Re-apply "QReadWriteLock: replace (QWaitCondition, QMutex) with std::(condition_variable, mutex)"

This reverts commit 1283ee324578e4cf5cc210d8d3c89647d6c56ec3.

We now have wrappers around std::mutex and std::condition_variable
that fall back to QMutex and QWaitCondition on the broken Integrity
toolchain. Use them.

Change-Id: I881aa931167b845b489713048b57ccc5f79d4237
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

src/corelib/thread/qreadwritelock.cpp

@@ -67,6 +67,9 @@ QT_BEGIN_NAMESPACE
  */
 
 namespace {
+
+using ms = std::chrono::milliseconds;
+
 enum {
     StateMask = 0x3,
     StateLockedForRead = 0x1,
@@ -276,7 +279,7 @@ bool QReadWriteLock::tryLockForRead(int timeout)
             d = d_ptr.loadAcquire();
             continue;
         }
-        return d->lockForRead(timeout);
+        return d->lockForRead(lock, timeout);
     }
 }
 
@@ -380,7 +383,7 @@ bool QReadWriteLock::tryLockForWrite(int timeout)
             d = d_ptr.loadAcquire();
             continue;
         }
-        return d->lockForWrite(timeout);
+        return d->lockForWrite(lock, timeout);
     }
 }
 
@@ -463,9 +466,9 @@ QReadWriteLock::StateForWaitCondition QReadWriteLock::stateForWaitCondition() co
 
 }
 
-bool QReadWriteLockPrivate::lockForRead(int timeout)
+bool QReadWriteLockPrivate::lockForRead(std::unique_lock<QtPrivate::mutex> &lock, int timeout)
 {
-    Q_ASSERT(!mutex.tryLock()); // mutex must be locked when entering this function
+    Q_ASSERT(!mutex.try_lock()); // mutex must be locked when entering this function
 
     QElapsedTimer t;
     if (timeout > 0)
@@ -479,10 +482,10 @@ bool QReadWriteLockPrivate::lockForRead(int timeout)
             if (elapsed > timeout)
                 return false;
             waitingReaders++;
-            readerCond.wait(&mutex, QDeadlineTimer(timeout - elapsed));
+            readerCond.wait_for(lock, ms{timeout - elapsed});
         } else {
             waitingReaders++;
-            readerCond.wait(&mutex);
+            readerCond.wait(lock);
         }
         waitingReaders--;
     }
@@ -491,9 +494,9 @@ bool QReadWriteLockPrivate::lockForRead(int timeout)
     return true;
 }
 
-bool QReadWriteLockPrivate::lockForWrite(int timeout)
+bool QReadWriteLockPrivate::lockForWrite(std::unique_lock<QtPrivate::mutex> &lock, int timeout)
 {
-    Q_ASSERT(!mutex.tryLock()); // mutex must be locked when entering this function
+    Q_ASSERT(!mutex.try_lock()); // mutex must be locked when entering this function
 
     QElapsedTimer t;
     if (timeout > 0)
@@ -508,15 +511,15 @@ bool QReadWriteLockPrivate::lockForWrite(int timeout)
                 if (waitingReaders && !waitingWriters && !writerCount) {
                     // We timed out and now there is no more writers or waiting writers, but some
                     // readers were queued (probably because of us). Wake the waiting readers.
-                    readerCond.wakeAll();
+                    readerCond.notify_all();
                 }
                 return false;
             }
             waitingWriters++;
-            writerCond.wait(&mutex, QDeadlineTimer(timeout - elapsed));
+            writerCond.wait_for(lock, ms{timeout - elapsed});
         } else {
             waitingWriters++;
-            writerCond.wait(&mutex);
+            writerCond.wait(lock);
         }
         waitingWriters--;
     }
@@ -529,11 +532,11 @@ bool QReadWriteLockPrivate::lockForWrite(int timeout)
 
 void QReadWriteLockPrivate::unlock()
 {
-    Q_ASSERT(!mutex.tryLock()); // mutex must be locked when entering this function
+    Q_ASSERT(!mutex.try_lock()); // mutex must be locked when entering this function
     if (waitingWriters)
-        writerCond.wakeOne();
+        writerCond.notify_one();
     else if (waitingReaders)
-        readerCond.wakeAll();
+        readerCond.notify_all();
 }
 
 static auto handleEquals(Qt::HANDLE handle)
@@ -555,7 +558,7 @@ bool QReadWriteLockPrivate::recursiveLockForRead(int timeout)
         return true;
     }
 
-    if (!lockForRead(timeout))
+    if (!lockForRead(lock, timeout))
         return false;
 
     Reader r = {self, 1};
@@ -574,7 +577,7 @@ bool QReadWriteLockPrivate::recursiveLockForWrite(int timeout)
         return true;
     }
 
-    if (!lockForWrite(timeout))
+    if (!lockForWrite(lock, timeout))
         return false;
 
     currentWriter = self;

src/corelib/thread/qreadwritelock_p.h

@@ -53,8 +53,8 @@
 //
 
 #include <QtCore/private/qglobal_p.h>
+#include <QtCore/private/qwaitcondition_p.h>
 #include <QtCore/qvarlengtharray.h>
-#include <QtCore/qwaitcondition.h>
 
 QT_REQUIRE_CONFIG(thread);
 
@@ -66,9 +66,9 @@ public:
     explicit QReadWriteLockPrivate(bool isRecursive = false)
         : recursive(isRecursive) {}
 
-    QMutex mutex;
-    QWaitCondition writerCond;
-    QWaitCondition readerCond;
+    QtPrivate::mutex mutex;
+    QtPrivate::condition_variable writerCond;
+    QtPrivate::condition_variable readerCond;
     int readerCount = 0;
     int writerCount = 0;
     int waitingReaders = 0;
@@ -76,8 +76,8 @@ public:
     const bool recursive;
 
     //Called with the mutex locked
-    bool lockForWrite(int timeout);
-    bool lockForRead(int timeout);
+    bool lockForWrite(std::unique_lock<QtPrivate::mutex> &lock, int timeout);
+    bool lockForRead(std::unique_lock<QtPrivate::mutex> &lock, int timeout);
     void unlock();
 
     //memory management