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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#pragma once
#include <functional>
#include <string>
#include "monitoring/instrumented_mutex.h"
#include "port/port.h"
#include "rocksdb/system_clock.h"
#include "util/mutexlock.h"
namespace ROCKSDB_NAMESPACE {
// Simple wrapper around port::Thread that supports calling a callback every
// X seconds. If you pass in 0, then it will call your callback repeatedly
// without delay.
class RepeatableThread {
public:
RepeatableThread(std::function<void()> function,
const std::string& thread_name, SystemClock* clock,
uint64_t delay_us, uint64_t initial_delay_us = 0)
: function_(function),
thread_name_("rocksdb:" + thread_name),
clock_(clock),
delay_us_(delay_us),
initial_delay_us_(initial_delay_us),
mutex_(clock),
cond_var_(&mutex_),
running_(true),
#ifndef NDEBUG
waiting_(false),
run_count_(0),
#endif
thread_([this] { thread(); }) {
}
void cancel() {
{
InstrumentedMutexLock l(&mutex_);
if (!running_) {
return;
}
running_ = false;
cond_var_.SignalAll();
}
thread_.join();
}
bool IsRunning() { return running_; }
~RepeatableThread() { cancel(); }
#ifndef NDEBUG
// Wait until RepeatableThread starting waiting, call the optional callback,
// then wait for one run of RepeatableThread. Tests can use provide a
// custom clock object to mock time, and use the callback here to bump current
// time and trigger RepeatableThread. See repeatable_thread_test for example.
//
// Note: only support one caller of this method.
void TEST_WaitForRun(std::function<void()> callback = nullptr) {
InstrumentedMutexLock l(&mutex_);
while (!waiting_) {
cond_var_.Wait();
}
uint64_t prev_count = run_count_;
if (callback != nullptr) {
callback();
}
cond_var_.SignalAll();
while (!(run_count_ > prev_count)) {
cond_var_.Wait();
}
}
#endif
private:
bool wait(uint64_t delay) {
InstrumentedMutexLock l(&mutex_);
if (running_ && delay > 0) {
uint64_t wait_until = clock_->NowMicros() + delay;
#ifndef NDEBUG
waiting_ = true;
cond_var_.SignalAll();
#endif
while (running_) {
cond_var_.TimedWait(wait_until);
if (clock_->NowMicros() >= wait_until) {
break;
}
}
#ifndef NDEBUG
waiting_ = false;
#endif
}
return running_;
}
void thread() {
#if defined(_GNU_SOURCE) && defined(__GLIBC_PREREQ)
#if __GLIBC_PREREQ(2, 12)
// Set thread name.
auto thread_handle = thread_.native_handle();
int ret __attribute__((__unused__)) =
pthread_setname_np(thread_handle, thread_name_.c_str());
assert(ret == 0);
#endif
#endif
assert(delay_us_ > 0);
if (!wait(initial_delay_us_)) {
return;
}
do {
function_();
#ifndef NDEBUG
{
InstrumentedMutexLock l(&mutex_);
run_count_++;
cond_var_.SignalAll();
}
#endif
} while (wait(delay_us_));
}
const std::function<void()> function_;
const std::string thread_name_;
SystemClock* clock_;
const uint64_t delay_us_;
const uint64_t initial_delay_us_;
// Mutex lock should be held when accessing running_, waiting_
// and run_count_.
InstrumentedMutex mutex_;
InstrumentedCondVar cond_var_;
bool running_;
#ifndef NDEBUG
// RepeatableThread waiting for timeout.
bool waiting_;
// Times function_ had run.
uint64_t run_count_;
#endif
port::Thread thread_;
};
} // namespace ROCKSDB_NAMESPACE
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