Package org.apache.curator

Class RetryLoop

java.lang.Object
org.apache.curator.RetryLoop
public abstract class RetryLoop extends 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);
     }
 }

Note: this an abstract class instead of an interface for historical reasons. It was originally a class and if it becomes an interface we risk IncompatibleClassChangeErrors with clients.

  • Constructor Details

    • RetryLoop

      public RetryLoop()

  • Method Details

    • getDefaultRetrySleeper

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

    • callWithRetry

      public static <T> T callWithRetry(CuratorZookeeperClient client, Callable<T> proc) throws 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:
      Exception - any non-retriable errors

    • shouldContinue

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

    • markComplete

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

    • takeException

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