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author | Qt Forward Merge Bot <qt_forward_merge_bot@qt-project.org> | 2018-03-31 01:00:13 +0200 |
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committer | Qt Forward Merge Bot <qt_forward_merge_bot@qt-project.org> | 2018-03-31 01:00:13 +0200 |
commit | ffb2c2ac6c3ba40acbe13a39899a72049585b427 (patch) | |
tree | dbee14e6d1641e02ea1fd5fc67ce001ab12776ef /src/corelib | |
parent | 6d0044f1dcffebc29dccd9d37d90f8abdb941a88 (diff) | |
parent | dbdd5f0ffbce52c8b789ed09f1aa3f1da6c02e23 (diff) |
Merge remote-tracking branch 'origin/5.11' into dev
Change-Id: I33b47095efdfe0ba698c6a88ca41ec911f432208
Diffstat (limited to 'src/corelib')
-rw-r--r-- | src/corelib/doc/snippets/code/src_corelib_tools_qbytearray.cpp | 6 | ||||
-rw-r--r-- | src/corelib/thread/qsemaphore.cpp | 33 |
2 files changed, 23 insertions, 16 deletions
diff --git a/src/corelib/doc/snippets/code/src_corelib_tools_qbytearray.cpp b/src/corelib/doc/snippets/code/src_corelib_tools_qbytearray.cpp index a17e541df3..d163129d54 100644 --- a/src/corelib/doc/snippets/code/src_corelib_tools_qbytearray.cpp +++ b/src/corelib/doc/snippets/code/src_corelib_tools_qbytearray.cpp @@ -395,10 +395,10 @@ QByteArray ba = QByteArray::number(12.3456, 'E', 3); //! [43] static const char mydata[] = { - 0x00, 0x00, 0x03, 0x84, 0x78, 0x9c, 0x3b, 0x76, - 0xec, 0x18, 0xc3, 0x31, 0x0a, 0xf1, 0xcc, 0x99, + '\x00', '\x00', '\x03', '\x84', '\x78', '\x9c', '\x3b', '\x76', + '\xec', '\x18', '\xc3', '\x31', '\x0a', '\xf1', '\xcc', '\x99', ... - 0x6d, 0x5b + '\x6d', '\x5b' }; QByteArray data = QByteArray::fromRawData(mydata, sizeof(mydata)); diff --git a/src/corelib/thread/qsemaphore.cpp b/src/corelib/thread/qsemaphore.cpp index 6c4a211222..9a5505bd1e 100644 --- a/src/corelib/thread/qsemaphore.cpp +++ b/src/corelib/thread/qsemaphore.cpp @@ -120,12 +120,12 @@ using namespace QtFutex; If the system has the ability to wake up a precise number of threads, has Linux's FUTEX_WAKE_OP functionality, and is 64-bit, instead of using a - single bit indicating a contended semaphore, we'll store the total number - of waiters in the high word. Additionally, all multi-token waiters will be - waiting on that high word. So when releasing n tokens on those systems, we - tell the kernel to wake up n single-token threads and all of the - multi-token ones. Which threads get woken up is unspecified, but it's - likely single-token threads will get woken up first. + single bit indicating a contended semaphore, we'll store the number of + tokens *plus* total number of waiters in the high word. Additionally, all + multi-token waiters will be waiting on that high word. So when releasing n + tokens on those systems, we tell the kernel to wake up n single-token + threads and all of the multi-token ones. Which threads get woken up is + unspecified, but it's likely single-token threads will get woken up first. */ #if defined(FUTEX_OP) && QT_POINTER_SIZE > 4 @@ -231,10 +231,14 @@ template <bool IsTimed> bool futexSemaphoreTryAcquire(QBasicAtomicInteger<quintp { // Try to acquire without waiting (we still loop because the testAndSet // call can fail). + quintptr nn = unsigned(n); + if (futexHasWaiterCount) + nn |= quint64(nn) << 32; // token count replicated in high word + quintptr curValue = u.loadAcquire(); while (futexAvailCounter(curValue) >= n) { // try to acquire - quintptr newValue = curValue - n; + quintptr newValue = curValue - nn; if (u.testAndSetOrdered(curValue, newValue, curValue)) return true; // succeeded! } @@ -242,7 +246,6 @@ template <bool IsTimed> bool futexSemaphoreTryAcquire(QBasicAtomicInteger<quintp return false; // we need to wait - quintptr valueToSubtract = unsigned(n); quintptr oneWaiter = quintptr(Q_UINT64_C(1) << 32); // zero on 32-bit if (futexHasWaiterCount) { // increase the waiter count @@ -250,14 +253,15 @@ template <bool IsTimed> bool futexSemaphoreTryAcquire(QBasicAtomicInteger<quintp // We don't use the fetched value from above so futexWait() fails if // it changed after the testAndSetOrdered above. + if ((quint64(curValue) >> 32) == 0x7fffffff) + return false; // overflow! curValue += oneWaiter; - // Also adjust valueToSubtract to subtract oneWaiter when we succeed in - // acquiring. - valueToSubtract += oneWaiter; + // Also adjust nn to subtract oneWaiter when we succeed in acquiring. + nn += oneWaiter; } - if (futexSemaphoreTryAcquire_loop<IsTimed>(u, curValue, valueToSubtract, timeout)) + if (futexSemaphoreTryAcquire_loop<IsTimed>(u, curValue, nn, timeout)) return true; if (futexHasWaiterCount) { @@ -345,7 +349,10 @@ void QSemaphore::release(int n) Q_ASSERT_X(n >= 0, "QSemaphore::release", "parameter 'n' must be non-negative"); if (futexAvailable()) { - quintptr prevValue = u.fetchAndAddRelease(n); + quintptr nn = unsigned(n); + if (futexHasWaiterCount) + nn |= quint64(nn) << 32; // token count replicated in high word + quintptr prevValue = u.fetchAndAddRelease(nn); if (futexNeedsWake(prevValue)) { #ifdef FUTEX_OP if (!futexHasWaiterCount) { |