svn commit: r1712785 - /jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/segment/SegmentNodeStore.java

[al...@apache.org]

Author: alexparvulescu
Date: Thu Nov  5 14:36:06 2015
New Revision: 1712785

URL: http://svn.apache.org/viewvc?rev=1712785&view=rev
Log:
OAK-3588 SegmentNodeStore allow tweaking of lock fairness

Modified:
    jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/segment/SegmentNodeStore.java

Modified: jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/segment/SegmentNodeStore.java
URL: http://svn.apache.org/viewvc/jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/segment/SegmentNodeStore.java?rev=1712785&r1=1712784&r2=1712785&view=diff
==============================================================================
--- jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/segment/SegmentNodeStore.java (original)
+++ jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/segment/SegmentNodeStore.java Thu Nov  5 14:36:06 2015
@@ -90,7 +90,7 @@ public class SegmentNodeStore implements
      * Only a single local commit is allowed at a time. When such
      * a commit is in progress, no external updates will be seen.
      */
-    private final Semaphore commitSemaphore = new Semaphore(1);
+    private final Semaphore commitSemaphore;
 
     private long maximumBackoff = MILLISECONDS.convert(10, SECONDS);
 
@@ -101,6 +101,12 @@ public class SegmentNodeStore implements
     private int checkpointsLockWaitTime = Integer.getInteger(
             "oak.checkpoints.lockWaitTime", 10);
 
+    /**
+     * Flag controlling the commit lock fairness
+     */
+    private boolean commitFairLock = Boolean
+            .getBoolean("oak.segmentNodeStore.commitFairLock");
+
     @Nonnull
     public static SegmentNodeStoreBuilder newSegmentNodeStore(
             @Nonnull SegmentStore store) {
@@ -117,6 +123,10 @@ public class SegmentNodeStore implements
     }
 
     SegmentNodeStore(SegmentStore store, boolean internal) {
+        if (commitFairLock) {
+            log.info("initializing SegmentNodeStore with the commitFairLock option enabled.");
+        }
+        this.commitSemaphore = new Semaphore(1, commitFairLock);
         this.store = store;
         this.head = new AtomicReference<SegmentNodeState>(store.getHead());
         this.changeDispatcher = new ChangeDispatcher(getRoot());