Package org.apache.curator

Class RetryLoop

  • public class RetryLoop
extends java.lang.Object

    Mechanism to perform an operation on Zookeeper that is safe against disconnections and "recoverable" errors.

    If an exception occurs during the operation, the RetryLoop will process it, check with the current retry policy and either attempt to reconnect or re-throw the exception

    Canonical usage:
     RetryLoop retryLoop = client.newRetryLoop();
 while ( retryLoop.shouldContinue() )
 {
     try
     {
         // do your work
         ZooKeeper      zk = client.getZooKeeper();    // it's important to re-get the ZK instance in case there was an error and the instance was re-created

         retryLoop.markComplete();
     }
     catch ( Exception e )
     {
         retryLoop.takeException(e);
     }
 }

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      static <T> T callWithRetry​(CuratorZookeeperClient client, java.util.concurrent.Callable<T> proc)
      Convenience utility: creates a retry loop calling the given proc and retrying if needed
      static RetrySleeper getDefaultRetrySleeper()
      Returns the default retry sleeper
      static boolean isRetryException​(java.lang.Throwable exception)
      Utility - return true if the given exception is retry-able
      void markComplete()
      Call this when your operation has successfully completed
      boolean shouldContinue()
      If true is returned, make an attempt at the operation
      static boolean shouldRetry​(int rc)
      Utility - return true if the given Zookeeper result code is retry-able
      void takeException​(java.lang.Exception exception)
      Pass any caught exceptions here

      • Methods inherited from class java.lang.Object

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

    • Method Detail

      • getDefaultRetrySleeper

        public static RetrySleeper getDefaultRetrySleeper()
        Returns the default retry sleeper
        Returns:
        sleeper

      • callWithRetry

        public static <T> T callWithRetry​(CuratorZookeeperClient client,
                                  java.util.concurrent.Callable<T> proc)
                           throws java.lang.Exception
        Convenience utility: creates a retry loop calling the given proc and retrying if needed
        Type Parameters:
        T - return type
        Parameters:
        client - Zookeeper
        proc - procedure to call with retry
        Returns:
        procedure result
        Throws:
        java.lang.Exception - any non-retriable errors

      • shouldContinue

        public boolean shouldContinue()
        If true is returned, make an attempt at the operation
        Returns:
        true/false

      • markComplete

        public void markComplete()
        Call this when your operation has successfully completed

      • shouldRetry

        public static boolean shouldRetry​(int rc)
        Utility - return true if the given Zookeeper result code is retry-able
        Parameters:
        rc - result code
        Returns:
        true/false

      • isRetryException

        public static boolean isRetryException​(java.lang.Throwable exception)
        Utility - return true if the given exception is retry-able
        Parameters:
        exception - exception to check
        Returns:
        true/false

      • takeException

        public void takeException​(java.lang.Exception exception)
                   throws java.lang.Exception
        Pass any caught exceptions here
        Parameters:
        exception - the exception
        Throws:
        java.lang.Exception - if not retry-able or the retry policy returned negative