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HDFS-6065. HDFS zero-copy reads should return null on EOF when doing ZCR (cmccabe)

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git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1575109 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Colin McCabe 2014-03-07 01:18:32 +00:00
parent 591be56052
commit 173c115951
8 changed files with 67 additions and 16 deletions
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16
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/HasEnhancedByteBufferAccess.java
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@ -50,13 +50,15 @@ public interface HasEnhancedByteBufferAccess {
* Options to use when reading.
*
* @return
* We will return null on EOF (and only on EOF).
* Otherwise, we will return a direct ByteBuffer containing at
* least one byte. You must free this ByteBuffer when you are
* done with it by calling releaseBuffer on it.
* The buffer will continue to be readable until it is released
* in this manner. However, the input stream's close method may
* warn about unclosed buffers.
* We will always return an empty buffer if maxLength was 0,
* whether or not we are at EOF.
* If maxLength > 0, we will return null if the stream has
* reached EOF.
* Otherwise, we will return a ByteBuffer containing at least one
* byte. You must free this ByteBuffer when you are done with it
* by calling releaseBuffer on it. The buffer will continue to be
* readable until it is released in this manner. However, the
* input stream's close method may warn about unclosed buffers.
* @throws
* IOException: if there was an error reading.
* UnsupportedOperationException: if factory was null, and we

3
hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
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@ -711,6 +711,9 @@ Release 2.4.0 - UNRELEASED
HDFS-6067. TestPread.testMaxOutHedgedReadPool is flaky (cmccabe)
HDFS-6065. HDFS zero-copy reads should return null on EOF when doing ZCR
(cmccabe)
BREAKDOWN OF HDFS-5698 SUBTASKS AND RELATED JIRAS
HDFS-5717. Save FSImage header in protobuf. (Haohui Mai via jing9)

21
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java
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@ -1556,13 +1556,27 @@ public synchronized void setDropBehind(Boolean dropBehind)
closeCurrentBlockReader();
}
/**
* The immutable empty buffer we return when we reach EOF when doing a
* zero-copy read.
*/
private static final ByteBuffer EMPTY_BUFFER =
ByteBuffer.allocateDirect(0).asReadOnlyBuffer();
@Override
public synchronized ByteBuffer read(ByteBufferPool bufferPool,
int maxLength, EnumSet<ReadOption> opts)
throws IOException, UnsupportedOperationException {
assert(maxLength > 0);
if (((blockReader == null) || (blockEnd == -1)) &&
(pos < getFileLength())) {
if (maxLength == 0) {
return EMPTY_BUFFER;
} else if (maxLength < 0) {
throw new IllegalArgumentException("can't read a negative " +
"number of bytes.");
}
if ((blockReader == null) || (blockEnd == -1)) {
if (pos >= getFileLength()) {
return null;
}
/*
* If we don't have a blockReader, or the one we have has no more bytes
* left to read, we call seekToBlockSource to get a new blockReader and
@ -1645,6 +1659,7 @@ private synchronized ByteBuffer tryReadZeroCopy(int maxLength,
@Override
public synchronized void releaseBuffer(ByteBuffer buffer) {
if (buffer == EMPTY_BUFFER) return;
Object val = extendedReadBuffers.remove(buffer);
if (val == null) {
throw new IllegalArgumentException("tried to release a buffer " +

6
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/client/ShortCircuitReplica.java
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@ -277,7 +277,11 @@ public ClientMmap getOrCreateClientMmap(boolean anchor) {
MappedByteBuffer loadMmapInternal() {
try {
FileChannel channel = dataStream.getChannel();
return channel.map(MapMode.READ_ONLY, 0, channel.size());
MappedByteBuffer mmap = channel.map(MapMode.READ_ONLY, 0, channel.size());
if (LOG.isTraceEnabled()) {
LOG.trace(this + ": created mmap of size " + channel.size());
}
return mmap;
} catch (IOException e) {
LOG.warn(this + ": mmap error", e);
return null;

4
hadoop-hdfs-project/hadoop-hdfs/src/main/native/libhdfs/expect.h
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@ -38,7 +38,7 @@ struct hdfsFile_internal;
#define EXPECT_NULL(x) \
do { \
void* __my_ret__ = x; \
const void* __my_ret__ = x; \
int __my_errno__ = errno; \
if (__my_ret__ != NULL) { \
fprintf(stderr, "TEST_ERROR: failed on %s:%d (errno: %d): " \
@ -50,7 +50,7 @@ struct hdfsFile_internal;
#define EXPECT_NONNULL(x) \
do { \
void* __my_ret__ = x; \
const void* __my_ret__ = x; \
int __my_errno__ = errno; \
if (__my_ret__ == NULL) { \
fprintf(stderr, "TEST_ERROR: failed on %s:%d (errno: %d): " \

8
hadoop-hdfs-project/hadoop-hdfs/src/main/native/libhdfs/hdfs.h
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@ -746,12 +746,16 @@ extern "C" {
* @param maxLength The maximum length to read. We may read fewer bytes
* than this length.
*
* @return On success, returns a new hadoopRzBuffer.
* @return On success, we will return a new hadoopRzBuffer.
* This buffer will continue to be valid and readable
* until it is released by readZeroBufferFree. Failure to
* release a buffer will lead to a memory leak.
* You can access the data within the hadoopRzBuffer with
* hadoopRzBufferGet. If you have reached EOF, the data
* within the hadoopRzBuffer will be NULL. You must still
* free hadoopRzBuffer instances containing NULL.
*
* NULL plus an errno code on an error.
* On failure, we will return NULL plus an errno code.
* errno = EOPNOTSUPP indicates that we could not do a
* zero-copy read, and there was no ByteBufferPool
* supplied.

19
hadoop-hdfs-project/hadoop-hdfs/src/main/native/libhdfs/test/test_libhdfs_zerocopy.c
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@ -38,6 +38,9 @@
#define TEST_ZEROCOPY_LAST_BLOCK_SIZE 3215
#define TEST_ZEROCOPY_NUM_BLOCKS 6
#define SMALL_READ_LEN 16
#define TEST_ZEROCOPY_FILE_LEN \
(((TEST_ZEROCOPY_NUM_BLOCKS - 1) * TEST_ZEROCOPY_FULL_BLOCK_SIZE) + \
TEST_ZEROCOPY_LAST_BLOCK_SIZE)
#define ZC_BUF_LEN 32768
@ -165,6 +168,22 @@ static int doTestZeroCopyReads(hdfsFS fs, const char *fileName)
EXPECT_ZERO(memcmp(block, hadoopRzBufferGet(buffer) +
(TEST_ZEROCOPY_FULL_BLOCK_SIZE - SMALL_READ_LEN), SMALL_READ_LEN));
hadoopRzBufferFree(file, buffer);
/* Check the result of a zero-length read. */
buffer = hadoopReadZero(file, opts, 0);
EXPECT_NONNULL(buffer);
EXPECT_NONNULL(hadoopRzBufferGet(buffer));
EXPECT_INT_EQ(0, hadoopRzBufferLength(buffer));
hadoopRzBufferFree(file, buffer);
/* Check the result of reading past EOF */
EXPECT_INT_EQ(0, hdfsSeek(fs, file, TEST_ZEROCOPY_FILE_LEN));
buffer = hadoopReadZero(file, opts, 1);
EXPECT_NONNULL(buffer);
EXPECT_NULL(hadoopRzBufferGet(buffer));
hadoopRzBufferFree(file, buffer);
/* Cleanup */
free(block);
hadoopRzOptionsFree(opts);
EXPECT_ZERO(hdfsCloseFile(fs, file));

4
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestEnhancedByteBufferAccess.java
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@ -753,6 +753,10 @@ public void testClientMmapDisable() throws Exception {
fsIn = fs.open(TEST_PATH);
ByteBuffer buf = fsIn.read(null, 1, EnumSet.of(ReadOption.SKIP_CHECKSUMS));
fsIn.releaseBuffer(buf);
// Test EOF behavior
IOUtils.skipFully(fsIn, TEST_FILE_LENGTH - 1);
buf = fsIn.read(null, 1, EnumSet.of(ReadOption.SKIP_CHECKSUMS));
Assert.assertEquals(null, buf);
} finally {
if (fsIn != null) fsIn.close();
if (fs != null) fs.close();