Class LinearBackoffManager

  • All Implemented Interfaces:
    BackoffManager

    @Contract(threading=SAFE)
    public class LinearBackoffManager
    extends AbstractBackoff
    An implementation of BackoffManager that uses a linear backoff strategy to adjust the maximum number of connections per route in an PoolingHttpClientConnectionManager. This class is designed to be thread-safe and can be used in multi-threaded environments.

    The linear backoff strategy increases or decreases the maximum number of connections per route by a fixed increment when backing off or probing, respectively. The adjustments are made based on a cool-down period, during which no further adjustments will be made.

    The LinearBackoffManager is intended to be used with a PoolingHttpClientConnectionManager, which provides the ConnPoolControl interface. This class interacts with the PoolingHttpClientConnectionManager to adjust the maximum number of connections per route.

    Example usage:

     PoolingHttpClientConnectionManager connectionManager = new PoolingHttpClientConnectionManager();
     LinearBackoffManager backoffManager = new LinearBackoffManager(connectionManager, 1);
     // Use the backoffManager with the connectionManager in your application
     
    Since:
    5.3
    See Also:
    BackoffManager, ConnPoolControl, PoolingHttpClientConnectionManager
    • Field Summary

      Fields 
      Modifier and Type Field Description
      private int increment
      The backoff increment used when adjusting connection pool sizes.
      private static org.slf4j.Logger LOG  
      private java.util.concurrent.ConcurrentHashMap<HttpRoute,​java.util.concurrent.atomic.AtomicInteger> routeAttempts  
    • Constructor Summary

      Constructors 
      Constructor Description
      LinearBackoffManager​(org.apache.hc.core5.pool.ConnPoolControl<HttpRoute> connPoolControl)
      Constructs a new LinearBackoffManager with the specified connection pool control.
      LinearBackoffManager​(org.apache.hc.core5.pool.ConnPoolControl<HttpRoute> connPoolControl, int increment)
      Constructs a new LinearBackoffManager with the specified connection pool control and backoff increment.
    • Field Detail

      • LOG

        private static final org.slf4j.Logger LOG
      • increment

        private final int increment
        The backoff increment used when adjusting connection pool sizes. The pool size will be increased or decreased by this value during the backoff process. The increment must be positive.
      • routeAttempts

        private final java.util.concurrent.ConcurrentHashMap<HttpRoute,​java.util.concurrent.atomic.AtomicInteger> routeAttempts
    • Constructor Detail

      • LinearBackoffManager

        public LinearBackoffManager​(org.apache.hc.core5.pool.ConnPoolControl<HttpRoute> connPoolControl)
        Constructs a new LinearBackoffManager with the specified connection pool control. The backoff increment is set to 1 by default.
        Parameters:
        connPoolControl - the connection pool control to be used by this LinearBackoffManager
      • LinearBackoffManager

        public LinearBackoffManager​(org.apache.hc.core5.pool.ConnPoolControl<HttpRoute> connPoolControl,
                                    int increment)
        Constructs a new LinearBackoffManager with the specified connection pool control and backoff increment.
        Parameters:
        connPoolControl - the connection pool control to be used by this LinearBackoffManager
        increment - the backoff increment to be used when adjusting connection pool sizes
        Throws:
        java.lang.IllegalArgumentException - if connPoolControl is null or increment is not positive
    • Method Detail

      • backOff

        public void backOff​(HttpRoute route)
        Description copied from class: AbstractBackoff
        Reduces the number of maximum allowed connections for the specified route based on the exponential backoff algorithm.
        Specified by:
        backOff in interface BackoffManager
        Overrides:
        backOff in class AbstractBackoff
        Parameters:
        route - the HttpRoute for which the backoff needs to be applied
      • probe

        public void probe​(HttpRoute route)
        Adjusts the maximum number of connections for the specified route, decreasing it by the increment value. The method ensures that adjustments only happen after the cool-down period has passed since the last adjustment.
        Specified by:
        probe in interface BackoffManager
        Overrides:
        probe in class AbstractBackoff
        Parameters:
        route - the HttpRoute for which the maximum number of connections will be decreased
      • shouldSkip

        private boolean shouldSkip​(HttpRoute route,
                                   java.time.Instant now)
        Determines whether an adjustment action (backoff or probe) should be skipped for the given HttpRoute based on the cool-down period. If the time elapsed since the last successful probe or backoff for the given route is less than the cool-down period, the method returns true. Otherwise, it returns false.

        This method is used by both backOff() and probe() methods to enforce the cool-down period before making adjustments to the connection pool size.

        Parameters:
        route - the HttpRoute to check
        now - the current Instant used to calculate the time since the last probe or backoff
        Returns:
        true if the cool-down period has not elapsed since the last probe or backoff, false otherwise
      • getBackedOffPoolSize

        protected int getBackedOffPoolSize​(int curr)
        Returns the new pool size after applying the linear backoff algorithm. The new pool size is calculated by adding the increment value to the current pool size.
        Specified by:
        getBackedOffPoolSize in class AbstractBackoff
        Parameters:
        curr - the current pool size
        Returns:
        the new pool size after applying the linear backoff
      • setBackoffFactor

        public void setBackoffFactor​(double d)
        This method is not used in LinearBackoffManager's implementation. It is provided to fulfill the interface requirement and for potential future extensions or modifications of LinearBackoffManager that may use the backoff factor.
        Specified by:
        setBackoffFactor in class AbstractBackoff
        Parameters:
        d - the backoff factor, not used in the current implementation