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From els...@apache.org
Subject [7/9] git commit: ACCUMULO-3249 Extra comments about issuing updates to replication status for WALs.
Date Thu, 23 Oct 2014 18:58:24 GMT
ACCUMULO-3249 Extra comments about issuing updates to replication status for WALs.


Project: http://git-wip-us.apache.org/repos/asf/accumulo/repo
Commit: http://git-wip-us.apache.org/repos/asf/accumulo/commit/6a713aa4
Tree: http://git-wip-us.apache.org/repos/asf/accumulo/tree/6a713aa4
Diff: http://git-wip-us.apache.org/repos/asf/accumulo/diff/6a713aa4

Branch: refs/heads/master
Commit: 6a713aa4282ddfd658de7af05a801f5791cd4eec
Parents: ceb131c
Author: Josh Elser <elserj@apache.org>
Authored: Wed Oct 22 14:53:19 2014 -0400
Committer: Josh Elser <elserj@apache.org>
Committed: Thu Oct 23 11:18:59 2014 -0400

----------------------------------------------------------------------
 .../apache/accumulo/tserver/tablet/DatafileManager.java   |  3 ++-
 .../java/org/apache/accumulo/tserver/tablet/Tablet.java   | 10 +++++++++-
 2 files changed, 11 insertions(+), 2 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/accumulo/blob/6a713aa4/server/tserver/src/main/java/org/apache/accumulo/tserver/tablet/DatafileManager.java
----------------------------------------------------------------------
diff --git a/server/tserver/src/main/java/org/apache/accumulo/tserver/tablet/DatafileManager.java
b/server/tserver/src/main/java/org/apache/accumulo/tserver/tablet/DatafileManager.java
index a84f092..5cdc1af 100644
--- a/server/tserver/src/main/java/org/apache/accumulo/tserver/tablet/DatafileManager.java
+++ b/server/tserver/src/main/java/org/apache/accumulo/tserver/tablet/DatafileManager.java
@@ -422,7 +422,8 @@ class DatafileManager {
 
       // Mark that we have data we want to replicate
       // This WAL could still be in use by other Tablets *from the same table*, so we can
only mark that there is data to replicate,
-      // but it is *not* closed
+      // but it is *not* closed. We know it is not closed by the fact that this MinC triggered.
A MinC cannot happen unless the
+      // tablet is online and thus these WALs are referenced by that tablet. Therefore, the
WAL replication status cannot be 'closed'.
       if (replicate) {
         if (log.isDebugEnabled()) {
           log.debug("Recording that data has been ingested into " + tablet.getExtent() +
" using " + logFileOnly);

http://git-wip-us.apache.org/repos/asf/accumulo/blob/6a713aa4/server/tserver/src/main/java/org/apache/accumulo/tserver/tablet/Tablet.java
----------------------------------------------------------------------
diff --git a/server/tserver/src/main/java/org/apache/accumulo/tserver/tablet/Tablet.java b/server/tserver/src/main/java/org/apache/accumulo/tserver/tablet/Tablet.java
index 8ba72b7..d82827e 100644
--- a/server/tserver/src/main/java/org/apache/accumulo/tserver/tablet/Tablet.java
+++ b/server/tserver/src/main/java/org/apache/accumulo/tserver/tablet/Tablet.java
@@ -621,11 +621,19 @@ public class Tablet implements TabletCommitter {
           log.debug("No replayed mutations applied, removing unused entries for " + extent);
           MetadataTableUtil.removeUnusedWALEntries(extent, logEntries, tabletServer.getLock());
 
+          // No replication update to be made because the fact that this tablet didn't use
any mutations
+          // from the WAL implies nothing about use of this WAL by other tablets. Do nothing.
+
           logEntries.clear();
         } else if (ReplicationConfigurationUtil.isEnabled(extent, tabletServer.getTableConfiguration(extent)))
{
-          // The logs are about to be re-used, we need to record that they have data for
this extent,
+          // The logs are about to be re-used by this tablet, we need to record that they
have data for this extent,
           // but that they may get more data. logEntries is not cleared which will cause
the elements
           // in logEntries to be added to the currentLogs for this Tablet below.
+          //
+          // This update serves the same purpose as an update during a MinC. We know that
the WAL was defined
+          // (written when the WAL was opened) but this lets us know there are mutations
written to this WAL
+          // that could potentially be replicated. Because the Tablet is using this WAL,
we can be sure that
+          // the WAL isn't closed (WRT replication Status) and thus we're safe to update
its progress.
           Status status = StatusUtil.openWithUnknownLength();
           for (LogEntry logEntry : logEntries) {
             log.debug("Writing updated status to metadata table for " + logEntry.logSet +
" " + ProtobufUtil.toString(status));


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