org.apache.pulsar.common.util

Class RateLimiter

java.lang.Object

org.apache.pulsar.common.util.RateLimiter

All Implemented Interfaces:

AutoCloseable

public class RateLimiter
extends Object
implements AutoCloseable

A Rate Limiter that distributes permits at a configurable rate. Each acquire() blocks if necessary until a permit is available, and then takes it. Each tryAcquire() tries to acquire permits from available permits, it returns true if it succeed else returns false. Rate limiter release configured permits at every configured rate time, so, on next ticket new fresh permits will be available.

For example: if RateLimiter is configured to release 10 permits at every 1 second then RateLimiter will allow to acquire 10 permits at any time with in that 1 second.

Comparison with other RateLimiter such as RateLimiter

• Per second rate-limiting: Per second rate-limiting not satisfied by Guava-RateLimiter
• Guava RateLimiter: For X permits: it releases X/1000 permits every msec. therefore, for permits=2/sec => it release 1st permit on first 500msec and 2nd permit on next 500ms. therefore, if 2 request comes with in 500msec duration then 2nd request fails to acquire permit though we have configured 2 permits/second.
• RateLimiter: it releases X permits every second. so, in above usecase: if 2 requests comes at the same time then both will acquire the permit.
• Faster: RateLimiter is light-weight and faster than Guava-RateLimiter

Constructor Summary

Constructors

Constructor and Description
RateLimiter(long permits, long rateTime, TimeUnit timeUnit)
RateLimiter(long permits, long rateTime, TimeUnit timeUnit, RateLimitFunction autoReadResetFunction)
RateLimiter(ScheduledExecutorService service, long permits, long rateTime, TimeUnit timeUnit, Supplier<Long> permitUpdater)
RateLimiter(ScheduledExecutorService service, long permits, long rateTime, TimeUnit timeUnit, Supplier<Long> permitUpdater, boolean isDispatchRateLimiter)

Method Summary

Modifier and Type	Method and Description
void	acquire() Acquires the given number of permits from this RateLimiter, blocking until the request be granted.
void	acquire(long acquirePermit) Acquires the given number of permits from this RateLimiter, blocking until the request be granted.
void	close()
protected ScheduledFuture<?>	createTask()
long	getAvailablePermits() Return available permits for this RateLimiter.
long	getRate() Returns configured permit rate per pre-configured rate-period.
long	getRateTime()
TimeUnit	getRateTimeUnit()
boolean	isClosed()
void	setRate(long permits) Resets new rate by configuring new value for permits per configured rate-period.
void	setRate(long permits, long rateTime, TimeUnit timeUnit, Supplier<Long> permitUpdaterByte) Resets new rate with new permits and rate-time.
String	toString()
boolean	tryAcquire() Acquires permits from this RateLimiter if it can be acquired immediately without delay.
boolean	tryAcquire(long acquirePermit) Acquires permits from this RateLimiter if it can be acquired immediately without delay.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

RateLimiter

public RateLimiter(long permits,
                   long rateTime,
                   TimeUnit timeUnit)

RateLimiter

public RateLimiter(long permits,
                   long rateTime,
                   TimeUnit timeUnit,
                   RateLimitFunction autoReadResetFunction)

RateLimiter

public RateLimiter(ScheduledExecutorService service,
                   long permits,
                   long rateTime,
                   TimeUnit timeUnit,
                   Supplier<Long> permitUpdater)

RateLimiter

public RateLimiter(ScheduledExecutorService service,
                   long permits,
                   long rateTime,
                   TimeUnit timeUnit,
                   Supplier<Long> permitUpdater,
                   boolean isDispatchRateLimiter)

Method Detail

close

public void close()

Specified by:

close in interface AutoCloseable

isClosed

public boolean isClosed()

acquire

public void acquire()
             throws InterruptedException

Acquires the given number of permits from this RateLimiter, blocking until the request be granted.

This method is equivalent to acquire(1).

Throws:

InterruptedException

acquire

public void acquire(long acquirePermit)
             throws InterruptedException

Acquires the given number of permits from this RateLimiter, blocking until the request be granted.

Parameters:

acquirePermit - the number of permits to acquire

Throws:

InterruptedException

tryAcquire

public boolean tryAcquire()

Acquires permits from this RateLimiter if it can be acquired immediately without delay.

This method is equivalent to tryAcquire(1).

Returns:

true if the permits were acquired, false otherwise

tryAcquire

public boolean tryAcquire(long acquirePermit)

Acquires permits from this RateLimiter if it can be acquired immediately without delay.

Parameters:

acquirePermit - the number of permits to acquire

Returns:

true if the permits were acquired, false otherwise

getAvailablePermits

public long getAvailablePermits()

Return available permits for this RateLimiter.

Returns:

returns 0 if permits is not available

setRate

public void setRate(long permits)

Resets new rate by configuring new value for permits per configured rate-period.

Parameters:

permits -

setRate

public void setRate(long permits,
                    long rateTime,
                    TimeUnit timeUnit,
                    Supplier<Long> permitUpdaterByte)

Resets new rate with new permits and rate-time.

Parameters:

permits -

rateTime -

timeUnit -

permitUpdaterByte -

getRate

public long getRate()

Returns configured permit rate per pre-configured rate-period.

Returns:

rate

getRateTime

public long getRateTime()

getRateTimeUnit

public TimeUnit getRateTimeUnit()

createTask

protected ScheduledFuture<?> createTask()

toString

public String toString()

Overrides:

toString in class Object