org.apache.curator.connection

Interface ConnectionHandlingPolicy

All Known Implementing Classes:

ClassicConnectionHandlingPolicy, StandardConnectionHandlingPolicy

public interface ConnectionHandlingPolicy

Abstracts connection handling so that Curator can emulate it's old, pre 3.0.0 handling and update to newer handling.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	ConnectionHandlingPolicy.CheckTimeoutsResult

Method Summary

Methods

Modifier and Type	Method and Description
<T> T	callWithRetry(CuratorZookeeperClient client, Callable<T> proc) Called by RetryLoop.callWithRetry(CuratorZookeeperClient, Callable) to do the work of retrying
ConnectionHandlingPolicy.CheckTimeoutsResult	checkTimeouts(Callable<String> getNewConnectionString, long connectionStartMs, int sessionTimeoutMs, int connectionTimeoutMs) Check timeouts.
int	getSimulatedSessionExpirationPercent() Prior to 3.0.0, Curator did not try to manage session expiration other than the functionality provided by ZooKeeper itself.

Method Detail

getSimulatedSessionExpirationPercent

int getSimulatedSessionExpirationPercent()

Prior to 3.0.0, Curator did not try to manage session expiration other than the functionality provided by ZooKeeper itself. Starting with 3.0.0, Curator has the option of attempting to monitor session expiration above what is provided by ZooKeeper. The percentage returned by this method determines how and if Curator will check for session expiration.

If this method returns 0, Curator does not do any additional checking for session expiration.

If a positive number is returned, Curator will check for session expiration as follows: when ZooKeeper sends a Disconnect event, Curator will start a timer. If re-connection is not achieved before the elapsed time exceeds the negotiated session time multiplied by the session expiration percent, Curator will simulate a session expiration. Due to timing/network issues, it is not possible for a client to match the server's session timeout with complete accuracy. Thus, the need for a session expiration percentage.

Returns:

a percentage from 0 to 100 (0 implied no extra session checking)

callWithRetry

<T> T callWithRetry(CuratorZookeeperClient client,
                  Callable<T> proc)
                throws Exception

Called by RetryLoop.callWithRetry(CuratorZookeeperClient, Callable) to do the work of retrying

Parameters:

client - client

proc - the procedure to retry

Returns:

result

Throws:

Exception - errors

checkTimeouts

ConnectionHandlingPolicy.CheckTimeoutsResult checkTimeouts(Callable<String> getNewConnectionString,
                                                         long connectionStartMs,
                                                         int sessionTimeoutMs,
                                                         int connectionTimeoutMs)
                                                           throws Exception

Check timeouts. NOTE: this method is only called when an attempt to access to the ZooKeeper instances is made and the connection has not completed.

Parameters:

getNewConnectionString - proc to call to check if there is a new connection string. Important: the internal state is cleared after this is called so you MUST handle the new connection string if non null is returned

connectionStartMs - the epoch/ms time that the connection was first initiated

sessionTimeoutMs - the configured/negotiated session timeout in milliseconds

connectionTimeoutMs - the configured connection timeout in milliseconds

Returns:

result

Throws:

Exception - errors