folly/folly/executors/FunctionScheduler.h

/*
 * 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 <chrono>
#include <condition_variable>
#include <mutex>
#include <thread>
#include <vector>

#include <folly/Function.h>
#include <folly/Range.h>
#include <folly/container/F14Map.h>
#include <folly/hash/Hash.h>

namespace folly {

/**
 * Schedules any number of functions to run at various intervals. E.g.,
 *
 *   FunctionScheduler fs;
 *
 *   fs.addFunction([&] { LOG(INFO) << "tick..."; }, seconds(1), "ticker");
 *   fs.addFunction(std::bind(&TestClass::doStuff, this), minutes(5), "stuff");
 *   fs.start();
 *   ........
 *   fs.cancelFunction("ticker");
 *   fs.addFunction([&] { LOG(INFO) << "tock..."; }, minutes(3), "tocker");
 *   ........
 *   fs.shutdown();
 *
 *
 * Note: the class uses only one thread - if you want to use more than one
 *       thread, either use multiple FunctionScheduler objects, or check out
 *       ThreadedRepeatingFunctionRunner.h for a much simpler contract of
 *       "run each function periodically in its own thread".
 *
 * start() schedules the functions, while shutdown() terminates further
 * scheduling (after any running function terminates).
 */
class FunctionScheduler { … };

} // namespace folly