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Fixed a race condition in starting a thread

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This commit is contained in:
Klaus Schmidinger
2004-12-19 10:58:20 +01:00
parent f5b1a74056
commit 9a8ef2b6c2
4 changed files with 30 additions and 29 deletions
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50
thread.c
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@@ -4,7 +4,7 @@
* See the main source file 'vdr.c' for copyright information and
* how to reach the author.
*
* $Id: thread.c 1.39 2004/11/26 14:16:07 kls Exp $
* $Id: thread.c 1.40 2004/12/19 10:43:14 kls Exp $
*/
#include "thread.h"
@@ -197,7 +197,8 @@ bool cThread::emergencyExitRequested = false;
cThread::cThread(const char *Description)
{
parentTid = childTid = 0;
running = false;
childTid = 0;
description = NULL;
SetDescription(Description);
}
@@ -221,35 +222,35 @@ void cThread::SetDescription(const char *Description, ...)
void *cThread::StartThread(cThread *Thread)
{
Thread->childTidMutex.Lock();
Thread->childTid = pthread_self();
Thread->childTidMutex.Unlock();
if (Thread->description)
dsyslog("%s thread started (pid=%d, tid=%ld)", Thread->description, getpid(), Thread->childTid);
dsyslog("%s thread started (pid=%d, tid=%ld)", Thread->description, getpid(), pthread_self());
Thread->Action();
if (Thread->description)
dsyslog("%s thread ended (pid=%d, tid=%ld)", Thread->description, getpid(), Thread->childTid);
Thread->childTidMutex.Lock();
Thread->childTid = 0;
Thread->childTidMutex.Unlock();
dsyslog("%s thread ended (pid=%d, tid=%ld)", Thread->description, getpid(), pthread_self());
Thread->running = false;
return NULL;
}
bool cThread::Start(void)
{
if (!childTid) {
parentTid = pthread_self();
pthread_t Tid;
pthread_create(&Tid, NULL, (void *(*) (void *))&StartThread, (void *)this);
pthread_detach(Tid); // auto-reap
pthread_setschedparam(Tid, SCHED_RR, 0);
if (!running) {
running = true;
if (pthread_create(&childTid, NULL, (void *(*) (void *))&StartThread, (void *)this) == 0) {
pthread_detach(childTid); // auto-reap
pthread_setschedparam(childTid, SCHED_RR, 0);
}
else {
LOG_ERROR;
running = false;
return false;
}
}
return true; //XXX return value of pthread_create()???
return true;
}
bool cThread::Active(void)
{
if (childTid) {
if (running) {
//
// Single UNIX Spec v2 says:
//
@@ -259,12 +260,12 @@ bool cThread::Active(void)
// As in kill(), if sig is zero, error checking is
// performed but no signal is actually sent.
//
cMutexLock MutexLock(&childTidMutex);
int err;
if ((err = pthread_kill(childTid, 0)) != 0) {
if (err != ESRCH)
LOG_ERROR;
childTid = 0;
running = false;
}
else
return true;
@@ -274,7 +275,7 @@ bool cThread::Active(void)
void cThread::Cancel(int WaitSeconds)
{
if (childTid) {
if (running) {
if (WaitSeconds > 0) {
for (time_t t0 = time(NULL) + WaitSeconds; time(NULL) < t0; ) {
if (!Active())
@@ -283,12 +284,9 @@ void cThread::Cancel(int WaitSeconds)
}
esyslog("ERROR: thread %ld won't end (waited %d seconds) - canceling it...", childTid, WaitSeconds);
}
childTidMutex.Lock();
if (childTid) {
pthread_cancel(childTid);
childTid = 0;
}
childTidMutex.Unlock();
pthread_cancel(childTid);
childTid = 0;
running = false;
}
}