Author: mszefler
Date: Wed Jun 20 10:41:25 2007
New Revision: 549168
URL: http://svn.apache.org/viewvc?view=rev&rev=549168
Log:
Added NStateLatch for hydrationlatch.
Added:
incubator/ode/trunk/bpel-runtime/src/main/java/org/apache/ode/bpel/engine/NStateLatch.java
(with props)
Added:
incubator/ode/trunk/bpel-runtime/src/main/java/org/apache/ode/bpel/engine/NStateLatch.java
URL:
http://svn.apache.org/viewvc/incubator/ode/trunk/bpel-runtime/src/main/java/org/apache/ode/bpel/engine/NStateLatch.java?view=auto&rev=549168
==============================================================================
---
incubator/ode/trunk/bpel-runtime/src/main/java/org/apache/ode/bpel/engine/NStateLatch.java
(added)
+++
incubator/ode/trunk/bpel-runtime/src/main/java/org/apache/ode/bpel/engine/NStateLatch.java
Wed Jun 20 10:41:25 2007
@@ -0,0 +1,110 @@
+package org.apache.ode.bpel.engine;
+
+import java.util.concurrent.locks.Condition;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
+
+/**
+ * An N state synchronization latch useful for implementing
hydration/dehydration. The
+ * latch functions as follows. At any time, the latch is in one of N states
and has a
+ * count. Clients can "latch" and "release" the latch, which
increments/decrements the
+ * count; however, when latching, a state must be specified. If the state does
not match
+ * the current state, the latch blocks until the count is zero. Essentially,
the latch
+ * can change state only when the count is zero. Every time the latch changes
state an
+ * optional [EMAIL PROTECTED] Runnable} corresponding to the new state is
executed.
+ *
+ *
+ * @author Maciej Szefler ( m s z e f l e r @ g m a i l . c o m )
+ *
+ */
+public class NStateLatch {
+
+ /** Current state. */
+ private int _state = -1;
+
+ /** Current depth (i.e. number of enter() calls) */
+ private int _depth = 0;
+
+ /** Action for state transition ?-->i */
+ protected Runnable _transitions[];
+
+ /** Synchronization lock .*/
+ private Lock _lock;
+
+ /** _depth == 0 condition. */
+ private Condition _depth0;
+
+ private boolean _transitioning = false;
+
+ /**
+ * Constructor, the array of [EMAIL PROTECTED] Runnable}s defines the
number of states and the transition
+ * actions.
+ * @param transitions action to perform when entering state x.
+ */
+ public NStateLatch(Runnable [] transitions) {
+ _transitions = transitions;
+ _lock = new ReentrantLock();
+ _depth0 = _lock.newCondition();
+ }
+
+ public void latch(int state) {
+ if (state >= _transitions.length || state < 0)
+ throw new IllegalArgumentException("Invalid state.");
+
+ _lock.lock();
+ try {
+
+ if (_transitioning )
+ throw new IllegalStateException("Manipulating latch from
transition. ");
+
+ if (_state != state) {
+ // wait for the depth to become 0
+ while (_depth != 0)
+ _depth0.awaitUninterruptibly();
+
+ if (_state != state) {
+ if (_transitions[state] != null)
+ try {
+ _transitioning = true;
+ _transitions[state].run();
+ } catch (Throwable t) {
+ t.printStackTrace();
+ } finally {
+ _transitioning = false;
+ }
+
+
+ _state = state;
+
+ }
+ }
+
+ _depth ++;
+
+
+ } finally {
+ _lock.unlock();
+ }
+ }
+
+ public void release(int state) {
+ _lock.lock();
+ try {
+
+ if (_transitioning )
+ throw new IllegalStateException("Manipulating latch from
transition. ");
+
+ if (_state != state)
+ throw new IllegalStateException("Wrong state.");
+ if (_depth <= 0)
+ throw new IllegalStateException("Too many release() calls.");
+
+ _depth --;
+
+ if (_depth == 0)
+ _depth0.signal();
+ } finally {
+ _lock.unlock();
+ }
+ }
+}
Propchange:
incubator/ode/trunk/bpel-runtime/src/main/java/org/apache/ode/bpel/engine/NStateLatch.java
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svn:eol-style = native
