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#include "base/thread_pool_delayed.hpp"
#include <array>
using namespace std;
namespace base
{
namespace thread_pool
{
namespace delayed
{
namespace
{
TaskLoop::TaskId MakeNextId(TaskLoop::TaskId id, TaskLoop::TaskId minId, TaskLoop::TaskId maxId)
{
if (id == maxId)
return minId;
return ++id;
}
} // namespace
ThreadPool::ThreadPool(size_t threadsCount /* = 1 */, Exit e /* = Exit::SkipPending */)
: m_exit(e)
, m_immediateLastId(kImmediateMaxId)
, m_delayedLastId(kDelayedMaxId)
{
for (size_t i = 0; i < threadsCount; ++i)
m_threads.emplace_back(threads::SimpleThread(&ThreadPool::ProcessTasks, this));
}
ThreadPool::~ThreadPool()
{
ShutdownAndJoin();
}
TaskLoop::PushResult ThreadPool::Push(Task && t)
{
return AddImmediate(move(t));
}
TaskLoop::PushResult ThreadPool::Push(Task const & t)
{
return AddImmediate(t);
}
TaskLoop::PushResult ThreadPool::PushDelayed(Duration const & delay, Task && t)
{
return AddDelayed(delay, move(t));
}
TaskLoop::PushResult ThreadPool::PushDelayed(Duration const & delay, Task const & t)
{
return AddDelayed(delay, t);
}
template <typename T>
TaskLoop::PushResult ThreadPool::AddImmediate(T && task)
{
return AddTask([&]() {
auto const newId = MakeNextId(m_immediateLastId, kImmediateMinId, kImmediateMaxId);
VERIFY(m_immediate.Emplace(newId, forward<T>(task)), ());
m_immediateLastId = newId;
return newId;
});
}
template <typename T>
TaskLoop::PushResult ThreadPool::AddDelayed(Duration const & delay, T && task)
{
auto const when = Now() + delay;
return AddTask([&]() {
auto const newId = MakeNextId(m_delayedLastId, kDelayedMinId, kDelayedMaxId);
m_delayed.Add(newId, make_shared<DelayedTask>(newId, when, forward<T>(task)));
m_delayedLastId = newId;
return newId;
});
}
template <typename Add>
TaskLoop::PushResult ThreadPool::AddTask(Add && add)
{
lock_guard<mutex> lk(m_mu);
if (m_shutdown)
return {};
auto const newId = add();
m_cv.notify_one();
return {true, newId};
}
void ThreadPool::ProcessTasks()
{
ImmediateQueue pendingImmediate;
DelayedQueue pendingDelayed;
while (true)
{
array<Task, QUEUE_TYPE_COUNT> tasks;
{
unique_lock<mutex> lk(m_mu);
if (!m_delayed.IsEmpty())
{
// We need to wait until the moment when the earliest delayed
// task may be executed, given that an immediate task or a
// delayed task with an earlier execution time may arrive
// while we are waiting.
auto const when = m_delayed.GetFirstValue()->m_when;
m_cv.wait_until(lk, when, [this, when]() {
return m_shutdown || !m_immediate.IsEmpty() || m_delayed.IsEmpty() ||
(!m_delayed.IsEmpty() && m_delayed.GetFirstValue()->m_when < when);
});
}
else
{
// When there are no delayed tasks in the queue, we need to
// wait until there is at least one immediate or delayed task.
m_cv.wait(lk,
[this]() { return m_shutdown || !m_immediate.IsEmpty() || !m_delayed.IsEmpty(); });
}
if (m_shutdown)
{
switch (m_exit)
{
case Exit::ExecPending:
ASSERT(pendingImmediate.IsEmpty(), ());
m_immediate.Swap(pendingImmediate);
ASSERT(pendingDelayed.IsEmpty(), ());
m_delayed.Swap(pendingDelayed);
break;
case Exit::SkipPending: break;
}
break;
}
auto const canExecImmediate = !m_immediate.IsEmpty();
auto const canExecDelayed =
!m_delayed.IsEmpty() && Now() >= m_delayed.GetFirstValue()->m_when;
if (canExecImmediate)
{
tasks[QUEUE_TYPE_IMMEDIATE] = move(m_immediate.Front());
m_immediate.PopFront();
}
if (canExecDelayed)
{
tasks[QUEUE_TYPE_DELAYED] = move(m_delayed.GetFirstValue()->m_task);
m_delayed.RemoveValue(m_delayed.GetFirstValue());
}
}
for (auto const & task : tasks)
{
if (task)
task();
}
}
for (; !pendingImmediate.IsEmpty(); pendingImmediate.PopFront())
pendingImmediate.Front()();
while (!pendingDelayed.IsEmpty())
{
auto const & top = *pendingDelayed.GetFirstValue();
while (true)
{
auto const now = Now();
if (now >= top.m_when)
break;
auto const delay = top.m_when - now;
this_thread::sleep_for(delay);
}
ASSERT(Now() >= top.m_when, ());
top.m_task();
pendingDelayed.RemoveValue(pendingDelayed.GetFirstValue());
}
}
bool ThreadPool::Cancel(TaskId id)
{
lock_guard<mutex> lk(m_mu);
if (m_shutdown || id == kNoId)
return false;
if (id <= kImmediateMaxId)
{
if (m_immediate.Erase(id))
{
m_cv.notify_one();
return true;
}
}
else
{
if (m_delayed.RemoveKey(id))
{
m_cv.notify_one();
return true;
}
}
return false;
}
bool ThreadPool::Shutdown(Exit e)
{
lock_guard<mutex> lk(m_mu);
if (m_shutdown)
return false;
m_shutdown = true;
m_exit = e;
m_cv.notify_all();
return true;
}
void ThreadPool::ShutdownAndJoin()
{
ASSERT(m_checker.CalledOnOriginalThread(), ());
Shutdown(m_exit);
for (auto & thread : m_threads)
{
if (thread.joinable())
thread.join();
}
m_threads.clear();
}
bool ThreadPool::IsShutDown()
{
lock_guard<mutex> lk(m_mu);
return m_shutdown;
}
} // namespace delayed
} // namespace thread_pool
} // namespace base
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