mirror of
https://github.com/cookiengineer/audacity
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139 lines
3.9 KiB
C
139 lines
3.9 KiB
C
/* ptlinux.c -- portable timer implementation for linux */
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/* IMPLEMENTATION NOTES (by Mark Nelson):
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Unlike Windows, Linux has no system call to request a periodic callback,
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so if Pt_Start() receives a callback parameter, it must create a thread
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that wakes up periodically and calls the provided callback function.
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If running as superuser, use setpriority() to renice thread to -20.
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One could also set the timer thread to a real-time priority (SCHED_FIFO
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and SCHED_RR), but this is dangerous for This is necessary because
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if the callback hangs it'll never return. A more serious reason
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is that the current scheduler implementation busy-waits instead
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of sleeping when realtime threads request a sleep of <=2ms (as a way
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to get around the 10ms granularity), which means the thread would never
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let anyone else on the CPU.
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CHANGE LOG
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18-Jul-03 Roger Dannenberg -- Simplified code to set priority of timer
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thread. Simplified implementation notes.
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*/
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/* stdlib, stdio, unistd, and sys/types were added because they appeared
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* in a Gentoo patch, but I'm not sure why they are needed. -RBD
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*/
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#include <stdlib.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include "porttime.h"
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#include "sys/time.h"
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#include "sys/resource.h"
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#include "sys/timeb.h"
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#include "pthread.h"
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#define TRUE 1
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#define FALSE 0
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static int time_started_flag = FALSE;
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static struct timeb time_offset = {0, 0, 0, 0};
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static pthread_t pt_thread_pid;
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static int pt_thread_created = FALSE;
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/* note that this is static data -- we only need one copy */
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typedef struct {
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int id;
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int resolution;
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PtCallback *callback;
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void *userData;
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} pt_callback_parameters;
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static int pt_callback_proc_id = 0;
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static void *Pt_CallbackProc(void *p)
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{
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pt_callback_parameters *parameters = (pt_callback_parameters *) p;
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int mytime = 1;
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/* to kill a process, just increment the pt_callback_proc_id */
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/* printf("pt_callback_proc_id %d, id %d\n", pt_callback_proc_id,
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parameters->id); */
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if (geteuid() == 0) setpriority(PRIO_PROCESS, 0, -20);
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while (pt_callback_proc_id == parameters->id) {
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/* wait for a multiple of resolution ms */
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struct timeval timeout;
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int delay = mytime++ * parameters->resolution - Pt_Time();
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if (delay < 0) delay = 0;
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timeout.tv_sec = 0;
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timeout.tv_usec = delay * 1000;
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select(0, NULL, NULL, NULL, &timeout);
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(*(parameters->callback))(Pt_Time(), parameters->userData);
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}
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/* printf("Pt_CallbackProc exiting\n"); */
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// free(parameters);
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return NULL;
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}
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PtError Pt_Start(int resolution, PtCallback *callback, void *userData)
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{
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if (time_started_flag) return ptNoError;
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ftime(&time_offset); /* need this set before process runs */
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if (callback) {
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int res;
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pt_callback_parameters *parms = (pt_callback_parameters *)
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malloc(sizeof(pt_callback_parameters));
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if (!parms) return ptInsufficientMemory;
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parms->id = pt_callback_proc_id;
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parms->resolution = resolution;
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parms->callback = callback;
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parms->userData = userData;
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res = pthread_create(&pt_thread_pid, NULL,
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Pt_CallbackProc, parms);
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if (res != 0) return ptHostError;
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pt_thread_created = TRUE;
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}
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time_started_flag = TRUE;
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return ptNoError;
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}
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PtError Pt_Stop()
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{
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/* printf("Pt_Stop called\n"); */
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pt_callback_proc_id++;
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if (pt_thread_created) {
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pthread_join(pt_thread_pid, NULL);
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pt_thread_created = FALSE;
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}
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time_started_flag = FALSE;
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return ptNoError;
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}
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int Pt_Started()
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{
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return time_started_flag;
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}
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PtTimestamp Pt_Time()
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{
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long seconds, milliseconds;
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struct timeb now;
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ftime(&now);
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seconds = now.time - time_offset.time;
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milliseconds = now.millitm - time_offset.millitm;
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return seconds * 1000 + milliseconds;
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}
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void Pt_Sleep(int32_t duration)
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{
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usleep(duration * 1000);
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}
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