/* * Copyright (c) Meta Platforms, Inc. and affiliates. * * 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. */ #pragma once #include #include #include #include #include #include #include #include namespace folly { class RequestContext; /** * WorkerProvider is a simple interface that can be used * to collect information about worker threads that are pulling work * from a given queue. */ class WorkerProvider { public: virtual ~WorkerProvider() {} /** * Abstract type returned by the collectThreadIds() method. * Implementations of the WorkerProvider interface need to define this class. * The intent is to return a guard along with a list of worker IDs which can * be removed on destruction of this object. */ class KeepAlive { public: virtual ~KeepAlive() = 0; }; // collectThreadIds() will return this aggregate type which includes an // instance of the WorkersGuard. struct IdsWithKeepAlive { std::unique_ptr guard; std::vector threadIds; }; // Capture the Thread IDs of all threads consuming from a given queue. // The provided vector should be populated with the OS Thread IDs and the // method should return a SharedMutex which the caller can lock. virtual IdsWithKeepAlive collectThreadIds() = 0; }; class ThreadIdWorkerProvider : public WorkerProvider { public: IdsWithKeepAlive collectThreadIds() override final; void addTid(pid_t tid); // Will block until all KeepAlives have been destroyed, if any exist void removeTid(pid_t tid); private: Synchronized> osThreadIds_; SharedMutex threadsExitMutex_; }; class QueueObserver { public: virtual ~QueueObserver() {} virtual intptr_t onEnqueued(const RequestContext*) = 0; virtual void onDequeued(intptr_t) = 0; }; class QueueObserverFactory { public: virtual ~QueueObserverFactory() {} virtual std::unique_ptr create(int8_t pri) = 0; static std::unique_ptr make( const std::string& context, size_t numPriorities, WorkerProvider* workerProvider = nullptr); }; using MakeQueueObserverFactory = std::unique_ptr( const std::string&, size_t, WorkerProvider*); #if FOLLY_HAVE_WEAK_SYMBOLS FOLLY_ATTR_WEAK MakeQueueObserverFactory make_queue_observer_factory; #else constexpr MakeQueueObserverFactory* make_queue_observer_factory = nullptr; #endif } // namespace folly