[system] add timer examples

system/timer/makefile

@@ -0,0 +1,9 @@
+all:
+	gcc sleep_example.c -o sleep_example
+	gcc simple_threading_timer.c -o simple_threading_timer -lrt
+	gcc signal_interrupt_timer.c -o signal_interrupt_timer -lrt
+
+clean:
+	rm sleep_example
+	rm simple_threading_timer
+	rm signal_interrupt_timer

system/timer/signal_interrupt_timer.c

@@ -0,0 +1,84 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <signal.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+
+#define UNUSED(x) (void)(x)
+
+pid_t gettid(void);
+
+struct t_eventData {
+    int myData;
+};
+
+static void handler(int sig, siginfo_t *si, void *uc)
+{
+    UNUSED(sig);
+    UNUSED(uc);
+    struct t_eventData *data = (struct t_eventData *) si->_sifields._rt.si_sigval.sival_ptr;
+    printf("[%lu] Timer fired %d - thread-id: %d\n", time(NULL), ++data->myData, gettid());
+}
+
+int main(int argc, char const *argv[])
+{
+    int res = 0;
+    timer_t timerId = 0;
+
+    struct sigevent sev = { 0 };
+    struct t_eventData eventData = { .myData = 0 };
+
+    /* specifies the action when receiving a signal */
+    struct sigaction sa = { 0 };
+
+    /* specify start delay and interval */
+    struct itimerspec its = {
+        .it_value.tv_sec  = 1,
+        .it_value.tv_nsec = 0,
+        .it_interval.tv_sec  = 1,
+        .it_interval.tv_nsec = 0
+    };
+
+    printf("Signal Interrupt Timer - thread-id: %d\n", gettid());
+
+    sev.sigev_notify = SIGEV_SIGNAL; // Linux-specific
+    sev.sigev_signo = SIGRTMIN;
+    sev.sigev_value.sival_ptr = &eventData;
+
+    /* create timer */
+    res = timer_create(CLOCK_REALTIME, &sev, &timerId);
+
+    if ( res != 0){
+        fprintf(stderr, "Error timer_create: %s\n", strerror(errno));
+        exit(-1);
+    }
+
+    /* specifz signal and handler */
+    sa.sa_flags = SA_SIGINFO;
+    sa.sa_sigaction = handler;
+
+    /* Initialize signal */
+    sigemptyset(&sa.sa_mask);
+
+    printf("Establishing handler for signal %d\n", SIGRTMIN);
+
+    /* Register signal handler */
+    if (sigaction(SIGRTMIN, &sa, NULL) == -1){
+        fprintf(stderr, "Error sigaction: %s\n", strerror(errno));
+        exit(-1);
+    }
+
+    /* start timer */
+    res = timer_settime(timerId, 0, &its, NULL);
+
+    if ( res != 0){
+        fprintf(stderr, "Error timer_settime: %s\n", strerror(errno));
+        exit(-1);
+    }
+
+    printf("Press ENTER to Exit\n");
+    while(getchar()!='\n'){}
+    return 0;
+}

system/timer/simple_threading_timer.c

@@ -0,0 +1,65 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <signal.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+
+pid_t gettid(void);
+
+struct t_eventData{
+    int myData;
+};
+
+void expired(union sigval timer_data)
+{
+    struct t_eventData *data = timer_data.sival_ptr;
+    printf("[%lu] Timer fired %d - thread-id: %d\n", time(NULL), ++data->myData, gettid());
+}
+
+int main(int argc, char const *argv[])
+{
+    int res = 0;
+    timer_t timerId = 0;
+
+    /*  sigevent specifies behaviour on expiration  */
+    struct sigevent sev = { 0 };
+    struct t_eventData eventData = { .myData = 0 };
+
+    /* specify start delay and interval
+     * it_value and it_interval must not be zero */
+
+    struct itimerspec its = {
+        .it_value.tv_sec  = 1,
+        .it_value.tv_nsec = 0,
+        .it_interval.tv_sec  = 1,
+        .it_interval.tv_nsec = 0
+    };
+
+    printf("Simple Threading Timer - thread-id: %d\n", gettid());
+
+    sev.sigev_notify = SIGEV_THREAD;
+    sev.sigev_notify_function = &expired;
+    sev.sigev_value.sival_ptr = &eventData;
+
+    /* create timer */
+    res = timer_create(CLOCK_REALTIME, &sev, &timerId);
+
+    if (res != 0) {
+        fprintf(stderr, "Error timer_create: %s\n", strerror(errno));
+        exit(-1);
+    }
+
+    /* start timer */
+    res = timer_settime(timerId, 0, &its, NULL);
+
+    if (res != 0) {
+        fprintf(stderr, "Error timer_settime: %s\n", strerror(errno));
+        exit(-1);
+    }
+
+    printf("Press ETNER Key to Exit\n");
+    while(getchar()!='\n'){}
+    return 0;
+}

system/timer/sleep_example.c

@@ -0,0 +1,34 @@
+#include <stdio.h>
+#include <signal.h>
+#include <unistd.h>
+#include <string.h>
+#include <time.h>
+
+static char msg[] = "I received a msg.";
+
+void show_msg(int signo)
+{
+    printf("[%lu] %s\n", time(NULL), msg);
+}
+
+int main(int argc, char const *argv[])
+{
+    struct sigaction act;
+    union sigval tsval;
+    act.sa_handler = show_msg;
+    act.sa_flags = 0;
+
+    sigemptyset(&act.sa_mask);
+    sigaction(50, &act, NULL);
+
+    printf("Start\n");
+
+    while (1) {
+        sleep(1);
+
+        /*向主进程发送信号，实际上是自己给自己发信号*/
+        sigqueue(getpid(), 50, tsval);
+    }
+
+    return 0;
+}