Author: rdonkin
Date: Mon Dec 1 11:35:27 2008
New Revision: 722193
URL: http://svn.apache.org/viewvc?rev=722193&view=rev
Log:
https://issues.apache.org/jira/browse/MIME4J-89 Improve thread synchronization
in MultiReferenceStorage. Contributed by Markus Wiederkehr MIME4J-89.
Modified:
james/mime4j/trunk/src/main/java/org/apache/james/mime4j/message/storage/MultiReferenceStorage.java
Modified:
james/mime4j/trunk/src/main/java/org/apache/james/mime4j/message/storage/MultiReferenceStorage.java
URL:
http://svn.apache.org/viewvc/james/mime4j/trunk/src/main/java/org/apache/james/mime4j/message/storage/MultiReferenceStorage.java?rev=722193&r1=722192&r2=722193&view=diff
==============================================================================
---
james/mime4j/trunk/src/main/java/org/apache/james/mime4j/message/storage/MultiReferenceStorage.java
(original)
+++
james/mime4j/trunk/src/main/java/org/apache/james/mime4j/message/storage/MultiReferenceStorage.java
Mon Dec 1 11:35:27 2008
@@ -50,6 +50,7 @@
*
* @param storage
* storage back-end that should be reference counted.
+ * @throws IllegalArgumentException when storage is null
*/
public MultiReferenceStorage(Storage storage) {
if (storage == null)
@@ -66,11 +67,8 @@
* if the reference counter is zero which implies that the
* backing storage has already been deleted.
*/
- public synchronized void addReference() {
- if (referenceCounter == 0)
- throw new IllegalStateException("storage has been deleted");
-
- referenceCounter++;
+ public void addReference() {
+ incrementCounter();
}
/**
@@ -79,14 +77,13 @@
* <p>
* A client that holds a reference to this object must make sure not to
* invoke this method a second time.
+ *
+ * @throws IllegalStateException
+ * if the reference counter is zero which implies that the
+ * backing storage has already been deleted.
*/
- public synchronized void delete() {
- if (referenceCounter == 0)
- return;
-
- referenceCounter--;
-
- if (referenceCounter == 0) {
+ public void delete() {
+ if (decrementCounter()) {
storage.delete();
}
}
@@ -100,4 +97,27 @@
return storage.getInputStream();
}
+ /**
+ * Synchronized increment of reference count.
+ */
+ private synchronized void incrementCounter() {
+ if (referenceCounter == 0)
+ throw new IllegalStateException("storage has been deleted");
+
+ referenceCounter++;
+ }
+
+ /**
+ * Synchronized decrement of reference count.
+ * @return true when counter has reached zero,
+ * false otherwise
+ * @throws IllegalArgumentException when counter
+ * is already zero
+ */
+ private synchronized boolean decrementCounter() {
+ if (referenceCounter == 0)
+ throw new IllegalStateException("storage has been deleted");
+
+ return --referenceCounter == 0;
+ }
}
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