| // Copyright 2022 The Bazel Authors. All rights reserved. |
| // |
| // Licensed 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 com.google.devtools.build.lib.worker; |
| |
| import com.google.common.collect.ImmutableSet; |
| import java.io.IOException; |
| |
| /** |
| * A worker pool that spawns multiple workers and delegates work to them. Allows separate |
| * configuration for singleplex and multiplex workers. While the configuration is per mnemonic, the |
| * actual pools need to be per WorkerKey, as different WorkerKeys may imply different process |
| * startup options. |
| * |
| * <p>This is useful when the worker cannot handle multiple parallel requests on its own and we need |
| * to pre-fork a couple of them instead. Multiplex workers <em>can</em> handle multiple parallel |
| * requests, but do so through WorkerProxy instances. |
| */ |
| public interface WorkerPool { |
| |
| /** |
| * Returns the current maximum number of workers allowed in the pool. |
| * |
| * @param key the worker key. |
| */ |
| int getMaxTotalPerKey(WorkerKey key); |
| |
| /** |
| * Returns the number of active workers. |
| * |
| * @param key the worker key. |
| */ |
| int getNumActive(WorkerKey key); |
| |
| /** |
| * Returns whether there is quota available to create or use an existing worker. |
| * |
| * <p>It is essentially #getMaxTotalPerKey() - #getNumActive() > 0, but meant to be handled |
| * atomically to prevent internal race conditions. |
| * |
| * @param key the worker key. |
| * @return whether there is quota available to either get an existing or create a new worker. |
| */ |
| boolean hasAvailableQuota(WorkerKey key); |
| |
| /** |
| * Evicts specified workers from the pool, destroying them. |
| * |
| * <p>It is possible that not all specified workers get evicted if they become active. |
| * |
| * @param workerIdsToEvict the worker ids to attempt to evict. |
| * @return a set of worker ids that were successfully evicted. |
| */ |
| ImmutableSet<Integer> evictWorkers(ImmutableSet<Integer> workerIdsToEvict) |
| throws InterruptedException; |
| |
| /** Returns the idle workers in the pool (note that these workers can still become active). */ |
| ImmutableSet<Integer> getIdleWorkers() throws InterruptedException; |
| |
| /** |
| * Borrows a persistent worker from the pool, creating if necessary and blocking if unavailable. |
| * |
| * @param key the worker key. |
| */ |
| Worker borrowObject(WorkerKey key) throws IOException, InterruptedException; |
| |
| /** |
| * Returns an active worker back to the pool. |
| * |
| * @param key the worker key. |
| * @param obj the worker to be returned. |
| */ |
| void returnObject(WorkerKey key, Worker obj); |
| |
| /** |
| * Invalidates the worker, thus destroying it. |
| * |
| * @param key the worker key. |
| * @param obj the worker to be invalidated. |
| */ |
| void invalidateObject(WorkerKey key, Worker obj) throws InterruptedException; |
| |
| void reset(); |
| |
| void close(); |
| } |