[jbosscache-commits] JBoss Cache SVN: r7920 - core/trunk/src/main/java/org/jboss/cache/util/concurrent/locks.

[jbosscache-commits at lists.jboss.org]

Author: manik.surtani at jboss.com
Date: 2009-03-19 05:59:50 -0400 (Thu, 19 Mar 2009)
New Revision: 7920

Modified:
   core/trunk/src/main/java/org/jboss/cache/util/concurrent/locks/PerElementLockContainer.java
Log:
JBCACHE-1494 - better impl

Modified: core/trunk/src/main/java/org/jboss/cache/util/concurrent/locks/PerElementLockContainer.java
===================================================================
--- core/trunk/src/main/java/org/jboss/cache/util/concurrent/locks/PerElementLockContainer.java	2009-03-19 08:35:15 UTC (rev 7919)
+++ core/trunk/src/main/java/org/jboss/cache/util/concurrent/locks/PerElementLockContainer.java	2009-03-19 09:59:50 UTC (rev 7920)
@@ -17,9 +17,10 @@
 
    protected abstract Lock newLock();
 
-   public Lock getLock(E object)
+   public final Lock getLock(E object)
    {
-      Lock l = newLock();
+      Lock l = locks.get(object);
+      if (l == null) l = newLock();
       Lock tmp = locks.putIfAbsent(object, l);
       if (tmp != null) l = tmp;
       return l;
@@ -53,30 +54,51 @@
 
    public void acquireLock(E object)
    {
-      Lock l = getLock(object);
-      l.lock();
-      // now check that the lock is still valid...
-      if (l != locks.get(object))
+      while (true)
       {
-         // we acquired the wrong lock!
-         l.unlock();
-         acquireLock(object);
+         Lock lock = getLock(object);
+         lock.lock();
+         // now check that the lock is still valid...
+         Lock currentLock = locks.putIfAbsent(object, lock);
+         if (currentLock != null && lock != currentLock)
+         {
+            // we acquired the wrong lock!
+            lock.unlock();
+         }
+         else
+         {
+            // we got the right lock!
+            break;
+         }
       }
    }
 
    public boolean acquireLock(E object, long timeout, TimeUnit unit) throws InterruptedException
    {
-      Lock l = getLock(object);
-      boolean result = l.tryLock(timeout, unit);
-
-      // now check that the lock is still valid...
-      if (result && l != locks.get(object))
+      while (true)
       {
-         // we acquired the wrong lock!
-         l.unlock();
-         result = acquireLock(object, timeout, unit);
+         Lock lock = getLock(object);
+         if (lock.tryLock(timeout, unit))
+         {
+            // now check that the lock is still valid...
+            Lock currentLock = locks.putIfAbsent(object, lock);
+            if (currentLock != null && lock != currentLock)
+            {
+               // we acquired the wrong lock!
+               lock.unlock();
+            }
+            else
+            {
+               // we got the right lock!
+               return true;
+            }
+         }
+         else
+         {
+            // if we haven't acquired the lock (i.e., timed out) return false
+            return false;
+         }
       }
-      return result;
    }
 
    public void releaseLock(E object)