getJclass(cachedJavaClass), getClassName(cachedJavaClass),
+            ctorSignature, args);
+
+    va_end(args);
+    return jthr;
+}
+
+jthrowable methodIdFromClass(jclass cls, const char *className,
+        const char *methName, const char *methSignature, MethType methType,
         JNIEnv *env, jmethodID *out)
 {
-    jclass cls;
     jthrowable jthr;
     jmethodID mid = 0;
 
-    jthr = globalClassReference(className, env, &cls);
-    if (jthr)
-        return jthr;
     jthr = validateMethodType(env, methType);
     if (jthr)
         return jthr;
@@ -255,54 +312,6 @@ jthrowable methodIdFromClass(const char *className, const char *methName,
     return NULL;
 }
 
-jthrowable globalClassReference(const char *className, JNIEnv *env, jclass *out)
-{
-    jthrowable jthr = NULL;
-    jclass local_clazz = NULL;
-    jclass clazz = NULL;
-    int ret;
-
-    mutexLock(&hdfsHashMutex);
-    if (!gClassRefHTable) {
-        gClassRefHTable = htable_alloc(MAX_HASH_TABLE_ELEM, ht_hash_string,
-            ht_compare_string);
-        if (!gClassRefHTable) {
-            jthr = newRuntimeError(env, "htable_alloc failed\n");
-            goto done;
-        }
-    }
-    clazz = htable_get(gClassRefHTable, className);
-    if (clazz) {
-        *out = clazz;
-        goto done;
-    }
-    local_clazz = (*env)->FindClass(env,className);
-    if (!local_clazz) {
-        jthr = getPendingExceptionAndClear(env);
-        goto done;
-    }
-    clazz = (*env)->NewGlobalRef(env, local_clazz);
-    if (!clazz) {
-        jthr = getPendingExceptionAndClear(env);
-        goto done;
-    }
-    ret = htable_put(gClassRefHTable, (void*)className, clazz);
-    if (ret) {
-        jthr = newRuntimeError(env, "htable_put failed with error "
-                               "code %d\n", ret);
-        goto done;
-    }
-    *out = clazz;
-    jthr = NULL;
-done:
-    mutexUnlock(&hdfsHashMutex);
-    (*env)->DeleteLocalRef(env, local_clazz);
-    if (jthr && clazz) {
-        (*env)->DeleteGlobalRef(env, clazz);
-    }
-    return jthr;
-}
-
 jthrowable classNameOfObject(jobject jobj, JNIEnv *env, char **name)
 {
     jthrowable jthr;
@@ -361,7 +370,6 @@ done:
     return jthr;
 }
 
-
 /**
  * Get the global JNI environemnt.
  *
@@ -461,14 +469,17 @@ static JNIEnv* getGlobalJNIEnv(void)
                     "with error: %d\n", rv);
             return NULL;
         }
-        jthr = invokeMethod(env, NULL, STATIC, NULL,
+
-                         "org/apache/hadoop/fs/FileSystem",
+        // We use findClassAndInvokeMethod here because the jclasses in
+        // jclasses.h have not loaded yet
+        jthr = findClassAndInvokeMethod(env, NULL, STATIC, NULL, HADOOP_FS,
                 "loadFileSystems", "()V");
         if (jthr) {
-            printExceptionAndFree(env, jthr, PRINT_EXC_ALL, "loadFileSystems");
+            printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
+                    "FileSystem: loadFileSystems failed");
+            return NULL;
         }
-    }
+    } else {
-    else {
         //Attach this thread to the VM
         vm = vmBuf[0];
         rv = (*vm)->AttachCurrentThread(vm, (void*)&env, 0);
@@ -539,6 +550,15 @@ JNIEnv* getJNIEnv(void)
 
     state->env = getGlobalJNIEnv();
     mutexUnlock(&jvmMutex);
+
+    jthrowable jthr = NULL;
+    jthr = initCachedClasses(state->env);
+    if (jthr) {
+      printExceptionAndFree(state->env, jthr, PRINT_EXC_ALL,
+                            "initCachedClasses failed");
+      goto fail;
+    }
+
     if (!state->env) {
       goto fail;
     }
@@ -628,8 +648,7 @@ jthrowable hadoopConfSetStr(JNIEnv *env, jobject jConfiguration,
     if (jthr)
         goto done;
     jthr = invokeMethod(env, NULL, INSTANCE, jConfiguration,
-            "org/apache/hadoop/conf/Configuration", "set", 
+            JC_CONFIGURATION, "set", "(Ljava/lang/String;Ljava/lang/String;)V",
-            "(Ljava/lang/String;Ljava/lang/String;)V",
             jkey, jvalue);
     if (jthr)
         goto done;

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfs/jni_helper.h

@@ -19,6 +19,8 @@
 #ifndef LIBHDFS_JNI_HELPER_H
 #define LIBHDFS_JNI_HELPER_H
 
+#include "jclasses.h"
+
 #include <jni.h>
 #include <stdio.h>
 
@@ -28,7 +30,6 @@
 
 #define PATH_SEPARATOR ':'
 
-
 /** Denote the method we want to invoke as STATIC or INSTANCE */
 typedef enum {
     STATIC,
@@ -66,12 +67,12 @@ jthrowable newJavaStr(JNIEnv *env, const char *str, jstring *out);
 void destroyLocalReference(JNIEnv *env, jobject jObject);
 
 /** invokeMethod: Invoke a Static or Instance method.
- * className: Name of the class where the method can be found
  * methName: Name of the method
  * methSignature: the signature of the method "(arg-types)ret-type"
  * methType: The type of the method (STATIC or INSTANCE)
  * instObj: Required if the methType is INSTANCE. The object to invoke
    the method on.
+ * class: The CachedJavaClass to call the method on.
  * env: The JNIEnv pointer
  * retval: The pointer to a union type which will contain the result of the
    method invocation, e.g. if the method returns an Object, retval will be
@@ -83,18 +84,34 @@ void destroyLocalReference(JNIEnv *env, jobject jObject);
    a valid exception reference, and the result stored at retval is undefined.
  */
 jthrowable invokeMethod(JNIEnv *env, jvalue *retval, MethType methType,
-                 jobject instObj, const char *className, const char *methName, 
+        jobject instObj, CachedJavaClass class,
-                 const char *methSignature, ...);
+        const char *methName, const char *methSignature, ...);
 
-jthrowable constructNewObjectOfClass(JNIEnv *env, jobject *out, const char *className, 
+/**
-                                  const char *ctorSignature, ...);
+ * findClassAndInvokeMethod: Same as invokeMethod, but it calls FindClass on
+ * the given className first and then calls invokeMethod. This method exists
+ * mainly for test infrastructure, any production code should use
+ * invokeMethod. Calling FindClass repeatedly can introduce performance
+ * overhead, so users should prefer invokeMethod and supply a CachedJavaClass.
+ */
+jthrowable findClassAndInvokeMethod(JNIEnv *env, jvalue *retval,
+        MethType methType, jobject instObj, const char *className,
+        const char *methName, const char *methSignature, ...);
 
-jthrowable methodIdFromClass(const char *className, const char *methName, 
+jthrowable constructNewObjectOfClass(JNIEnv *env, jobject *out,
-                            const char *methSignature, MethType methType, 
+        const char *className, const char *ctorSignature, ...);
+
+/**
+ * Same as constructNewObjectOfClass but it takes in a CachedJavaClass
+ * rather than a className. This avoids an extra call to FindClass.
+ */
+jthrowable constructNewObjectOfCachedClass(JNIEnv *env, jobject *out,
+        CachedJavaClass cachedJavaClass, const char *ctorSignature, ...);
+
+jthrowable methodIdFromClass(jclass cls, const char *className,
+        const char *methName, const char *methSignature, MethType methType,
         JNIEnv *env, jmethodID *out);
 
-jthrowable globalClassReference(const char *className, JNIEnv *env, jclass *out);
-
 /** classNameOfObject: Get an object's class name.
  * @param jobj: The object.
  * @param env: The JNIEnv pointer.

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfs/os/mutexes.h

@@ -30,12 +30,12 @@
 
 #include "platform.h"
 
-/** Mutex protecting the class reference hash table. */
-extern mutex hdfsHashMutex;
-
 /** Mutex protecting singleton JVM instance. */
 extern mutex jvmMutex;
 
+/** Mutex protecting initialization of jclasses in jclasses.h. */
+extern mutex jclassInitMutex;
+
 /**
  * Locks a mutex.
  *

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfs/os/posix/mutexes.c

@@ -21,8 +21,8 @@
 #include <pthread.h>
 #include <stdio.h>
 
-mutex hdfsHashMutex = PTHREAD_MUTEX_INITIALIZER;
 mutex jvmMutex;
+mutex jclassInitMutex = PTHREAD_MUTEX_INITIALIZER;
 pthread_mutexattr_t jvmMutexAttr;
 
 __attribute__((constructor)) static void init() {

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfs/os/posix/thread_local_storage.c

@@ -97,7 +97,7 @@ static void get_current_thread_id(JNIEnv* env, char* id, int max) {
   jthrowable jthr = NULL;
   const char *thr_name_str;
 
-  jthr = invokeMethod(env, &jVal, STATIC, NULL, "java/lang/Thread",
+  jthr = findClassAndInvokeMethod(env, &jVal, STATIC, NULL, "java/lang/Thread",
           "currentThread", "()Ljava/lang/Thread;");
   if (jthr) {
     snprintf(id, max, "%s", UNKNOWN);
@@ -107,8 +107,8 @@ static void get_current_thread_id(JNIEnv* env, char* id, int max) {
   }
   thr = jVal.l;
 
-  jthr = invokeMethod(env, &jVal, INSTANCE, thr, "java/lang/Thread",
+  jthr = findClassAndInvokeMethod(env, &jVal, INSTANCE, thr,
-                      "getId", "()J");
+          "java/lang/Thread", "getId", "()J");
   if (jthr) {
     snprintf(id, max, "%s", UNKNOWN);
     printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
@@ -117,8 +117,8 @@ static void get_current_thread_id(JNIEnv* env, char* id, int max) {
   }
   thr_id = jVal.j;
 
-  jthr = invokeMethod(env, &jVal, INSTANCE, thr, "java/lang/Thread",
+  jthr = findClassAndInvokeMethod(env, &jVal, INSTANCE, thr,
-                      "toString", "()Ljava/lang/String;");
+          "java/lang/Thread", "toString", "()Ljava/lang/String;");
   if (jthr) {
     snprintf(id, max, "%s:%ld", UNKNOWN, thr_id);
     printExceptionAndFree(env, jthr, PRINT_EXC_ALL,

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfs/os/windows/mutexes.c

@@ -20,8 +20,8 @@
 
 #include <windows.h>
 
-mutex hdfsHashMutex;
 mutex jvmMutex;
+mutex jclassInitMutex;
 
 /**
  * Unfortunately, there is no simple static initializer for a critical section.
@@ -34,8 +34,8 @@ mutex jvmMutex;
  * http://msdn.microsoft.com/en-us/library/bb918180.aspx
  */
 static void __cdecl initializeMutexes(void) {
-  InitializeCriticalSection(&hdfsHashMutex);
   InitializeCriticalSection(&jvmMutex);
+  InitializeCriticalSection(&jclassInitMutex);
 }
 #pragma section(".CRT$XCU", read)
 __declspec(allocate(".CRT$XCU"))