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-rw-r--r--java/JACE/Concurrency/RWMutex.java268
1 files changed, 0 insertions, 268 deletions
diff --git a/java/JACE/Concurrency/RWMutex.java b/java/JACE/Concurrency/RWMutex.java
deleted file mode 100644
index abb30ce3bc8..00000000000
--- a/java/JACE/Concurrency/RWMutex.java
+++ /dev/null
@@ -1,268 +0,0 @@
-package JACE.Concurrency;
-
-import java.util.*;
-import JACE.ASX.*;
-
-/**
- * A read/write lock allows multiple
- * readers or a single writer to access the guarded element.
- * <P>
- * <EM>This class does not support recursive semantics.</EM>
- */
-public class RWMutex extends LockAdapter
-{
- public synchronized int tryAcquire ()
- {
- if (referenceCount_ == 0) {
- referenceCount_ = -1;
- setOwner ();
- return AbstractLock.SUCCESS;
- } else
- return AbstractLock.FAILURE;
- }
-
- public synchronized int tryAcquireRead ()
- {
- if (referenceCount_ > -1 && waiters_.size () == 0) {
- referenceCount_++;
- setOwner ();
- return AbstractLock.SUCCESS;
- } else
- return AbstractLock.FAILURE;
- }
-
- public int acquire(TimeValue timeout)
- throws TimeoutException, InterruptedException
- {
- return acquireWrite(timeout);
- }
-
- public void waitUntilIsOwner (RWWaitObject waitObj, TimeValue timeout)
- throws TimeoutException, InterruptedException
- {
- boolean exceptionOccured = true;
- try {
- sleepHook ();
- synchronized (waitObj) {
- waitObj.timedWait (timeout);
- }
- exceptionOccured = false;
- } finally {
-
- synchronized (this) {
-
- if (exceptionOccured) {
- if (!waiters_.removeElement (waitObj)) {
- setOwner ();
- release ();
- }
- } else
- setOwner();
- }
- }
- }
-
- public int acquireRead(TimeValue timeout)
- throws TimeoutException, InterruptedException
- {
- RWWaitObject waitObj = null;
-
- synchronized (this) {
-
- if (referenceCount_ > -1 && waiters_.size () == 0) {
- referenceCount_++;
- setOwner ();
- return AbstractLock.SUCCESS;
- }
-
- waitObj = new RWWaitObject (true);
-
- waiters_.addElement (waitObj);
- }
-
- waitUntilIsOwner (waitObj, timeout);
-
- return AbstractLock.SLEEPHOOK;
- }
-
- public int acquireWrite(TimeValue timeout)
- throws TimeoutException, InterruptedException
- {
- RWWaitObject waitObj = null;
-
- synchronized (this) {
-
- if (referenceCount_ == 0) {
- referenceCount_ = -1;
- setOwner ();
- return AbstractLock.SUCCESS;
- }
-
- waitObj = new RWWaitObject (false);
-
- waiters_.addElement (waitObj);
- }
-
- waitUntilIsOwner (waitObj, timeout);
-
- // When the writer gets here, it has been cleared to go by
- // whatever thread specifically gave control to this writer in
- // release. The referenceCount_ and numberOfWaitingWriters_
- // variables are also adjusted by the releasing thread since
- // it already has a synchronization lock. Not doing that,
- // and then having another synchronized (this) block in here
- // could lead to a situation in which another thread sneaks
- // in inbetween when this thread leaves timedWait and goes to
- // adjust them.
-
- return AbstractLock.SLEEPHOOK;
- }
-
-
- public synchronized int release ()
- {
- if (!isOwner ())
- return AbstractLock.FAILURE;
-
- clearOwner ();
-
- // Releasing a reader.
- if (referenceCount_ > 0) {
- referenceCount_--;
-
- if (referenceCount_ != 0)
- return AbstractLock.SUCCESS;
-
- } else {
- // releasing a writer
- referenceCount_ = 0;
- }
-
- if (waiters_.size () == 0)
- return AbstractLock.SUCCESS;
-
- if (releaseFirstReaders () == 0) {
- RWWaitObject waitObj = (RWWaitObject)waiters_.firstElement ();
- waiters_.removeElementAt (0);
-
- referenceCount_ = -1;
-
- waitObj.condition (true);
- synchronized (waitObj) {
- waitObj.signal ();
- }
- }
-
- return AbstractLock.SUCCESS;
- }
-
- // Releases all waiting readers up to the first waiting writer
- // or the end of the queue. Returns the number of readers
- // released.
- protected int releaseFirstReaders ()
- {
- int releasedReaders = 0;
-
- do {
-
- RWWaitObject waitObj = (RWWaitObject)waiters_.firstElement ();
- if (!waitObj.isReader ())
- break;
-
- waiters_.removeElementAt (0);
-
- referenceCount_++;
- releasedReaders++;
-
- waitObj.condition (true);
- synchronized (waitObj) {
- waitObj.signal ();
- }
-
- } while (waiters_.size () > 0);
-
- return releasedReaders;
- }
-
- public int renew (int requeuePosition,
- JACE.ASX.TimeValue timeout)
- throws InterruptedException,
- TimeoutException
- {
- RWWaitObject waitObj = null;
-
- synchronized (this) {
-
- if (!isOwner ())
- return AbstractLock.FAILURE;
-
- if (requeuePosition == 0 || waiters_.size () == 0)
- return AbstractLock.SUCCESS;
-
- waitObj = new RWWaitObject (referenceCount_ > 0);
-
- if (requeuePosition < 0 || requeuePosition > waiters_.size ()) {
- requeuePosition = waiters_.size ();
- }
-
- waiters_.insertElementAt (waitObj, requeuePosition);
-
- release ();
- }
-
- waitUntilIsOwner (waitObj, timeout);
-
- // When the writer gets here, it has been cleared to go by
- // whatever thread specifically gave control to this writer in
- // release. The referenceCount_ and numberOfWaitingWriters_
- // variables are also adjusted by the releasing thread since
- // it already has a synchronization lock. Not doing that,
- // and then having another synchronized (this) block in here
- // could lead to a situation in which another thread sneaks
- // in inbetween when this thread leaves timedWait and goes to
- // adjust them.
-
- return AbstractLock.SUCCESS;
- }
-
- static class RWWaitObject extends WaitObject
- {
- public RWWaitObject (boolean isReader)
- {
- isReader_ = isReader;
- }
-
- public boolean isReader ()
- {
- return isReader_;
- }
-
- private boolean isReader_ = false;
- }
-
- protected boolean isOwner ()
- {
- return owners_.containsKey (accessorID());
- }
-
- protected void setOwner ()
- {
- owners_.put (accessorID(), this);
- }
-
- protected void clearOwner ()
- {
- owners_.remove (accessorID());
- }
-
- private Vector waiters_ = new Vector ();
-
- private int referenceCount_ = 0;
- // Value is -1 if writer has the lock, else this keeps track of the
- // number of readers holding the lock.
-
- private Hashtable owners_ = new Hashtable ();
-
- private int nestingLevel_ = 0;
-}
-
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