[jboss-cvs] jboss-cache/src/main/org/jboss/cache/lock ReadWriteLockWithUpgrade.java

[Ben W. <bw...@us...>]

  User: bwang00 
  Date: 04/04/24 14:10:25

  Modified:    src/main/org/jboss/cache/lock ReadWriteLockWithUpgrade.java
  Log:
  Bug fix when upgrade lock failed and next write lock would fail as well.
  
  Revision  Changes    Path
  1.5       +15 -4     jboss-cache/src/main/org/jboss/cache/lock/ReadWriteLockWithUpgrade.java
  
  Index: ReadWriteLockWithUpgrade.java
  ===================================================================
  RCS file: /cvsroot/jboss/jboss-cache/src/main/org/jboss/cache/lock/ReadWriteLockWithUpgrade.java,v
  retrieving revision 1.4
  retrieving revision 1.5
  diff -u -r1.4 -r1.5
  --- ReadWriteLockWithUpgrade.java	24 Apr 2004 18:57:20 -0000	1.4
  +++ ReadWriteLockWithUpgrade.java	24 Apr 2004 21:10:25 -0000	1.5
  @@ -109,7 +109,8 @@
      }
   
      /**
  -    * Attempt to obtain an upgrade to writer lock.
  +    * Attempt to obtain an upgrade to writer lock. If successful, the read lock is upgraded to
  +    * write lock. If fails, the owner retains the read lock.
       *
       * @param msecs Time to wait in millisecons.
       * @return Sync object. Null if not successful or timeout.
  @@ -138,8 +139,16 @@
            readerLock_.release();
   //      log("upgradeLock(): readerLock released");
            try {
  -            if (!writerLock_.attempt(msecs)) return null;
  -            ;
  +            if (!writerLock_.attempt(msecs)) {
  +               synchronized (writerLock_) { // need to roll it back.
  +                  waitingUpgrader_--;
  +               }
  +               if(!readerLock_.attempt(msecs)) {
  +                  throw new IllegalStateException("ReadWriteLockWithUpgrade.upgradeLockAttempt():" +
  +                        " failed to upgrade to write lock and also failed to re-obtain the read lock");
  +               }
  +               return null;
  +            }
            } catch (InterruptedException ex) {
               return null;
            }
  @@ -446,8 +455,10 @@
               if (msecs <= 0) {
                  // Upgrade thread has prioirty.
                  if (waitingUpgrader_ != 0) {
  -                  if (upgraderLocal_.get() != null)
  +                  if (upgraderLocal_.get() != null) {
  +                     log_.info("attempt(): upgrade to write lock");
                        return startWrite();
  +                  }
                     else
                        return false;
                  } else