barrier/lib/arch/CArchMultithreadPosix.cpp

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/*
* synergy -- mouse and keyboard sharing utility
* Copyright (C) 2002 Chris Schoeneman
*
* This package is free software you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* found in the file COPYING that should have accompanied this file.
*
* This package is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include "CArchMultithreadPosix.h"
#include "CArch.h"
#include "XArch.h"
#include <signal.h>
#if TIME_WITH_SYS_TIME
# include <sys/time.h>
# include <time.h>
#else
# if HAVE_SYS_TIME_H
# include <sys/time.h>
# else
# include <time.h>
# endif
#endif
#include <cerrno>
#define SIGWAKEUP SIGUSR1
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#if !HAVE_PTHREAD_SIGNAL
// boy, is this platform broken. forget about pthread signal
// handling and let signals through to every process. synergy
// will not terminate cleanly when it gets SIGTERM or SIGINT.
# define pthread_sigmask sigprocmask
# define pthread_kill(tid_, sig_) kill(0, (sig_))
# define sigwait(set_, sig_)
# undef HAVE_POSIX_SIGWAIT
# define HAVE_POSIX_SIGWAIT 1
#endif
//
// CArchThreadImpl
//
class CArchThreadImpl {
public:
CArchThreadImpl();
public:
int m_refCount;
IArchMultithread::ThreadID m_id;
pthread_t m_thread;
IArchMultithread::ThreadFunc m_func;
void* m_userData;
bool m_cancel;
bool m_cancelling;
bool m_exited;
void* m_result;
};
CArchThreadImpl::CArchThreadImpl() :
m_refCount(1),
m_id(0),
m_func(NULL),
m_userData(NULL),
m_cancel(false),
m_cancelling(false),
m_exited(false),
m_result(NULL)
{
// do nothing
}
//
// CArchMultithreadPosix
//
CArchMultithreadPosix* CArchMultithreadPosix::s_instance = NULL;
CArchMultithreadPosix::CArchMultithreadPosix() :
m_newThreadCalled(false),
m_nextID(0)
{
assert(s_instance == NULL);
s_instance = this;
// create mutex for thread list
m_threadMutex = newMutex();
// create thread for calling (main) thread and add it to our
// list. no need to lock the mutex since we're the only thread.
m_mainThread = new CArchThreadImpl;
m_mainThread->m_thread = pthread_self();
insert(m_mainThread);
// install SIGWAKEUP handler. this causes SIGWAKEUP to interrupt
// system calls. we use that when cancelling a thread to force it
// to wake up immediately if it's blocked in a system call. we
// won't need this until another thread is created but it's fine
// to install it now.
struct sigaction act;
sigemptyset(&act.sa_mask);
# if defined(SA_INTERRUPT)
act.sa_flags = SA_INTERRUPT;
# else
act.sa_flags = 0;
# endif
act.sa_handler = &threadCancel;
sigaction(SIGWAKEUP, &act, NULL);
// set desired signal dispositions. let SIGWAKEUP through but
// ignore SIGPIPE (we'll handle EPIPE).
sigset_t sigset;
sigemptyset(&sigset);
sigaddset(&sigset, SIGWAKEUP);
pthread_sigmask(SIG_UNBLOCK, &sigset, NULL);
sigemptyset(&sigset);
sigaddset(&sigset, SIGPIPE);
pthread_sigmask(SIG_BLOCK, &sigset, NULL);
}
CArchMultithreadPosix::~CArchMultithreadPosix()
{
assert(s_instance != NULL);
closeMutex(m_threadMutex);
s_instance = NULL;
}
CArchCond
CArchMultithreadPosix::newCondVar()
{
CArchCondImpl* cond = new CArchCondImpl;
int status = pthread_cond_init(&cond->m_cond, NULL);
assert(status == 0);
return cond;
}
void
CArchMultithreadPosix::closeCondVar(CArchCond cond)
{
int status = pthread_cond_destroy(&cond->m_cond);
assert(status == 0);
delete cond;
}
void
CArchMultithreadPosix::signalCondVar(CArchCond cond)
{
int status = pthread_cond_signal(&cond->m_cond);
assert(status == 0);
}
void
CArchMultithreadPosix::broadcastCondVar(CArchCond cond)
{
int status = pthread_cond_broadcast(&cond->m_cond);
assert(status == 0);
}
bool
CArchMultithreadPosix::waitCondVar(CArchCond cond,
CArchMutex mutex, double timeout)
{
// get final time
struct timeval now;
gettimeofday(&now, NULL);
struct timespec finalTime;
finalTime.tv_sec = now.tv_sec;
finalTime.tv_nsec = now.tv_usec * 1000;
if (timeout >= 0.0) {
const long timeout_sec = (long)timeout;
const long timeout_nsec = (long)(1.0e+9 * (timeout - timeout_sec));
finalTime.tv_sec += timeout_sec;
finalTime.tv_nsec += timeout_nsec;
if (finalTime.tv_nsec >= 1000000000) {
finalTime.tv_nsec -= 1000000000;
finalTime.tv_sec += 1;
}
}
// repeat until we reach the final time
int status;
for (;;) {
// get current time
gettimeofday(&now, NULL);
struct timespec endTime;
endTime.tv_sec = now.tv_sec;
endTime.tv_nsec = now.tv_usec * 1000;
// done if past final timeout
if (timeout >= 0.0) {
if (endTime.tv_sec > finalTime.tv_sec ||
(endTime.tv_sec == finalTime.tv_sec &&
endTime.tv_nsec >= finalTime.tv_nsec)) {
status = ETIMEDOUT;
break;
}
}
// compute the next timeout
endTime.tv_nsec += 50000000;
if (endTime.tv_nsec >= 1000000000) {
endTime.tv_nsec -= 1000000000;
endTime.tv_sec += 1;
}
// don't wait past final timeout
if (timeout >= 0.0) {
if (endTime.tv_sec > finalTime.tv_sec ||
(endTime.tv_sec == finalTime.tv_sec &&
endTime.tv_nsec >= finalTime.tv_nsec)) {
endTime = finalTime;
}
}
// see if we should cancel this thread
testCancelThread();
// wait
status = pthread_cond_timedwait(&cond->m_cond,
&mutex->m_mutex, &endTime);
// check for cancel again
testCancelThread();
// check wait status
if (status != ETIMEDOUT && status != EINTR) {
break;
}
}
switch (status) {
case 0:
// success
return true;
case ETIMEDOUT:
return false;
default:
assert(0 && "condition variable wait error");
return false;
}
}
CArchMutex
CArchMultithreadPosix::newMutex()
{
pthread_mutexattr_t attr;
int status = pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
assert(status == 0);
CArchMutexImpl* mutex = new CArchMutexImpl;
status = pthread_mutex_init(&mutex->m_mutex, &attr);
assert(status == 0);
return mutex;
}
void
CArchMultithreadPosix::closeMutex(CArchMutex mutex)
{
int status = pthread_mutex_destroy(&mutex->m_mutex);
assert(status == 0);
delete mutex;
}
void
CArchMultithreadPosix::lockMutex(CArchMutex mutex)
{
int status = pthread_mutex_lock(&mutex->m_mutex);
switch (status) {
case 0:
// success
return;
case EDEADLK:
assert(0 && "lock already owned");
break;
case EAGAIN:
assert(0 && "too many recursive locks");
break;
default:
assert(0 && "unexpected error");
break;
}
}
void
CArchMultithreadPosix::unlockMutex(CArchMutex mutex)
{
int status = pthread_mutex_unlock(&mutex->m_mutex);
switch (status) {
case 0:
// success
return;
case EPERM:
assert(0 && "thread doesn't own a lock");
break;
default:
assert(0 && "unexpected error");
break;
}
}
CArchThread
CArchMultithreadPosix::newThread(ThreadFunc func, void* data)
{
assert(func != NULL);
// initialize signal handler. we do this here instead of the
// constructor so we can avoid daemonizing (using fork())
// when there are multiple threads. clients can safely
// use condition variables and mutexes before creating a
// new thread and they can safely use the only thread
// they have access to, the main thread, so they really
// can't tell the difference.
if (!m_newThreadCalled) {
m_newThreadCalled = true;
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#if HAVE_PTHREAD_SIGNAL
startSignalHandler();
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#endif
}
lockMutex(m_threadMutex);
// create thread impl for new thread
CArchThreadImpl* thread = new CArchThreadImpl;
thread->m_func = func;
thread->m_userData = data;
// mask some signals in all threads except the main thread
sigset_t sigset, oldsigset;
sigemptyset(&sigset);
sigaddset(&sigset, SIGINT);
sigaddset(&sigset, SIGTERM);
pthread_sigmask(SIG_BLOCK, &sigset, &oldsigset);
// create the thread. pthread_create() on RedHat 7.2 smp fails
// if passed a NULL attr so use a default attr.
pthread_attr_t attr;
int status = pthread_attr_init(&attr);
if (status == 0) {
status = pthread_create(&thread->m_thread, &attr,
&CArchMultithreadPosix::threadFunc, thread);
pthread_attr_destroy(&attr);
}
// restore signals
pthread_sigmask(SIG_SETMASK, &oldsigset, NULL);
// check if thread was started
if (status != 0) {
// failed to start thread so clean up
delete thread;
thread = NULL;
}
else {
// add thread to list
insert(thread);
// increment ref count to account for the thread itself
refThread(thread);
}
// note that the child thread will wait until we release this mutex
unlockMutex(m_threadMutex);
return thread;
}
CArchThread
CArchMultithreadPosix::newCurrentThread()
{
lockMutex(m_threadMutex);
CArchThreadImpl* thread = find(pthread_self());
unlockMutex(m_threadMutex);
assert(thread != NULL);
return thread;
}
void
CArchMultithreadPosix::closeThread(CArchThread thread)
{
assert(thread != NULL);
// decrement ref count and clean up thread if no more references
if (--thread->m_refCount == 0) {
// detach from thread (unless it's the main thread)
if (thread->m_func != NULL) {
pthread_detach(thread->m_thread);
}
// remove thread from list
lockMutex(m_threadMutex);
assert(findNoRef(thread->m_thread) == thread);
erase(thread);
unlockMutex(m_threadMutex);
// done with thread
delete thread;
}
}
CArchThread
CArchMultithreadPosix::copyThread(CArchThread thread)
{
refThread(thread);
return thread;
}
void
CArchMultithreadPosix::cancelThread(CArchThread thread)
{
assert(thread != NULL);
// set cancel and wakeup flags if thread can be cancelled
bool wakeup = false;
lockMutex(m_threadMutex);
if (!thread->m_exited && !thread->m_cancelling) {
thread->m_cancel = true;
wakeup = true;
}
unlockMutex(m_threadMutex);
// force thread to exit system calls if wakeup is true
if (wakeup) {
pthread_kill(thread->m_thread, SIGWAKEUP);
}
}
void
CArchMultithreadPosix::setPriorityOfThread(CArchThread thread, int /*n*/)
{
assert(thread != NULL);
// FIXME
}
void
CArchMultithreadPosix::testCancelThread()
{
// find current thread
lockMutex(m_threadMutex);
CArchThreadImpl* thread = findNoRef(pthread_self());
unlockMutex(m_threadMutex);
// test cancel on thread
testCancelThreadImpl(thread);
}
bool
CArchMultithreadPosix::wait(CArchThread target, double timeout)
{
assert(target != NULL);
lockMutex(m_threadMutex);
// find current thread
CArchThreadImpl* self = findNoRef(pthread_self());
// ignore wait if trying to wait on ourself
if (target == self) {
unlockMutex(m_threadMutex);
return false;
}
// ref the target so it can't go away while we're watching it
refThread(target);
unlockMutex(m_threadMutex);
try {
// do first test regardless of timeout
testCancelThreadImpl(self);
if (isExitedThread(target)) {
closeThread(target);
return true;
}
// wait and repeat test if there's a timeout
if (timeout != 0.0) {
const double start = ARCH->time();
do {
// wait a little
ARCH->sleep(0.05);
// repeat test
testCancelThreadImpl(self);
if (isExitedThread(target)) {
closeThread(target);
return true;
}
// repeat wait and test until timed out
} while (timeout < 0.0 || (ARCH->time() - start) <= timeout);
}
closeThread(target);
return false;
}
catch (...) {
closeThread(target);
throw;
}
}
IArchMultithread::EWaitResult
CArchMultithreadPosix::waitForEvent(CArchThread, double /*timeout*/)
{
// not implemented
return kTimeout;
}
bool
CArchMultithreadPosix::isSameThread(CArchThread thread1, CArchThread thread2)
{
return (thread1 == thread2);
}
bool
CArchMultithreadPosix::isExitedThread(CArchThread thread)
{
lockMutex(m_threadMutex);
bool exited = thread->m_exited;
unlockMutex(m_threadMutex);
return exited;
}
void*
CArchMultithreadPosix::getResultOfThread(CArchThread thread)
{
lockMutex(m_threadMutex);
void* result = thread->m_result;
unlockMutex(m_threadMutex);
return result;
}
IArchMultithread::ThreadID
CArchMultithreadPosix::getIDOfThread(CArchThread thread)
{
return thread->m_id;
}
void
CArchMultithreadPosix::startSignalHandler()
{
// set signal mask. the main thread blocks these signals and
// the signal handler thread will listen for them.
sigset_t sigset;
sigemptyset(&sigset);
sigaddset(&sigset, SIGINT);
sigaddset(&sigset, SIGTERM);
pthread_sigmask(SIG_BLOCK, &sigset, NULL);
// fire up the INT and TERM signal handler thread. we could
// instead arrange to catch and handle these signals but
// we'd be unable to cancel the main thread since no pthread
// calls are allowed in a signal handler.
pthread_attr_t attr;
int status = pthread_attr_init(&attr);
if (status == 0) {
status = pthread_create(&m_signalThread, &attr,
&CArchMultithreadPosix::threadSignalHandler,
m_mainThread);
pthread_attr_destroy(&attr);
}
if (status != 0) {
// can't create thread to wait for signal so don't block
// the signals.
sigemptyset(&sigset);
sigaddset(&sigset, SIGINT);
sigaddset(&sigset, SIGTERM);
pthread_sigmask(SIG_UNBLOCK, &sigset, NULL);
}
}
CArchThreadImpl*
CArchMultithreadPosix::find(pthread_t thread)
{
CArchThreadImpl* impl = findNoRef(thread);
if (impl != NULL) {
refThread(impl);
}
return impl;
}
CArchThreadImpl*
CArchMultithreadPosix::findNoRef(pthread_t thread)
{
// linear search
for (CThreadList::const_iterator index = m_threadList.begin();
index != m_threadList.end(); ++index) {
if ((*index)->m_thread == thread) {
return *index;
}
}
return NULL;
}
void
CArchMultithreadPosix::insert(CArchThreadImpl* thread)
{
assert(thread != NULL);
// thread shouldn't already be on the list
assert(findNoRef(thread->m_thread) == NULL);
// set thread id. note that we don't worry about m_nextID
// wrapping back to 0 and duplicating thread ID's since the
// likelihood of synergy running that long is vanishingly
// small.
thread->m_id = ++m_nextID;
// append to list
m_threadList.push_back(thread);
}
void
CArchMultithreadPosix::erase(CArchThreadImpl* thread)
{
for (CThreadList::iterator index = m_threadList.begin();
index != m_threadList.end(); ++index) {
if (*index == thread) {
m_threadList.erase(index);
break;
}
}
}
void
CArchMultithreadPosix::refThread(CArchThreadImpl* thread)
{
assert(thread != NULL);
assert(findNoRef(thread->m_thread) != NULL);
++thread->m_refCount;
}
void
CArchMultithreadPosix::testCancelThreadImpl(CArchThreadImpl* thread)
{
assert(thread != NULL);
// update cancel state
lockMutex(m_threadMutex);
bool cancel = false;
if (thread->m_cancel && !thread->m_cancelling) {
thread->m_cancelling = true;
thread->m_cancel = false;
cancel = true;
}
unlockMutex(m_threadMutex);
// unwind thread's stack if cancelling
if (cancel) {
throw XThreadCancel();
}
}
void*
CArchMultithreadPosix::threadFunc(void* vrep)
{
// get the thread
CArchThreadImpl* thread = reinterpret_cast<CArchThreadImpl*>(vrep);
// setup pthreads
pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL);
pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED, NULL);
// run thread
s_instance->doThreadFunc(thread);
// terminate the thread
return NULL;
}
void
CArchMultithreadPosix::doThreadFunc(CArchThread thread)
{
// default priority is slightly below normal
setPriorityOfThread(thread, 1);
// wait for parent to initialize this object
lockMutex(m_threadMutex);
unlockMutex(m_threadMutex);
void* result = NULL;
try {
// go
result = (*thread->m_func)(thread->m_userData);
}
catch (XThreadCancel&) {
// client called cancel()
}
catch (...) {
// note -- don't catch (...) to avoid masking bugs
lockMutex(m_threadMutex);
thread->m_exited = true;
unlockMutex(m_threadMutex);
closeThread(thread);
throw;
}
// thread has exited
lockMutex(m_threadMutex);
thread->m_result = result;
thread->m_exited = true;
unlockMutex(m_threadMutex);
// done with thread
closeThread(thread);
}
void
CArchMultithreadPosix::threadCancel(int)
{
// do nothing
}
void*
CArchMultithreadPosix::threadSignalHandler(void* vrep)
{
CArchThreadImpl* mainThread = reinterpret_cast<CArchThreadImpl*>(vrep);
// detach
pthread_detach(pthread_self());
// add signal to mask
sigset_t sigset;
sigemptyset(&sigset);
sigaddset(&sigset, SIGINT);
sigaddset(&sigset, SIGTERM);
// also wait on SIGABRT. on linux (others?) this thread (process)
// will persist after all the other threads evaporate due to an
// assert unless we wait on SIGABRT. that means our resources (like
// the socket we're listening on) are not released and never will be
// until the lingering thread is killed. i don't know why sigwait()
// should protect the thread from being killed. note that sigwait()
// doesn't actually return if we receive SIGABRT and, for some
// reason, we don't have to block SIGABRT.
sigaddset(&sigset, SIGABRT);
// we exit the loop via thread cancellation in sigwait()
for (;;) {
// wait
#if HAVE_POSIX_SIGWAIT
int signal;
sigwait(&sigset, &signal);
#else
sigwait(&sigset);
#endif
// if we get here then the signal was raised. cancel the main
// thread so it can shut down cleanly.
ARCH->cancelThread(mainThread);
}
}