1 2 /** 3 * Copyright (C) 2018-present MongoDB, Inc. 4 * 5 * This program is free software: you can redistribute it and/or modify 6 * it under the terms of the Server Side Public License, version 1, 7 * as published by MongoDB, Inc. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * Server Side Public License for more details. 13 * 14 * You should have received a copy of the Server Side Public License 15 * along with this program. If not, see 16 * <http://www.mongodb.com/licensing/server-side-public-license>. 17 * 18 * As a special exception, the copyright holders give permission to link the 19 * code of portions of this program with the OpenSSL library under certain 20 * conditions as described in each individual source file and distribute 21 * linked combinations including the program with the OpenSSL library. You 22 * must comply with the Server Side Public License in all respects for 23 * all of the code used other than as permitted herein. If you modify file(s) 24 * with this exception, you may extend this exception to your version of the 25 * file(s), but you are not obligated to do so. If you do not wish to do so, 26 * delete this exception statement from your version. If you delete this 27 * exception statement from all source files in the program, then also delete 28 * it in the license file. 29 */ 30 31 #pragma once 32 33 #include <deque> 34 35 #include "mongo/base/status.h" 36 #include "mongo/platform/atomic_word.h" 37 #include "mongo/stdx/condition_variable.h" 38 #include "mongo/stdx/mutex.h" 39 #include "mongo/transport/service_executor.h" 40 #include "mongo/transport/service_executor_task_names.h" 41 42 namespace mongo { 43 namespace transport { 44 45 /** 46 * The reserved service executor emulates a thread per connection. 47 * Each connection has its own worker thread where jobs get scheduled. 48 * 49 * The executor will start reservedThreads on start, and create a new thread every time it 50 * starts a new thread, ensuring there are always reservedThreads available for work - this 51 * means that even when you hit the NPROC ulimit, there will still be threads ready to 52 * accept work. When threads exit, they will go back to waiting for work if there are fewer 53 * than reservedThreads available. 54 */ 55 class ServiceExecutorReserved final : public ServiceExecutor { 56 public: 57 explicit ServiceExecutorReserved(ServiceContext* ctx, std::string name, size_t reservedThreads); 58 59 Status start() override; 60 Status shutdown(Milliseconds timeout) override; 61 Status schedule(Task task, ScheduleFlags flags, ServiceExecutorTaskName taskName) override; 62 transportMode()63 Mode transportMode() const override { 64 return Mode::kSynchronous; 65 } 66 67 void appendStats(BSONObjBuilder* bob) const override; 68 69 private: 70 Status _startWorker(); 71 72 static thread_local std::deque<Task> _localWorkQueue; 73 static thread_local int _localRecursionDepth; 74 static thread_local int64_t _localThreadIdleCounter; 75 76 AtomicBool _stillRunning{false}; 77 78 mutable stdx::mutex _mutex; 79 stdx::condition_variable _threadWakeup; 80 stdx::condition_variable _shutdownCondition; 81 82 std::deque<Task> _readyTasks; 83 84 AtomicUInt32 _numRunningWorkerThreads{0}; 85 size_t _numReadyThreads{0}; 86 size_t _numStartingThreads{0}; 87 88 const std::string _name; 89 const size_t _reservedThreads; 90 }; 91 92 } // namespace transport 93 } // namespace mongo 94