org.apache.hadoop.yarn.api

Interface ClientSCMProtocol

@InterfaceAudience.Public
 @InterfaceStability.Unstable
public interface ClientSCMProtocol

The protocol between clients and the SharedCacheManager to claim and release resources in the shared cache.

Method Summary

Modifier and Type	Method and Description
ReleaseSharedCacheResourceResponse	release(ReleaseSharedCacheResourceRequest request) The interface used by clients to release a resource with the SharedCacheManager. This method is called once an application is no longer using a claimed resource in the shared cache.
UseSharedCacheResourceResponse	use(UseSharedCacheResourceRequest request) The interface used by clients to claim a resource with the SharedCacheManager. The client uses a checksum to identify the resource and an ApplicationId to identify which application will be using the resource.

Method Detail

use

UseSharedCacheResourceResponse use(UseSharedCacheResourceRequest request)
                            throws YarnException,
                                   IOException

The interface used by clients to claim a resource with the SharedCacheManager. The client uses a checksum to identify the resource and an ApplicationId to identify which application will be using the resource.

The SharedCacheManager responds with whether or not the resource exists in the cache. If the resource exists, a Path to the resource in the shared cache is returned. If the resource does not exist, the response is empty.

Parameters:

request - request to claim a resource in the shared cache

Returns:

response indicating if the resource is already in the cache

Throws:

YarnException - exceptions from yarn servers.

IOException - io error occur.

release

ReleaseSharedCacheResourceResponse release(ReleaseSharedCacheResourceRequest request)
                                    throws YarnException,
                                           IOException

The interface used by clients to release a resource with the SharedCacheManager. This method is called once an application is no longer using a claimed resource in the shared cache. The client uses a checksum to identify the resource and an ApplicationId to identify which application is releasing the resource.

Note: This method is an optimization and the client is not required to call it for correctness.

Currently the SharedCacheManager sends an empty response.

Parameters:

request - request to release a resource in the shared cache

Returns:

(empty) response on releasing the resource

Throws:

YarnException - exceptions from yarn servers.

IOException - io error occur.