| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.beam.runners.fnexecution.control; |
| |
| import java.time.Duration; |
| import java.util.concurrent.TimeoutException; |
| import javax.annotation.concurrent.ThreadSafe; |
| |
| /** |
| * A pool of control clients that brokers incoming SDK harness connections (in the form of {@link |
| * InstructionRequestHandler InstructionRequestHandlers}. |
| * |
| * <p>Incoming instruction handlers usually come from the control plane gRPC service. Typical use: |
| * |
| * <pre> |
| * // Within owner of the pool, who may or may not own the control plane server as well |
| * ControlClientPool pool = ... |
| * FnApiControlClientPoolService service = |
| * FnApiControlClientPoolService.offeringClientsToSink(pool.getSink(), headerAccessor) |
| * // Incoming gRPC control connections will now be added to the client pool. |
| * |
| * // Within code that interacts with the instruction handler. The get call blocks until an |
| * // incoming client is available: |
| * ControlClientSource clientSource = ... InstructionRequestHandler |
| * instructionHandler = clientSource.get("worker-id"); |
| * </pre> |
| * |
| * <p>All {@link ControlClientPool} implementations must be thread-safe. |
| */ |
| @ThreadSafe |
| public interface ControlClientPool { |
| |
| /** Sink for control clients. */ |
| Sink getSink(); |
| |
| /** Source of control clients. */ |
| Source getSource(); |
| |
| /** A sink for {@link InstructionRequestHandler InstructionRequestHandlers} keyed by worker id. */ |
| @FunctionalInterface |
| interface Sink { |
| |
| /** |
| * Puts an {@link InstructionRequestHandler} into a client pool. Worker ids must be unique per |
| * pool. |
| */ |
| void put(String workerId, InstructionRequestHandler instructionHandler) throws Exception; |
| } |
| |
| /** A source of {@link InstructionRequestHandler InstructionRequestHandlers}. */ |
| @FunctionalInterface |
| interface Source { |
| |
| /** |
| * Retrieves the {@link InstructionRequestHandler} for the given worker id, blocking until |
| * available or the request times out. Worker ids must be unique per pool. A given worker id |
| * must not be requested multiple times. Note that if the given worker id is never entered into |
| * the pool, this call will never return. |
| * |
| * @throws TimeoutException if the request times out |
| * @throws InterruptedException if interrupted while waiting |
| */ |
| InstructionRequestHandler take(String workerId, Duration timeout) throws Exception; |
| } |
| } |