org.xnio.ChannelThreadPools Maven / Gradle / Ivy
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*
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
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*/
package org.xnio;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
import org.jboss.logging.Logger;
/**
* Utility methods for channel thread pools.
*
* @author David M. Lloyd
*/
public final class ChannelThreadPools {
private static final ChannelThread[] NO_THREADS = new ChannelThread[0];
private ChannelThreadPools() {
}
/**
* Create a thread pool using a random load-balancing strategy. This pool access strategy has an O(1) access
* time, using a PRNG to choose the thread.
*
* @param the channel thread type
* @return the thread pool
*/
public static ChannelThreadPool createRandomPool() {
return new Random();
}
/**
* Create a thread pool using a lightest-load algorithm. The thread with the lightest channel load is always
* returned. This pool access strategy has an O(n) access time.
*
* @param the channel thread type
* @return the thread pool
*/
public static ChannelThreadPool createLightestLoadPool() {
return new LightestLoad();
}
/**
* Create a thread pool using a round-robin load-balancing strategy. This pool access strategy has an O(1) access
* time, using a counter to choose the thread.
*
* @param the channel thread type
* @return the thread pool
*/
public static ChannelThreadPool createRoundRobinPool() {
return new RoundRobin();
}
/**
* Create a singleton thread pool. Such a pool always returns the same thread.
*
* @param thread the thread to return
* @param the thread type
* @return the singleton thread pool
*/
public static ChannelThreadPool singleton(final T thread) {
return new Singleton(thread);
}
/**
* Create read threads and add them to a pool. If thread creation fails, then all the added threads will be
* shut down before the method returns.
*
* @param xnio the XNIO provider from which the threads should be created
* @param pool the thread pool to add to
* @param count the number of threads to create
* @param optionMap the option map to apply to the created threads
* @return the passed-in thread pool
* @throws IOException if creation of a thread fails
*/
public static ChannelThreadPool addReadThreadsToPool(Xnio xnio, ChannelThreadPool pool, int count, OptionMap optionMap) throws IOException {
return addReadThreadsToPool(xnio, pool, null, count, optionMap);
}
/**
* Create read threads and add them to a pool. If thread creation fails, then all the added threads will be
* shut down before the method returns.
*
* @param xnio the XNIO provider from which the threads should be created
* @param pool the thread pool to add to
* @param threadGroup the thread group for newly created threads
* @param count the number of threads to create
* @param optionMap the option map to apply to the created threads
* @return the passed-in thread pool
* @throws IOException if creation of a thread fails
*/
public static ChannelThreadPool addReadThreadsToPool(Xnio xnio, ChannelThreadPool pool, ThreadGroup threadGroup, int count, OptionMap optionMap) throws IOException {
boolean ok = false;
final List threads = new ArrayList(count);
try {
for (int i = 0; i < count; i ++) {
final ReadChannelThread thread = xnio.createReadChannelThread(threadGroup, optionMap);
threads.add(thread);
}
ok = true;
} finally {
if (! ok) {
for (ReadChannelThread thread : threads) {
thread.shutdown();
}
}
}
for (ReadChannelThread thread : threads) {
pool.addToPool(thread);
}
return pool;
}
/**
* Create write threads and add them to a pool. If thread creation fails, then all the added threads will be
* shut down before the method returns.
*
* @param xnio the XNIO provider from which the threads should be created
* @param pool the thread pool to add to
* @param count the number of threads to create
* @param optionMap the option map to apply to the created threads
* @return the passed-in thread pool
* @throws IOException if creation of a thread fails
*/
public static ChannelThreadPool addWriteThreadsToPool(Xnio xnio, ChannelThreadPool pool, int count, OptionMap optionMap) throws IOException {
return addWriteThreadsToPool(xnio, pool, null, count, optionMap);
}
/**
* Create write threads and add them to a pool. If thread creation fails, then all the added threads will be
* shut down before the method returns.
*
* @param xnio the XNIO provider from which the threads should be created
* @param pool the thread pool to add to
* @param threadGroup the thread group for newly created threads
* @param count the number of threads to create
* @param optionMap the option map to apply to the created threads
* @return the passed-in thread pool
* @throws IOException if creation of a thread fails
*/
public static ChannelThreadPool addWriteThreadsToPool(Xnio xnio, ChannelThreadPool pool, ThreadGroup threadGroup, int count, OptionMap optionMap) throws IOException {
boolean ok = false;
final List threads = new ArrayList(count);
try {
for (int i = 0; i < count; i ++) {
final WriteChannelThread thread = xnio.createWriteChannelThread(threadGroup, optionMap);
threads.add(thread);
}
ok = true;
} finally {
if (! ok) {
for (WriteChannelThread thread : threads) {
thread.shutdown();
}
}
}
for (WriteChannelThread thread : threads) {
pool.addToPool(thread);
}
return pool;
}
/**
* Shut down a whole thread pool.
*
* @param pool the thread pool
* @see ChannelThread#shutdown()
*/
public static void shutdown(final ChannelThreadPool> pool) {
ChannelThread thread;
while ((thread = pool.getThread()) != null) {
thread.shutdown();
}
}
private static final Logger poolLog = Logger.getLogger("org.xnio.thread-pools");
private abstract static class SimpleThreadPool implements ChannelThreadPool {
private final Set threadSet = new HashSet();
private final ChannelThread.Listener listener = new ChannelThread.Listener() {
@SuppressWarnings("unchecked")
public void handleTerminationInitiated(final ChannelThread thread) {
thread.removeTerminationListener(this);
final Set threadSet = SimpleThreadPool.this.threadSet;
synchronized (threadSet) {
if (threadSet.remove(thread)) {
pool = threadSet.toArray((T[]) new ChannelThread[threadSet.size()]);
}
}
}
public void handleTerminationComplete(final ChannelThread thread) {
}
};
@SuppressWarnings("unchecked")
volatile T[] pool = (T[]) NO_THREADS;
public void addToPool(final T thread) {
poolLog.tracef("Adding thread %s to pool %s", thread, this);
final Set threadSet = this.threadSet;
synchronized (threadSet) {
if (threadSet.add(thread)) {
final T[] pool = this.pool;
final int oldLen = pool.length;
final T[] newPool = Arrays.copyOf(pool, oldLen + 1);
newPool[oldLen] = thread;
thread.addTerminationListener(listener);
this.pool = newPool;
}
}
}
}
private static class RoundRobin extends SimpleThreadPool {
@SuppressWarnings("unused")
private volatile int idx;
@SuppressWarnings("unchecked")
private static final AtomicIntegerFieldUpdater idxUpdater = AtomicIntegerFieldUpdater.newUpdater(RoundRobin.class, "idx");
public T getThread() {
final T[] pool = this.pool;
final int len = pool.length;
if (len == 0) {
return null;
}
return pool[idxUpdater.getAndIncrement(this) % len];
}
}
private static class LightestLoad extends SimpleThreadPool {
public T getThread() {
final T[] pool = this.pool;
final int len = pool.length;
if (len == 0) {
return null;
}
int best = Integer.MAX_VALUE;
int bestIdx = -1;
for (int i = 0; i < len; i++) {
final int load = pool[i].getLoad();
if (load < best) {
bestIdx = i;
}
}
final T thread = pool[bestIdx];
poolLog.tracef("Returning thread %s from pool %s", thread, this);
return thread;
}
}
private static class Random extends SimpleThreadPool {
private final java.util.Random random;
Random() {
this(new java.util.Random());
}
Random(final java.util.Random random) {
this.random = random;
}
public T getThread() {
final T[] pool = this.pool;
final int len = pool.length;
if (len == 0) {
return null;
}
final T thread = pool[random.nextInt(len)];
poolLog.tracef("Returning thread %s from pool %s", thread, this);
return thread;
}
}
private static class Singleton implements ChannelThreadPool {
private final T thread;
Singleton(final T thread) {
this.thread = thread;
}
public T getThread() {
poolLog.tracef("Returning thread %s from pool %s", thread, this);
return thread;
}
public void addToPool(final T thread) {
throw new IllegalArgumentException("Pool is full");
}
}
}
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