Package io.github.resilience4j.ratelimiter.internal

Class SemaphoreBasedRateLimiter

java.lang.Object
io.github.resilience4j.ratelimiter.internal.SemaphoreBasedRateLimiter
All Implemented Interfaces:
RateLimiter
public class SemaphoreBasedRateLimiter extends Object implements RateLimiter
A RateLimiter implementation that consists of Semaphore and scheduler that will refresh permissions after each RateLimiterConfig.getLimitRefreshPeriod(), you can invoke shutdown() to close the limiter.

  • Constructor Details

    • SemaphoreBasedRateLimiter

      public SemaphoreBasedRateLimiter(String name, RateLimiterConfig rateLimiterConfig)
      Creates a RateLimiter.
      Parameters:
      name - the name of the RateLimiter
      rateLimiterConfig - The RateLimiter configuration.

    • SemaphoreBasedRateLimiter

      public SemaphoreBasedRateLimiter(String name, RateLimiterConfig rateLimiterConfig, Map<String,String> tags)
      Creates a RateLimiter.
      Parameters:
      name - the name of the RateLimiter
      rateLimiterConfig - The RateLimiter configuration.
      tags - tags to assign to the RateLimiter

    • SemaphoreBasedRateLimiter

      public SemaphoreBasedRateLimiter(String name, RateLimiterConfig rateLimiterConfig, @Nullable ScheduledExecutorService scheduler)
      Creates a RateLimiter.
      Parameters:
      name - the name of the RateLimiter
      rateLimiterConfig - The RateLimiter configuration.
      scheduler - executor that will refresh permissions

    • SemaphoreBasedRateLimiter

      public SemaphoreBasedRateLimiter(String name, RateLimiterConfig rateLimiterConfig, @Nullable ScheduledExecutorService scheduler, Map<String,String> tags)
      Creates a RateLimiter.
      Parameters:
      name - the name of the RateLimiter
      rateLimiterConfig - The RateLimiter configuration.
      scheduler - executor that will refresh permissions
      tags - tags to assign to the RateLimiter

  • Method Details

    • changeTimeoutDuration

      public void changeTimeoutDuration(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

    • acquirePermission

      public boolean acquirePermission(int permits)
      Acquires the given number of permits from this rate limiter, blocking until one is available, or the thread is interrupted. Maximum wait time is RateLimiterConfig.getTimeoutDuration()

      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:
      acquirePermission in interface RateLimiter
      Parameters:
      permits - number of permits - use for systems where 1 call != 1 permit
      Returns:
      true if a permit was acquired and false if waiting timeoutDuration elapsed before a permit was acquired

    • reservePermission

      public long reservePermission()
      Reserving permissions is not supported in the semaphore based implementation. Semaphores are totally blocking by it's nature. So this non-blocking API isn't supported. Use RateLimiter.acquirePermission()
      Specified by:
      reservePermission in interface RateLimiter
      Returns:
      long amount of nanoseconds you should wait for reserved permissions. if negative, it means you failed to reserve.
      Throws:
      UnsupportedOperationException - always for this implementation

    • reservePermission

      public long reservePermission(int permits)
      Description copied from interface: RateLimiter
      Reserves the given number permits 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 RateLimiterConfig.getTimeoutDuration() is less then time to wait for permission.
      Specified by:
      reservePermission in interface RateLimiter
      Parameters:
      permits - number of permits - use for systems where 1 call != 1 permit
      Returns:
      long amount of nanoseconds you should wait for reserved permissions. if negative, it means you failed to reserve.
      Throws:
      UnsupportedOperationException - always for this implementation
      See Also:

    • drainPermissions

      public void drainPermissions()
      Description copied from interface: RateLimiter
      Drains all the permits left in the current period.
      Specified by:
      drainPermissions in interface RateLimiter

    • getName

      public 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 String toString()
      Overrides:
      toString in class Object

    • getTags

      public Map<String,String> getTags()
      Description copied from interface: RateLimiter
      Returns an unmodifiable map with tags assigned to this RateLimiter.
      Specified by:
      getTags in interface RateLimiter
      Returns:
      the tags assigned to this Retry in an unmodifiable map

    • shutdown

      public void shutdown()
      Close the scheduled task that refresh permissions if you don't use the SemaphoreBasedRateLimiter anymore. Otherwise, the SemaphoreBasedRateLimiter instance will not be garbage collected even if you hold the reference, meaning if you create millions of instance, there could be a memory leak. (https://github.com/resilience4j/resilience4j/issues/1683)