com.spotify.folsom.retry

Class RetryingClient

java.lang.Object

com.spotify.folsom.retry.RetryingClient

All Implemented Interfaces:

ObservableClient, RawMemcacheClient

public class RetryingClient
extends java.lang.Object
implements RawMemcacheClient

A simple wrapping client that retries once (but only for MemcacheClosedException's). This helps avoid some transient problems when a node suddenly stops. It's mostly useful in combination with a client that internally routes to multiple nodes such as the Ketama client or RoundRobin client. It won't prevent all MemcacheClosedException's from propagating, it will just reduce the frequency in some cases.

The retrying is intentionally strict about when to retry and how many times to retries in order to minimize risk of causing more problems then it would solve.

Field Summary

Fields

Modifier and Type	Field and Description
private RawMemcacheClient	delegate

Constructor Summary

Constructors

Constructor and Description
RetryingClient(RawMemcacheClient delegate)

Method Summary

Modifier and Type	Method and Description
java.lang.Throwable	getConnectionFailure() Returns the unrecoverable connection failure, if any.
boolean	isConnected() Is the client connected to a server?
int	numActiveConnections() How many active socket connections do we have (i.e.
int	numTotalConnections() How many actual socket connections do we have, including currently disconnected clients.
void	registerForConnectionChanges(ConnectionChangeListener listener) Register for connection change events.
<T> java.util.concurrent.CompletionStage<T>	send(Request<T> request)
void	shutdown() Shut down the client.
java.lang.String	toString()
void	unregisterForConnectionChanges(ConnectionChangeListener listener) Unregister the provided listener so that it no longer receives connection change callbacks.

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.spotify.folsom.ObservableClient

awaitConnected, awaitDisconnected, awaitFullyConnected, awaitFullyDisconnected, awaitFuture, connectFuture, disconnectFuture, fullyConnectedFuture, fullyDisconnectFuture

Field Detail

delegate

private final RawMemcacheClient delegate

Constructor Detail

RetryingClient

public RetryingClient(RawMemcacheClient delegate)

Method Detail

send

public <T> java.util.concurrent.CompletionStage<T> send(Request<T> request)

Specified by:

send in interface RawMemcacheClient

shutdown

public void shutdown()

Description copied from interface: RawMemcacheClient

Shut down the client. Use ObservableClient.registerForConnectionChanges(ConnectionChangeListener) to to get notified when it has (possibly) finished shutting down

Specified by:

shutdown in interface RawMemcacheClient

isConnected

public boolean isConnected()

Description copied from interface: ObservableClient

Is the client connected to a server?

Specified by:

isConnected in interface ObservableClient

Returns:

true if the client is connected

getConnectionFailure

public java.lang.Throwable getConnectionFailure()

Description copied from interface: ObservableClient

Returns the unrecoverable connection failure, if any.

Specified by:

getConnectionFailure in interface ObservableClient

Returns:

null, if there's no connection failure

numTotalConnections

public int numTotalConnections()

Description copied from interface: RawMemcacheClient

How many actual socket connections do we have, including currently disconnected clients.

Specified by:

numTotalConnections in interface ObservableClient

Specified by:

numTotalConnections in interface RawMemcacheClient

Returns:

the number of total connections

numActiveConnections

public int numActiveConnections()

Description copied from interface: RawMemcacheClient

How many active socket connections do we have (i.e. not disconnected)

Specified by:

numActiveConnections in interface ObservableClient

Specified by:

numActiveConnections in interface RawMemcacheClient

Returns:

the number of active connections

registerForConnectionChanges

public void registerForConnectionChanges(ConnectionChangeListener listener)

Description copied from interface: ObservableClient

Register for connection change events. This should trigger at least once for every connection change. You should immediately get an initial callback, so that if you are creating a CompletionStage looking for a connection state that has already been reached it will return immediately.

Specified by:

registerForConnectionChanges in interface ObservableClient

Parameters:

listener - the listener to notify of connection changes

unregisterForConnectionChanges

public void unregisterForConnectionChanges(ConnectionChangeListener listener)

Description copied from interface: ObservableClient

Unregister the provided listener so that it no longer receives connection change callbacks.

Specified by:

unregisterForConnectionChanges in interface ObservableClient

Parameters:

listener - the listener to unregister.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object