redisson中RRateLimiter分布式限流器的使用
序
本文主要研究一下redisson的RRateLimiter
RRateLimiter
redisson/src/main/java/org/redisson/api/RRateLimiter.java
public interface RRateLimiter extends RRateLimiterAsync, RExpirable { /** * Initializes RateLimiter's state and stores config to Redis server. * * @param mode - rate mode * @param rate - rate * @param rateInterval - rate time interval * @param rateIntervalUnit - rate time interval unit * @return {@code true} if rate was set and {@code false} * otherwise */ boolean trySetRate(RateType mode, long rate, long rateInterval, RateIntervalUnit rateIntervalUnit); /** * Updates RateLimiter's state and stores config to Redis server. * * @param mode - rate mode * @param rate - rate * @param rateInterval - rate time interval * @param rateIntervalUnit - rate time interval unit */ void setRate(RateType mode, long rate, long rateInterval, RateIntervalUnit rateIntervalUnit); /** * Acquires a permit only if one is available at the * time of invocation. * * <p>Acquires a permit, if one is available and returns immediately, * with the value {@code true}, * reducing the number of available permits by one. * * <p>If no permit is available then this method will return * immediately with the value {@code false}. * * @return {@code true} if a permit was acquired and {@code false} * otherwise */ boolean tryAcquire(); /** * Acquires the given number of <code>permits</code> only if all are available at the * time of invocation. * * <p>Acquires a permits, if all are available and returns immediately, * with the value {@code true}, * reducing the number of available permits by given number of permits. * * <p>If no permits are available then this method will return * immediately with the value {@code false}. * * @param permits the number of permits to acquire * @return {@code true} if a permit was acquired and {@code false} * otherwise */ boolean tryAcquire(long permits); /** * Acquires a permit from this RateLimiter, blocking until one is available. * * <p>Acquires a permit, if one is available and returns immediately, * reducing the number of available permits by one. * */ void acquire(); /** * Acquires a specified <code>permits</code> from this RateLimiter, * blocking until one is available. * * <p>Acquires the given number of permits, if they are available * and returns immediately, reducing the number of available permits * by the given amount. * * @param permits the number of permits to acquire */ void acquire(long permits); /** * Acquires a permit from this RateLimiter, if one becomes available * within the given waiting time. * * <p>Acquires a permit, if one is available and returns immediately, * with the value {@code true}, * reducing the number of available permits by one. * * <p>If no permit is available then the current thread becomes * disabled for thread scheduling purposes and lies dormant until * specified waiting time elapses. * * <p>If a permit is acquired then the value {@code true} is returned. * * <p>If the specified waiting time elapses then the value {@code false} * is returned. If the time is less than or equal to zero, the method * will not wait at all. * * @param timeout the maximum time to wait for a permit * @param unit the time unit of the {@code timeout} argument * @return {@code true} if a permit was acquired and {@code false} * if the waiting time elapsed before a permit was acquired */ boolean tryAcquire(long timeout, TimeUnit unit); /** * Acquires the given number of <code>permits</code> only if all are available * within the given waiting time. * * <p>Acquires the given number of permits, if all are available and returns immediately, * with the value {@code true}, reducing the number of available permits by one. * * <p>If no permit is available then the current thread becomes * disabled for thread scheduling purposes and lies dormant until * the specified waiting time elapses. * * <p>If a permits is acquired then the value {@code true} is returned. * * <p>If the specified waiting time elapses then the value {@code false} * is returned. If the time is less than or equal to zero, the method * will not wait at all. * * @param permits amount * @param timeout the maximum time to wait for a permit * @param unit the time unit of the {@code timeout} argument * @return {@code true} if a permit was acquired and {@code false} * if the waiting time elapsed before a permit was acquired */ boolean tryAcquire(long permits, long timeout, TimeUnit unit); /** * Returns current configuration of this RateLimiter object. * * @return config object */ RateLimiterConfig getConfig(); /** * Returns amount of available permits. * * @return number of permits */ long availablePermits(); }
RRateLimiter继承了RRateLimiterAsync、RExpirable接口,它主要定义了trySetRate、setRate、tryAcquire、acquire、getConfig、availablePermits方法
RRateLimiterAsync
redisson/src/main/java/org/redisson/api/RRateLimiterAsync.java
public interface RRateLimiterAsync extends RExpirableAsync { /** * Initializes RateLimiter's state and stores config to Redis server. * * @param mode - rate mode * @param rate - rate * @param rateInterval - rate time interval * @param rateIntervalUnit - rate time interval unit * @return {@code true} if rate was set and {@code false} * otherwise */ RFuture<Boolean> trySetRateAsync(RateType mode, long rate, long rateInterval, RateIntervalUnit rateIntervalUnit); /** * Acquires a permit only if one is available at the * time of invocation. * * <p>Acquires a permit, if one is available and returns immediately, * with the value {@code true}, * reducing the number of available permits by one. * * <p>If no permit is available then this method will return * immediately with the value {@code false}. * * @return {@code true} if a permit was acquired and {@code false} * otherwise */ RFuture<Boolean> tryAcquireAsync(); /** * Acquires the given number of <code>permits</code> only if all are available at the * time of invocation. * * <p>Acquires a permits, if all are available and returns immediately, * with the value {@code true}, * reducing the number of available permits by given number of permits. * * <p>If no permits are available then this method will return * immediately with the value {@code false}. * * @param permits the number of permits to acquire * @return {@code true} if a permit was acquired and {@code false} * otherwise */ RFuture<Boolean> tryAcquireAsync(long permits); /** * Acquires a permit from this RateLimiter, blocking until one is available. * * <p>Acquires a permit, if one is available and returns immediately, * reducing the number of available permits by one. * * @return void */ RFuture<Void> acquireAsync(); /** * Acquires a specified <code>permits</code> from this RateLimiter, * blocking until one is available. * * <p>Acquires the given number of permits, if they are available * and returns immediately, reducing the number of available permits * by the given amount. * * @param permits the number of permits to acquire * @return void */ RFuture<Void> acquireAsync(long permits); /** * Acquires a permit from this RateLimiter, if one becomes available * within the given waiting time. * * <p>Acquires a permit, if one is available and returns immediately, * with the value {@code true}, * reducing the number of available permits by one. * * <p>If no permit is available then the current thread becomes * disabled for thread scheduling purposes and lies dormant until * specified waiting time elapses. * * <p>If a permit is acquired then the value {@code true} is returned. * * <p>If the specified waiting time elapses then the value {@code false} * is returned. If the time is less than or equal to zero, the method * will not wait at all. * * @param timeout the maximum time to wait for a permit * @param unit the time unit of the {@code timeout} argument * @return {@code true} if a permit was acquired and {@code false} * if the waiting time elapsed before a permit was acquired */ RFuture<Boolean> tryAcquireAsync(long timeout, TimeUnit unit); /** * Acquires the given number of <code>permits</code> only if all are available * within the given waiting time. * * <p>Acquires the given number of permits, if all are available and returns immediately, * with the value {@code true}, reducing the number of available permits by one. * * <p>If no permit is available then the current thread becomes * disabled for thread scheduling purposes and lies dormant until * the specified waiting time elapses. * * <p>If a permits is acquired then the value {@code true} is returned. * * <p>If the specified waiting time elapses then the value {@code false} * is returned. If the time is less than or equal to zero, the method * will not wait at all. * * @param permits amount * @param timeout the maximum time to wait for a permit * @param unit the time unit of the {@code timeout} argument * @return {@code true} if a permit was acquired and {@code false} * if the waiting time elapsed before a permit was acquired */ RFuture<Boolean> tryAcquireAsync(long permits, long timeout, TimeUnit unit); /** * Updates RateLimiter's state and stores config to Redis server. * * * @param mode - rate mode * @param rate - rate * @param rateInterval - rate time interval * @param rateIntervalUnit - rate time interval unit * @return {@code true} if rate was set and {@code false} * otherwise */ RFuture<Void> setRateAsync(RateType mode, long rate, long rateInterval, RateIntervalUnit rateIntervalUnit); /** * Returns current configuration of this RateLimiter object. * * @return config object */ RFuture<RateLimiterConfig> getConfigAsync(); /** * Returns amount of available permits. * * @return number of permits */ RFuture<Long> availablePermitsAsync(); }
RRateLimiterAsync继承了RExpirableAsync,它是async版本的RRateLimiter,它主要定义了trySetRateAsync、setRateAsync、tryAcquireAsync、acquireAsync、getConfigAsync、availablePermitsAsync方法
RedissonRateLimiter
redisson/src/main/java/org/redisson/RedissonRateLimiter.java
public class RedissonRateLimiter extends RedissonExpirable implements RRateLimiter { //...... @Override public boolean tryAcquire() { return tryAcquire(1); } @Override public RFuture<Boolean> tryAcquireAsync() { return tryAcquireAsync(1L); } @Override public boolean tryAcquire(long permits) { return get(tryAcquireAsync(RedisCommands.EVAL_NULL_BOOLEAN, permits)); } @Override public RFuture<Boolean> tryAcquireAsync(long permits) { return tryAcquireAsync(RedisCommands.EVAL_NULL_BOOLEAN, permits); } @Override public void acquire() { get(acquireAsync()); } @Override public RFuture<Void> acquireAsync() { return acquireAsync(1); } @Override public void acquire(long permits) { get(acquireAsync(permits)); } @Override public RFuture<Void> acquireAsync(long permits) { CompletionStage<Void> f = tryAcquireAsync(permits, -1, null).thenApply(res -> null); return new CompletableFutureWrapper<>(f); } @Override public boolean tryAcquire(long timeout, TimeUnit unit) { return get(tryAcquireAsync(timeout, unit)); } @Override public RFuture<Boolean> tryAcquireAsync(long timeout, TimeUnit unit) { return tryAcquireAsync(1, timeout, unit); } @Override public boolean tryAcquire(long permits, long timeout, TimeUnit unit) { return get(tryAcquireAsync(permits, timeout, unit)); } }
RedissonRateLimiter继承了RedissonExpirable,实现了RRateLimiter接口
trySetRate
public boolean trySetRate(RateType type, long rate, long rateInterval, RateIntervalUnit unit) { return get(trySetRateAsync(type, rate, rateInterval, unit)); } public RFuture<Boolean> trySetRateAsync(RateType type, long rate, long rateInterval, RateIntervalUnit unit) { return commandExecutor.evalWriteNoRetryAsync(getRawName(), LongCodec.INSTANCE, RedisCommands.EVAL_BOOLEAN, "redis.call('hsetnx', KEYS[1], 'rate', ARGV[1]);" + "redis.call('hsetnx', KEYS[1], 'interval', ARGV[2]);" + "return redis.call('hsetnx', KEYS[1], 'type', ARGV[3]);", Collections.singletonList(getRawName()), rate, unit.toMillis(rateInterval), type.ordinal()); }
trySetRate委托给了trySetRateAsync,这里主要是使用hsetnx来设置rate、interval、type三个值
setRate
public void setRate(RateType type, long rate, long rateInterval, RateIntervalUnit unit) { get(setRateAsync(type, rate, rateInterval, unit)); } public RFuture<Void> setRateAsync(RateType type, long rate, long rateInterval, RateIntervalUnit unit) { return commandExecutor.evalWriteAsync(getRawName(), LongCodec.INSTANCE, RedisCommands.EVAL_BOOLEAN, "local valueName = KEYS[2];" + "local permitsName = KEYS[4];" + "if ARGV[3] == '1' then " + " valueName = KEYS[3];" + " permitsName = KEYS[5];" + "end " +"redis.call('hset', KEYS[1], 'rate', ARGV[1]);" + "redis.call('hset', KEYS[1], 'interval', ARGV[2]);" + "redis.call('hset', KEYS[1], 'type', ARGV[3]);" + "redis.call('del', valueName, permitsName);", Arrays.asList(getRawName(), getValueName(), getClientValueName(), getPermitsName(), getClientPermitsName()), rate, unit.toMillis(rateInterval), type.ordinal()); }
setRate委托给了setRateAsync,这里使用hset来写入rate、interval、type三个值,如果存在则覆盖;另外这里删除了valueName、permitsName这两个key
tryAcquire
public boolean tryAcquire(long permits) { return get(tryAcquireAsync(RedisCommands.EVAL_NULL_BOOLEAN, permits)); } private <T> RFuture<T> tryAcquireAsync(RedisCommand<T> command, Long value) { byte[] random = getServiceManager().generateIdArray(); return commandExecutor.evalWriteAsync(getRawName(), LongCodec.INSTANCE, command, "local rate = redis.call('hget', KEYS[1], 'rate');" + "local interval = redis.call('hget', KEYS[1], 'interval');" + "local type = redis.call('hget', KEYS[1], 'type');" + "assert(rate ~= false and interval ~= false and type ~= false, 'RateLimiter is not initialized')" + "local valueName = KEYS[2];" + "local permitsName = KEYS[4];" + "if type == '1' then " + "valueName = KEYS[3];" + "permitsName = KEYS[5];" + "end;" + "assert(tonumber(rate) >= tonumber(ARGV[1]), 'Requested permits amount could not exceed defined rate'); " + "local currentValue = redis.call('get', valueName); " + "local res;" + "if currentValue ~= false then " + "local expiredValues = redis.call('zrangebyscore', permitsName, 0, tonumber(ARGV[2]) - interval); " + "local released = 0; " + "for i, v in ipairs(expiredValues) do " + "local random, permits = struct.unpack('Bc0I', v);" + "released = released + permits;" + "end; " + "if released > 0 then " + "redis.call('zremrangebyscore', permitsName, 0, tonumber(ARGV[2]) - interval); " + "if tonumber(currentValue) + released > tonumber(rate) then " + "currentValue = tonumber(rate) - redis.call('zcard', permitsName); " + "else " + "currentValue = tonumber(currentValue) + released; " + "end; " + "redis.call('set', valueName, currentValue);" + "end;" + "if tonumber(currentValue) < tonumber(ARGV[1]) then " + "local firstValue = redis.call('zrange', permitsName, 0, 0, 'withscores'); " + "res = 3 + interval - (tonumber(ARGV[2]) - tonumber(firstValue[2]));" + "else " + "redis.call('zadd', permitsName, ARGV[2], struct.pack('Bc0I', string.len(ARGV[3]), ARGV[3], ARGV[1])); " + "redis.call('decrby', valueName, ARGV[1]); " + "res = nil; " + "end; " + "else " + "redis.call('set', valueName, rate); " + "redis.call('zadd', permitsName, ARGV[2], struct.pack('Bc0I', string.len(ARGV[3]), ARGV[3], ARGV[1])); " + "redis.call('decrby', valueName, ARGV[1]); " + "res = nil; " + "end;" + "local ttl = redis.call('pttl', KEYS[1]); " + "if ttl > 0 then " + "redis.call('pexpire', valueName, ttl); " + "redis.call('pexpire', permitsName, ttl); " + "end; " + "return res;", Arrays.asList(getRawName(), getValueName(), getClientValueName(), getPermitsName(), getClientPermitsName()), value, System.currentTimeMillis(), random); }
tryAcquire委托给了tryAcquireAsync,它通过一个lua脚本来执行,首先通过hget获取rate、interval、type的值,然后根据type来确定valueName、permitsName,如果type为0则valueName是getValueName(),permitsName是getPermitsName(),如果type=1则valueName是getClientValueName(),permitsName是getClientPermitsName();之后获取valueName的值,若为false则直接用设置rate、permits,并递减valueName;若为true则获取expiredValues计算released值,再计算出currentValue,若不够扣则计算返回值,若够扣则通过zadd添加当前permit(
System.currentTimeMillis()
),然后递减valueName
acquire
public void acquire() { get(acquireAsync()); } public RFuture<Void> acquireAsync() { return acquireAsync(1); } public RFuture<Void> acquireAsync(long permits) { CompletionStage<Void> f = tryAcquireAsync(permits, -1, null).thenApply(res -> null); return new CompletableFutureWrapper<>(f); } public RFuture<Boolean> tryAcquireAsync(long permits, long timeout, TimeUnit unit) { long timeoutInMillis = -1; if (timeout >= 0) { timeoutInMillis = unit.toMillis(timeout); } CompletableFuture<Boolean> f = tryAcquireAsync(permits, timeoutInMillis); return new CompletableFutureWrapper<>(f); } private CompletableFuture<Boolean> tryAcquireAsync(long permits, long timeoutInMillis) { long s = System.currentTimeMillis(); RFuture<Long> future = tryAcquireAsync(RedisCommands.EVAL_LONG, permits); return future.thenCompose(delay -> { if (delay == null) { return CompletableFuture.completedFuture(true); } if (timeoutInMillis == -1) { CompletableFuture<Boolean> f = new CompletableFuture<>(); getServiceManager().getGroup().schedule(() -> { CompletableFuture<Boolean> r = tryAcquireAsync(permits, timeoutInMillis); commandExecutor.transfer(r, f); }, delay, TimeUnit.MILLISECONDS); return f; } long el = System.currentTimeMillis() - s; long remains = timeoutInMillis - el; if (remains <= 0) { return CompletableFuture.completedFuture(false); } CompletableFuture<Boolean> f = new CompletableFuture<>(); if (remains < delay) { getServiceManager().getGroup().schedule(() -> { f.complete(false); }, remains, TimeUnit.MILLISECONDS); } else { long start = System.currentTimeMillis(); getServiceManager().getGroup().schedule(() -> { long elapsed = System.currentTimeMillis() - start; if (remains <= elapsed) { f.complete(false); return; } CompletableFuture<Boolean> r = tryAcquireAsync(permits, remains - elapsed); commandExecutor.transfer(r, f); }, delay, TimeUnit.MILLISECONDS); } return f; }).toCompletableFuture(); }
acquire也是复用了tryAcquireAsync方法,只获取不到时会根据返回的delay进行重新调度,若timeoutInMillis不为-1则会根据超时时间进行计算和重新调度
availablePermits
public long availablePermits() { return get(availablePermitsAsync()); } public RFuture<Long> availablePermitsAsync() { return commandExecutor.evalWriteAsync(getRawName(), LongCodec.INSTANCE, RedisCommands.EVAL_LONG, "local rate = redis.call('hget', KEYS[1], 'rate');" + "local interval = redis.call('hget', KEYS[1], 'interval');" + "local type = redis.call('hget', KEYS[1], 'type');" + "assert(rate ~= false and interval ~= false and type ~= false, 'RateLimiter is not initialized')" + "local valueName = KEYS[2];" + "local permitsName = KEYS[4];" + "if type == '1' then " + "valueName = KEYS[3];" + "permitsName = KEYS[5];" + "end;" + "local currentValue = redis.call('get', valueName); " + "if currentValue == false then " + "redis.call('set', valueName, rate); " + "return rate; " + "else " + "local expiredValues = redis.call('zrangebyscore', permitsName, 0, tonumber(ARGV[1]) - interval); " + "local released = 0; " + "for i, v in ipairs(expiredValues) do " + "local random, permits = struct.unpack('Bc0I', v);" + "released = released + permits;" + "end; " + "if released > 0 then " + "redis.call('zremrangebyscore', permitsName, 0, tonumber(ARGV[1]) - interval); " + "currentValue = tonumber(currentValue) + released; " + "redis.call('set', valueName, currentValue);" + "end;" + "return currentValue; " + "end;", Arrays.asList(getRawName(), getValueName(), getClientValueName(), getPermitsName(), getClientPermitsName()), System.currentTimeMillis()); }
availablePermits委托给了availablePermitsAsync,它执行lua脚本,先通过hget获取rate、interval、type的值,然后根据type来确定valueName、permitsName,如果type为0则valueName是getValueName(),permitsName是getPermitsName(),如果type=1则valueName是getClientValueName(),permitsName是getClientPermitsName();之后获取valueName对应的值currentValue,若值为false则重新设置rate,否则通过expiredValues重新计算released,若released大于0则更新到currentValue,最后返回currentValue
小结
redisson的RRateLimiter提供了trySetRate、setRate、tryAcquire、acquire、getConfig、availablePermits方法
- 其RateType有OVERALL(
值为0
)、PER_CLIENT(值为1
)两个类型,如果type为0则valueName是getValueName(),permitsName是getPermitsName(),如果type=1则valueName是getClientValueName(),permitsName是getClientPermitsName() - 它主要定义了几个key,一个是getRawName,类型为hash,其key有rate、interval、type;一个是key为valueName,存储了当前的permits;一个是key为permitsName,类型是sorted set,其score为System.currentTimeMillis(),value通过struct.pack了随机数长度、随机数、此次permit的value
- trySetRate委托给了trySetRateAsync,这里主要是使用hsetnx来设置rate、interval、type三个值;setRate委托给了setRateAsync,这里使用hset来写入rate、interval、type三个值,如果存在则覆盖;另外这里删除了valueName、permitsName这两个key
- tryAcquire委托给了tryAcquireAsync,它通过一个lua脚本来执行,首先通过hget获取rate、interval、type的值,之后获取valueName的值,若为false则直接用设置rate、permits,并递减valueName;若为true则获取expiredValues计算released值,再计算出currentValue,若不够扣则计算返回值(告诉调用方可以延时多长时间再重试),若够扣则通过zadd添加当前permit(
System.currentTimeMillis()
),然后递减valueName - acquire是也是复用了tryAcquireAsync方法,只获取不到时会根据返回的delay进行重新调度,若timeoutInMillis不为-1则会根据超时时间进行计算和重新调度
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