co.cask.tephra.distributed

Interface ThriftClientProvider

All Known Implementing Classes:

AbstractClientProvider, PooledClientProvider, SingleUseClientProvider, ThreadLocalClientProvider

public interface ThriftClientProvider

This interface is used to provide thrift tx service clients: there is only one (singleton) tx service per JVM, but many threads may use it concurrently. However, being a thrift client, it is not thread-safe. In order to avoid serializing all tx calls by synchronizing on the tx service client, we employ a pool of clients. But in different scenarios there are different strategies for pooling: If there are many short-lived threads, it is wise to have a shared pool between all threads. But if there are few long-lived threads, it may be better to have thread-local client for each thread. This interface provides an abstraction of the pooling strategy.

Method Summary

Methods

Modifier and Type	Method and Description
void	discardClient(TransactionServiceThriftClient client) Discard an tx client from the provider's pool.
TransactionServiceThriftClient	getClient() Retrieve an tx client for exclusive use by the current thread.
void	initialize() Initialize the provider.
void	returnClient(TransactionServiceThriftClient client) Release an tx client back to the provider's pool.

Method Detail

initialize

void initialize()
                throws org.apache.thrift.TException

Initialize the provider. At this point, it should be verified that tx service is up and running and getClient() can create new clients when necessary.

Throws:

org.apache.thrift.TException

getClient

TransactionServiceThriftClient getClient()
                                         throws org.apache.thrift.TException

Retrieve an tx client for exclusive use by the current thread. The tx must be returned to the provider after use.

Returns:

an tx client, connected and fully functional

Throws:

org.apache.thrift.TException

returnClient

void returnClient(TransactionServiceThriftClient client)

Release an tx client back to the provider's pool.

Parameters:

client - The client to release

discardClient

void discardClient(TransactionServiceThriftClient client)

Discard an tx client from the provider's pool. This is called after a client becomes disfunctional, for instance, due to a socket exception. The provider must make sure to close the client, and it must remove the client from its arsenal and be prepared to create a new client subsequently.

Parameters:

client - The client to discard