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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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