134 lines
4.2 KiB
C++
134 lines
4.2 KiB
C++
// Copyright (c) 2015-2016 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include "scheduler.h"
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#include "reverselock.h"
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#include <assert.h>
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#include <boost/bind/bind.hpp>
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#include <utility>
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CScheduler::CScheduler() : nThreadsServicingQueue(0), stopRequested(false), stopWhenEmpty(false)
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{
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}
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CScheduler::~CScheduler()
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{
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assert(nThreadsServicingQueue == 0);
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}
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#if BOOST_VERSION < 105000
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static boost::system_time toPosixTime(const boost::chrono::system_clock::time_point& t)
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{
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return boost::posix_time::from_time_t(boost::chrono::system_clock::to_time_t(t));
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}
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#endif
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void CScheduler::serviceQueue()
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{
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boost::unique_lock<boost::mutex> lock(newTaskMutex);
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++nThreadsServicingQueue;
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// newTaskMutex is locked throughout this loop EXCEPT
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// when the thread is waiting or when the user's function
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// is called.
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while (!shouldStop()) {
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try {
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while (!shouldStop() && taskQueue.empty()) {
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// Wait until there is something to do.
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newTaskScheduled.wait(lock);
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}
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// Wait until either there is a new task, or until
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// the time of the first item on the queue:
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// wait_until needs boost 1.50 or later; older versions have timed_wait:
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#if BOOST_VERSION < 105000
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while (!shouldStop() && !taskQueue.empty() &&
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newTaskScheduled.timed_wait(lock, toPosixTime(taskQueue.begin()->first))) {
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// Keep waiting until timeout
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}
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#else
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// Some boost versions have a conflicting overload of wait_until that returns void.
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// Explicitly use a template here to avoid hitting that overload.
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while (!shouldStop() && !taskQueue.empty()) {
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boost::chrono::system_clock::time_point timeToWaitFor = taskQueue.begin()->first;
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if (newTaskScheduled.wait_until<>(lock, timeToWaitFor) == boost::cv_status::timeout)
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break; // Exit loop after timeout, it means we reached the time of the event
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}
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#endif
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// If there are multiple threads, the queue can empty while we're waiting (another
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// thread may service the task we were waiting on).
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if (shouldStop() || taskQueue.empty())
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continue;
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Function f = taskQueue.begin()->second;
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taskQueue.erase(taskQueue.begin());
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{
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// Unlock before calling f, so it can reschedule itself or another task
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// without deadlocking:
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reverse_lock<boost::unique_lock<boost::mutex> > rlock(lock);
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f();
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}
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} catch (...) {
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--nThreadsServicingQueue;
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throw;
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}
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}
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--nThreadsServicingQueue;
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newTaskScheduled.notify_one();
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}
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void CScheduler::stop(bool drain)
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{
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{
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boost::unique_lock<boost::mutex> lock(newTaskMutex);
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if (drain)
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stopWhenEmpty = true;
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else
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stopRequested = true;
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}
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newTaskScheduled.notify_all();
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}
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void CScheduler::schedule(CScheduler::Function f, boost::chrono::system_clock::time_point t)
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{
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{
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boost::unique_lock<boost::mutex> lock(newTaskMutex);
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taskQueue.insert(std::make_pair(t, f));
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}
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newTaskScheduled.notify_one();
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}
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void CScheduler::scheduleFromNow(CScheduler::Function f, int64_t deltaSeconds)
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{
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schedule(f, boost::chrono::system_clock::now() + boost::chrono::seconds(deltaSeconds));
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}
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static void Repeat(CScheduler* s, CScheduler::Function f, int64_t deltaSeconds)
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{
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f();
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s->scheduleFromNow(boost::bind(&Repeat, s, f, deltaSeconds), deltaSeconds);
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}
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void CScheduler::scheduleEvery(CScheduler::Function f, int64_t deltaSeconds)
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{
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scheduleFromNow(boost::bind(&Repeat, this, f, deltaSeconds), deltaSeconds);
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}
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size_t CScheduler::getQueueInfo(boost::chrono::system_clock::time_point &first,
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boost::chrono::system_clock::time_point &last) const
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{
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boost::unique_lock<boost::mutex> lock(newTaskMutex);
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size_t result = taskQueue.size();
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if (!taskQueue.empty()) {
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first = taskQueue.begin()->first;
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last = taskQueue.rbegin()->first;
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}
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return result;
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}
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