001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.camel.util.concurrent; 018 019import java.util.PriorityQueue; 020import java.util.concurrent.Executor; 021import java.util.concurrent.TimeUnit; 022import java.util.concurrent.atomic.AtomicLong; 023import java.util.concurrent.locks.Condition; 024import java.util.concurrent.locks.ReentrantLock; 025import java.util.function.Consumer; 026 027public class AsyncCompletionService<V> { 028 029 private final Executor executor; 030 private final boolean ordered; 031 private final PriorityQueue<Task> queue = new PriorityQueue<>(); 032 private final AtomicLong nextId = new AtomicLong(); 033 private final AtomicLong index = new AtomicLong(); 034 private final ReentrantLock lock; 035 private final Condition available; 036 037 public AsyncCompletionService(Executor executor, boolean ordered) { 038 this(executor, ordered, null); 039 } 040 041 public AsyncCompletionService(Executor executor, boolean ordered, ReentrantLock lock) { 042 this.executor = executor; 043 this.ordered = ordered; 044 this.lock = lock != null ? lock : new ReentrantLock(); 045 this.available = this.lock.newCondition(); 046 } 047 048 public ReentrantLock getLock() { 049 return lock; 050 } 051 052 public void submit(Consumer<Consumer<V>> runner) { 053 Task f = new Task(nextId.getAndIncrement(), runner); 054 this.executor.execute(f); 055 } 056 057 public void skip() { 058 index.incrementAndGet(); 059 } 060 061 public V pollUnordered() { 062 final ReentrantLock lock = this.lock; 063 lock.lock(); 064 try { 065 Task t = queue.poll(); 066 return t != null ? t.result : null; 067 } finally { 068 lock.unlock(); 069 } 070 } 071 072 public V poll() { 073 final ReentrantLock lock = this.lock; 074 lock.lock(); 075 try { 076 Task t = queue.peek(); 077 if (t != null && (!ordered || index.compareAndSet(t.id, t.id + 1))) { 078 queue.poll(); 079 return t.result; 080 } else { 081 return null; 082 } 083 } finally { 084 lock.unlock(); 085 } 086 } 087 088 public V poll(long timeout, TimeUnit unit) throws InterruptedException { 089 long nanos = unit.toNanos(timeout); 090 final ReentrantLock lock = this.lock; 091 lock.lockInterruptibly(); 092 try { 093 for (;;) { 094 Task t = queue.peek(); 095 if (t != null && (!ordered || index.compareAndSet(t.id, t.id + 1))) { 096 queue.poll(); 097 return t.result; 098 } 099 if (nanos <= 0) { 100 return null; 101 } else { 102 nanos = available.awaitNanos(nanos); 103 } 104 } 105 } finally { 106 lock.unlock(); 107 } 108 } 109 110 public V take() throws InterruptedException { 111 final ReentrantLock lock = this.lock; 112 lock.lockInterruptibly(); 113 try { 114 for (;;) { 115 Task t = queue.peek(); 116 if (t != null && (!ordered || index.compareAndSet(t.id, t.id + 1))) { 117 queue.poll(); 118 return t.result; 119 } 120 available.await(); 121 } 122 } finally { 123 lock.unlock(); 124 } 125 } 126 127 private void complete(Task task) { 128 final ReentrantLock lock = this.lock; 129 lock.lock(); 130 try { 131 queue.add(task); 132 available.signalAll(); 133 } finally { 134 lock.unlock(); 135 } 136 } 137 138 private class Task implements Runnable, Comparable<Task> { 139 private final long id; 140 private final Consumer<Consumer<V>> runner; 141 private V result; 142 143 Task(long id, Consumer<Consumer<V>> runner) { 144 this.id = id; 145 this.runner = runner; 146 } 147 148 @Override 149 public void run() { 150 runner.accept(this::setResult); 151 } 152 153 protected void setResult(V result) { 154 this.result = result; 155 complete(this); 156 } 157 158 @Override 159 public int compareTo(Task other) { 160 return Long.compare(this.id, other.id); 161 } 162 163 @Override 164 public String toString() { 165 return "SubmitOrderedFutureTask[" + this.id + "]"; 166 } 167 } 168}