org.apache.hadoop.hbase.client

Interface RetryingCallable<T>

Type Parameters:

T - result class from executing this

All Known Implementing Classes:

CancellableRegionServerCallable, ClientServiceCallable, FlushRegionCallable, MasterCallable, MultiServerCallable, NoncedRegionServerCallable, RegionAdminServiceCallable, RegionReplicaReplicationEndpoint.RegionReplicaReplayCallable, RegionServerCallable, ReversedScannerCallable, RpcRetryingCallable, RpcRetryingCallerWithReadReplicas.ReplicaRegionServerCallable, ScannerCallable, ScannerCallableWithReplicas, ScannerCallableWithReplicas.RetryingRPC

@InterfaceAudience.Private
public interface RetryingCallable<T>

A Callable<T> that will be retried. If call(int) invocation throws exceptions, we will call throwable(Throwable, boolean) with whatever the exception was.

Method Summary

Modifier and Type	Method and Description
T	call(int callTimeout) Computes a result, or throws an exception if unable to do so.
String	getExceptionMessageAdditionalDetail()
void	prepare(boolean reload) Prepare by setting up any connections to servers, etc., ahead of call invocation.
long	sleep(long pause, int tries)
void	throwable(Throwable t, boolean retrying) Called when call throws an exception and we are going to retry; take action to make it so we succeed on next call (clear caches, do relookup of locations, etc.).

Method Detail

prepare

void prepare(boolean reload)
      throws IOException

Prepare by setting up any connections to servers, etc., ahead of call invocation. TODO: We call prepare before EVERY call. Seems wrong. FIX!!!!

Parameters:

reload - Set this to true if need to requery locations

Throws:

IOException - e

throwable

void throwable(Throwable t,
               boolean retrying)

Called when call throws an exception and we are going to retry; take action to make it so we succeed on next call (clear caches, do relookup of locations, etc.).

Parameters:

t - throwable which was thrown

retrying - True if we are in retrying mode (we are not in retrying mode when max retries == 1; we ARE in retrying mode if retries > 1 even when we are the last attempt)

getExceptionMessageAdditionalDetail

String getExceptionMessageAdditionalDetail()

Returns:

Some details from the implementation that we would like to add to a terminating exception; i.e. a fatal exception is being thrown ending retries and we might like to add more implementation-specific detail on to the exception being thrown.

sleep

long sleep(long pause,
           int tries)

Parameters:

pause - time to pause

tries - amount of tries until till sleep

Returns:

Suggestion on how much to sleep between retries

call

T call(int callTimeout)
throws Exception

Computes a result, or throws an exception if unable to do so.

Parameters:

callTimeout - - the time available for this call. 0 for infinite.

Returns:

computed result

Throws:

Exception - if unable to compute a result