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HDFS-9147. Fix the setting of visibleLength in ExternalBlockReader. (Colin P. McCabe via Lei (Eddy) Xu) 

(cherry picked from commit e5992ef4df)
This commit is contained in:
Lei Xu 2015-09-28 13:39:00 -07:00
parent 74092f2144
commit 213ff984ee
4 changed files with 20 additions and 13 deletions
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5
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/BlockReaderFactory.java
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@ -392,6 +392,7 @@ public class BlockReaderFactory implements ShortCircuitReplicaCreator {
Constructor<? extends ReplicaAccessorBuilder> ctor =
cls.getConstructor();
ReplicaAccessorBuilder builder = ctor.newInstance();
long visibleLength = startOffset + length;
ReplicaAccessor accessor = builder.
setAllowShortCircuitReads(allowShortCircuitLocalReads).
setBlock(block.getBlockId(), block.getBlockPoolId()).
@ -401,7 +402,7 @@ public class BlockReaderFactory implements ShortCircuitReplicaCreator {
setConfiguration(configuration).
setFileName(fileName).
setVerifyChecksum(verifyChecksum).
setVisibleLength(length).
setVisibleLength(visibleLength).
build();
if (accessor == null) {
if (LOG.isTraceEnabled()) {
@ -409,7 +410,7 @@ public class BlockReaderFactory implements ShortCircuitReplicaCreator {
cls.getName());
}
} else {
return new ExternalBlockReader(accessor, length, startOffset);
return new ExternalBlockReader(accessor, visibleLength, startOffset);
}
} catch (Throwable t) {
LOG.warn("Failed to construct new object of type " +

14
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/ExternalBlockReader.java
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@ -68,7 +68,8 @@ public final class ExternalBlockReader implements BlockReader {
if (n <= 0) {
return 0;
}
// You can't skip past the end of the replica.
// You can't skip past the last offset that we want to read with this
// block reader.
long oldPos = pos;
pos += n;
if (pos > visibleLength) {
@ -79,12 +80,11 @@ public final class ExternalBlockReader implements BlockReader {
@Override
public int available() throws IOException {
// We return the amount of bytes that we haven't read yet from the
// replica, based on our current position. Some of the other block
// readers return a shorter length than that. The only advantage to
// returning a shorter length is that the DFSInputStream will
// trash your block reader and create a new one if someone tries to
// seek() beyond the available() region.
// We return the amount of bytes between the current offset and the visible
// length. Some of the other block readers return a shorter length than
// that. The only advantage to returning a shorter length is that the
// DFSInputStream will trash your block reader and create a new one if
// someone tries to seek() beyond the available() region.
long diff = visibleLength - pos;
if (diff > Integer.MAX_VALUE) {
return Integer.MAX_VALUE;

3
hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
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@ -1097,6 +1097,9 @@ Release 2.8.0 - UNRELEASED
HDFS-9107. Prevent NN's unrecoverable death spiral after full GC (Daryn
Sharp via Colin P. McCabe)
HDFS-9147. Fix the setting of visibleLength in ExternalBlockReader. (Colin
P. McCabe via Lei (Eddy) Xu)
Release 2.7.2 - UNRELEASED
INCOMPATIBLE CHANGES

11
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestExternalBlockReader.java
View File

@ -190,7 +190,7 @@ public class TestExternalBlockReader {
"than 0 at " + pos);
return 0;
}
int i = 0, nread = 0, ipos;
int i = off, nread = 0, ipos;
for (ipos = (int)pos;
(ipos < contents.length) && (nread < len);
ipos++) {
@ -280,7 +280,10 @@ public class TestExternalBlockReader {
HdfsDataInputStream stream =
(HdfsDataInputStream)dfs.open(new Path("/a"));
byte buf[] = new byte[TEST_LENGTH];
IOUtils.readFully(stream, buf, 0, TEST_LENGTH);
stream.seek(1000);
IOUtils.readFully(stream, buf, 1000, TEST_LENGTH - 1000);
stream.seek(0);
IOUtils.readFully(stream, buf, 0, 1000);
byte expected[] = DFSTestUtil.
calculateFileContentsFromSeed(SEED, TEST_LENGTH);
ReadStatistics stats = stream.getReadStatistics();
@ -293,7 +296,7 @@ public class TestExternalBlockReader {
Assert.assertNotNull(block);
LinkedList<SyntheticReplicaAccessor> accessorList = accessors.get(uuid);
Assert.assertNotNull(accessorList);
Assert.assertEquals(2, accessorList.size());
Assert.assertEquals(3, accessorList.size());
SyntheticReplicaAccessor accessor = accessorList.get(0);
Assert.assertTrue(accessor.builder.allowShortCircuit);
Assert.assertEquals(block.getBlockPoolId(),
@ -307,7 +310,7 @@ public class TestExternalBlockReader {
accessor.getGenerationStamp());
Assert.assertTrue(accessor.builder.verifyChecksum);
Assert.assertEquals(1024L, accessor.builder.visibleLength);
Assert.assertEquals(1024L, accessor.totalRead);
Assert.assertEquals(24L, accessor.totalRead);
Assert.assertEquals("", accessor.getError());
Assert.assertEquals(1, accessor.numCloses);
byte[] tempBuf = new byte[5];