Redisson-DelayedQueue-原理

本文主要是介绍Redisson-DelayedQueue-原理，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

Unit-Test

RedissonDelayedQueueTest

常规测试

@Test
public void testCommon() throws InterruptedException {RBlockingQueue<String> destinationQueue = redisson.getBlockingQueue("delay_queue"); // 目标队列RDelayedQueue<String> delayedQueue = redisson.getDelayedQueue(destinationQueue); // 只是对目标队列的一个封装destinationQueue.offer("22_1");destinationQueue.offer("22_2");delayedQueue.offer("1_1_1", 2, TimeUnit.SECONDS);delayedQueue.offer("1_1_2", 3, TimeUnit.SECONDS);for (int i = 0; i < 4; i++) {String e0 = destinationQueue.poll();System.out.println("=========> e0: " + e0);}Thread.sleep(2000);System.out.println("------------------");for (int i = 0; i < 2; i++) {String e1 = destinationQueue.poll();System.out.println("=========> e1: " + e1);}Thread.sleep(2000);System.out.println("------------------");for (int i = 0; i < 2; i++) {String e2 = destinationQueue.poll();System.out.println("=========> e2: " + e2);}
}// 输出
=========> e0: 22_1
=========> e0: 22_2
=========> e0: null
=========> e0: null
------------------
// 等待 2s 之后，才获取到
=========> e1: 1_1_1
=========> e1: null
------------------
// 再等 2s 之后，才获取到
=========> e2: 1_1_2
=========> e2: null

说明

源码类：RedissonDelayedQueue

/*** 构造器，将目标队列转入，并启用定时转移任务 */
protected RedissonDelayedQueue(QueueTransferService queueTransferService, Codec codec, final CommandAsyncExecutor commandExecutor, String name) {super(codec, commandExecutor, name);channelName = prefixName("redisson_delay_queue_channel", getRawName());queueName = prefixName("redisson_delay_queue", getRawName());timeoutSetName = prefixName("redisson_delay_queue_timeout", getRawName());QueueTransferTask task = new QueueTransferTask(commandExecutor.getConnectionManager()) {@Overrideprotected RFuture<Long> pushTaskAsync() {return commandExecutor.evalWriteAsync(getRawName(), LongCodec.INSTANCE, RedisCommands.EVAL_LONG,"local expiredValues = redis.call('zrangebyscore', KEYS[2], 0, ARGV[1], 'limit', 0, ARGV[2]); "+ "if #expiredValues > 0 then "+ "for i, v in ipairs(expiredValues) do "+ "local randomId, value = struct.unpack('dLc0', v);"+ "redis.call('rpush', KEYS[1], value);" // 添加到目标队列里面去+ "redis.call('lrem', KEYS[3], 1, v);" // 删除缓存队列+ "end; "+ "redis.call('zrem', KEYS[2], unpack(expiredValues));" // 删除延迟排序的任务+ "end; "// get startTime from scheduler queue head task+ "local v = redis.call('zrange', KEYS[2], 0, 0, 'WITHSCORES'); "+ "if v[1] ~= nil then "+ "return v[2]; "+ "end "+ "return nil;",Arrays.asList(getRawName(), timeoutSetName, queueName),System.currentTimeMillis(), 100);}...};// 开启任务queueTransferService.schedule(queueName, task);this.queueTransferService = queueTransferService;
}/*** 添加延时的队列元素 */
@Override
public void offer(V e, long delay, TimeUnit timeUnit) {get(offerAsync(e, delay, timeUnit));
}/*** Lua 添加延时的队列元素 */
@Override
public RFuture<Void> offerAsync(V e, long delay, TimeUnit timeUnit) {...long delayInMs = timeUnit.toMillis(delay);long timeout = System.currentTimeMillis() + delayInMs;long randomId = ThreadLocalRandom.current().nextLong();return commandExecutor.evalWriteNoRetryAsync(getRawName(), codec, RedisCommands.EVAL_VOID,"local value = struct.pack('dLc0', tonumber(ARGV[2]), string.len(ARGV[3]), ARGV[3]);" + "redis.call('zadd', KEYS[2], ARGV[1], value);" // 添加到 ZSet 排序+ "redis.call('rpush', KEYS[3], value);" // 添加到缓存队列// if new object added to queue head when publish its startTime // to all scheduler workers + "local v = redis.call('zrange', KEYS[2], 0, 0); "+ "if v[1] == value then "+ "redis.call('publish', KEYS[4], ARGV[1]); "+ "end;",Arrays.asList(getRawName(), timeoutSetName, queueName, channelName),timeout, randomId, encode(e));
}