summaryrefslogtreecommitdiff
path: root/thread.c
blob: 363190d843cacdf46321418de1cc126c26ac9b56 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
/*
 * 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 1.7 2000/12/24 12:27:21 kls Exp $
 */

#include "thread.h"
#include <errno.h>
#include <signal.h>
#include <sys/wait.h>
#include <unistd.h>
#include "tools.h"

// --- cThread ---------------------------------------------------------------

// The signal handler is necessary to be able to use SIGIO to wake up any
// pending 'select()' call.

bool cThread::signalHandlerInstalled = false;

cThread::cThread(void)
{
  if (!signalHandlerInstalled) {
     signal(SIGIO, SignalHandler);
     signalHandlerInstalled = true;
     }
  running = false;
  parentPid = threadPid = lockingPid = 0;
  locked = 0;
}

cThread::~cThread()
{
}

void cThread::SignalHandler(int signum)
{
  signal(signum, SignalHandler);
}

void *cThread::StartThread(cThread *Thread)
{
  Thread->threadPid = getpid();
  Thread->Action();
  return NULL;
}

bool cThread::Start(void)
{
  if (!running) {
     running = true;
     parentPid = getpid();
     pthread_create(&thread, NULL, (void *(*) (void *))&StartThread, (void *)this);
     usleep(10000); // otherwise calling Active() immediately after Start() causes a "pure virtual method called" error
     }
  return true; //XXX return value of pthread_create()???
}

bool cThread::Active(void)
{
  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)
{
  if (WaitSeconds > 0) {
     for (time_t t0 = time(NULL) + WaitSeconds; time(NULL) < t0; ) {
         if (!Active())
            return;
         usleep(10000);
         }
     esyslog(LOG_ERR, "ERROR: thread %d won't end (waited %d seconds) - cancelling it...", threadPid, WaitSeconds);
     }
  pthread_cancel(thread);
}

bool cThread::Lock(void)
{
  if (!lockingPid || lockingPid != getpid()) {
     Mutex.Lock();
     lockingPid = getpid();
     }
  locked++;
  return true;
}

void cThread::Unlock(void)
{
  if (!--locked) {
     lockingPid = 0;
     Mutex.Unlock();
     }
}

void cThread::WakeUp(void)
{
  kill(parentPid, SIGIO); // makes any waiting 'select()' call return immediately
}

// --- cThreadLock -----------------------------------------------------------

cThreadLock::cThreadLock(cThread *Thread)
{
  thread = NULL;
  locked = false;
  Lock(Thread);
}

cThreadLock::~cThreadLock()
{
  if (thread && locked)
     thread->Unlock();
}

bool cThreadLock::Lock(cThread *Thread)
{
  if (Thread && !thread) {
     thread = Thread;
     locked = Thread->Lock();
     return locked;
     }
  return false;
}

bool cThreadLock::Locked(void)
{
  return locked;
}