Wait for writes on synchronous read digest mismatch

patch by Niklas Ekstrom; reviewed by jbellis and vijay for CASSANDRA-4792
apache · Oct 11, 2012 · 936302c · 936302c
1 parent 4355aa8
commit 936302c
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Showing 2 changed files with 6 additions and 3 deletions.
diff --git a/CHANGES.txt b/CHANGES.txt
@@ -1,4 +1,5 @@
 1.1.6
+ * Wait for writes on synchronous read digest mismatch (CASSANDRA-4792)
  * fix commitlog replay for nanotime-infected sstables (CASSANDRA-4782)
  * preflight check ttl for maximum of 20 years (CASSANDRA-4771)
  * (Pig) fix widerow input with single column rows (CASSANDRA-4789)

diff --git a/src/java/org/apache/cassandra/service/StorageProxy.java b/src/java/org/apache/cassandra/service/StorageProxy.java
@@ -762,9 +762,6 @@ private static List<Row> fetchRows(List<ReadCommand> initialCommands, Consistenc
                 {
                     ReadCommand command = repairCommands.get(i);
                     RepairCallback handler = repairResponseHandlers.get(i);
-                    // wait for the repair writes to be acknowledged, to minimize impact on any replica that's
-                    // behind on writes in case the out-of-sync row is read multiple times in quick succession
-                    FBUtilities.waitOnFutures(handler.resolver.repairResults, DatabaseDescriptor.getRpcTimeout());
 
                     Row row;
                     try
@@ -776,6 +773,11 @@ private static List<Row> fetchRows(List<ReadCommand> initialCommands, Consistenc
                         throw new AssertionError(e); // full data requested from each node here, no digests should be sent
                     }
 
+                    // wait for the repair writes to be acknowledged, to minimize impact on any replica that's
+                    // behind on writes in case the out-of-sync row is read multiple times in quick succession
+                    FBUtilities.waitOnFutures(handler.resolver.repairResults, DatabaseDescriptor.getRpcTimeout());
+
+                    // retry any potential short reads
                     ReadCommand retryCommand = command.maybeGenerateRetryCommand(handler, row);
                     if (retryCommand != null)
                     {