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From jji...@apache.org
Subject [02/10] cassandra git commit: Commitlog replay may fail if last mutation is within 4 bytes of end of segment
Date Mon, 13 Mar 2017 05:00:20 GMT
Commitlog replay may fail if last mutation is within 4 bytes of end of segment

Patch by Jeff Jirsa; Reviewed by Branimir Lambov for CASSANDRA-13282


Project: http://git-wip-us.apache.org/repos/asf/cassandra/repo
Commit: http://git-wip-us.apache.org/repos/asf/cassandra/commit/beb9658d
Tree: http://git-wip-us.apache.org/repos/asf/cassandra/tree/beb9658d
Diff: http://git-wip-us.apache.org/repos/asf/cassandra/diff/beb9658d

Branch: refs/heads/cassandra-3.0
Commit: beb9658dd5e18e3a6a4e8431b6549ae4c33365a9
Parents: 5ef8a8b
Author: Jeff Jirsa <jeff@jeffjirsa.net>
Authored: Sun Mar 12 21:54:04 2017 -0700
Committer: Jeff Jirsa <jeff@jeffjirsa.net>
Committed: Sun Mar 12 21:54:04 2017 -0700

----------------------------------------------------------------------
 CHANGES.txt                                     |  1 +
 .../db/commitlog/CommitLogReplayer.java         | 11 +++++++++++
 .../cassandra/db/commitlog/CommitLogTest.java   | 20 ++++++++++++++++----
 3 files changed, 28 insertions(+), 4 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/cassandra/blob/beb9658d/CHANGES.txt
----------------------------------------------------------------------
diff --git a/CHANGES.txt b/CHANGES.txt
index 09e4039..2839291 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -9,6 +9,7 @@
  * Fix failing COPY TO STDOUT (CASSANDRA-12497)
  * Fix ColumnCounter::countAll behaviour for reverse queries (CASSANDRA-13222)
  * Exceptions encountered calling getSeeds() breaks OTC thread (CASSANDRA-13018)
+ * Commitlog replay may fail if last mutation is within 4 bytes of end of segment (CASSANDRA-13282)
 Merged from 2.1:
  * Remove unused repositories (CASSANDRA-13278)
  * Log stacktrace of uncaught exceptions (CASSANDRA-13108)

http://git-wip-us.apache.org/repos/asf/cassandra/blob/beb9658d/src/java/org/apache/cassandra/db/commitlog/CommitLogReplayer.java
----------------------------------------------------------------------
diff --git a/src/java/org/apache/cassandra/db/commitlog/CommitLogReplayer.java b/src/java/org/apache/cassandra/db/commitlog/CommitLogReplayer.java
index a58aeb4..3cf4d0f 100644
--- a/src/java/org/apache/cassandra/db/commitlog/CommitLogReplayer.java
+++ b/src/java/org/apache/cassandra/db/commitlog/CommitLogReplayer.java
@@ -439,6 +439,17 @@ public class CommitLogReplayer
             int serializedSize;
             try
             {
+                // We rely on reading serialized size == 0 (LEGACY_END_OF_SEGMENT_MARKER)
to identify the end
+                // of a segment, which happens naturally due to the 0 padding of the empty
segment on creation.
+                // However, with 2.1 era commitlogs it's possible that the last mutation
ended less than 4 bytes 
+                // from the end of the file, which means that we'll be unable to read an
a full int and instead 
+                // read an EOF here
+                if(end - reader.getFilePointer() < 4)
+                {
+                    logger.trace("Not enough bytes left for another mutation in this CommitLog
segment, continuing");
+                    return false;
+                }
+
                 // any of the reads may hit EOF
                 serializedSize = reader.readInt();
                 if (serializedSize == LEGACY_END_OF_SEGMENT_MARKER)

http://git-wip-us.apache.org/repos/asf/cassandra/blob/beb9658d/test/unit/org/apache/cassandra/db/commitlog/CommitLogTest.java
----------------------------------------------------------------------
diff --git a/test/unit/org/apache/cassandra/db/commitlog/CommitLogTest.java b/test/unit/org/apache/cassandra/db/commitlog/CommitLogTest.java
index 9999b42..9b63885 100644
--- a/test/unit/org/apache/cassandra/db/commitlog/CommitLogTest.java
+++ b/test/unit/org/apache/cassandra/db/commitlog/CommitLogTest.java
@@ -137,12 +137,24 @@ public class CommitLogTest
     }
 
     @Test
+    public void testRecoveryWithShortPadding() throws Exception
+    {
+        // If we have 0-3 bytes remaining, commitlog replayer
+        // should pass, because there's insufficient room
+        // left in the segment for the legacy size marker.
+        testRecovery(new byte[1], null);
+        testRecovery(new byte[2], null);
+        testRecovery(new byte[3], null);
+    }
+
+    @Test
     public void testRecoveryWithShortSize() throws Exception
     {
-        runExpecting(new WrappedRunnable() {
-            public void runMayThrow() throws Exception
-            {
-                testRecovery(new byte[2], CommitLogDescriptor.VERSION_20);
+        runExpecting(new WrappedRunnable()  {
+            public void runMayThrow() throws Exception {
+                byte[] data = new byte[5];
+                data[3] = 1; // Not a legacy marker, give it a fake (short) size
+                testRecovery(data, CommitLogDescriptor.VERSION_20);
             }
         }, CommitLogReplayException.class);
     }


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