From 53ac6966e65a907785505fd1da1ac196730cd442 Mon Sep 17 00:00:00 2001
From: Jean-Noel Rouvignac <jean-noel.rouvignac@forgerock.com>
Date: Fri, 22 Nov 2013 08:24:47 +0000
Subject: [PATCH] Checkpoint commit for OPENDJ-1174 Transfer responsibility for populating the ChangeNumberIndexDB to ChangelogDB

---
 opends/src/server/org/opends/server/replication/server/changelog/je/ChangeNumberIndexer.java |  110 ++++++++++++++++++++++++++++++++++---------------------
 1 files changed, 68 insertions(+), 42 deletions(-)

diff --git a/opends/src/server/org/opends/server/replication/server/changelog/je/ChangeNumberIndexer.java b/opends/src/server/org/opends/server/replication/server/changelog/je/ChangeNumberIndexer.java
index c82bc4e..dbb68f7 100644
--- a/opends/src/server/org/opends/server/replication/server/changelog/je/ChangeNumberIndexer.java
+++ b/opends/src/server/org/opends/server/replication/server/changelog/je/ChangeNumberIndexer.java
@@ -31,6 +31,7 @@
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.ConcurrentSkipListMap;
 
+import org.opends.messages.Message;
 import org.opends.server.api.DirectoryThread;
 import org.opends.server.loggers.debug.DebugTracer;
 import org.opends.server.replication.common.CSN;
@@ -61,29 +62,41 @@
   private ChangelogState changelogState;
 
   /*
-   * previousCookie and mediumConsistencyPoint must be thread safe, because
+   * mediumConsistencyRUV and lastSeenUpdates must be thread safe, because
    * 1) initialization can happen while the replication server starts receiving
    * updates 2) many updates can happen concurrently. This solution also avoids
    * using a queue that could fill up before we have consumed all its content.
    */
   /**
+   * Holds the cross domain medium consistency Replication Update Vector for the
+   * current replication server, also known as the previous cookie.
+   * <p>
    * Stores the value of the cookie before the change currently processed is
    * inserted in the DB. After insert, it is updated with the CSN of the change
    * currently processed (thus becoming the "current" cookie just before the
    * change is returned.
-   */
-  private final MultiDomainServerState previousCookie =
-      new MultiDomainServerState();
-
-  /**
-   * Holds the medium consistency point for the current replication server.
    *
    * @see <a href=
    * "https://wikis.forgerock.org/confluence/display/OPENDJ/OpenDJ+Domain+Names"
-   * >OpenDJ Domain Names for a description of what the medium consistency point
-   * is</a>
+   * >OpenDJ Domain Names - medium consistency RUV</a>
    */
-  private final MultiDomainServerState mediumConsistencyPoint =
+  private final MultiDomainServerState mediumConsistencyRUV =
+      new MultiDomainServerState();
+  /**
+   * Holds the cross domain medium consistency CSN for the current replication
+   * server.
+   *
+   * @see <a href=
+   * "https://wikis.forgerock.org/confluence/display/OPENDJ/OpenDJ+Domain+Names"
+   * >OpenDJ Domain Names - medium consistency CSN</a>
+   */
+  private volatile CSN mediumConsistencyCSN;
+
+  /**
+   * Holds the most recent changes or heartbeats received for each serverIds
+   * cross domain.
+   */
+  private final MultiDomainServerState lastSeenUpdates =
       new MultiDomainServerState();
 
   /**
@@ -103,8 +116,8 @@
   private Map<DN, Map<Integer, DBCursor<UpdateMsg>>> allCursors =
       new HashMap<DN, Map<Integer, DBCursor<UpdateMsg>>>();
   /** This map can be updated by multiple threads. */
-  private ConcurrentMap<Integer, DN> newCursors =
-      new ConcurrentSkipListMap<Integer, DN>();
+  private ConcurrentMap<CSN, DN> newCursors =
+      new ConcurrentSkipListMap<CSN, DN>();
 
   /**
    * Builds a ChangeNumberIndexer object.
@@ -131,11 +144,8 @@
    */
   public void publishHeartbeat(DN baseDN, CSN heartbeatCSN)
   {
-    mediumConsistencyPoint.update(baseDN, heartbeatCSN);
-    final CompositeDBCursor<DN> localCursor = crossDomainDBCursor;
-    final DN changeBaseDN = localCursor.getData();
-    final CSN changeCSN = localCursor.getRecord().getCSN();
-    tryNotify(changeBaseDN, changeCSN);
+    lastSeenUpdates.update(baseDN, heartbeatCSN);
+    tryNotify(baseDN);
   }
 
   /**
@@ -152,18 +162,18 @@
       throws ChangelogException
   {
     final CSN csn = updateMsg.getCSN();
-    mediumConsistencyPoint.update(baseDN, csn);
-    newCursors.put(csn.getServerId(), baseDN);
-    tryNotify(baseDN, csn);
+    lastSeenUpdates.update(baseDN, csn);
+    newCursors.put(csn, baseDN);
+    tryNotify(baseDN);
   }
 
   /**
    * Notifies the Change number indexer thread if it will be able to do some
    * work.
    */
-  private void tryNotify(final DN baseDN, final CSN csn)
+  private void tryNotify(DN baseDN)
   {
-    if (mediumConsistencyPoint.cover(baseDN, csn))
+    if (canMoveForwardMediumConsistencyPoint(baseDN))
     {
       synchronized (this)
       {
@@ -172,13 +182,25 @@
     }
   }
 
+  private boolean canMoveForwardMediumConsistencyPoint(DN baseDN)
+  {
+    final CSN mcCSN = mediumConsistencyCSN;
+    if (mcCSN != null)
+    {
+      final CSN lastSeenSameServerId =
+          lastSeenUpdates.getCSN(baseDN, mcCSN.getServerId());
+      return mcCSN.isOlderThan(lastSeenSameServerId);
+    }
+    return true;
+  }
+
   private void initialize() throws ChangelogException, DirectoryException
   {
     final ChangeNumberIndexRecord newestRecord =
         changelogDB.getChangeNumberIndexDB().getNewestRecord();
     if (newestRecord != null)
     {
-      previousCookie.update(
+      mediumConsistencyRUV.update(
           new MultiDomainServerState(newestRecord.getPreviousCookie()));
     }
 
@@ -190,13 +212,12 @@
       final DN baseDN = entry.getKey();
       for (Integer serverId : entry.getValue())
       {
-        final ServerState previousSS = previousCookie.get(baseDN);
-        final CSN csn = previousSS != null ? previousSS.getCSN(serverId) : null;
+        final CSN csn = mediumConsistencyRUV.getCSN(baseDN, serverId);
         ensureCursorExists(baseDN, serverId, csn);
       }
 
       ServerState latestKnownState = domainDB.getDomainNewestCSNs(baseDN);
-      mediumConsistencyPoint.update(baseDN, latestKnownState);
+      lastSeenUpdates.update(baseDN, latestKnownState);
     }
 
     crossDomainDBCursor = newCompositeDBCursor();
@@ -206,14 +227,11 @@
       final UpdateMsg record = crossDomainDBCursor.getRecord();
       if (!record.getCSN().equals(newestRecord.getCSN()))
       {
-        // TODO JNR remove
-        throw new RuntimeException("They do not equal! recordCSN="
-            + record.getCSN() + " newestRecordCSN=" + newestRecord.getCSN());
+        // TODO JNR i18n safety check, should never happen
+        throw new ChangelogException(Message.raw("They do not equal! recordCSN="
+            + record.getCSN() + " newestRecordCSN=" + newestRecord.getCSN()));
       }
-      // TODO JNR is it possible to use the following line instead?
-      // previousCookie.update(newestRecord.getBaseDN(), record.getCSN());
-      // TODO JNR would this mean updating the if above?
-      previousCookie.update(crossDomainDBCursor.getData(), record.getCSN());
+      mediumConsistencyRUV.update(newestRecord.getBaseDN(), record.getCSN());
       crossDomainDBCursor.next();
     }
 
@@ -281,7 +299,7 @@
     }
     catch (ChangelogException e)
     {
-      // TODO Auto-generated catch block
+      // TODO JNR error message i18n
       if (debugEnabled())
         TRACER.debugCaught(DebugLogLevel.ERROR, e);
       return;
@@ -310,14 +328,14 @@
         final DN baseDN = crossDomainDBCursor.getData();
         // FIXME problem: what if the serverId is not part of the ServerState?
         // right now, thread will be blocked
-        if (!mediumConsistencyPoint.cover(baseDN, csn))
+        if (!canMoveForwardMediumConsistencyPoint(baseDN))
         {
           // the oldest record to insert is newer than the medium consistency
           // point. Let's wait for a change that can be published.
           synchronized (this)
           {
             // double check to protect against a missed call to notify()
-            if (!mediumConsistencyPoint.cover(baseDN, csn))
+            if (!canMoveForwardMediumConsistencyPoint(baseDN))
             {
               wait();
               // loop to check if changes older than the medium consistency
@@ -329,11 +347,11 @@
 
         // OK, the oldest change is older than the medium consistency point
         // let's publish it to the CNIndexDB
+        final String previousCookie = mediumConsistencyRUV.toString();
         final ChangeNumberIndexRecord record =
-            new ChangeNumberIndexRecord(previousCookie.toString(), baseDN, csn);
+            new ChangeNumberIndexRecord(previousCookie, baseDN, csn);
         changelogDB.getChangeNumberIndexDB().addRecord(record);
-        // update, so it becomes the previous cookie for the next change
-        previousCookie.update(baseDN, csn);
+        moveForwardMediumConsistencyPoint(csn, baseDN);
 
         // advance cursor, success/failure will be checked later
         crossDomainDBCursor.next();
@@ -351,16 +369,24 @@
     }
   }
 
+  private void moveForwardMediumConsistencyPoint(final CSN csn, final DN baseDN)
+  {
+    // update, so it becomes the previous cookie for the next change
+    mediumConsistencyRUV.update(baseDN, csn);
+    mediumConsistencyCSN = csn;
+  }
+
   private void createNewCursors() throws ChangelogException
   {
     if (!newCursors.isEmpty())
     {
       boolean newCursorAdded = false;
-      for (Iterator<Entry<Integer, DN>> iter = newCursors.entrySet().iterator();
+      for (Iterator<Entry<CSN, DN>> iter = newCursors.entrySet().iterator();
           iter.hasNext();)
       {
-        final Entry<Integer, DN> entry = iter.next();
-        if (!ensureCursorExists(entry.getValue(), entry.getKey(), null))
+        final Entry<CSN, DN> entry = iter.next();
+        final CSN csn = entry.getKey();
+        if (!ensureCursorExists(entry.getValue(), csn.getServerId(), null))
         {
           newCursorAdded = true;
         }

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