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vdr/thread.c

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/*
* thread.c: A simple thread base class
*
* See the main source file 'vdr.c' for copyright information and
* how to reach the author.
*
* $Id: thread.c 1.23 2002/11/02 14:00:25 kls Exp $
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*/
#include "thread.h"
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#include <errno.h>
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#include <signal.h>
#include <sys/resource.h>
#include <sys/time.h>
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#include <sys/wait.h>
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#include <unistd.h>
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#include "tools.h"
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// --- cCondVar --------------------------------------------------------------
cCondVar::cCondVar(void)
{
pthread_cond_init(&cond, 0);
}
cCondVar::~cCondVar()
{
pthread_cond_destroy(&cond);
}
void cCondVar::Wait(cMutex &Mutex)
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{
if (Mutex.locked && Mutex.lockingPid == getpid()) {
int locked = Mutex.locked;
Mutex.locked = 0; // have to clear the locked count here, as pthread_cond_wait
// does an implizit unlock of the mutex
pthread_cond_wait(&cond, &Mutex.mutex);
Mutex.locked = locked;
}
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}
bool cCondVar::TimedWait(cMutex &Mutex, int TimeoutMs)
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{
bool r = true; // true = condition signaled false = timeout
if (Mutex.locked && Mutex.lockingPid == getpid()) {
struct timeval now; // unfortunately timedwait needs the absolute time, not the delta :-(
if (gettimeofday(&now, NULL) == 0) { // get current time
now.tv_usec += TimeoutMs * 1000; // add the timeout
while (now.tv_usec >= 1000000) { // take care of an overflow
now.tv_sec++;
now.tv_usec -= 1000000;
}
struct timespec abstime; // build timespec for timedwait
abstime.tv_sec = now.tv_sec; // seconds
abstime.tv_nsec = now.tv_usec * 1000; // nano seconds
int locked = Mutex.locked;
Mutex.locked = 0; // have to clear the locked count here, as pthread_cond_timedwait
// does an implizit unlock of the mutex.
if (pthread_cond_timedwait(&cond, &Mutex.mutex, &abstime) == ETIMEDOUT)
r = false;
Mutex.locked = locked;
}
}
return r;
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}
void cCondVar::Broadcast(void)
{
pthread_cond_broadcast(&cond);
}
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/*
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void cCondVar::Signal(void)
{
pthread_cond_signal(&cond);
}
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*/
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// --- cMutex ----------------------------------------------------------------
cMutex::cMutex(void)
{
lockingPid = 0;
locked = 0;
pthread_mutex_init(&mutex, NULL);
}
cMutex::~cMutex()
{
pthread_mutex_destroy(&mutex);
}
void cMutex::Lock(void)
{
if (getpid() != lockingPid || !locked) {
pthread_mutex_lock(&mutex);
lockingPid = getpid();
}
locked++;
}
void cMutex::Unlock(void)
{
if (!--locked) {
lockingPid = 0;
pthread_mutex_unlock(&mutex);
}
}
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// --- cThread ---------------------------------------------------------------
// The signal handler is necessary to be able to use SIGIO to wake up any
// pending 'select()' call.
time_t cThread::lastPanic = 0;
int cThread::panicLevel = 0;
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bool cThread::signalHandlerInstalled = false;
bool cThread::emergencyExitRequested = false;
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cThread::cThread(void)
{
if (!signalHandlerInstalled) {
signal(SIGIO, SignalHandler);
signalHandlerInstalled = true;
}
running = false;
parentPid = threadPid = 0;
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}
cThread::~cThread()
{
}
void cThread::SignalHandler(int signum)
{
signal(signum, SignalHandler);
}
void *cThread::StartThread(cThread *Thread)
{
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Thread->threadPid = getpid();
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Thread->Action();
return NULL;
}
bool cThread::Start(void)
{
if (!running) {
running = true;
parentPid = getpid();
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pthread_create(&thread, NULL, (void *(*) (void *))&StartThread, (void *)this);
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pthread_setschedparam(thread, SCHED_RR, 0);
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usleep(10000); // otherwise calling Active() immediately after Start() causes a "pure virtual method called" error
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}
return true; //XXX return value of pthread_create()???
}
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bool cThread::Active(void)
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{
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if (threadPid) {
if (kill(threadPid, SIGIO) < 0) { // couldn't find another way of checking whether the thread is still running - any ideas?
if (errno == ESRCH)
threadPid = 0;
else
LOG_ERROR;
}
else
return true;
}
return false;
}
void cThread::Cancel(int WaitSeconds)
{
running = false;
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if (WaitSeconds > 0) {
for (time_t t0 = time(NULL) + WaitSeconds; time(NULL) < t0; ) {
if (!Active())
return;
usleep(10000);
}
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esyslog("ERROR: thread %d won't end (waited %d seconds) - cancelling it...", threadPid, WaitSeconds);
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}
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pthread_cancel(thread);
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}
void cThread::WakeUp(void)
{
kill(parentPid, SIGIO); // makes any waiting 'select()' call return immediately
}
#define MAXPANICLEVEL 10
void cThread::RaisePanic(void)
{
if (lastPanic > 0) {
if (time(NULL) - lastPanic < 5)
panicLevel++;
else if (panicLevel > 0)
panicLevel--;
}
lastPanic = time(NULL);
if (panicLevel > MAXPANICLEVEL) {
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esyslog("ERROR: max. panic level exceeded");
EmergencyExit(true);
}
else
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dsyslog("panic level: %d", panicLevel);
}
bool cThread::EmergencyExit(bool Request)
{
if (!Request)
return emergencyExitRequested;
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esyslog("initiating emergency exit");
return emergencyExitRequested = true; // yes, it's an assignment, not a comparison!
}
// --- cMutexLock ------------------------------------------------------------
cMutexLock::cMutexLock(cMutex *Mutex)
{
mutex = NULL;
locked = false;
Lock(Mutex);
}
cMutexLock::~cMutexLock()
{
if (mutex && locked)
mutex->Unlock();
}
bool cMutexLock::Lock(cMutex *Mutex)
{
if (Mutex && !mutex) {
mutex = Mutex;
Mutex->Lock();
locked = true;
return true;
}
return false;
}
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// --- cThreadLock -----------------------------------------------------------
cThreadLock::cThreadLock(cThread *Thread)
{
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thread = NULL;
locked = false;
Lock(Thread);
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}
cThreadLock::~cThreadLock()
{
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if (thread && locked)
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thread->Unlock();
}
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bool cThreadLock::Lock(cThread *Thread)
{
if (Thread && !thread) {
thread = Thread;
Thread->Lock();
locked = true;
return true;
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}
return false;
}
// --- cPipe -----------------------------------------------------------------
// cPipe::Open() and cPipe::Close() are based on code originally received from
// Andreas Vitting <Andreas@huji.de>
cPipe::cPipe(void)
{
pid = -1;
f = NULL;
}
cPipe::~cPipe()
{
Close();
}
bool cPipe::Open(const char *Command, const char *Mode)
{
int fd[2];
if (pipe(fd) < 0) {
LOG_ERROR;
return false;
}
if ((pid = fork()) < 0) { // fork failed
LOG_ERROR;
close(fd[0]);
close(fd[1]);
return false;
}
char *mode = "w";
int iopipe = 0;
if (pid > 0) { // parent process
if (strcmp(Mode, "r") == 0) {
mode = "r";
iopipe = 1;
}
close(fd[iopipe]);
f = fdopen(fd[1 - iopipe], mode);
if ((f = fdopen(fd[1 - iopipe], mode)) == NULL) {
LOG_ERROR;
close(fd[1 - iopipe]);
}
return f != NULL;
}
else { // child process
int iofd = STDOUT_FILENO;
if (strcmp(Mode, "w") == 0) {
mode = "r";
iopipe = 1;
iofd = STDIN_FILENO;
}
close(fd[iopipe]);
if (dup2(fd[1 - iopipe], iofd) == -1) { // now redirect
LOG_ERROR;
close(fd[1 - iopipe]);
_exit(-1);
}
else {
int MaxPossibleFileDescriptors = getdtablesize();
for (int i = STDERR_FILENO + 1; i < MaxPossibleFileDescriptors; i++)
close(i); //close all dup'ed filedescriptors
if (execl("/bin/sh", "sh", "-c", Command, NULL) == -1) {
LOG_ERROR_STR(Command);
close(fd[1 - iopipe]);
_exit(-1);
}
}
_exit(0);
}
}
int cPipe::Close(void)
{
int ret = -1;
if (f) {
fclose(f);
f = NULL;
}
if (pid > 0) {
int status = 0;
int i = 5;
while (i > 0) {
ret = waitpid(pid, &status, WNOHANG);
if (ret < 0) {
if (errno != EINTR && errno != ECHILD) {
LOG_ERROR;
break;
}
}
else if (ret == pid)
break;
i--;
usleep(100000);
}
if (!i) {
kill(pid, SIGKILL);
ret = -1;
}
else if (ret == -1 || !WIFEXITED(status))
ret = -1;
pid = -1;
}
return ret;
}
// --- SystemExec ------------------------------------------------------------
int SystemExec(const char *Command)
{
pid_t pid;
if ((pid = fork()) < 0) { // fork failed
LOG_ERROR;
return -1;
}
if (pid > 0) { // parent process
int status;
if (waitpid(pid, &status, 0) < 0) {
LOG_ERROR;
return -1;
}
return status;
}
else { // child process
int MaxPossibleFileDescriptors = getdtablesize();
for (int i = STDERR_FILENO + 1; i < MaxPossibleFileDescriptors; i++)
close(i); //close all dup'ed filedescriptors
if (execl("/bin/sh", "sh", "-c", Command, NULL) == -1) {
LOG_ERROR_STR(Command);
_exit(-1);
}
_exit(0);
}
}