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io.netty.util.Recycler Maven / Gradle / Ivy
/*
* Copyright 2013 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:
*
* https://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.util;
import io.netty.util.concurrent.FastThreadLocal;
import io.netty.util.internal.ObjectPool;
import io.netty.util.internal.PlatformDependent;
import io.netty.util.internal.SystemPropertyUtil;
import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;
import io.netty.util.internal.shaded.org.jctools.queues.MessagePassingQueue;
import java.util.ArrayDeque;
import java.util.Queue;
import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
import static io.netty.util.internal.PlatformDependent.newMpscQueue;
import static java.lang.Math.max;
import static java.lang.Math.min;
/**
* Light-weight object pool based on a thread-local stack.
*
* @param the type of the pooled object
*/
public abstract class Recycler {
private static final InternalLogger logger = InternalLoggerFactory.getInstance(Recycler.class);
private static final Handle NOOP_HANDLE = new Handle() {
@Override
public void recycle(Object object) {
// NOOP
}
@Override
public String toString() {
return "NOOP_HANDLE";
}
};
private static final int DEFAULT_INITIAL_MAX_CAPACITY_PER_THREAD = 4 * 1024; // Use 4k instances as default.
private static final int DEFAULT_MAX_CAPACITY_PER_THREAD;
private static final int RATIO;
private static final int DEFAULT_QUEUE_CHUNK_SIZE_PER_THREAD;
private static final boolean BLOCKING_POOL;
static {
// In the future, we might have different maxCapacity for different object types.
// e.g. io.netty.recycler.maxCapacity.writeTask
// io.netty.recycler.maxCapacity.outboundBuffer
int maxCapacityPerThread = SystemPropertyUtil.getInt("io.netty.recycler.maxCapacityPerThread",
SystemPropertyUtil.getInt("io.netty.recycler.maxCapacity", DEFAULT_INITIAL_MAX_CAPACITY_PER_THREAD));
if (maxCapacityPerThread < 0) {
maxCapacityPerThread = DEFAULT_INITIAL_MAX_CAPACITY_PER_THREAD;
}
DEFAULT_MAX_CAPACITY_PER_THREAD = maxCapacityPerThread;
DEFAULT_QUEUE_CHUNK_SIZE_PER_THREAD = SystemPropertyUtil.getInt("io.netty.recycler.chunkSize", 32);
// By default we allow one push to a Recycler for each 8th try on handles that were never recycled before.
// This should help to slowly increase the capacity of the recycler while not be too sensitive to allocation
// bursts.
RATIO = max(0, SystemPropertyUtil.getInt("io.netty.recycler.ratio", 8));
BLOCKING_POOL = SystemPropertyUtil.getBoolean("io.netty.recycler.blocking", false);
if (logger.isDebugEnabled()) {
if (DEFAULT_MAX_CAPACITY_PER_THREAD == 0) {
logger.debug("-Dio.netty.recycler.maxCapacityPerThread: disabled");
logger.debug("-Dio.netty.recycler.ratio: disabled");
logger.debug("-Dio.netty.recycler.chunkSize: disabled");
logger.debug("-Dio.netty.recycler.blocking: disabled");
} else {
logger.debug("-Dio.netty.recycler.maxCapacityPerThread: {}", DEFAULT_MAX_CAPACITY_PER_THREAD);
logger.debug("-Dio.netty.recycler.ratio: {}", RATIO);
logger.debug("-Dio.netty.recycler.chunkSize: {}", DEFAULT_QUEUE_CHUNK_SIZE_PER_THREAD);
logger.debug("-Dio.netty.recycler.blocking: {}", BLOCKING_POOL);
}
}
}
private final int maxCapacityPerThread;
private final int interval;
private final int chunkSize;
private final FastThreadLocal> threadLocal = new FastThreadLocal>() {
@Override
protected LocalPool initialValue() {
return new LocalPool(maxCapacityPerThread, interval, chunkSize);
}
@Override
protected void onRemoval(LocalPool value) throws Exception {
super.onRemoval(value);
value.pooledHandles.clear();
}
};
protected Recycler() {
this(DEFAULT_MAX_CAPACITY_PER_THREAD);
}
protected Recycler(int maxCapacityPerThread) {
this(maxCapacityPerThread, RATIO, DEFAULT_QUEUE_CHUNK_SIZE_PER_THREAD);
}
/**
* @deprecated Use one of the following instead:
* {@link #Recycler()}, {@link #Recycler(int)}, {@link #Recycler(int, int, int)}.
*/
@Deprecated
@SuppressWarnings("unused") // Parameters we can't remove due to compatibility.
protected Recycler(int maxCapacityPerThread, int maxSharedCapacityFactor) {
this(maxCapacityPerThread, RATIO, DEFAULT_QUEUE_CHUNK_SIZE_PER_THREAD);
}
/**
* @deprecated Use one of the following instead:
* {@link #Recycler()}, {@link #Recycler(int)}, {@link #Recycler(int, int, int)}.
*/
@Deprecated
@SuppressWarnings("unused") // Parameters we can't remove due to compatibility.
protected Recycler(int maxCapacityPerThread, int maxSharedCapacityFactor,
int ratio, int maxDelayedQueuesPerThread) {
this(maxCapacityPerThread, ratio, DEFAULT_QUEUE_CHUNK_SIZE_PER_THREAD);
}
/**
* @deprecated Use one of the following instead:
* {@link #Recycler()}, {@link #Recycler(int)}, {@link #Recycler(int, int, int)}.
*/
@Deprecated
@SuppressWarnings("unused") // Parameters we can't remove due to compatibility.
protected Recycler(int maxCapacityPerThread, int maxSharedCapacityFactor,
int ratio, int maxDelayedQueuesPerThread, int delayedQueueRatio) {
this(maxCapacityPerThread, ratio, DEFAULT_QUEUE_CHUNK_SIZE_PER_THREAD);
}
protected Recycler(int maxCapacityPerThread, int ratio, int chunkSize) {
interval = max(0, ratio);
if (maxCapacityPerThread <= 0) {
this.maxCapacityPerThread = 0;
this.chunkSize = 0;
} else {
this.maxCapacityPerThread = max(4, maxCapacityPerThread);
this.chunkSize = max(2, min(chunkSize, this.maxCapacityPerThread >> 1));
}
}
@SuppressWarnings("unchecked")
public final T get() {
if (maxCapacityPerThread == 0) {
return newObject((Handle) NOOP_HANDLE);
}
LocalPool localPool = threadLocal.get();
DefaultHandle handle = localPool.claim();
T obj;
if (handle == null) {
handle = localPool.newHandle();
if (handle != null) {
obj = newObject(handle);
handle.set(obj);
} else {
obj = newObject((Handle) NOOP_HANDLE);
}
} else {
obj = handle.get();
}
return obj;
}
/**
* @deprecated use {@link Handle#recycle(Object)}.
*/
@Deprecated
public final boolean recycle(T o, Handle handle) {
if (handle == NOOP_HANDLE) {
return false;
}
handle.recycle(o);
return true;
}
final int threadLocalSize() {
return threadLocal.get().pooledHandles.size();
}
protected abstract T newObject(Handle handle);
@SuppressWarnings("ClassNameSameAsAncestorName") // Can't change this due to compatibility.
public interface Handle extends ObjectPool.Handle { }
private static final class DefaultHandle implements Handle {
private static final int STATE_CLAIMED = 0;
private static final int STATE_AVAILABLE = 1;
private static final AtomicIntegerFieldUpdater> STATE_UPDATER;
static {
AtomicIntegerFieldUpdater updater = AtomicIntegerFieldUpdater.newUpdater(DefaultHandle.class, "state");
//noinspection unchecked
STATE_UPDATER = (AtomicIntegerFieldUpdater>) updater;
}
@SuppressWarnings({"FieldMayBeFinal", "unused"}) // Updated by STATE_UPDATER.
private volatile int state; // State is initialised to STATE_CLAIMED (aka. 0) so they can be released.
private final LocalPool localPool;
private T value;
DefaultHandle(LocalPool localPool) {
this.localPool = localPool;
}
@Override
public void recycle(Object object) {
if (object != value) {
throw new IllegalArgumentException("object does not belong to handle");
}
localPool.release(this);
}
T get() {
return value;
}
void set(T value) {
this.value = value;
}
boolean availableToClaim() {
if (state != STATE_AVAILABLE) {
return false;
}
return STATE_UPDATER.compareAndSet(this, STATE_AVAILABLE, STATE_CLAIMED);
}
void toAvailable() {
int prev = STATE_UPDATER.getAndSet(this, STATE_AVAILABLE);
if (prev == STATE_AVAILABLE) {
throw new IllegalStateException("Object has been recycled already.");
}
}
}
private static final class LocalPool {
private final int ratioInterval;
private final MessagePassingQueue> pooledHandles;
private int ratioCounter;
@SuppressWarnings("unchecked")
LocalPool(int maxCapacity, int ratioInterval, int chunkSize) {
this.ratioInterval = ratioInterval;
if (BLOCKING_POOL) {
pooledHandles = new BlockingMessageQueue>(maxCapacity);
} else {
pooledHandles = (MessagePassingQueue>) newMpscQueue(chunkSize, maxCapacity);
}
ratioCounter = ratioInterval; // Start at interval so the first one will be recycled.
}
DefaultHandle claim() {
DefaultHandle handle;
do {
handle = pooledHandles.relaxedPoll();
} while (handle != null && !handle.availableToClaim());
return handle;
}
void release(DefaultHandle handle) {
handle.toAvailable();
pooledHandles.relaxedOffer(handle);
}
DefaultHandle newHandle() {
if (++ratioCounter >= ratioInterval) {
ratioCounter = 0;
return new DefaultHandle(this);
}
return null;
}
}
/**
* This is an implementation of {@link MessagePassingQueue}, similar to what might be returned from
* {@link PlatformDependent#newMpscQueue(int)}, but intended to be used for debugging purpose.
* The implementation relies on synchronised monitor locks for thread-safety.
* The {@code drain} and {@code fill} bulk operations are not supported by this implementation.
*/
private static final class BlockingMessageQueue implements MessagePassingQueue {
private final Queue deque;
private final int maxCapacity;
BlockingMessageQueue(int maxCapacity) {
this.maxCapacity = maxCapacity;
// This message passing queue is backed by an ArrayDeque instance,
// made thread-safe by synchronising on `this` BlockingMessageQueue instance.
// Why ArrayDeque?
// We use ArrayDeque instead of LinkedList or LinkedBlockingQueue because it's more space efficient.
// We use ArrayDeque instead of ArrayList because we need the queue APIs.
// We use ArrayDeque instead of ConcurrentLinkedQueue because CLQ is unbounded and has O(n) size().
// We use ArrayDeque instead of ArrayBlockingQueue because ABQ allocates its max capacity up-front,
// and these queues will usually have large capacities, in potentially great numbers (one per thread),
// but often only have comparatively few items in them.
deque = new ArrayDeque();
}
@Override
public synchronized boolean offer(T e) {
if (deque.size() == maxCapacity) {
return false;
}
return deque.offer(e);
}
@Override
public synchronized T poll() {
return deque.poll();
}
@Override
public synchronized T peek() {
return deque.peek();
}
@Override
public synchronized int size() {
return deque.size();
}
@Override
public synchronized void clear() {
deque.clear();
}
@Override
public synchronized boolean isEmpty() {
return deque.isEmpty();
}
@Override
public int capacity() {
return maxCapacity;
}
@Override
public boolean relaxedOffer(T e) {
return offer(e);
}
@Override
public T relaxedPoll() {
return poll();
}
@Override
public T relaxedPeek() {
return peek();
}
@Override
public int drain(Consumer c, int limit) {
throw new UnsupportedOperationException();
}
@Override
public int fill(Supplier s, int limit) {
throw new UnsupportedOperationException();
}
@Override
public int drain(Consumer c) {
throw new UnsupportedOperationException();
}
@Override
public int fill(Supplier s) {
throw new UnsupportedOperationException();
}
@Override
public void drain(Consumer c, WaitStrategy wait, ExitCondition exit) {
throw new UnsupportedOperationException();
}
@Override
public void fill(Supplier s, WaitStrategy wait, ExitCondition exit) {
throw new UnsupportedOperationException();
}
}
}
