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/***************************************************************************
libkwave/WorkerThread.cpp - worker thread for Kwave
-------------------
begin : Sun Apr 06 2008
copyright : (C) 2008 by Thomas Eschenbacher
email : Thomas.Eschenbacher@gmx.de
***************************************************************************/
/***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************/
#include "config.h"
#include <signal.h>
#include <QApplication>
#include <QtGlobal> // for qWarning()
#undef DEBUG_FIND_DEADLOCKS
#ifdef DEBUG_FIND_DEADLOCKS
#include <execinfo.h> // for backtrace()
#endif
#include <errno.h>
#include "libkwave/Runnable.h"
#include "libkwave/WorkerThread.h"
/** maximum number of attempts to stop the worker thread */
#define MAX_ATTEMPTS_TO_STOP 8
/** set to true once a handler for SIGHUP is in place */
static bool g_signal_handler_is_in_place = false;
//***************************************************************************
extern "C" void _dummy_SIGHUP_handler(int);
//***************************************************************************
void _dummy_SIGHUP_handler(int)
{
qWarning("\r\n--- SIGHUP ---\r\n");
}
//***************************************************************************
Kwave::WorkerThread::WorkerThread(Kwave::Runnable *runnable, QVariant params)
:QThread(nullptr),
m_runnable(runnable),
m_params(params),
m_lock(), m_lock_sighup(),
m_tid(pthread_self()),
m_owner_tid(pthread_self())
{
/* NOTE: we assume that this gets called from the GUI thread only */
Q_ASSERT(this->thread() == QThread::currentThread());
Q_ASSERT(this->thread() == qApp->thread());
/* install handler for SIGHUP */
if (!g_signal_handler_is_in_place) {
/*
* NOTE: the old signal handler is lost. But as long as we do not use
* SIGHUP in any other place of the application and we need to
* have a dummy handler only, that should not matter
*/
signal(SIGHUP, _dummy_SIGHUP_handler);
g_signal_handler_is_in_place = true;
}
}
//***************************************************************************
Kwave::WorkerThread::~WorkerThread()
{
if (isRunning()) {
qDebug("WorkerThread::~WorkerThread(): waiting for normal shutdown");
wait(2000);
qDebug("WorkerThread::~WorkerThread(): stopping");
stop(2000);
}
Q_ASSERT(!isRunning());
}
//***************************************************************************
void Kwave::WorkerThread::cancel()
{
requestInterruption();
emit sigCancel();
}
//***************************************************************************
int Kwave::WorkerThread::stop(unsigned int timeout)
{
QMutexLocker lock(&m_lock);
if (!isRunning()) return 0; // already down
if (timeout < 1000) timeout = 1000;
// set the "should stop" flag
requestInterruption();
// send one SIGHUP in advance
{
QMutexLocker _lock(&m_lock_sighup);
if (!pthread_equal(m_tid, m_owner_tid))
pthread_kill(m_tid, SIGHUP);
if (!isRunning()) return 0;
}
// try to stop cooperatively
if (!isRunning()) return 0;
wait(timeout/10);
if (!isRunning()) return 0;
// try to interrupt by HUP signal
qWarning("WorkerThread::stop(): sending SIGHUP");
for (unsigned int i = 0; i < MAX_ATTEMPTS_TO_STOP; i++) {
{
QMutexLocker _lock(&m_lock_sighup);
if (!isRunning()) return 0;
if (!pthread_equal(m_tid, m_owner_tid))
pthread_kill(m_tid, SIGHUP);
}
if (!isRunning()) return 0;
wait(timeout/10);
if (!isRunning()) return 0;
}
#ifdef DEBUG_FIND_DEADLOCKS
if (running()) {
qDebug("WorkerThread::stop(): pthread_self()=%08X",
(unsigned int)pthread_self());
void *buf[256];
size_t n = backtrace(buf, 256);
backtrace_symbols_fd(buf, n, 2);
}
#endif
qDebug("WorkerThread::stop(): canceling thread");
terminate();
return -1;
}
//***************************************************************************
void Kwave::WorkerThread::run()
{
Q_ASSERT(m_runnable);
if (!m_runnable) return;
/* get the POSIX thread ID, needed for sending SIGHUP */
{
QMutexLocker _lock(&m_lock_sighup);
m_tid = pthread_self();
}
/* call the run(...) function */
m_runnable->run_wrapper(m_params);
/* avoid sending any SIGHUP by setting the m_tid to "invalid" */
{
QMutexLocker _lock(&m_lock_sighup);
m_tid = m_owner_tid;
}
}
//***************************************************************************
//***************************************************************************
#include "moc_WorkerThread.cpp"
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