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ICU-10097 Replace ICURWLock implementation with JDK's ReentrantReadWriteLock. At the same time, disabled the stats collection (never used by ICU library consumers) by default.
X-SVN-Rev: 33543
This commit is contained in:
Yoshito Umaoka
parent
4524c8c33d
commit
10f1e3259e
4 changed files with 43 additions and 137 deletions
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@ -1,19 +1,23 @@
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/**
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*******************************************************************************
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* Copyright (C) 2001-2006, International Business Machines Corporation and *
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* Copyright (C) 2001-2013, International Business Machines Corporation and *
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* others. All Rights Reserved. *
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*******************************************************************************
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*/
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package com.ibm.icu.impl;
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// See Allan Holub's 1999 column in JavaWorld, and Doug Lea's code for RWLocks with writer preference.
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import java.util.concurrent.locks.ReentrantReadWriteLock;
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/**
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* <p>A simple Reader/Writer lock. This assumes that there will
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* be little writing contention. It also doesn't allow
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* active readers to acquire and release a write lock, or
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* deal with priority inversion issues.</p>
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* <p>A Reader/Writer lock originally written for ICU service
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* implementation. The internal implementation was replaced
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* with the JDK's stock read write lock (ReentrantReadWriteLock)
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* for ICU 52.</p>
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*
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* <p>This assumes that there will be little writing contention.
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* It also doesn't allow active readers to acquire and release
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* a write lock, or deal with priority inversion issues.</p>
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*
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* <p>Access to the lock should be enclosed in a try/finally block
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* in order to ensure that the lock is always released in case of
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@ -31,13 +35,9 @@ package com.ibm.icu.impl;
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* to return statistics on the use of the lock.</p>
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*/
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public class ICURWLock {
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private Object writeLock = new Object();
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private Object readLock = new Object();
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private int wwc; // waiting writers
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private int rc; // active readers, -1 if there's an active writer
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private int wrc; // waiting readers
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private ReentrantReadWriteLock rwl = new ReentrantReadWriteLock();
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private Stats stats = new Stats(); // maybe don't init to start...
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private Stats stats = null;
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/**
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* Internal class used to gather statistics on the RWLock.
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@ -120,84 +120,6 @@ public class ICURWLock {
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return stats == null ? null : new Stats(stats);
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}
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// utilities
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private synchronized boolean gotRead() {
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++rc;
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if (stats != null) {
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++stats._rc;
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if (rc > 1) ++stats._mrc;
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}
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return true;
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}
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private synchronized boolean getRead() {
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if (rc >= 0 && wwc == 0) {
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return gotRead();
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}
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++wrc;
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return false;
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}
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private synchronized boolean retryRead() {
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if (stats != null) ++stats._wrc;
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if (rc >= 0 && wwc == 0) {
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--wrc;
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return gotRead();
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}
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return false;
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}
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private synchronized boolean finishRead() {
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if (rc > 0) {
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return (0 == --rc && wwc > 0);
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}
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throw new IllegalStateException("no current reader to release");
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}
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private synchronized boolean gotWrite() {
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rc = -1;
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if (stats != null) {
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++stats._wc;
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}
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return true;
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}
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private synchronized boolean getWrite() {
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if (rc == 0) {
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return gotWrite();
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}
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++wwc;
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return false;
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}
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private synchronized boolean retryWrite() {
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if (stats != null) ++stats._wwc;
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if (rc == 0) {
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--wwc;
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return gotWrite();
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}
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return false;
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}
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private static final int NOTIFY_NONE = 0;
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private static final int NOTIFY_WRITERS = 1;
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private static final int NOTIFY_READERS = 2;
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private synchronized int finishWrite() {
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if (rc < 0) {
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rc = 0;
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if (wwc > 0) {
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return NOTIFY_WRITERS;
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} else if (wrc > 0) {
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return NOTIFY_READERS;
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} else {
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return NOTIFY_NONE;
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}
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}
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throw new IllegalStateException("no current writer to release");
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}
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/**
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* <p>Acquire a read lock, blocking until a read lock is
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* available. Multiple readers can concurrently hold the read
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@ -209,20 +131,18 @@ public class ICURWLock {
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* releaseRead when done (for example, in a finally block).</p>
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*/
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public void acquireRead() {
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if (!getRead()) {
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for (;;) {
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try {
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synchronized (readLock) {
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readLock.wait();
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}
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if (retryRead()) {
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return;
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}
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if (stats != null) { // stats is null by default
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synchronized (this) {
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stats._rc++;
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if (rwl.getReadLockCount() > 0) {
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stats._mrc++;
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}
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catch (InterruptedException e) {
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if (rwl.isWriteLocked()) {
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stats._wrc++;
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}
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}
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}
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rwl.readLock().lock();
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}
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/**
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@ -234,11 +154,7 @@ public class ICURWLock {
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* controlled by acquireRead.</p>
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*/
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public void releaseRead() {
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if (finishRead()) {
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synchronized (writeLock) {
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writeLock.notify();
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}
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}
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rwl.readLock().unlock();
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}
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/**
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@ -253,20 +169,15 @@ public class ICURWLock {
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* block).<p>
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*/
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public void acquireWrite() {
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if (!getWrite()) {
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for (;;) {
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try {
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synchronized (writeLock) {
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writeLock.wait();
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}
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if (retryWrite()) {
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return;
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}
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}
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catch (InterruptedException e) {
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if (stats != null) { // stats is null by default
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synchronized (this) {
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stats._wc++;
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if (rwl.getReadLockCount() > 0 || rwl.isWriteLocked()) {
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stats._wwc++;
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}
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}
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}
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rwl.writeLock().lock();
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}
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/**
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@ -279,19 +190,6 @@ public class ICURWLock {
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* acquireWrite.</p>
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*/
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public void releaseWrite() {
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switch (finishWrite()) {
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case NOTIFY_WRITERS:
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synchronized (writeLock) {
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writeLock.notify();
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}
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break;
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case NOTIFY_READERS:
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synchronized (readLock) {
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readLock.notifyAll();
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}
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break;
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case NOTIFY_NONE:
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break;
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}
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rwl.writeLock().unlock();
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}
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}
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@ -1,6 +1,6 @@
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/**
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*******************************************************************************
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* Copyright (C) 2001-2011, International Business Machines Corporation and *
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* Copyright (C) 2001-2013, International Business Machines Corporation and *
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* others. All Rights Reserved. *
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*******************************************************************************
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*/
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@ -959,8 +959,10 @@ public class ICUService extends ICUNotifier {
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}
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/**
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* Return a string describing the statistics for this service.
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* This also resets the statistics. Used for debugging purposes.
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* When the statistics for this service is already enabled,
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* return the log and resets he statistics.
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* When the statistics is not enabled, this method enable
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* the statistics. Used for debugging purposes.
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*/
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public String stats() {
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ICURWLock.Stats stats = factoryLock.resetStats();
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@ -1,6 +1,6 @@
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/**
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*******************************************************************************
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* Copyright (C) 2001-2010, International Business Machines Corporation and *
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* Copyright (C) 2001-2013, International Business Machines Corporation and *
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* others. All Rights Reserved. *
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*******************************************************************************
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*/
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@ -879,6 +879,8 @@ public class ICUServiceTest extends TestFmwk
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// ICURWLock
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ICURWLock rwlock = new ICURWLock();
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rwlock.resetStats();
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rwlock.acquireRead();
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rwlock.releaseRead();
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@ -896,7 +898,7 @@ public class ICUServiceTest extends TestFmwk
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rwlock.releaseRead();
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errln("no error thrown");
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}
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catch (IllegalStateException e) {
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catch (Exception e) {
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logln("OK: " + e.getMessage());
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}
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@ -904,7 +906,7 @@ public class ICUServiceTest extends TestFmwk
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rwlock.releaseWrite();
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errln("no error thrown");
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}
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catch (IllegalStateException e) {
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catch (Exception e) {
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logln("OK: " + e.getMessage());
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}
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@ -1,6 +1,6 @@
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/**
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*******************************************************************************
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* Copyright (C) 2001-2010, International Business Machines Corporation and *
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* Copyright (C) 2001-2013, International Business Machines Corporation and *
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* others. All Rights Reserved. *
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*******************************************************************************
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*/
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@ -371,6 +371,7 @@ public class ICUServiceThreadTest extends TestFmwk
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stableService = new ICULocaleService();
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registerFactories(stableService, getFactoryCollection(50));
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}
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if (PRINTSTATS) stableService.stats(); // Enable the stats collection
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return stableService;
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}
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private ICUService stableService;
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@ -413,6 +414,7 @@ public class ICUServiceThreadTest extends TestFmwk
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// run register/unregister on a service
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public void Test03_ConcurrentRegUnreg() {
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ICUService service = new ICULocaleService();
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if (PRINTSTATS) service.stats(); // Enable the stats collection
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for (int i = 0; i < 5; ++i) {
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new RegisterFactoryThread("[" + i + "]", service, 0, this).start();
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}
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@ -425,6 +427,7 @@ public class ICUServiceThreadTest extends TestFmwk
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public void Test04_WitheringService() {
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ICUService service = new ICULocaleService();
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if (PRINTSTATS) service.stats(); // Enable the stats collection
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Collection fc = getFactoryCollection(50);
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registerFactories(service, fc);
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@ -452,6 +455,7 @@ public class ICUServiceThreadTest extends TestFmwk
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// run for ten seconds
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public void Test05_ConcurrentEverything() {
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ICUService service = new ICULocaleService();
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if (PRINTSTATS) service.stats(); // Enable the stats collection
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new RegisterFactoryThread("", service, 500, this).start();
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