gui: Don't sleep before executing the status command.

This results in uncacceptable delays when the status command fails
for any reason, for example because the server is down.

Replace this code by introducing a struct timeval variable "next_exec",
which stores the earliest possible time to restart the status command.

Move all status fetching code before the select() call in do_select()
to open_stat_pipe() and rename the function to status_pre_select(),
which is more appropriate.

diff --git a/configure.ac b/configure.ac
index 4512c6fd38f7209aad203c14cfe31dc66d4e1d56..35c9fd58d6073bdb68c2ee5723225973837480b1 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -153,7 +153,7 @@ client_errlist_objs="client net string fd sched stdin stdout time sideband
 client_ldflags=""
 
 gui_cmdline_objs="add_cmdline(gui)"
-gui_errlist_objs="exec signal string stat ringbuffer fd gui gui_theme"
+gui_errlist_objs="exec signal string stat ringbuffer fd gui gui_theme time"
 gui_objs="$gui_cmdline_objs $gui_errlist_objs"
 play_errlist_objs="play fd sched ggo buffer_tree time string net
        afh_recv afh_common

diff --git a/gui.c b/gui.c
index 6e44b09d37cc574846f1de0a4d325e586c69dad0..fb70dd830a2f6233b3a3463c3098656d7ed6fd64 100644 (file)
--- a/gui.c
+++ b/gui.c
@@ -10,6 +10,7 @@
 #include <signal.h>
 #include <sys/types.h>
 #include <curses.h>
+#include <sys/time.h>
 
 #include "gui.cmdline.h"
 #include "para.h"
@@ -930,30 +931,33 @@ static void handle_signal(int sig)
        }
 }
 
-static int open_stat_pipe(void)
+static void status_pre_select(fd_set *rfds, int *max_fileno, struct timeval *tv)
 {
-       static int init = 1;
+       static struct timeval next_exec, atm, diff;
        int ret, fds[3] = {0, 1, 0};
        pid_t pid;
 
-       if (init)
-               init = 0;
-       else
-               /*
-                * Sleep a bit to avoid a busy loop. As the call to sleep() may
-                * be interrupted by SIGCHLD, we simply wait until the call
-                * succeeds.
-                */
-               while (sleep(2))
-                       ; /* nothing */
+       if (stat_pipe >= 0)
+               goto success;
+       /* Avoid busy loop */
+       gettimeofday(&atm, NULL);
+       if (tv_diff(&next_exec, &atm, &diff) > 0) {
+               if (tv_diff(&diff, tv, NULL) < 0)
+                       *tv = diff;
+               return;
+       }
+       next_exec.tv_sec = atm.tv_sec + 2;
        ret = para_exec_cmdline_pid(&pid, conf.stat_cmd_arg, fds);
        if (ret < 0)
-               return ret;
+               return;
        ret = mark_fd_nonblocking(fds[1]);
-       if (ret >= 0)
-               return fds[1];
-       close(fds[1]);
-       return ret;
+       if (ret < 0) {
+               close(fds[1]);
+               return;
+       }
+       stat_pipe = fds[1];
+success:
+       para_fd_set(stat_pipe, rfds, max_fileno);
 }
 
 #define COMMAND_BUF_SIZE 32768
@@ -985,10 +989,7 @@ repeat:
 //     ret = refresh_status();
        FD_ZERO(&rfds);
        max_fileno = 0;
-       if (stat_pipe < 0)
-               stat_pipe = open_stat_pipe();
-       if (stat_pipe >= 0)
-               para_fd_set(stat_pipe, &rfds, &max_fileno);
+       status_pre_select(&rfds, &max_fileno, &tv);
        /* signal pipe */
        para_fd_set(signal_pipe, &rfds, &max_fileno);
        /* command pipe only for COMMAND_MODE */