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-rw-r--r--src/Globals.h2
-rw-r--r--src/OSSupport/Event.cpp154
-rw-r--r--src/OSSupport/Event.h33
3 files changed, 53 insertions, 136 deletions
diff --git a/src/Globals.h b/src/Globals.h
index 582f5fdaa..eb59f499e 100644
--- a/src/Globals.h
+++ b/src/Globals.h
@@ -251,6 +251,8 @@ template class SizeChecker<UInt16, 2>;
#include <set>
#include <queue>
#include <limits>
+#include <chrono>
+
diff --git a/src/OSSupport/Event.cpp b/src/OSSupport/Event.cpp
index 87bc110ce..e05de8e15 100644
--- a/src/OSSupport/Event.cpp
+++ b/src/OSSupport/Event.cpp
@@ -12,90 +12,23 @@
-cEvent::cEvent(void)
+cEvent::cEvent(void) :
+ m_ShouldWait(true)
{
-#ifdef _WIN32
- m_Event = CreateEvent(nullptr, FALSE, FALSE, nullptr);
- if (m_Event == nullptr)
- {
- LOGERROR("cEvent: cannot create event, GLE = %u. Aborting server.", (unsigned)GetLastError());
- abort();
- }
-#else // *nix
- m_bIsNamed = false;
- m_Event = new sem_t;
- if (sem_init(m_Event, 0, 0))
- {
- // This path is used by MacOS, because it doesn't support unnamed semaphores.
- delete m_Event;
- m_bIsNamed = true;
-
- AString EventName;
- Printf(EventName, "cEvent%p", this);
- m_Event = sem_open(EventName.c_str(), O_CREAT, 777, 0);
- if (m_Event == SEM_FAILED)
- {
- AString error = GetOSErrorString(errno);
- LOGERROR("cEvent: Cannot create event, err = %s. Aborting server.", error.c_str());
- abort();
- }
- // Unlink the semaphore immediately - it will continue to function but will not pollute the namespace
- // We don't store the name, so can't call this in the destructor
- if (sem_unlink(EventName.c_str()) != 0)
- {
- AString error = GetOSErrorString(errno);
- LOGWARN("ERROR: Could not unlink cEvent. (%s)", error.c_str());
- }
- }
-#endif // *nix
}
-cEvent::~cEvent()
+void cEvent::Wait(void)
{
-#ifdef _WIN32
- CloseHandle(m_Event);
-#else
- if (m_bIsNamed)
- {
- if (sem_close(m_Event) != 0)
- {
- AString error = GetOSErrorString(errno);
- LOGERROR("ERROR: Could not close cEvent. (%s)", error.c_str());
- }
- }
- else
+ std::unique_lock<std::mutex> Lock(m_Mutex);
+ while (m_ShouldWait)
{
- sem_destroy(m_Event);
- delete m_Event;
- m_Event = nullptr;
+ m_CondVar.wait(Lock);
}
-#endif
-}
-
-
-
-
-
-void cEvent::Wait(void)
-{
- #ifdef _WIN32
- DWORD res = WaitForSingleObject(m_Event, INFINITE);
- if (res != WAIT_OBJECT_0)
- {
- LOGWARN("cEvent: waiting for the event failed: %u, GLE = %u. Continuing, but server may be unstable.", (unsigned)res, (unsigned)GetLastError());
- }
- #else
- int res = sem_wait(m_Event);
- if (res != 0)
- {
- AString error = GetOSErrorString(errno);
- LOGWARN("cEvent: waiting for the event failed: %i, err = %s. Continuing, but server may be unstable.", res, error.c_str());
- }
- #endif
+ m_ShouldWait = true;
}
@@ -104,45 +37,34 @@ void cEvent::Wait(void)
bool cEvent::Wait(int a_TimeoutMSec)
{
- #ifdef _WIN32
- DWORD res = WaitForSingleObject(m_Event, (DWORD)a_TimeoutMSec);
- switch (res)
+ std::chrono::steady_clock::time_point dst = std::chrono::steady_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::steady_clock::now() < dst))
+ {
+ switch (m_CondVar.wait_until(Lock, dst))
{
- case WAIT_OBJECT_0: return true; // Regular event signalled
- case WAIT_TIMEOUT: return false; // Regular event timeout
- default:
+ case std::cv_status::no_timeout:
{
- LOGWARN("cEvent: waiting for the event failed: %u, GLE = %u. Continuing, but server may be unstable.", (unsigned)res, (unsigned)GetLastError());
- return false;
+ // The wait was successful, check for spurious wakeup:
+ if (!m_ShouldWait)
+ {
+ m_ShouldWait = true;
+ return true;
+ }
+ // This was a spurious wakeup, wait again:
+ continue;
}
- }
- #else
- // Get the current time:
- timespec timeout;
- if (clock_gettime(CLOCK_REALTIME, &timeout) == -1)
- {
- LOGWARN("cEvent: Getting current time failed: %i, err = %s. Continuing, but the server may be unstable.", errno, GetOSErrorString(errno).c_str());
- return false;
- }
-
- // Add the specified timeout:
- timeout.tv_sec += a_TimeoutMSec / 1000;
- timeout.tv_nsec += (a_TimeoutMSec % 1000) * 1000000; // 1 msec = 1000000 usec
-
- // Wait with timeout:
- int res = sem_timedwait(m_Event, &timeout);
- switch (res)
- {
- case 0: return true; // Regular event signalled
- case ETIMEDOUT: return false; // Regular even timeout
- default:
+
+ case std::cv_status::timeout:
{
- AString error = GetOSErrorString(errno);
- LOGWARN("cEvent: waiting for the event failed: %i, err = %s. Continuing, but server may be unstable.", res, error.c_str());
+ // The wait timed out, return failure:
return false;
}
- }
- #endif
+ } // switch (wait_until())
+ } // while (m_ShouldWait && not timeout)
+
+ // The wait timed out in the while() condition:
+ return false;
}
@@ -151,19 +73,11 @@ bool cEvent::Wait(int a_TimeoutMSec)
void cEvent::Set(void)
{
- #ifdef _WIN32
- if (!SetEvent(m_Event))
- {
- LOGWARN("cEvent: Could not set cEvent: GLE = %u", (unsigned)GetLastError());
- }
- #else
- int res = sem_post(m_Event);
- if (res != 0)
- {
- AString error = GetOSErrorString(errno);
- LOGWARN("cEvent: Could not set cEvent: %i, err = %s", res, error.c_str());
- }
- #endif
+ {
+ std::unique_lock<std::mutex> Lock(m_Mutex);
+ m_ShouldWait = false;
+ }
+ m_CondVar.notify_one();
}
diff --git a/src/OSSupport/Event.h b/src/OSSupport/Event.h
index e2fa65a05..5818115be 100644
--- a/src/OSSupport/Event.h
+++ b/src/OSSupport/Event.h
@@ -1,16 +1,17 @@
// Event.h
-// Interfaces to the cEvent object representing an OS-specific synchronization primitive that can be waited-for
-// Implemented as an Event on Win and as a 1-semaphore on *nix
+// Interfaces to the cEvent object representing a synchronization primitive that can be waited-for
+// Implemented using C++11 condition variable and mutex
#pragma once
-#ifndef CEVENT_H_INCLUDED
-#define CEVENT_H_INCLUDED
+
+#include <mutex>
+#include <condition_variable>
@@ -20,9 +21,13 @@ class cEvent
{
public:
cEvent(void);
- ~cEvent();
+ /** Waits until the event has been set.
+ If the event has been set before it has been waited for, Wait() returns immediately. */
void Wait(void);
+
+ /** Sets the event - releases one thread that has been waiting in Wait().
+ If there was no thread waiting, the next call to Wait() will not block. */
void Set (void);
/** Waits for the event until either it is signalled, or the (relative) timeout is passed.
@@ -31,20 +36,16 @@ public:
private:
- #ifdef _WIN32
- HANDLE m_Event;
- #else
- sem_t * m_Event;
- bool m_bIsNamed;
- #endif
-} ;
-
-
-
+ /** Used for checking for spurious wakeups. */
+ bool m_ShouldWait;
+ /** Mutex protecting m_ShouldWait from multithreaded access. */
+ std::mutex m_Mutex;
+ /** The condition variable used as the Event. */
+ std::condition_variable m_CondVar;
+} ;
-#endif // CEVENT_H_INCLUDED
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-09 02:51:18 +0100