382 lines
12 KiB
C
382 lines
12 KiB
C
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/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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#include <folly/Function.h>
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#include <folly/Range.h>
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#include <folly/hash/Hash.h>
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#include <chrono>
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#include <condition_variable>
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#include <mutex>
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#include <thread>
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#include <unordered_map>
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#include <vector>
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namespace folly {
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/**
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* Schedules any number of functions to run at various intervals. E.g.,
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*
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* FunctionScheduler fs;
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*
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* fs.addFunction([&] { LOG(INFO) << "tick..."; }, seconds(1), "ticker");
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* fs.addFunction(std::bind(&TestClass::doStuff, this), minutes(5), "stuff");
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* fs.start();
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* ........
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* fs.cancelFunction("ticker");
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* fs.addFunction([&] { LOG(INFO) << "tock..."; }, minutes(3), "tocker");
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* ........
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* fs.shutdown();
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*
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*
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* Note: the class uses only one thread - if you want to use more than one
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* thread, either use multiple FunctionScheduler objects, or check out
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* ThreadedRepeatingFunctionRunner.h for a much simpler contract of
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* "run each function periodically in its own thread".
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*
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* start() schedules the functions, while shutdown() terminates further
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* scheduling.
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*/
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class FunctionScheduler {
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public:
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FunctionScheduler();
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~FunctionScheduler();
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/**
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* By default steady is false, meaning schedules may lag behind overtime.
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* This could be due to long running tasks or time drift because of randomness
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* in thread wakeup time.
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* By setting steady to true, FunctionScheduler will attempt to catch up.
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* i.e. more like a cronjob
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*
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* NOTE: it's only safe to set this before calling start()
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*/
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void setSteady(bool steady) {
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steady_ = steady;
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}
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/*
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* Parameters to control the function interval.
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*
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* If isPoisson is true, then use std::poisson_distribution to pick the
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* interval between each invocation of the function.
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*
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* If isPoisson is false, then always use the fixed interval specified to
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* addFunction().
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*/
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struct LatencyDistribution {
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bool isPoisson;
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double poissonMean;
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LatencyDistribution(bool poisson, double mean)
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: isPoisson(poisson), poissonMean(mean) {}
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};
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/**
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* Adds a new function to the FunctionScheduler.
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*
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* Functions will not be run until start() is called. When start() is
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* called, each function will be run after its specified startDelay.
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* Functions may also be added after start() has been called, in which case
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* startDelay is still honored.
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*
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* Throws an exception on error. In particular, each function must have a
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* unique name--two functions cannot be added with the same name.
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*/
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void addFunction(
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Function<void()>&& cb,
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std::chrono::milliseconds interval,
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StringPiece nameID = StringPiece(),
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std::chrono::milliseconds startDelay = std::chrono::milliseconds(0));
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/*
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* Add a new function to the FunctionScheduler with a specified
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* LatencyDistribution
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*/
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void addFunction(
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Function<void()>&& cb,
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std::chrono::milliseconds interval,
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const LatencyDistribution& latencyDistr,
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StringPiece nameID = StringPiece(),
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std::chrono::milliseconds startDelay = std::chrono::milliseconds(0));
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/**
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* Adds a new function to the FunctionScheduler to run only once.
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*/
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void addFunctionOnce(
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Function<void()>&& cb,
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StringPiece nameID = StringPiece(),
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std::chrono::milliseconds startDelay = std::chrono::milliseconds(0));
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/**
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* Add a new function to the FunctionScheduler with the time
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* interval being distributed uniformly within the given interval
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* [minInterval, maxInterval].
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*/
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void addFunctionUniformDistribution(
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Function<void()>&& cb,
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std::chrono::milliseconds minInterval,
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std::chrono::milliseconds maxInterval,
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StringPiece nameID,
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std::chrono::milliseconds startDelay);
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/**
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* Add a new function to the FunctionScheduler whose start times are attempted
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* to be scheduled so that they are congruent modulo the interval.
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* Note: The scheduling of the next run time happens right before the function
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* invocation, so the first time a function takes more time than the interval,
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* it will be reinvoked immediately.
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*/
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void addFunctionConsistentDelay(
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Function<void()>&& cb,
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std::chrono::milliseconds interval,
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StringPiece nameID = StringPiece(),
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std::chrono::milliseconds startDelay = std::chrono::milliseconds(0));
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/**
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* A type alias for function that is called to determine the time
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* interval for the next scheduled run.
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*/
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using IntervalDistributionFunc = Function<std::chrono::milliseconds()>;
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/**
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* A type alias for function that returns the next run time, given the current
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* run time and the current start time.
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*/
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using NextRunTimeFunc = Function<std::chrono::steady_clock::time_point(
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std::chrono::steady_clock::time_point,
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std::chrono::steady_clock::time_point)>;
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/**
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* Add a new function to the FunctionScheduler. The scheduling interval
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* is determined by the interval distribution functor, which is called
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* every time the next function execution is scheduled. This allows
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* for supporting custom interval distribution algorithms in addition
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* to built in constant interval; and Poisson and jitter distributions
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* (@see FunctionScheduler::addFunction and
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* @see FunctionScheduler::addFunctionJitterInterval).
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*/
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void addFunctionGenericDistribution(
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Function<void()>&& cb,
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IntervalDistributionFunc&& intervalFunc,
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const std::string& nameID,
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const std::string& intervalDescr,
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std::chrono::milliseconds startDelay);
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/**
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* Like addFunctionGenericDistribution, adds a new function to the
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* FunctionScheduler, but the next run time is determined directly by the
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* given functor, rather than by adding an interval.
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*/
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void addFunctionGenericNextRunTimeFunctor(
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Function<void()>&& cb,
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NextRunTimeFunc&& fn,
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const std::string& nameID,
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const std::string& intervalDescr,
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std::chrono::milliseconds startDelay);
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/**
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* Cancels the function with the specified name, so it will no longer be run.
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*
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* Returns false if no function exists with the specified name.
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*/
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bool cancelFunction(StringPiece nameID);
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bool cancelFunctionAndWait(StringPiece nameID);
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/**
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* All functions registered will be canceled.
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*/
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void cancelAllFunctions();
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void cancelAllFunctionsAndWait();
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/**
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* Resets the specified function's timer.
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* When resetFunctionTimer is called, the specified function's timer will
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* be reset with the same parameters it was passed initially, including
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* its startDelay. If the startDelay was 0, the function will be invoked
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* immediately.
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*
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* Returns false if no function exists with the specified name.
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*/
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bool resetFunctionTimer(StringPiece nameID);
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/**
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* Starts the scheduler.
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*
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* Returns false if the scheduler was already running.
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*/
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bool start();
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/**
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* Stops the FunctionScheduler.
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*
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* It may be restarted later by calling start() again.
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* Returns false if the scheduler was not running.
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*/
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bool shutdown();
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/**
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* Set the name of the worker thread.
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*/
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void setThreadName(StringPiece threadName);
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private:
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struct RepeatFunc {
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Function<void()> cb;
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NextRunTimeFunc nextRunTimeFunc;
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std::chrono::steady_clock::time_point nextRunTime;
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std::string name;
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std::chrono::milliseconds startDelay;
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std::string intervalDescr;
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bool runOnce;
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RepeatFunc(
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Function<void()>&& cback,
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IntervalDistributionFunc&& intervalFn,
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const std::string& nameID,
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const std::string& intervalDistDescription,
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std::chrono::milliseconds delay,
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bool once)
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: RepeatFunc(
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std::move(cback),
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getNextRunTimeFunc(std::move(intervalFn)),
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nameID,
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intervalDistDescription,
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delay,
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once) {}
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RepeatFunc(
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Function<void()>&& cback,
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NextRunTimeFunc&& nextRunTimeFn,
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const std::string& nameID,
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const std::string& intervalDistDescription,
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std::chrono::milliseconds delay,
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bool once)
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: cb(std::move(cback)),
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nextRunTimeFunc(std::move(nextRunTimeFn)),
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nextRunTime(),
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name(nameID),
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startDelay(delay),
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intervalDescr(intervalDistDescription),
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runOnce(once) {}
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static NextRunTimeFunc getNextRunTimeFunc(
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IntervalDistributionFunc&& intervalFn) {
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return [intervalFn = std::move(intervalFn)](
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std::chrono::steady_clock::time_point /* curNextRunTime */,
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std::chrono::steady_clock::time_point curTime) mutable {
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return curTime + intervalFn();
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};
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}
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std::chrono::steady_clock::time_point getNextRunTime() const {
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return nextRunTime;
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}
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void setNextRunTimeStrict(std::chrono::steady_clock::time_point curTime) {
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nextRunTime = nextRunTimeFunc(nextRunTime, curTime);
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}
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void setNextRunTimeSteady() {
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nextRunTime = nextRunTimeFunc(nextRunTime, nextRunTime);
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}
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void resetNextRunTime(std::chrono::steady_clock::time_point curTime) {
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nextRunTime = curTime + startDelay;
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}
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void cancel() {
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// Simply reset cb to an empty function.
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cb = {};
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}
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bool isValid() const {
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return bool(cb);
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}
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};
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struct RunTimeOrder {
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bool operator()(
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const std::unique_ptr<RepeatFunc>& f1,
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const std::unique_ptr<RepeatFunc>& f2) const {
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return f1->getNextRunTime() > f2->getNextRunTime();
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}
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};
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typedef std::vector<std::unique_ptr<RepeatFunc>> FunctionHeap;
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typedef std::unordered_map<StringPiece, RepeatFunc*, Hash> FunctionMap;
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void run();
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void runOneFunction(
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std::unique_lock<std::mutex>& lock,
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std::chrono::steady_clock::time_point now);
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void cancelFunction(const std::unique_lock<std::mutex>& lock, RepeatFunc* it);
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void addFunctionToHeap(
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const std::unique_lock<std::mutex>& lock,
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std::unique_ptr<RepeatFunc> func);
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template <typename RepeatFuncNextRunTimeFunc>
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void addFunctionToHeapChecked(
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Function<void()>&& cb,
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RepeatFuncNextRunTimeFunc&& fn,
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const std::string& nameID,
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const std::string& intervalDescr,
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std::chrono::milliseconds startDelay,
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bool runOnce);
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void addFunctionInternal(
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Function<void()>&& cb,
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NextRunTimeFunc&& fn,
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const std::string& nameID,
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const std::string& intervalDescr,
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std::chrono::milliseconds startDelay,
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bool runOnce);
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void addFunctionInternal(
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Function<void()>&& cb,
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IntervalDistributionFunc&& fn,
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const std::string& nameID,
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const std::string& intervalDescr,
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std::chrono::milliseconds startDelay,
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bool runOnce);
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// Return true if the current function is being canceled
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bool cancelAllFunctionsWithLock(std::unique_lock<std::mutex>& lock);
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bool cancelFunctionWithLock(
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std::unique_lock<std::mutex>& lock,
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StringPiece nameID);
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std::thread thread_;
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// Mutex to protect our member variables.
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std::mutex mutex_;
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bool running_{false};
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// The functions to run.
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// This is a heap, ordered by next run time.
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FunctionHeap functions_;
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FunctionMap functionsMap_;
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RunTimeOrder fnCmp_;
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// The function currently being invoked by the running thread.
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// This is null when the running thread is idle
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RepeatFunc* currentFunction_{nullptr};
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// Condition variable that is signalled whenever a new function is added
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// or when the FunctionScheduler is stopped.
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std::condition_variable runningCondvar_;
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std::string threadName_;
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bool steady_{false};
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bool cancellingCurrentFunction_{false};
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};
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} // namespace folly
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