2 * Copyright 2016 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 #include <folly/experimental/FunctionScheduler.h>
21 #include <folly/Conv.h>
22 #include <folly/Random.h>
23 #include <folly/String.h>
24 #include <folly/ThreadName.h>
26 using std::chrono::milliseconds;
27 using std::chrono::steady_clock;
33 struct ConstIntervalFunctor {
34 const milliseconds constInterval;
36 explicit ConstIntervalFunctor(milliseconds interval)
37 : constInterval(interval) {
38 if (interval < milliseconds::zero()) {
39 throw std::invalid_argument(
41 "time interval must be non-negative");
45 milliseconds operator()() const { return constInterval; }
48 struct PoissonDistributionFunctor {
49 std::default_random_engine generator;
50 std::poisson_distribution<int> poissonRandom;
52 explicit PoissonDistributionFunctor(double meanPoissonMs)
53 : poissonRandom(meanPoissonMs) {
54 if (meanPoissonMs < 0.0) {
55 throw std::invalid_argument(
57 "Poisson mean interval must be non-negative");
61 milliseconds operator()() { return milliseconds(poissonRandom(generator)); }
64 struct UniformDistributionFunctor {
65 std::default_random_engine generator;
66 std::uniform_int_distribution<> dist;
68 UniformDistributionFunctor(milliseconds minInterval, milliseconds maxInterval)
69 : generator(Random::rand32()),
70 dist(minInterval.count(), maxInterval.count()) {
71 if (minInterval > maxInterval) {
72 throw std::invalid_argument(
74 "min time interval must be less or equal than max interval");
76 if (minInterval < milliseconds::zero()) {
77 throw std::invalid_argument(
79 "time interval must be non-negative");
83 milliseconds operator()() { return milliseconds(dist(generator)); }
86 } // anonymous namespace
88 FunctionScheduler::FunctionScheduler() {}
90 FunctionScheduler::~FunctionScheduler() {
91 // make sure to stop the thread (if running)
95 void FunctionScheduler::addFunction(Function<void()>&& cb,
96 milliseconds interval,
98 milliseconds startDelay) {
99 addFunctionGenericDistribution(
101 ConstIntervalFunctor(interval),
103 to<std::string>(interval.count(), "ms"),
107 void FunctionScheduler::addFunction(Function<void()>&& cb,
108 milliseconds interval,
109 const LatencyDistribution& latencyDistr,
111 milliseconds startDelay) {
112 if (latencyDistr.isPoisson) {
113 addFunctionGenericDistribution(
115 PoissonDistributionFunctor(latencyDistr.poissonMean),
117 to<std::string>(latencyDistr.poissonMean, "ms (Poisson mean)"),
120 addFunction(std::move(cb), interval, nameID, startDelay);
124 void FunctionScheduler::addFunctionUniformDistribution(
125 Function<void()>&& cb,
126 milliseconds minInterval,
127 milliseconds maxInterval,
129 milliseconds startDelay) {
130 addFunctionGenericDistribution(
132 UniformDistributionFunctor(minInterval, maxInterval),
135 "[", minInterval.count(), " , ", maxInterval.count(), "] ms"),
139 void FunctionScheduler::addFunctionGenericDistribution(
140 Function<void()>&& cb,
141 IntervalDistributionFunc&& intervalFunc,
142 const std::string& nameID,
143 const std::string& intervalDescr,
144 milliseconds startDelay) {
146 throw std::invalid_argument(
147 "FunctionScheduler: Scheduled function must be set");
150 throw std::invalid_argument(
151 "FunctionScheduler: interval distribution function must be set");
153 if (startDelay < milliseconds::zero()) {
154 throw std::invalid_argument(
155 "FunctionScheduler: start delay must be non-negative");
158 std::unique_lock<std::mutex> l(mutex_);
159 // check if the nameID is unique
160 for (const auto& f : functions_) {
161 if (f.isValid() && f.name == nameID) {
162 throw std::invalid_argument(
163 to<std::string>("FunctionScheduler: a function named \"",
165 "\" already exists"));
168 if (currentFunction_ && currentFunction_->name == nameID) {
169 throw std::invalid_argument(to<std::string>(
170 "FunctionScheduler: a function named \"", nameID, "\" already exists"));
177 std::move(intervalFunc),
183 bool FunctionScheduler::cancelFunction(StringPiece nameID) {
184 std::unique_lock<std::mutex> l(mutex_);
186 if (currentFunction_ && currentFunction_->name == nameID) {
187 // This function is currently being run. Clear currentFunction_
188 // The running thread will see this and won't reschedule the function.
189 currentFunction_ = nullptr;
193 for (auto it = functions_.begin(); it != functions_.end(); ++it) {
194 if (it->isValid() && it->name == nameID) {
195 cancelFunction(l, it);
202 void FunctionScheduler::cancelFunction(const std::unique_lock<std::mutex>& l,
203 FunctionHeap::iterator it) {
204 // This function should only be called with mutex_ already locked.
205 DCHECK(l.mutex() == &mutex_);
206 DCHECK(l.owns_lock());
209 // Internally gcc has an __adjust_heap() function to fill in a hole in the
210 // heap. Unfortunately it isn't part of the standard API.
212 // For now we just leave the RepeatFunc in our heap, but mark it as unused.
213 // When its nextTimeInterval comes up, the runner thread will pop it from
214 // the heap and simply throw it away.
217 // We're not running, so functions_ doesn't need to be maintained in heap
219 functions_.erase(it);
223 void FunctionScheduler::cancelAllFunctions() {
224 std::unique_lock<std::mutex> l(mutex_);
228 bool FunctionScheduler::resetFunctionTimer(StringPiece nameID) {
229 std::unique_lock<std::mutex> l(mutex_);
230 if (currentFunction_ && currentFunction_->name == nameID) {
231 RepeatFunc* funcPtrCopy = currentFunction_;
232 // This function is currently being run. Clear currentFunction_
233 // to avoid rescheduling it, and add the function again to honor the
235 currentFunction_ = nullptr;
236 addFunctionToHeap(l, std::move(*funcPtrCopy));
240 // Since __adjust_heap() isn't a part of the standard API, there's no way to
241 // fix the heap ordering if we adjust the key (nextRunTime) for the existing
242 // RepeatFunc. Instead, we just cancel it and add an identical object.
243 for (auto it = functions_.begin(); it != functions_.end(); ++it) {
244 if (it->isValid() && it->name == nameID) {
245 RepeatFunc funcCopy(std::move(*it));
246 cancelFunction(l, it);
247 addFunctionToHeap(l, std::move(funcCopy));
254 bool FunctionScheduler::start() {
255 std::unique_lock<std::mutex> l(mutex_);
262 VLOG(1) << "Starting FunctionScheduler with " << functions_.size()
264 auto now = steady_clock::now();
265 // Reset the next run time. for all functions.
266 // note: this is needed since one can shutdown() and start() again
267 for (auto& f : functions_) {
268 f.resetNextRunTime(now);
269 VLOG(1) << " - func: " << (f.name.empty() ? "(anon)" : f.name.c_str())
270 << ", period = " << f.intervalDescr
271 << ", delay = " << f.startDelay.count() << "ms";
273 std::make_heap(functions_.begin(), functions_.end(), fnCmp_);
275 thread_ = std::thread([&] { this->run(); });
279 void FunctionScheduler::shutdown() {
281 std::lock_guard<std::mutex> g(mutex_);
287 runningCondvar_.notify_one();
292 void FunctionScheduler::run() {
293 std::unique_lock<std::mutex> lock(mutex_);
295 if (!threadName_.empty()) {
296 folly::setThreadName(threadName_);
300 // If we have nothing to run, wait until a function is added or until we
302 if (functions_.empty()) {
303 runningCondvar_.wait(lock);
307 auto now = steady_clock::now();
309 // Move the next function to run to the end of functions_
310 std::pop_heap(functions_.begin(), functions_.end(), fnCmp_);
312 // Check to see if the function was cancelled.
313 // If so, just remove it and continue around the loop.
314 if (!functions_.back().isValid()) {
315 functions_.pop_back();
319 auto sleepTime = functions_.back().getNextRunTime() - now;
320 if (sleepTime < milliseconds::zero()) {
321 // We need to run this function now
322 runOneFunction(lock, now);
324 // Re-add the function to the heap, and wait until we actually
326 std::push_heap(functions_.begin(), functions_.end(), fnCmp_);
327 runningCondvar_.wait_for(lock, sleepTime);
332 void FunctionScheduler::runOneFunction(std::unique_lock<std::mutex>& lock,
333 steady_clock::time_point now) {
334 DCHECK(lock.mutex() == &mutex_);
335 DCHECK(lock.owns_lock());
337 // The function to run will be at the end of functions_ already.
339 // Fully remove it from functions_ now.
340 // We need to release mutex_ while we invoke this function, and we need to
341 // maintain the heap property on functions_ while mutex_ is unlocked.
342 RepeatFunc func(std::move(functions_.back()));
343 functions_.pop_back();
345 VLOG(5) << func.name << "function has been canceled while waiting";
348 currentFunction_ = &func;
350 // Update the function's next run time.
352 // This allows scheduler to catch up
353 func.setNextRunTimeSteady();
355 // Note that we set nextRunTime based on the current time where we started
356 // the function call, rather than the time when the function finishes.
357 // This ensures that we call the function once every time interval, as
358 // opposed to waiting time interval seconds between calls. (These can be
359 // different if the function takes a significant amount of time to run.)
360 func.setNextRunTimeStrict(now);
363 // Release the lock while we invoke the user's function
366 // Invoke the function
368 VLOG(5) << "Now running " << func.name;
370 } catch (const std::exception& ex) {
371 LOG(ERROR) << "Error running the scheduled function <"
372 << func.name << ">: " << exceptionStr(ex);
375 // Re-acquire the lock
378 if (!currentFunction_) {
379 // The function was cancelled while we were running it.
380 // We shouldn't reschedule it;
383 // Clear currentFunction_
384 CHECK_EQ(currentFunction_, &func);
385 currentFunction_ = nullptr;
387 // Re-insert the function into our functions_ heap.
388 // We only maintain the heap property while running_ is set. (running_ may
389 // have been cleared while we were invoking the user's function.)
390 functions_.push_back(std::move(func));
392 std::push_heap(functions_.begin(), functions_.end(), fnCmp_);
396 void FunctionScheduler::addFunctionToHeap(
397 const std::unique_lock<std::mutex>& lock,
399 // This function should only be called with mutex_ already locked.
400 DCHECK(lock.mutex() == &mutex_);
401 DCHECK(lock.owns_lock());
403 functions_.emplace_back(std::move(func));
405 functions_.back().resetNextRunTime(steady_clock::now());
406 std::push_heap(functions_.begin(), functions_.end(), fnCmp_);
407 // Signal the running thread to wake up and see if it needs to change
408 // its current scheduling decision.
409 runningCondvar_.notify_one();
413 void FunctionScheduler::setThreadName(StringPiece threadName) {
414 std::unique_lock<std::mutex> l(mutex_);
415 threadName_ = threadName.str();