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// Copyright (c) 2015 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include "scheduler.h"
#include <assert.h>
#include <boost/bind.hpp>
#include <utility>
CScheduler::CScheduler() : nThreadsServicingQueue(0)
{
}
CScheduler::~CScheduler()
{
assert(nThreadsServicingQueue == 0);
}
#if BOOST_VERSION < 105000
static boost::system_time toPosixTime(const boost::chrono::system_clock::time_point& t)
{
boost::chrono::system_clock::duration d = t.time_since_epoch();
boost::chrono::microseconds usecs = boost::chrono::duration_cast<boost::chrono::microseconds>(d);
boost::system_time result = boost::posix_time::from_time_t(0) +
boost::posix_time::microseconds(usecs.count());
return result;
}
#endif
void CScheduler::serviceQueue()
{
boost::unique_lock<boost::mutex> lock(newTaskMutex);
++nThreadsServicingQueue;
// newTaskMutex is locked throughout this loop EXCEPT
// when the thread is waiting or when the user's function
// is called.
while (1) {
try {
while (taskQueue.empty()) {
// Wait until there is something to do.
newTaskScheduled.wait(lock);
}
// Wait until either there is a new task, or until
// the time of the first item on the queue:
// wait_until needs boost 1.50 or later; older versions have timed_wait:
#if BOOST_VERSION < 105000
while (!taskQueue.empty() && newTaskScheduled.timed_wait(lock, toPosixTime(taskQueue.begin()->first))) {
// Keep waiting until timeout
}
#else
while (!taskQueue.empty() && newTaskScheduled.wait_until(lock, taskQueue.begin()->first) != boost::cv_status::timeout) {
// Keep waiting until timeout
}
#endif
// If there are multiple threads, the queue can empty while we're waiting (another
// thread may service the task we were waiting on).
if (taskQueue.empty())
continue;
Function f = taskQueue.begin()->second;
taskQueue.erase(taskQueue.begin());
// Unlock before calling f, so it can reschedule itself or another task
// without deadlocking:
lock.unlock();
f();
lock.lock();
} catch (...) {
--nThreadsServicingQueue;
throw;
}
}
}
void CScheduler::schedule(CScheduler::Function f, boost::chrono::system_clock::time_point t)
{
{
boost::unique_lock<boost::mutex> lock(newTaskMutex);
taskQueue.insert(std::make_pair(t, f));
}
newTaskScheduled.notify_one();
}
void CScheduler::scheduleFromNow(CScheduler::Function f, int64_t deltaSeconds)
{
schedule(f, boost::chrono::system_clock::now() + boost::chrono::seconds(deltaSeconds));
}
static void Repeat(CScheduler* s, CScheduler::Function f, int64_t deltaSeconds)
{
f();
s->scheduleFromNow(boost::bind(&Repeat, s, f, deltaSeconds), deltaSeconds);
}
void CScheduler::scheduleEvery(CScheduler::Function f, int64_t deltaSeconds)
{
scheduleFromNow(boost::bind(&Repeat, this, f, deltaSeconds), deltaSeconds);
}
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