helper_thread: Introduce the wait_for_action() function

This patch makes helper_thread_main() easier to read.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>

diff --git a/helper_thread.c b/helper_thread.c
index 88937ade0decf9e9f6d6200879eee6a751543157..40f99a5e8eba9bd33e56172031f80b143cd02e45 100644 (file)
--- a/helper_thread.c
+++ b/helper_thread.c
@@ -140,6 +140,38 @@ void helper_thread_exit(void)
        pthread_join(helper_data->thread, NULL);
 }
 
+/*
+ * Waits for an action from fd during at least timeout_ms. `fd` must be in
+ * non-blocking mode.
+ */
+static uint8_t wait_for_action(int fd, unsigned int timeout_ms)
+{
+       struct timeval timeout = {
+               .tv_sec  = timeout_ms / 1000,
+               .tv_usec = (timeout_ms % 1000) * 1000,
+       };
+       fd_set rfds, efds;
+       uint8_t action = 0;
+       int res;
+
+       res = read_from_pipe(fd, &action, sizeof(action));
+       if (res > 0 || timeout_ms == 0)
+               return action;
+       FD_ZERO(&rfds);
+       FD_SET(fd, &rfds);
+       FD_ZERO(&efds);
+       FD_SET(fd, &efds);
+       res = select(fd + 1, &rfds, NULL, &efds, &timeout);
+       if (res < 0) {
+               log_err("fio: select() call in helper thread failed: %s",
+                       strerror(errno));
+               return A_EXIT;
+       }
+       if (FD_ISSET(fd, &rfds))
+               read_from_pipe(fd, &action, sizeof(action));
+       return action;
+}
+
 static unsigned int task_helper(struct timespec *last, struct timespec *now, unsigned int period, void do_task())
 {
        unsigned int next, since;
@@ -164,7 +196,6 @@ static void *helper_thread_main(void *data)
        unsigned int msec_to_next_event, next_log, next_si = status_interval;
        unsigned int next_ss = STEADYSTATE_MSEC;
        struct timespec ts, last_du, last_ss, last_si;
-       char action;
        int ret = 0;
 
        sk_out_assign(hd->sk_out);
@@ -182,26 +213,11 @@ static void *helper_thread_main(void *data)
        msec_to_next_event = DISK_UTIL_MSEC;
        while (!ret && !hd->exit) {
                uint64_t since_du;
-               struct timeval timeout = {
-                       .tv_sec  = msec_to_next_event / 1000,
-                       .tv_usec = (msec_to_next_event % 1000) * 1000,
-               };
-               fd_set rfds, efds;
-
-               if (read_from_pipe(hd->pipe[0], &action, sizeof(action)) < 0) {
-                       FD_ZERO(&rfds);
-                       FD_SET(hd->pipe[0], &rfds);
-                       FD_ZERO(&efds);
-                       FD_SET(hd->pipe[0], &efds);
-                       if (select(1, &rfds, NULL, &efds, &timeout) < 0) {
-                               log_err("fio: select() call in helper thread failed: %s",
-                                       strerror(errno));
-                               ret = 1;
-                       }
-                       if (read_from_pipe(hd->pipe[0], &action, sizeof(action)) <
-                           0)
-                               action = 0;
-               }
+               uint8_t action;
+
+               action = wait_for_action(hd->pipe[0], msec_to_next_event);
+               if (action == A_EXIT)
+                       break;
 
                fio_get_mono_time(&ts);