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Revert "Remove pthread storage for thread local data"

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The change introduced crashes in some tests that only surfaced
in certain CMake configurations.

This reverts commit 76c3eee4020cae681857ee17406c655f61f9082c.

Pick-to: 5.15
Task-number: QTBUG-85357
Change-Id: Ief93aa41e2d487d73b879133e7df0fd5ce0451bd
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
This commit is contained in:
Alexandru Croitor 2020-07-02 10:53:10 +02:00
parent 1048d83fc2
commit 6a47b5850b
1 changed files with 60 additions and 22 deletions
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82
src/corelib/thread/qthread_unix.cpp
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@ -109,43 +109,81 @@ static_assert(sizeof(pthread_t) <= sizeof(Qt::HANDLE));
enum { ThreadPriorityResetFlag = 0x80000000 }; enum { ThreadPriorityResetFlag = 0x80000000 };
class QThreadDataHolder static thread_local QThreadData *currentThreadData = nullptr;
static pthread_once_t current_thread_data_once = PTHREAD_ONCE_INIT;
static pthread_key_t current_thread_data_key;
static void destroy_current_thread_data(void *p)
{ {
public: #if defined(Q_OS_VXWORKS)
QThreadData* data; // Calling setspecific(..., 0) sets the value to 0 for ALL threads.
// The 'set to 1' workaround adds a bit of an overhead though,
~QThreadDataHolder() // since this function is called twice now.
{ if (p == (void *)1)
if (!data) return;
return; #endif
// POSIX says the value in our key is set to zero before calling
if (data->isAdopted) { // this destructor function, so we need to set it back to the
QThread *thread = data->thread.loadAcquire(); // right value...
Q_ASSERT(thread); pthread_setspecific(current_thread_data_key, p);
QThreadPrivate *thread_p = static_cast<QThreadPrivate *>(QObjectPrivate::get(thread)); QThreadData *data = static_cast<QThreadData *>(p);
Q_ASSERT(!thread_p->finished); if (data->isAdopted) {
thread_p->finish(thread); QThread *thread = data->thread.loadAcquire();
} Q_ASSERT(thread);
data->deref(); QThreadPrivate *thread_p = static_cast<QThreadPrivate *>(QObjectPrivate::get(thread));
Q_ASSERT(!thread_p->finished);
thread_p->finish(thread);
} }
}; data->deref();
// ... but we must reset it to zero before returning so we aren't
// called again (POSIX allows implementations to call destructor
// functions repeatedly until all values are zero)
pthread_setspecific(current_thread_data_key,
#if defined(Q_OS_VXWORKS)
(void *)1);
#else
nullptr);
#endif
}
static void create_current_thread_data_key()
{
pthread_key_create(&current_thread_data_key, destroy_current_thread_data);
}
static void destroy_current_thread_data_key()
{
pthread_once(&current_thread_data_once, create_current_thread_data_key);
pthread_key_delete(current_thread_data_key);
// Reset current_thread_data_once in case we end up recreating
// the thread-data in the rare case of QObject construction
// after destroying the QThreadData.
pthread_once_t pthread_once_init = PTHREAD_ONCE_INIT;
current_thread_data_once = pthread_once_init;
}
Q_DESTRUCTOR_FUNCTION(destroy_current_thread_data_key)
static thread_local QThreadDataHolder currentThreadData;
// Utility functions for getting, setting and clearing thread specific data. // Utility functions for getting, setting and clearing thread specific data.
static QThreadData *get_thread_data() static QThreadData *get_thread_data()
{ {
return currentThreadData.data; return currentThreadData;
} }
static void set_thread_data(QThreadData *data) static void set_thread_data(QThreadData *data)
{ {
currentThreadData.data = data; currentThreadData = data;
pthread_once(&current_thread_data_once, create_current_thread_data_key);
pthread_setspecific(current_thread_data_key, data);
} }
static void clear_thread_data() static void clear_thread_data()
{ {
currentThreadData.data = nullptr; currentThreadData = nullptr;
pthread_setspecific(current_thread_data_key, nullptr);
} }
template <typename T> template <typename T>