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Posted to commits@cassandra.apache.org by sl...@apache.org on 2012/02/22 14:23:58 UTC
[4/4] git commit: Fix short read protection
Fix short read protection
patch by slebresne; reviewed by driftx for CASSANDRA-3934
Project: http://git-wip-us.apache.org/repos/asf/cassandra/repo
Commit: http://git-wip-us.apache.org/repos/asf/cassandra/commit/8413d831
Tree: http://git-wip-us.apache.org/repos/asf/cassandra/tree/8413d831
Diff: http://git-wip-us.apache.org/repos/asf/cassandra/diff/8413d831
Branch: refs/heads/trunk
Commit: 8413d831d12099e8f2764438f0f31ec8ea1830b0
Parents: 44ac7a0
Author: Sylvain Lebresne <sy...@datastax.com>
Authored: Wed Feb 22 14:21:53 2012 +0100
Committer: Sylvain Lebresne <sy...@datastax.com>
Committed: Wed Feb 22 14:21:53 2012 +0100
----------------------------------------------------------------------
CHANGES.txt | 1 +
.../cassandra/db/RetriedSliceFromReadCommand.java | 2 +-
.../apache/cassandra/db/SliceFromReadCommand.java | 25 ++++++++++----
3 files changed, 20 insertions(+), 8 deletions(-)
----------------------------------------------------------------------
http://git-wip-us.apache.org/repos/asf/cassandra/blob/8413d831/CHANGES.txt
----------------------------------------------------------------------
diff --git a/CHANGES.txt b/CHANGES.txt
index 5869d32..966f940 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -23,6 +23,7 @@
* remove the wait on hint future during write (CASSANDRA-3870)
* (cqlsh) ignore missing CfDef opts (CASSANDRA-3933)
* (cqlsh) look for cqlshlib relative to realpath (CASSANDRA-3767)
+ * Fix short read protection (CASSANDRA-3934)
Merged from 0.8:
* (Pig) fix CassandraStorage to use correct comparator in Super ColumnFamily
case (CASSANDRA-3251)
http://git-wip-us.apache.org/repos/asf/cassandra/blob/8413d831/src/java/org/apache/cassandra/db/RetriedSliceFromReadCommand.java
----------------------------------------------------------------------
diff --git a/src/java/org/apache/cassandra/db/RetriedSliceFromReadCommand.java b/src/java/org/apache/cassandra/db/RetriedSliceFromReadCommand.java
index 6890f9d..5e0ca13 100644
--- a/src/java/org/apache/cassandra/db/RetriedSliceFromReadCommand.java
+++ b/src/java/org/apache/cassandra/db/RetriedSliceFromReadCommand.java
@@ -53,7 +53,7 @@ public class RetriedSliceFromReadCommand extends SliceFromReadCommand
}
@Override
- public int getRequestedCount()
+ public int getOriginalRequestedCount()
{
return originalCount;
}
http://git-wip-us.apache.org/repos/asf/cassandra/blob/8413d831/src/java/org/apache/cassandra/db/SliceFromReadCommand.java
----------------------------------------------------------------------
diff --git a/src/java/org/apache/cassandra/db/SliceFromReadCommand.java b/src/java/org/apache/cassandra/db/SliceFromReadCommand.java
index 51c1602..58b5e22 100644
--- a/src/java/org/apache/cassandra/db/SliceFromReadCommand.java
+++ b/src/java/org/apache/cassandra/db/SliceFromReadCommand.java
@@ -76,10 +76,16 @@ public class SliceFromReadCommand extends ReadCommand
int liveColumnsInRow = row != null ? row.cf.getLiveColumnCount() : 0;
assert maxLiveColumns <= count;
- if ((maxLiveColumns == count) && (liveColumnsInRow < count))
+ // We generate a retry if at least one node reply with count live columns but after merge we have less
+ // than the total number of column we are interested in (which may be < count on a retry)
+ if ((maxLiveColumns == count) && (liveColumnsInRow < getOriginalRequestedCount()))
{
- int retryCount = count + count - liveColumnsInRow;
- return new RetriedSliceFromReadCommand(table, key, queryPath, start, finish, reversed, count, retryCount);
+ // We asked t (= count) live columns and got l (=liveColumnsInRow) ones.
+ // From that, we can estimate that on this row, for x requested
+ // columns, only l/t end up live after reconciliation. So for next
+ // round we want to ask x column so that x * (l/t) == t, i.e. x = t^2/l.
+ int retryCount = ((count * count) / liveColumnsInRow) + 1;
+ return new RetriedSliceFromReadCommand(table, key, queryPath, start, finish, reversed, getOriginalRequestedCount(), retryCount);
}
return null;
@@ -93,11 +99,11 @@ public class SliceFromReadCommand extends ReadCommand
int liveColumnsInRow = row.cf.getLiveColumnCount();
- if (liveColumnsInRow > getRequestedCount())
+ if (liveColumnsInRow > getOriginalRequestedCount())
{
- int columnsToTrim = liveColumnsInRow - getRequestedCount();
+ int columnsToTrim = liveColumnsInRow - getOriginalRequestedCount();
- logger.debug("trimming {} live columns to the originally requested {}", row.cf.getLiveColumnCount(), getRequestedCount());
+ logger.debug("trimming {} live columns to the originally requested {}", row.cf.getLiveColumnCount(), getOriginalRequestedCount());
Collection<IColumn> columns;
if (reversed)
@@ -122,7 +128,12 @@ public class SliceFromReadCommand extends ReadCommand
}
}
- protected int getRequestedCount()
+ /**
+ * The original number of columns requested by the user.
+ * This can be different from count when the slice command is a retry (see
+ * RetriedSliceFromReadCommand)
+ */
+ protected int getOriginalRequestedCount()
{
return count;
}