org.apache.drill.exec.expr.fn.registry

Class RemoteFunctionRegistry

java.lang.Object

org.apache.drill.exec.expr.fn.registry.RemoteFunctionRegistry

All Implemented Interfaces:

AutoCloseable

public class RemoteFunctionRegistry
extends Object
implements AutoCloseable

Is responsible for remote function registry management. Creates all remote registry areas at startup and validates them, during init establishes connections with three udf related stores. Provides tools to work with three udf related stores, gives access to remote registry areas.

There are three udf stores:

REGISTRY - persistent store, stores remote function registry UserBitShared.Registry under udf path which contains information about all dynamically registered jars and their function signatures. If connection is created for the first time, puts empty remote registry. UNREGISTRATION - transient store, stores information under udf/unregister path. udf/unregister path is persistent by itself but any child created will be transient. Whenever user submits request to unregister jar, child path with jar name is created under this store. This store also holds unregistration listener, which notifies all drill bits when child path is created, so they can start local unregistration process. JARS - transient store, stores information under udf/jars path. udf/jars path is persistent by itself but any child created will be transient. Servers as lock, not allowing to perform any action on the same time. There two types of actions: RemoteFunctionRegistry.Action.REGISTRATION and RemoteFunctionRegistry.Action.UNREGISTRATION. Before starting any action, users tries to create child path with jar name under this store and if such path already exists, receives action being performed on that very jar. When user finishes its action, he deletes child path with jar name.

There are three udf areas:

STAGING - area where user copies binary and source jars before starting registration process. REGISTRY - area where registered jars are stored. TMP - area where source and binary jars are backed up in unique folder during registration process.