From 8e08f43e0386e355c6e32282e5f5eadc5904ec2d Mon Sep 17 00:00:00 2001
From: PHILO-HE <feilong.he@intel.com>
Date: Tue, 14 Dec 2021 17:15:12 +0800
Subject: [PATCH] HDFS-16014: Fix an issue in checking native pmdk lib by
 'hadoop checknative' command (#3762)

---
 .../org/apache/hadoop/io/nativeio/NativeIO.java   |  2 +-
 .../src/org/apache/hadoop/io/nativeio/pmdk_load.c | 15 ++++++++++++---
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/nativeio/NativeIO.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/nativeio/NativeIO.java
index 79b489b3d1..ebe7f213ce 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/nativeio/NativeIO.java
+++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/nativeio/NativeIO.java
@@ -141,7 +141,7 @@ public String getMessage() {
       }
     }
 
-    // Denotes the state of supporting PMDK. The value is set by JNI.
+    // Denotes the state of supporting PMDK. The actual value is set via JNI.
     private static SupportState pmdkSupportState =
         SupportState.UNSUPPORTED;
 
diff --git a/hadoop-common-project/hadoop-common/src/main/native/src/org/apache/hadoop/io/nativeio/pmdk_load.c b/hadoop-common-project/hadoop-common/src/main/native/src/org/apache/hadoop/io/nativeio/pmdk_load.c
index 502508cbf3..f1a1df5c9d 100644
--- a/hadoop-common-project/hadoop-common/src/main/native/src/org/apache/hadoop/io/nativeio/pmdk_load.c
+++ b/hadoop-common-project/hadoop-common/src/main/native/src/org/apache/hadoop/io/nativeio/pmdk_load.c
@@ -35,13 +35,14 @@
 #endif
 
 PmdkLibLoader * pmdkLoader;
+// 1 represents loaded. Otherwise, not loaded.
+int pmdkLoaded;
 
 /**
  *  pmdk_load.c
  *  Utility of loading the libpmem library and the required functions.
  *  Building of this codes won't rely on any libpmem source codes, but running
  *  into this will rely on successfully loading of the dynamic library.
- *
  */
 
 static const char* load_functions() {
@@ -56,6 +57,10 @@ static const char* load_functions() {
   return NULL;
 }
 
+/**
+ * It should be idempotent to call this function for checking
+ * whether PMDK lib is successfully loaded.
+ */
 void load_pmdk_lib(char* err, size_t err_len) {
   const char* errMsg;
   const char* library = NULL;
@@ -67,10 +72,13 @@ void load_pmdk_lib(char* err, size_t err_len) {
 
   err[0] = '\0';
 
-  if (pmdkLoader != NULL) {
+  if (pmdkLoaded == 1) {
     return;
   }
-  pmdkLoader = calloc(1, sizeof(PmdkLibLoader));
+
+  if (pmdkLoader == NULL) {
+    pmdkLoader = calloc(1, sizeof(PmdkLibLoader));
+  }
 
   // Load PMDK library
   #ifdef UNIX
@@ -103,4 +111,5 @@ void load_pmdk_lib(char* err, size_t err_len) {
   }
 
   pmdkLoader->libname = strdup(library);
+  pmdkLoaded = 1;
 }