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/*
* Copyright 2015 The Netty Project
*
* The Netty Project licenses this file to you under the Apache License,
* version 2.0 (the "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
package io.netty.channel.pool;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.util.concurrent.EventExecutor;
import io.netty.util.concurrent.Future;
import io.netty.util.concurrent.FutureListener;
import io.netty.util.concurrent.Promise;
import io.netty.util.internal.EmptyArrays;
import io.netty.util.internal.OneTimeTask;
import java.nio.channels.ClosedChannelException;
import java.util.ArrayDeque;
import java.util.Queue;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
/**
* {@link ChannelPool} implementation that takes another {@link ChannelPool} implementation and enforce a maximum
* number of concurrent connections.
*/
public final class FixedChannelPool extends SimpleChannelPool {
private static final IllegalStateException FULL_EXCEPTION =
new IllegalStateException("Too many outstanding acquire operations");
private static final TimeoutException TIMEOUT_EXCEPTION =
new TimeoutException("Acquire operation took longer then configured maximum time");
static {
FULL_EXCEPTION.setStackTrace(EmptyArrays.EMPTY_STACK_TRACE);
TIMEOUT_EXCEPTION.setStackTrace(EmptyArrays.EMPTY_STACK_TRACE);
}
public enum AcquireTimeoutAction {
/**
* Create a new connection when the timeout is detected.
*/
NEW,
/**
* Fail the {@link Future} of the acquire call with a {@link TimeoutException}.
*/
FAIL
}
private final EventExecutor executor;
private final long acquireTimeoutNanos;
private final Runnable timeoutTask;
// There is no need to worry about synchronization as everything that modified the queue or counts is done
// by the above EventExecutor.
private final Queue pendingAcquireQueue = new ArrayDeque();
private final int maxConnections;
private final int maxPendingAcquires;
private int acquiredChannelCount;
private int pendingAcquireCount;
private boolean closed;
/**
* Creates a new instance using the {@link ChannelHealthChecker#ACTIVE}.
*
* @param bootstrap the {@link Bootstrap} that is used for connections
* @param handler the {@link ChannelPoolHandler} that will be notified for the different pool actions
* @param maxConnections the numnber of maximal active connections, once this is reached new tries to acquire
* a {@link Channel} will be delayed until a connection is returned to the pool again.
*/
public FixedChannelPool(Bootstrap bootstrap,
ChannelPoolHandler handler, int maxConnections) {
this(bootstrap, handler, maxConnections, Integer.MAX_VALUE);
}
/**
* Creates a new instance using the {@link ChannelHealthChecker#ACTIVE}.
*
* @param bootstrap the {@link Bootstrap} that is used for connections
* @param handler the {@link ChannelPoolHandler} that will be notified for the different pool actions
* @param maxConnections the numnber of maximal active connections, once this is reached new tries to
* acquire a {@link Channel} will be delayed until a connection is returned to the
* pool again.
* @param maxPendingAcquires the maximum number of pending acquires. Once this is exceed acquire tries will
* be failed.
*/
public FixedChannelPool(Bootstrap bootstrap,
ChannelPoolHandler handler, int maxConnections, int maxPendingAcquires) {
this(bootstrap, handler, ChannelHealthChecker.ACTIVE, null, -1, maxConnections, maxPendingAcquires);
}
/**
* Creates a new instance.
*
* @param bootstrap the {@link Bootstrap} that is used for connections
* @param handler the {@link ChannelPoolHandler} that will be notified for the different pool actions
* @param healthCheck the {@link ChannelHealthChecker} that will be used to check if a {@link Channel} is
* still healty when obtain from the {@link ChannelPool}
* @param action the {@link AcquireTimeoutAction} to use or {@code null} if non should be used.
* In this case {@param acquireTimeoutMillis} must be {@code -1}.
* @param acquireTimeoutMillis the time (in milliseconds) after which an pending acquire must complete or
* the {@link AcquireTimeoutAction} takes place.
* @param maxConnections the numnber of maximal active connections, once this is reached new tries to
* acquire a {@link Channel} will be delayed until a connection is returned to the
* pool again.
* @param maxPendingAcquires the maximum number of pending acquires. Once this is exceed acquire tries will
* be failed.
*/
public FixedChannelPool(Bootstrap bootstrap,
ChannelPoolHandler handler,
ChannelHealthChecker healthCheck, AcquireTimeoutAction action,
final long acquireTimeoutMillis,
int maxConnections, int maxPendingAcquires) {
this(bootstrap, handler, healthCheck, action, acquireTimeoutMillis, maxConnections, maxPendingAcquires, true);
}
/**
* Creates a new instance.
*
* @param bootstrap the {@link Bootstrap} that is used for connections
* @param handler the {@link ChannelPoolHandler} that will be notified for the different pool actions
* @param healthCheck the {@link ChannelHealthChecker} that will be used to check if a {@link Channel} is
* still healty when obtain from the {@link ChannelPool}
* @param action the {@link AcquireTimeoutAction} to use or {@code null} if non should be used.
* In this case {@param acquireTimeoutMillis} must be {@code -1}.
* @param acquireTimeoutMillis the time (in milliseconds) after which an pending acquire must complete or
* the {@link AcquireTimeoutAction} takes place.
* @param maxConnections the numnber of maximal active connections, once this is reached new tries to
* acquire a {@link Channel} will be delayed until a connection is returned to the
* pool again.
* @param maxPendingAcquires the maximum number of pending acquires. Once this is exceed acquire tries will
* be failed.
* @param releaseHealthCheck will check channel health before offering back if this parameter set to
* {@code true}.
*/
public FixedChannelPool(Bootstrap bootstrap,
ChannelPoolHandler handler,
ChannelHealthChecker healthCheck, AcquireTimeoutAction action,
final long acquireTimeoutMillis,
int maxConnections, int maxPendingAcquires, final boolean releaseHealthCheck) {
super(bootstrap, handler, healthCheck, releaseHealthCheck);
if (maxConnections < 1) {
throw new IllegalArgumentException("maxConnections: " + maxConnections + " (expected: >= 1)");
}
if (maxPendingAcquires < 1) {
throw new IllegalArgumentException("maxPendingAcquires: " + maxPendingAcquires + " (expected: >= 1)");
}
if (action == null && acquireTimeoutMillis == -1) {
timeoutTask = null;
acquireTimeoutNanos = -1;
} else if (action == null && acquireTimeoutMillis != -1) {
throw new NullPointerException("action");
} else if (action != null && acquireTimeoutMillis < 0) {
throw new IllegalArgumentException("acquireTimeoutMillis: " + acquireTimeoutMillis + " (expected: >= 1)");
} else {
acquireTimeoutNanos = TimeUnit.MILLISECONDS.toNanos(acquireTimeoutMillis);
switch (action) {
case FAIL:
timeoutTask = new TimeoutTask() {
@Override
public void onTimeout(AcquireTask task) {
// Fail the promise as we timed out.
task.promise.setFailure(TIMEOUT_EXCEPTION);
}
};
break;
case NEW:
timeoutTask = new TimeoutTask() {
@Override
public void onTimeout(AcquireTask task) {
// Increment the acquire count and delegate to super to actually acquire a Channel which will
// create a new connetion.
task.acquired();
FixedChannelPool.super.acquire(task.promise);
}
};
break;
default:
throw new Error();
}
}
executor = bootstrap.group().next();
this.maxConnections = maxConnections;
this.maxPendingAcquires = maxPendingAcquires;
}
@Override
public Future acquire(final Promise promise) {
try {
if (executor.inEventLoop()) {
acquire0(promise);
} else {
executor.execute(new OneTimeTask() {
@Override
public void run() {
acquire0(promise);
}
});
}
} catch (Throwable cause) {
promise.setFailure(cause);
}
return promise;
}
private void acquire0(final Promise promise) {
assert executor.inEventLoop();
if (closed) {
promise.setFailure(new IllegalStateException("FixedChannelPooled was closed"));
return;
}
if (acquiredChannelCount < maxConnections) {
assert acquiredChannelCount >= 0;
// We need to create a new promise as we need to ensure the AcquireListener runs in the correct
// EventLoop
Promise p = executor.newPromise();
AcquireListener l = new AcquireListener(promise);
l.acquired();
p.addListener(l);
super.acquire(p);
} else {
if (pendingAcquireCount >= maxPendingAcquires) {
promise.setFailure(FULL_EXCEPTION);
} else {
AcquireTask task = new AcquireTask(promise);
if (pendingAcquireQueue.offer(task)) {
++pendingAcquireCount;
if (timeoutTask != null) {
task.timeoutFuture = executor.schedule(timeoutTask, acquireTimeoutNanos, TimeUnit.NANOSECONDS);
}
} else {
promise.setFailure(FULL_EXCEPTION);
}
}
assert pendingAcquireCount > 0;
}
}
@Override
public Future release(final Channel channel, final Promise promise) {
final Promise p = executor.newPromise();
super.release(channel, p.addListener(new FutureListener() {
@Override
public void operationComplete(Future future) throws Exception {
assert executor.inEventLoop();
if (closed) {
promise.setFailure(new IllegalStateException("FixedChannelPooled was closed"));
return;
}
if (future.isSuccess()) {
decrementAndRunTaskQueue();
promise.setSuccess(null);
} else {
Throwable cause = future.cause();
// Check if the exception was not because of we passed the Channel to the wrong pool.
if (!(cause instanceof IllegalArgumentException)) {
decrementAndRunTaskQueue();
}
promise.setFailure(future.cause());
}
}
}));
return p;
}
private void decrementAndRunTaskQueue() {
--acquiredChannelCount;
// We should never have a negative value.
assert acquiredChannelCount >= 0;
// Run the pending acquire tasks before notify the original promise so if the user would
// try to acquire again from the ChannelFutureListener and the pendingAcquireCount is >=
// maxPendingAcquires we may be able to run some pending tasks first and so allow to add
// more.
runTaskQueue();
}
private void runTaskQueue() {
while (acquiredChannelCount < maxConnections) {
AcquireTask task = pendingAcquireQueue.poll();
if (task == null) {
break;
}
// Cancel the timeout if one was scheduled
ScheduledFuture timeoutFuture = task.timeoutFuture;
if (timeoutFuture != null) {
timeoutFuture.cancel(false);
}
--pendingAcquireCount;
task.acquired();
super.acquire(task.promise);
}
// We should never have a negative value.
assert pendingAcquireCount >= 0;
assert acquiredChannelCount >= 0;
}
// AcquireTask extends AcquireListener to reduce object creations and so GC pressure
private final class AcquireTask extends AcquireListener {
final Promise promise;
final long expireNanoTime = System.nanoTime() + acquireTimeoutNanos;
ScheduledFuture timeoutFuture;
public AcquireTask(Promise promise) {
super(promise);
// We need to create a new promise as we need to ensure the AcquireListener runs in the correct
// EventLoop.
this.promise = executor.newPromise().addListener(this);
}
}
private abstract class TimeoutTask implements Runnable {
@Override
public final void run() {
assert executor.inEventLoop();
long nanoTime = System.nanoTime();
for (;;) {
AcquireTask task = pendingAcquireQueue.peek();
// Compare nanoTime as descripted in the javadocs of System.nanoTime()
//
// See https://docs.oracle.com/javase/7/docs/api/java/lang/System.html#nanoTime()
// See https://github.com/netty/netty/issues/3705
if (task == null || nanoTime - task.expireNanoTime < 0) {
break;
}
pendingAcquireQueue.remove();
--pendingAcquireCount;
onTimeout(task);
}
}
public abstract void onTimeout(AcquireTask task);
}
private class AcquireListener implements FutureListener {
private final Promise originalPromise;
protected boolean acquired;
AcquireListener(Promise originalPromise) {
this.originalPromise = originalPromise;
}
@Override
public void operationComplete(Future future) throws Exception {
assert executor.inEventLoop();
if (closed) {
originalPromise.setFailure(new IllegalStateException("FixedChannelPooled was closed"));
return;
}
if (future.isSuccess()) {
originalPromise.setSuccess(future.getNow());
} else {
if (acquired) {
decrementAndRunTaskQueue();
} else {
runTaskQueue();
}
originalPromise.setFailure(future.cause());
}
}
public void acquired() {
if (acquired) {
return;
}
acquiredChannelCount++;
acquired = true;
}
}
@Override
public void close() {
executor.execute(new OneTimeTask() {
@Override
public void run() {
if (!closed) {
closed = true;
for (;;) {
AcquireTask task = pendingAcquireQueue.poll();
if (task == null) {
break;
}
ScheduledFuture f = task.timeoutFuture;
if (f != null) {
f.cancel(false);
}
task.promise.setFailure(new ClosedChannelException());
}
acquiredChannelCount = 0;
pendingAcquireCount = 0;
FixedChannelPool.super.close();
}
}
});
}
}
