RetryPolicies (Hadoop 0.20.2-cdh3u5 API)
Date: 2012-10-05

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## org.apache.hadoop.io.retry
Class RetryPolicies

    java.lang.Object
      org.apache.hadoop.io.retry.RetryPolicies

    public class RetryPolicies

extends Object

A collection of useful implementations of `RetryPolicy`.

Field Summary
`static RetryPolicy` | `RETRY_FOREVER` Keep trying forever.
`static RetryPolicy` | `TRY_ONCE_DONT_FAIL` Try once, and fail silently for `void` methods, or by re-throwing the exception for non-`void` methods.
`static RetryPolicy` | `TRY_ONCE_THEN_FAIL` Try once, and fail by re-throwing the exception.

Constructor Summary
`RetryPolicies()`

Method Summary
`static RetryPolicy` | `exponentialBackoffRetry(int maxRetries, long sleepTime, TimeUnit timeUnit)` Keep trying a limited number of times, waiting a growing amount of time between attempts, and then fail by re-throwing the exception.
`static RetryPolicy` | `retryByException(RetryPolicy defaultPolicy, Map<Class<? extends Exception>,RetryPolicy> exceptionToPolicyMap)` Set a default policy with some explicit handlers for specific exceptions.
`static RetryPolicy` | `retryByRemoteException(RetryPolicy defaultPolicy, Map<Class<? extends Exception>,RetryPolicy> exceptionToPolicyMap)` A retry policy for RemoteException Set a default policy with some explicit handlers for specific exceptions.
`static RetryPolicy` | `retryUpToMaximumCountWithFixedSleep(int maxRetries, long sleepTime, TimeUnit timeUnit)` Keep trying a limited number of times, waiting a fixed time between attempts, and then fail by re-throwing the exception.
`static RetryPolicy` | `retryUpToMaximumCountWithProportionalSleep(int maxRetries, long sleepTime, TimeUnit timeUnit)` Keep trying a limited number of times, waiting a growing amount of time between attempts, and then fail by re-throwing the exception.
`static RetryPolicy` | `retryUpToMaximumTimeWithFixedSleep(long maxTime, long sleepTime, TimeUnit timeUnit)` Keep trying for a maximum time, waiting a fixed time between attempts, and then fail by re-throwing the exception.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### TRY_ONCE_THEN_FAIL

    public static final RetryPolicy TRY_ONCE_THEN_FAIL

  Try once, and fail by re-throwing the exception. This corresponds to having no retry mechanism in place.

### TRY_ONCE_DONT_FAIL

    public static final RetryPolicy TRY_ONCE_DONT_FAIL

  Try once, and fail silently for `void` methods, or by re-throwing the exception for non-`void` methods.

### RETRY_FOREVER

    public static final RetryPolicy RETRY_FOREVER

  Keep trying forever.

Constructor Detail

### RetryPolicies

    public RetryPolicies()

Method Detail

### retryUpToMaximumCountWithFixedSleep

    public static final RetryPolicy retryUpToMaximumCountWithFixedSleep(int maxRetries,
                                                                        long sleepTime,
                                                                        TimeUnit timeUnit)

  Keep trying a limited number of times, waiting a fixed time between attempts, and then fail by re-throwing the exception.

### retryUpToMaximumTimeWithFixedSleep

    public static final RetryPolicy retryUpToMaximumTimeWithFixedSleep(long maxTime,
                                                                       long sleepTime,
                                                                       TimeUnit timeUnit)

  Keep trying for a maximum time, waiting a fixed time between attempts, and then fail by re-throwing the exception.

### retryUpToMaximumCountWithProportionalSleep

    public static final RetryPolicy retryUpToMaximumCountWithProportionalSleep(int maxRetries,
                                                                               long sleepTime,
                                                                               TimeUnit timeUnit)

  Keep trying a limited number of times, waiting a growing amount of time between attempts, and then fail by re-throwing the exception. The time between attempts is `sleepTime` mutliplied by the number of tries so far.

### exponentialBackoffRetry

    public static final RetryPolicy exponentialBackoffRetry(int maxRetries,
                                                            long sleepTime,
                                                            TimeUnit timeUnit)

  Keep trying a limited number of times, waiting a growing amount of time between attempts, and then fail by re-throwing the exception. The time between attempts is `sleepTime` mutliplied by a random number in the range of [0, 2 to the number of retries)

### retryByException

    public static final RetryPolicy retryByException(RetryPolicy defaultPolicy,
                                                     Map<Class<? extends Exception>,RetryPolicy> exceptionToPolicyMap)

  Set a default policy with some explicit handlers for specific exceptions.

### retryByRemoteException

    public static final RetryPolicy retryByRemoteException(RetryPolicy defaultPolicy,
                                                           Map<Class<? extends Exception>,RetryPolicy> exceptionToPolicyMap)

  A retry policy for RemoteException Set a default policy with some explicit handlers for specific exceptions.

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