Package org.apache.hadoop.hbase.coprocessor

Interface ClientMetaObserver

@LimitedPrivate("Coprocesssor")
@Evolving
public interface ClientMetaObserver

Defines coprocessor hooks for interacting operations for ClientMetaService which is responsible for ZooKeeperless HBase service discovery.

Since most implementations will be interested in only a subset of hooks, this class uses 'default' functions to avoid having to add unnecessary overrides. When the functions are non-empty, it's simply to satisfy the compiler by returning value of expected (non-void) type. It is done in a way that these default definitions act as no-op. So our suggestion to implementation would be to not call these 'default' methods from overrides.

Exception Handling

For all functions, exception handling is done as follows:

• Exceptions of type IOException are reported back to client.
• For any other kind of exception:
  • If the configuration CoprocessorHost.ABORT_ON_ERROR_KEY is set to true, then the server aborts.
  • Otherwise, coprocessor is removed from the server and DoNotRetryIOException is returned to the client.

Method Summary

Modifier and Type	Method	Description
default ServerName	postGetActiveMaster(ObserverContext<ClientMetaCoprocessorEnvironment> ctx, ServerName serverName)	Called after we got the active master.
default List<ServerName>	postGetBootstrapNodes(ObserverContext<ClientMetaCoprocessorEnvironment> ctx, List<ServerName> bootstrapNodes)	Called after we got bootstrap nodes.
default String	postGetClusterId(ObserverContext<ClientMetaCoprocessorEnvironment> ctx, String clusterId)	Called after we got the cluster ID.
default Map<ServerName,Boolean>	postGetMasters(ObserverContext<ClientMetaCoprocessorEnvironment> ctx, Map<ServerName,Boolean> serverNames)	Called after we got the master servers.
default List<HRegionLocation>	postGetMetaLocations(ObserverContext<ClientMetaCoprocessorEnvironment> ctx, List<HRegionLocation> metaLocations)	Called after we got the meta region locations.
default void	preGetActiveMaster(ObserverContext<ClientMetaCoprocessorEnvironment> ctx)	Called before getting the active master.
default void	preGetBootstrapNodes(ObserverContext<ClientMetaCoprocessorEnvironment> ctx)	Called before getting bootstrap nodes.
default void	preGetClusterId(ObserverContext<ClientMetaCoprocessorEnvironment> ctx)	Called before getting the cluster ID.
default void	preGetMasters(ObserverContext<ClientMetaCoprocessorEnvironment> ctx)	Called before getting the master servers.
default void	preGetMetaLocations(ObserverContext<ClientMetaCoprocessorEnvironment> ctx)	Called before getting the meta region locations.

Method Details

preGetClusterId

default void preGetClusterId(ObserverContext<ClientMetaCoprocessorEnvironment> ctx)
                      throws IOException

Called before getting the cluster ID.

Parameters:

ctx - the environment to interact with the framework

Throws:

IOException

postGetClusterId

default String postGetClusterId(ObserverContext<ClientMetaCoprocessorEnvironment> ctx,
 String clusterId)
                         throws IOException

Called after we got the cluster ID.

Parameters:

ctx - the environment to interact with the framework

clusterId - the actual cluster ID

Returns:

the cluster ID which is returned to the client.

Throws:

IOException

preGetActiveMaster

default void preGetActiveMaster(ObserverContext<ClientMetaCoprocessorEnvironment> ctx)
                         throws IOException

Called before getting the active master.

Parameters:

ctx - the environment to interact with the framework

Throws:

IOException

postGetActiveMaster

default ServerName postGetActiveMaster(ObserverContext<ClientMetaCoprocessorEnvironment> ctx,
 ServerName serverName)
                                throws IOException

Called after we got the active master.

Parameters:

ctx - the environment to interact with the framework

serverName - the actual active master address. It can be null if there is no active master.

Returns:

the active master address which is returned to the client. It can be null.

Throws:

IOException

preGetMasters

default void preGetMasters(ObserverContext<ClientMetaCoprocessorEnvironment> ctx)
                    throws IOException

Called before getting the master servers.

Parameters:

ctx - the environment to interact with the framework

Throws:

IOException

postGetMasters

default Map<ServerName,Boolean> postGetMasters(ObserverContext<ClientMetaCoprocessorEnvironment> ctx,
 Map<ServerName,Boolean> serverNames)
                                        throws IOException

Called after we got the master servers.

Parameters:

ctx - the environment to interact with the framework

serverNames - the actual master servers addresses and active statuses

Returns:

the master servers addresses and active statuses which are returned to the client.

Throws:

IOException

preGetBootstrapNodes

default void preGetBootstrapNodes(ObserverContext<ClientMetaCoprocessorEnvironment> ctx)
                           throws IOException

Called before getting bootstrap nodes.

Parameters:

ctx - the environment to interact with the framework

Throws:

IOException

postGetBootstrapNodes

default List<ServerName> postGetBootstrapNodes(ObserverContext<ClientMetaCoprocessorEnvironment> ctx,
 List<ServerName> bootstrapNodes)
                                        throws IOException

Called after we got bootstrap nodes.

Parameters:

ctx - the environment to interact with the framework

bootstrapNodes - the actual bootstrap nodes

Returns:

the bootstrap nodes which are returned to the client.

Throws:

IOException

preGetMetaLocations

default void preGetMetaLocations(ObserverContext<ClientMetaCoprocessorEnvironment> ctx)
                          throws IOException

Called before getting the meta region locations.

Parameters:

ctx - the environment to interact with the framework

Throws:

IOException

postGetMetaLocations

default List<HRegionLocation> postGetMetaLocations(ObserverContext<ClientMetaCoprocessorEnvironment> ctx,
 List<HRegionLocation> metaLocations)
                                            throws IOException

Called after we got the meta region locations.

Parameters:

ctx - the environment to interact with the framework

metaLocations - the actual meta region locations

Returns:

the meta region locations which are returned to the client.

Throws:

IOException