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// Event.cpp
// Interfaces to the cEvent object representing a synchronization primitive that can be waited-for
// Implemented using C++11 condition variable and mutex
#include "Globals.h" // NOTE: MSVC stupidness requires this to be the same across all modules
#include "Event.h"
#include "Errors.h"
cEvent::cEvent(void) :
m_ShouldWait(true)
{
}
void cEvent::Wait(void)
{
std::unique_lock<std::mutex> Lock(m_Mutex);
while (m_ShouldWait)
{
m_CondVar.wait(Lock);
}
m_ShouldWait = true;
}
bool cEvent::Wait(unsigned a_TimeoutMSec)
{
auto dst = std::chrono::system_clock::now() + std::chrono::milliseconds(a_TimeoutMSec);
std::unique_lock<std::mutex> Lock(m_Mutex); // We assume that this lock is acquired without much delay - we are the only user of the mutex
while (m_ShouldWait && (std::chrono::system_clock::now() <= dst))
{
switch (m_CondVar.wait_until(Lock, dst))
{
case std::cv_status::no_timeout:
{
// The wait was successful, check for spurious wakeup:
if (!m_ShouldWait)
{
m_ShouldWait = true;
return true;
}
// This was a spurious wakeup, wait again:
continue;
}
case std::cv_status::timeout:
{
// The wait timed out, return failure:
return false;
}
} // switch (wait_until())
} // while (m_ShouldWait && not timeout)
// The wait timed out in the while condition:
return false;
}
void cEvent::Set(void)
{
{
std::unique_lock<std::mutex> Lock(m_Mutex);
m_ShouldWait = false;
}
m_CondVar.notify_one();
}
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