Port QWaitCondition to QDeadlineTimer

Since pthread_cond_timedwait takes absolute time instead of relative
time like most POSIX API, there's a small gain in performance here: we
avoid an extra system call to get the current time.

Task-number: QTBUG-64266
Change-Id: I25d85d86649448d5b2b3fffd1451138568091f50
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

8 files changed, 60 insertions, 25 deletions

diff --git a/src/corelib/kernel/qdeadlinetimer.cpp b/src/corelib/kernel/qdeadlinetimer.cpp
index d8a670310b..97b98a1376 100644
--- a/src/corelib/kernel/qdeadlinetimer.cpp
+++ b/src/corelib/kernel/qdeadlinetimer.cpp
@@ -39,7 +39,6 @@
 
 #include "qdeadlinetimer.h"
 #include "qdeadlinetimer_p.h"
-#include <qpair.h>
 
 QT_BEGIN_NAMESPACE
 
diff --git a/src/corelib/kernel/qdeadlinetimer.h b/src/corelib/kernel/qdeadlinetimer.h
index 6c10e1025e..1a4ee04a96 100644
--- a/src/corelib/kernel/qdeadlinetimer.h
+++ b/src/corelib/kernel/qdeadlinetimer.h
@@ -43,6 +43,7 @@
 #include <QtCore/qelapsedtimer.h>
 #include <QtCore/qmetatype.h>
 #include <QtCore/qnamespace.h>
+#include <QtCore/qpair.h>
 
 #ifdef max
 // un-pollute the namespace. We need std::numeric_limits::max() and std::chrono::duration::max()
@@ -186,6 +187,10 @@ private:
     unsigned type;
 
     qint64 rawRemainingTimeNSecs() const Q_DECL_NOTHROW;
+
+public:
+    // This is not a public function, it's here only for Qt's internal convenience...
+    QPair<qint64, unsigned> _q_data() const { return qMakePair(t1, t2); }
 };
 
 Q_DECLARE_SHARED(QDeadlineTimer)
diff --git a/src/corelib/thread/qmutex_p.h b/src/corelib/thread/qmutex_p.h
index 4e6f522a37..ec9bfc1152 100644
--- a/src/corelib/thread/qmutex_p.h
+++ b/src/corelib/thread/qmutex_p.h
@@ -58,6 +58,7 @@
 #include <QtCore/qnamespace.h>
 #include <QtCore/qmutex.h>
 #include <QtCore/qatomic.h>
+#include <QtCore/qdeadlinetimer.h>
 
 #if defined(Q_OS_MAC)
 # include <mach/semaphore.h>
@@ -146,7 +147,7 @@ public:
 // helper functions for qmutex_unix.cpp and qwaitcondition_unix.cpp
 // they are in qwaitcondition_unix.cpp actually
 void qt_initialize_pthread_cond(pthread_cond_t *cond, const char *where);
-void qt_abstime_for_timeout(struct timespec *ts, int timeout);
+void qt_abstime_for_timeout(struct timespec *ts, QDeadlineTimer deadline);
 #endif
 
 QT_END_NAMESPACE
diff --git a/src/corelib/thread/qmutex_unix.cpp b/src/corelib/thread/qmutex_unix.cpp
index 3e1e531be4..91f02ba3ec 100644
--- a/src/corelib/thread/qmutex_unix.cpp
+++ b/src/corelib/thread/qmutex_unix.cpp
@@ -130,7 +130,7 @@ bool QMutexPrivate::wait(int timeout)
             errorCode = pthread_cond_wait(&cond, &mutex);
         } else {
             timespec ti;
-            qt_abstime_for_timeout(&ti, timeout);
+            qt_abstime_for_timeout(&ti, QDeadlineTimer(timeout));
             errorCode = pthread_cond_timedwait(&cond, &mutex, &ti);
         }
         if (errorCode) {
diff --git a/src/corelib/thread/qsemaphore.cpp b/src/corelib/thread/qsemaphore.cpp
index 012628ef63..6497792bf5 100644
--- a/src/corelib/thread/qsemaphore.cpp
+++ b/src/corelib/thread/qsemaphore.cpp
@@ -424,11 +424,9 @@ bool QSemaphore::tryAcquire(int n, int timeout)
 
     QDeadlineTimer timer(timeout);
     QMutexLocker locker(&d->mutex);
-    qint64 remainingTime = timer.remainingTime();
-    while (n > d->avail && remainingTime != 0) {
-        if (!d->cond.wait(locker.mutex(), remainingTime))
+    while (n > d->avail && !timer.hasExpired()) {
+        if (!d->cond.wait(locker.mutex(), timer))
             return false;
-        remainingTime = timer.remainingTime();
     }
     if (n > d->avail)
         return false;
diff --git a/src/corelib/thread/qwaitcondition.h b/src/corelib/thread/qwaitcondition.h
index a0c6766833..e42efbdfca 100644
--- a/src/corelib/thread/qwaitcondition.h
+++ b/src/corelib/thread/qwaitcondition.h
@@ -49,6 +49,7 @@ QT_BEGIN_NAMESPACE
 
 #ifndef QT_NO_THREAD
 
+class QDeadlineTimer;
 class QWaitConditionPrivate;
 class QMutex;
 class QReadWriteLock;
@@ -59,8 +60,11 @@ public:
     QWaitCondition();
     ~QWaitCondition();
 
+    // ### Qt 6: remove unsigned long overloads
     bool wait(QMutex *lockedMutex, unsigned long time = ULONG_MAX);
+    bool wait(QMutex *lockedMutex, QDeadlineTimer deadline);
     bool wait(QReadWriteLock *lockedReadWriteLock, unsigned long time = ULONG_MAX);
+    bool wait(QReadWriteLock *lockedReadWriteLock, QDeadlineTimer deadline);
 
     void wakeOne();
     void wakeAll();
diff --git a/src/corelib/thread/qwaitcondition_unix.cpp b/src/corelib/thread/qwaitcondition_unix.cpp
index 6adee5412e..1628ede3a2 100644
--- a/src/corelib/thread/qwaitcondition_unix.cpp
+++ b/src/corelib/thread/qwaitcondition_unix.cpp
@@ -44,6 +44,8 @@
 #include "qreadwritelock.h"
 #include "qatomic.h"
 #include "qstring.h"
+#include "qdeadlinetimer.h"
+#include "private/qdeadlinetimer_p.h"
 #include "qelapsedtimer.h"
 #include "private/qcore_unix_p.h"
 
@@ -93,23 +95,25 @@ void qt_initialize_pthread_cond(pthread_cond_t *cond, const char *where)
     pthread_condattr_destroy(&condattr);
 }
 
-void qt_abstime_for_timeout(timespec *ts, int timeout)
+void qt_abstime_for_timeout(timespec *ts, QDeadlineTimer deadline)
 {
 #ifdef Q_OS_MAC
     // on Mac, qt_gettime() (on qelapsedtimer_mac.cpp) returns ticks related to the Mach absolute time
     // that doesn't work with pthread
     // Mac also doesn't have clock_gettime
     struct timeval tv;
+    qint64 nsec = deadline.remainingTimeNSecs();
     gettimeofday(&tv, 0);
-    ts->tv_sec = tv.tv_sec;
-    ts->tv_nsec = tv.tv_usec * 1000;
-#else
-    *ts = qt_gettime();
-#endif
+    ts->tv_sec = tv.tv_sec + nsec / (1000 * 1000 * 1000);
+    ts->tv_nsec = tv.tv_usec * 1000 + nsec % (1000 * 1000 * 1000);
 
-    ts->tv_sec += timeout / 1000;
-    ts->tv_nsec += timeout % 1000 * Q_UINT64_C(1000) * 1000;
     normalizedTimespec(*ts);
+#else
+    // depends on QDeadlineTimer's internals!!
+    Q_STATIC_ASSERT(QDeadlineTimerNanosecondsInT2);
+    ts->tv_sec = deadline._q_data().first;
+    ts->tv_nsec = deadline._q_data().second;
+#endif
 }
 
 class QWaitConditionPrivate {
@@ -119,26 +123,27 @@ public:
     int waiters;
     int wakeups;
 
-    int wait_relative(unsigned long time)
+    int wait_relative(QDeadlineTimer deadline)
     {
         timespec ti;
 #ifdef Q_OS_ANDROID
-        if (local_cond_timedwait_relative) {
-            ti.tv_sec = time / 1000;
-            ti.tv_nsec = time % 1000 * Q_UINT64_C(1000) * 1000;
+        if (!local_condattr_setclock && local_cond_timedwait_relative) {
+            qint64 nsec = deadline.remainingTimeNSecs();
+            ti.tv_sec = nsec / (1000 * 1000 * 1000);
+            ti.tv_nsec = nsec - ti.tv_sec * 1000 * 1000 * 1000;
             return local_cond_timedwait_relative(&cond, &mutex, &ti);
         }
 #endif
-        qt_abstime_for_timeout(&ti, time);
+        qt_abstime_for_timeout(&ti, deadline);
         return pthread_cond_timedwait(&cond, &mutex, &ti);
     }
 
-    bool wait(unsigned long time)
+    bool wait(QDeadlineTimer deadline)
     {
         int code;
         forever {
-            if (time != ULONG_MAX) {
-                code = wait_relative(time);
+            if (!deadline.isForever()) {
+                code = wait_relative(deadline);
             } else {
                 code = pthread_cond_wait(&cond, &mutex);
             }
@@ -201,6 +206,13 @@ void QWaitCondition::wakeAll()
 
 bool QWaitCondition::wait(QMutex *mutex, unsigned long time)
 {
+    if (time > std::numeric_limits<qint64>::max())
+        return wait(mutex, QDeadlineTimer(QDeadlineTimer::Forever));
+    return wait(mutex, QDeadlineTimer(time));
+}
+
+bool QWaitCondition::wait(QMutex *mutex, QDeadlineTimer deadline)
+{
     if (! mutex)
         return false;
     if (mutex->isRecursive()) {
@@ -212,7 +224,7 @@ bool QWaitCondition::wait(QMutex *mutex, unsigned long time)
     ++d->waiters;
     mutex->unlock();
 
-    bool returnValue = d->wait(time);
+    bool returnValue = d->wait(deadline);
 
     mutex->lock();
 
@@ -221,6 +233,11 @@ bool QWaitCondition::wait(QMutex *mutex, unsigned long time)
 
 bool QWaitCondition::wait(QReadWriteLock *readWriteLock, unsigned long time)
 {
+    return wait(readWriteLock, QDeadlineTimer(time));
+}
+
+bool QWaitCondition::wait(QReadWriteLock *readWriteLock, QDeadlineTimer deadline)
+{
     if (!readWriteLock)
         return false;
     auto previousState = readWriteLock->stateForWaitCondition();
@@ -236,7 +253,7 @@ bool QWaitCondition::wait(QReadWriteLock *readWriteLock, unsigned long time)
 
     readWriteLock->unlock();
 
-    bool returnValue = d->wait(time);
+    bool returnValue = d->wait(deadline);
 
     if (previousState == QReadWriteLock::LockedForWrite)
         readWriteLock->lockForWrite();
diff --git a/src/corelib/thread/qwaitcondition_win.cpp b/src/corelib/thread/qwaitcondition_win.cpp
index e6610f18c8..61e4c2bcb1 100644
--- a/src/corelib/thread/qwaitcondition_win.cpp
+++ b/src/corelib/thread/qwaitcondition_win.cpp
@@ -38,6 +38,7 @@
 ****************************************************************************/
 
 #include "qwaitcondition.h"
+#include "qdeadlinetimer.h"
 #include "qnamespace.h"
 #include "qmutex.h"
 #include "qreadwritelock.h"
@@ -184,6 +185,11 @@ bool QWaitCondition::wait(QMutex *mutex, unsigned long time)
     return returnValue;
 }
 
+bool QWaitCondition::wait(QMutex *mutex, QDeadlineTimer deadline)
+{
+    return wait(mutex, deadline.remainingTime());
+}
+
 bool QWaitCondition::wait(QReadWriteLock *readWriteLock, unsigned long time)
 {
     if (!readWriteLock)
@@ -210,6 +216,11 @@ bool QWaitCondition::wait(QReadWriteLock *readWriteLock, unsigned long time)
     return returnValue;
 }
 
+bool QWaitCondition::wait(QReadWriteLock *readWriteLock, QDeadlineTimer deadline)
+{
+    return wait(readWriteLock, deadline.remainingTime());
+}
+
 void QWaitCondition::wakeOne()
 {
     // wake up the first waiting thread in the queue