ozeigermann 2005/01/07 15:33:24
Modified: transaction/src/java/org/apache/commons/transaction/locking
ReadWriteLockManager.java GenericLock.java
ReadWriteLock.java
Log:
Made write lock preferred over read lock like one would expect from a
read/write lock
Revision Changes Path
1.3 +8 -6
jakarta-commons/transaction/src/java/org/apache/commons/transaction/locking/ReadWriteLockManager.java
Index: ReadWriteLockManager.java
===================================================================
RCS file:
/home/cvs/jakarta-commons/transaction/src/java/org/apache/commons/transaction/locking/ReadWriteLockManager.java,v
retrieving revision 1.2
retrieving revision 1.3
diff -u -r1.2 -r1.3
--- ReadWriteLockManager.java 17 Dec 2004 00:21:15 -0000 1.2
+++ ReadWriteLockManager.java 7 Jan 2005 23:33:24 -0000 1.3
@@ -97,7 +97,8 @@
* will be thrown when the lock can not be acquired
*/
public void readLock(Object ownerId, Object resourceId) throws
LockException {
- lock(ownerId, resourceId, ReadWriteLock.READ_LOCK, true);
+ lock(ownerId, resourceId, ReadWriteLock.READ_LOCK,
GenericLock.COMPATIBILITY_REENTRANT,
+ false, globalTimeoutMSecs);
}
/**
@@ -116,7 +117,8 @@
* will be thrown when the lock can not be acquired
*/
public void writeLock(Object ownerId, Object resourceId) throws
LockException {
- lock(ownerId, resourceId, ReadWriteLock.WRITE_LOCK, true);
+ lock(ownerId, resourceId, ReadWriteLock.WRITE_LOCK,
GenericLock.COMPATIBILITY_REENTRANT,
+ true, globalTimeoutMSecs);
}
protected GenericLock createLock(Object resourceId) {
1.9 +15 -4
jakarta-commons/transaction/src/java/org/apache/commons/transaction/locking/GenericLock.java
Index: GenericLock.java
===================================================================
RCS file:
/home/cvs/jakarta-commons/transaction/src/java/org/apache/commons/transaction/locking/GenericLock.java,v
retrieving revision 1.8
retrieving revision 1.9
diff -u -r1.8 -r1.9
--- GenericLock.java 7 Jan 2005 13:52:42 -0000 1.8
+++ GenericLock.java 7 Jan 2005 23:33:24 -0000 1.9
@@ -194,6 +194,17 @@
}
/**
+ * Tries to blockingly acquire a lock which can be preferred.
+ *
+ * @see #acquire(Object, int, boolean, int, boolean, long)
+ */
+ public synchronized boolean acquire(Object ownerId, int targetLockLevel,
boolean preferred,
+ long timeoutMSecs) throws InterruptedException {
+ return acquire(ownerId, targetLockLevel, true,
COMPATIBILITY_REENTRANT, preferred,
+ timeoutMSecs);
+ }
+
+ /**
* Tries to acquire a certain lock level on this lock. Does the same as
* [EMAIL PROTECTED]
org.apache.commons.transaction.locking.MultiLevelLock#acquire(java.lang.Object,
int, boolean, boolean, long)}
* except that it allows for different compatibility settings. There is
an
1.3 +9 -7
jakarta-commons/transaction/src/java/org/apache/commons/transaction/locking/ReadWriteLock.java
Index: ReadWriteLock.java
===================================================================
RCS file:
/home/cvs/jakarta-commons/transaction/src/java/org/apache/commons/transaction/locking/ReadWriteLock.java,v
retrieving revision 1.2
retrieving revision 1.3
diff -u -r1.2 -r1.3
--- ReadWriteLock.java 13 Dec 2004 10:51:40 -0000 1.2
+++ ReadWriteLock.java 7 Jan 2005 23:33:24 -0000 1.3
@@ -32,7 +32,9 @@
* Reads are shared which means there can be any number of concurrent read
* accesses allowed by this lock. Writes are exclusive. This means when
there is
* a write access no other access neither read nor write are allowed by this
- * lock. <br>
+ * lock. Additionally, writes are preferred over reads in order to avoid
starvation. The idea
+ * is that there are many readers, but few writers and if things work out
bad the writer would
+ * never be served at all. That's why it is preferred.<br>
* <br>
* Calls to both [EMAIL PROTECTED] #acquireRead(Object, long)}and
* [EMAIL PROTECTED] #acquireWrite(Object, long)}are blocking and reentrant.
Blocking
@@ -80,7 +82,7 @@
* when the thread waiting on this method is interrupted
*/
public boolean acquireRead(Object ownerId, long timeoutMSecs) throws
InterruptedException {
- return acquire(ownerId, READ_LOCK, true, true, timeoutMSecs);
+ return acquire(ownerId, READ_LOCK, false, timeoutMSecs);
}
/**
@@ -98,6 +100,6 @@
* when the thread waiting on this method is interrupted
*/
public boolean acquireWrite(Object ownerId, long timeoutMSecs) throws
InterruptedException {
- return acquire(ownerId, WRITE_LOCK, true, true, timeoutMSecs);
+ return acquire(ownerId, WRITE_LOCK, true, timeoutMSecs);
}
}
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