RSemaphore implementation. #207
Nikita
9 years ago
parent
73553bdabd
commit
42fa838e1d
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/**
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* Copyright 2014 Nikita Koksharov, Nickolay Borbit
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.redisson;
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import java.util.Arrays;
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import java.util.Collections;
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import java.util.UUID;
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import java.util.concurrent.TimeUnit;
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import org.redisson.client.codec.LongCodec;
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import org.redisson.client.codec.StringCodec;
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import org.redisson.client.protocol.RedisCommands;
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import org.redisson.command.CommandExecutor;
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import org.redisson.core.RSemaphore;
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import org.redisson.pubsub.LockPubSub;
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import io.netty.util.concurrent.Future;
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/**
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* Distributed implementation of {@link java.util.concurrent.locks.Lock}
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* Implements reentrant lock.<br>
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* Lock will be removed automatically if client disconnects.
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*
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* @author Nikita Koksharov
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*
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*/
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public class RedissonSemaphore extends RedissonExpirable implements RSemaphore {
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final UUID id;
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public static final Long unlockMessage = 0L;
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private static final LockPubSub PUBSUB = new LockPubSub();
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final CommandExecutor commandExecutor;
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protected RedissonSemaphore(CommandExecutor commandExecutor, String name, UUID id) {
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super(commandExecutor, name);
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this.commandExecutor = commandExecutor;
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this.id = id;
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}
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private String getEntryName() {
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return id + ":" + getName();
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}
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String getChannelName() {
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return "redisson_semaphore__channel__{" + getName() + "}";
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}
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@Override
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public void acquire() throws InterruptedException {
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acquire(1);
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}
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@Override
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public void acquire(int permits) throws InterruptedException {
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if (tryAcquire(permits)) {
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return;
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}
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Future<RedissonLockEntry> future = subscribe().sync();
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try {
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while (true) {
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if (tryAcquire(permits)) {
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return;
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}
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getEntry().getLatch().acquire();
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}
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} finally {
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unsubscribe(future);
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}
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}
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@Override
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public boolean tryAcquire() {
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return tryAcquire(1);
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}
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@Override
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public boolean tryAcquire(int permits) {
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return commandExecutor.evalWrite(getName(), LongCodec.INSTANCE, RedisCommands.EVAL_BOOLEAN,
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"local value = redis.call('get', KEYS[1]); " +
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"if (value ~= false and value >= ARGV[1]) then " +
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"redis.call('decrby', KEYS[1], ARGV[1]); " +
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"return 1; " +
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"end; " +
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"return 0;",
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Collections.<Object>singletonList(getName()), permits);
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}
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@Override
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public boolean tryAcquire(int permits, long waitTime, TimeUnit unit) throws InterruptedException {
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if (tryAcquire(permits)) {
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return true;
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}
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long time = unit.toMillis(waitTime);
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Future<RedissonLockEntry> future = subscribe();
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if (!future.await(time, TimeUnit.MILLISECONDS)) {
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return false;
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}
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try {
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while (true) {
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if (tryAcquire(permits)) {
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return true;
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}
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if (time <= 0) {
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return false;
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}
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// waiting for message
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long current = System.currentTimeMillis();
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getEntry().getLatch().tryAcquire(time, TimeUnit.MILLISECONDS);
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long elapsed = System.currentTimeMillis() - current;
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time -= elapsed;
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}
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} finally {
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unsubscribe(future);
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}
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}
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private RedissonLockEntry getEntry() {
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return PUBSUB.getEntry(getEntryName());
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}
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private Future<RedissonLockEntry> subscribe() {
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return PUBSUB.subscribe(getEntryName(), getChannelName(), commandExecutor.getConnectionManager());
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}
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private void unsubscribe(Future<RedissonLockEntry> future) {
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PUBSUB.unsubscribe(future.getNow(), getEntryName(), getChannelName(), commandExecutor.getConnectionManager());
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}
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@Override
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public boolean tryAcquire(long time, TimeUnit unit) throws InterruptedException {
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return tryAcquire(1, time, unit);
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}
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@Override
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public void release() {
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release(1);
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}
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@Override
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public void release(int permits) {
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commandExecutor.evalWrite(getName(), StringCodec.INSTANCE, RedisCommands.EVAL_OBJECT,
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"redis.call('incrby', KEYS[1], ARGV[1]); " +
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"redis.call('publish', KEYS[2], ARGV[2]); ",
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Arrays.<Object>asList(getName(), getChannelName()), permits, unlockMessage);
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}
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@Override
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public int availablePermits() {
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Long res = commandExecutor.read(getName(), LongCodec.INSTANCE, RedisCommands.GET, getName());
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if (res == null) {
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return 0;
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}
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return res.intValue();
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}
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}
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@ -0,0 +1,49 @@
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/**
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* Copyright 2014 Nikita Koksharov, Nickolay Borbit
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.redisson.core;
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import java.util.concurrent.TimeUnit;
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/**
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* Distributed implementation of {@link java.util.concurrent.locks.Lock}
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* Implements reentrant lock.
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* Use {@link RSemaphore#getHoldCount()} to get a holds count.
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*
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* @author Nikita Koksharov
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*
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*/
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public interface RSemaphore extends RExpirable {
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void acquire() throws InterruptedException;
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void acquire(int permits) throws InterruptedException;
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boolean tryAcquire();
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boolean tryAcquire(int permits);
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boolean tryAcquire(long timeout, TimeUnit unit) throws InterruptedException;
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boolean tryAcquire(int permits, long waitTime, TimeUnit unit) throws InterruptedException;
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void release();
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void release(int permits);
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int availablePermits();
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}
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