io.github.resilience4j.ratelimiter.internal

Class SemaphoreBasedRateLimiter

java.lang.Object

io.github.resilience4j.ratelimiter.internal.SemaphoreBasedRateLimiter

All Implemented Interfaces:

RateLimiter

public class SemaphoreBasedRateLimiter
extends java.lang.Object
implements RateLimiter

A RateLimiter implementation that consists of Semaphore and scheduler that will refresh permissions after each RateLimiterConfig.limitRefreshPeriod.

Nested Class Summary

Nested classes/interfaces inherited from interface io.github.resilience4j.ratelimiter.RateLimiter

RateLimiter.EventPublisher, RateLimiter.Metrics

Constructor Summary

Constructors

Constructor and Description
SemaphoreBasedRateLimiter(java.lang.String name, RateLimiterConfig rateLimiterConfig) Creates a RateLimiter.
SemaphoreBasedRateLimiter(java.lang.String name, RateLimiterConfig rateLimiterConfig, java.util.concurrent.ScheduledExecutorService scheduler) Creates a RateLimiter.

Method Summary

Modifier and Type	Method and Description
void	changeLimitForPeriod(int limitForPeriod) Dynamic rate limiter configuration change.
void	changeTimeoutDuration(java.time.Duration timeoutDuration) Dynamic rate limiter configuration change.
RateLimiter.EventPublisher	getEventPublisher() Returns an EventPublisher which can be used to register event consumers.
RateLimiter.Metrics	getMetrics() Get the Metrics of this RateLimiter.
java.lang.String	getName() Get the name of this RateLimiter
boolean	getPermission(java.time.Duration timeoutDuration) Acquires a permission from this rate limiter, blocking until one is available.
RateLimiterConfig	getRateLimiterConfig() Get the RateLimiterConfig of this RateLimiter.
long	reservePermission(java.time.Duration timeoutDuration) Reserves a permission from this rate limiter and returns nanoseconds you should wait for it.
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Methods inherited from interface io.github.resilience4j.ratelimiter.RateLimiter

decorateCallable, decorateCheckedFunction, decorateCheckedRunnable, decorateCheckedSupplier, decorateCompletionStage, decorateConsumer, decorateFunction, decorateRunnable, decorateSupplier, executeCallable, executeCheckedSupplier, executeRunnable, executeSupplier, of, of, ofDefaults, waitForPermission

Constructor Detail

SemaphoreBasedRateLimiter

public SemaphoreBasedRateLimiter(java.lang.String name,
                                 RateLimiterConfig rateLimiterConfig)

Creates a RateLimiter.

Parameters:

name - the name of the RateLimiter

rateLimiterConfig - The RateLimiter configuration.

SemaphoreBasedRateLimiter

public SemaphoreBasedRateLimiter(java.lang.String name,
                                 RateLimiterConfig rateLimiterConfig,
                                 @Nullable
                                 java.util.concurrent.ScheduledExecutorService scheduler)

Creates a RateLimiter.

Parameters:

name - the name of the RateLimiter

rateLimiterConfig - The RateLimiter configuration.

scheduler - executor that will refresh permissions

Method Detail

changeTimeoutDuration

public void changeTimeoutDuration(java.time.Duration timeoutDuration)

Dynamic rate limiter configuration change. This method allows to change timeout duration of current limiter. NOTE! New timeout duration won't affect threads that are currently waiting for permission.

Specified by:

changeTimeoutDuration in interface RateLimiter

Parameters:

timeoutDuration - new timeout duration

changeLimitForPeriod

public void changeLimitForPeriod(int limitForPeriod)

Dynamic rate limiter configuration change. This method allows to change count of permissions available during refresh period. NOTE! New limit won't affect current period permissions and will apply only from next one.

Specified by:

changeLimitForPeriod in interface RateLimiter

Parameters:

limitForPeriod - new permissions limit

getPermission

public boolean getPermission(java.time.Duration timeoutDuration)

Acquires a permission from this rate limiter, blocking until one is available.

If the current thread is interrupted while waiting for a permit then it won't throw InterruptedException, but its interrupt status will be set.

Specified by:

getPermission in interface RateLimiter

Parameters:

timeoutDuration - the maximum time to wait

Returns:

true if a permit was acquired and false if waiting timeoutDuration elapsed before a permit was acquired

reservePermission

public long reservePermission(java.time.Duration timeoutDuration)

Reserves a permission from this rate limiter and returns nanoseconds you should wait for it. If returned long is negative, it means that you failed to reserve permission, possibly your timeoutDuration is less then time to wait for permission. SemaphoreBasedRateLimiter is totally blocking by it's nature. So this non-blocking API isn't supported. It will return negative numbers all the time.

Specified by:

reservePermission in interface RateLimiter

Parameters:

timeoutDuration - the maximum time you want to wait.

Returns:

long amount of nanoseconds you should wait for reserved permission. if negative, it means you failed to reserve.

getName

public java.lang.String getName()

Get the name of this RateLimiter

Specified by:

getName in interface RateLimiter

Returns:

the name of this RateLimiter

getMetrics

public RateLimiter.Metrics getMetrics()

Get the Metrics of this RateLimiter.

Specified by:

getMetrics in interface RateLimiter

Returns:

the Metrics of this RateLimiter

getEventPublisher

public RateLimiter.EventPublisher getEventPublisher()

Description copied from interface: RateLimiter

Returns an EventPublisher which can be used to register event consumers.

Specified by:

getEventPublisher in interface RateLimiter

Returns:

an EventPublisher

getRateLimiterConfig

public RateLimiterConfig getRateLimiterConfig()

Get the RateLimiterConfig of this RateLimiter.

Specified by:

getRateLimiterConfig in interface RateLimiter

Returns:

the RateLimiterConfig of this RateLimiter

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object