Author: jbellis
Date: Tue Dec 28 21:23:50 2010
New Revision: 1053443
URL: http://svn.apache.org/viewvc?rev=1053443&view=rev
Log:
simplify and update comments for RRR.resolve
patch by jbellis
Modified:
cassandra/branches/cassandra-0.7/src/java/org/apache/cassandra/service/ReadResponseResolver.java
Modified:
cassandra/branches/cassandra-0.7/src/java/org/apache/cassandra/service/ReadResponseResolver.java
URL:
http://svn.apache.org/viewvc/cassandra/branches/cassandra-0.7/src/java/org/apache/cassandra/service/ReadResponseResolver.java?rev=1053443&r1=1053442&r2=1053443&view=diff
==============================================================================
---
cassandra/branches/cassandra-0.7/src/java/org/apache/cassandra/service/ReadResponseResolver.java
(original)
+++
cassandra/branches/cassandra-0.7/src/java/org/apache/cassandra/service/ReadResponseResolver.java
Tue Dec 28 21:23:50 2010
@@ -54,13 +54,17 @@ public class ReadResponseResolver implem
}
/*
- * This method for resolving read data should look at the timestamps of
each
- * of the columns that are read and should pick up columns with the latest
- * timestamp. For those columns where the timestamp is not the latest a
- * repair request should be scheduled.
- *
- */
- public Row resolve() throws DigestMismatchException, IOException
+ * This method handles two different scenarios:
+ *
+ * 1) we're handling the initial read, of data from the closest replica +
digests
+ * from the rest. In this case we check the digests against each other,
+ * throw an exception if there is a mismatch, otherwise return the data
row.
+ *
+ * 2) there was a mismatch on the initial read, so we redid the digest
requests
+ * as full data reads. In this case we need to compute the most recent
version
+ * of each column, and send diffs to out-of-date replicas.
+ */
+ public Row resolve() throws DigestMismatchException, IOException
{
if (logger_.isDebugEnabled())
logger_.debug("resolving " + results.size() + " responses");
@@ -70,50 +74,27 @@ public class ReadResponseResolver implem
List<InetAddress> endpoints = new ArrayList<InetAddress>();
ByteBuffer digest = null;
- /*
- * Populate the list of rows from each of the messages
- * Check to see if there is a digest query. If a digest
- * query exists then we need to compare the digest with
- * the digest of the data that is received.
- */
+ // validate digests against each other; throw immediately on mismatch.
+ // also, collects data results into versions/endpoints lists.
for (Map.Entry<Message, ReadResponse> entry : results.entrySet())
{
ReadResponse result = entry.getValue();
Message message = entry.getKey();
- if (result.isDigestQuery())
- {
- if (digest == null)
- {
- digest = result.digest();
- }
- else
- {
- ByteBuffer digest2 = result.digest();
- if (!digest.equals(digest2))
- throw new DigestMismatchException(key, digest,
digest2);
- }
- }
- else
+ ByteBuffer resultDigest = result.isDigestQuery() ? result.digest()
: ColumnFamily.digest(result.row().cf);
+ if (digest == null)
+ digest = resultDigest;
+ else if (!digest.equals(resultDigest))
+ throw new DigestMismatchException(key, digest, resultDigest);
+
+ if (!result.isDigestQuery())
{
versions.add(result.row().cf);
endpoints.add(message.getFrom());
}
}
- // If there was a digest query compare it with all the data
digests
- // If there is a mismatch then throw an exception so that read
repair can happen.
- if (digest != null)
- {
-
- for (ColumnFamily cf : versions)
- {
- ByteBuffer digest2 = ColumnFamily.digest(cf);
- if (!digest.equals(digest2))
- throw new DigestMismatchException(key, digest, digest2);
- }
- if (logger_.isDebugEnabled())
- logger_.debug("digests verified");
- }
+ if (logger_.isDebugEnabled())
+ logger_.debug("digests verified");
ColumnFamily resolved;
if (versions.size() > 1)
