HDFS-1907. Fix position read for reading still-being-written file in DFSInputStream. Contributed by John George
git-svn-id: https://svn.apache.org/repos/asf/hadoop/hdfs/trunk@1131124 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/CHANGES.txt b/CHANGES.txt
index 5253cc0..d877672 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -678,6 +678,9 @@
HDFS-1995. Federation: Minor bug fixes and modification cluster web UI.
(Tanping Wang via suresh)
+ HDFS-1907. Fix position read for reading still-being-written file in
+ DFSInputStream. (John George via szetszwo)
+
Release 0.22.0 - Unreleased
INCOMPATIBLE CHANGES
diff --git a/src/java/org/apache/hadoop/hdfs/DFSInputStream.java b/src/java/org/apache/hadoop/hdfs/DFSInputStream.java
index 0052d65..0051cc8 100644
--- a/src/java/org/apache/hadoop/hdfs/DFSInputStream.java
+++ b/src/java/org/apache/hadoop/hdfs/DFSInputStream.java
@@ -306,11 +306,22 @@
blocks = getFinalizedBlockRange(offset, length);
}
else {
- if (length + offset > locatedBlocks.getFileLength()) {
+ final boolean readPastEnd = offset + length > locatedBlocks.getFileLength();
+ /* if requested length is greater than current file length
+ * then, it could possibly be from the current block being
+ * written to. First get the finalized block range and then
+ * if necessary, get the length of last block being written
+ * to.
+ */
+ if (readPastEnd)
length = locatedBlocks.getFileLength() - offset;
- }
+
blocks = getFinalizedBlockRange(offset, length);
- blocks.add(locatedBlocks.getLastLocatedBlock());
+ /* requested length is greater than what finalized blocks
+ * have.
+ */
+ if (readPastEnd)
+ blocks.add(locatedBlocks.getLastLocatedBlock());
}
return blocks;
}
diff --git a/src/test/hdfs/org/apache/hadoop/hdfs/TestWriteRead.java b/src/test/hdfs/org/apache/hadoop/hdfs/TestWriteRead.java
index 181319c..e293c96 100644
--- a/src/test/hdfs/org/apache/hadoop/hdfs/TestWriteRead.java
+++ b/src/test/hdfs/org/apache/hadoop/hdfs/TestWriteRead.java
@@ -106,12 +106,23 @@
positionReadOption = false;
String fname = filenameOption;
+ positionReadOption = false; // sequential read
// need to run long enough to fail: takes 25 to 35 seec on Mac
int stat = testWriteAndRead(fname, WR_NTIMES, WR_CHUNK_SIZE);
LOG.info("Summary status from test1: status= " + stat);
- Assert.assertTrue(stat == 0);
+ Assert.assertEquals(0, stat);
}
-
+
+ /** Junit Test position read while writing. */
+ @Test
+ public void TestWriteReadPos() throws IOException {
+ String fname = filenameOption;
+ positionReadOption = true; // position read
+ int stat = testWriteAndRead(fname, WR_NTIMES, WR_CHUNK_SIZE);
+ Assert.assertEquals(0, stat);
+ }
+
+
// equivalent of TestWriteRead1
private int clusterTestWriteRead1() throws IOException {
int stat = testWriteAndRead(filenameOption, loopOption, chunkSizeOption);
