Hi

What is this useful for?

This seems like a job for hooks if they are ever finished.


On Mon, Aug 04, 2014 at 01:59:26PM -0400, Nathaniel W Filardo wrote:
> Greetings list,
> 
> The attached patch adds options to new-window, new-session, and split-window
> (commands which create panes) to signal a wait_channel when that pane is
> destroyed, for example after the contained process exits.  Towards this end,
> it changes the life-cycle management code in cmd-wait-for.c to allow
> external holds on a wait_channel structure; these are only taken, at the
> moment, by the aforementioned commands.
> 
> It's something of an afternoon hack-job, so it might not be ideal.
> Comments and criticisms welcome; rotten tomatoes possibly understood but
> less welcome. ;)
> 
> Cheers!
> --nwf;

> diff --git a/cmd-new-session.c b/cmd-new-session.c
> index b36de70..4cf72fc 100644
> --- a/cmd-new-session.c
> +++ b/cmd-new-session.c
> @@ -38,7 +38,7 @@ const struct cmd_entry cmd_new_session_entry = {
>       "Ac:dDF:n:Ps:t:x:y:", 0, -1,
>       "[-AdDP] [-c start-directory] [-F format] [-n window-name] "
>       "[-s session-name] " CMD_TARGET_SESSION_USAGE " [-x width] "
> -     "[-y height] [command]",
> +     "[-y height] [-W channel] [command]",
>       CMD_STARTSERVER|CMD_CANTNEST,
>       NULL,
>       cmd_new_session_exec
> @@ -61,6 +61,7 @@ cmd_new_session_exec(struct cmd *self, struct cmd_q *cmdq)
>       u_int                    sx, sy;
>       struct format_tree      *ft;
>       struct environ_entry    *envent;
> +     struct wait_channel *wc = NULL;
>  
>       if (args_has(args, 't') && (args->argc != 0 || args_has(args, 'n'))) {
>               cmdq_error(cmdq, "command or window name given with target");
> @@ -214,10 +215,13 @@ cmd_new_session_exec(struct cmd *self, struct cmd_q 
> *cmdq)
>       if (c != NULL)
>               environ_update(update, &c->environ, &env);
>  
> +     if (args_has(args, 'W'))
> +             wc = wait_channel_hold_by_name(args_get(args,'W'));
> +
>       /* Create the new session. */
>       idx = -1 - options_get_number(&global_s_options, "base-index");
>       s = session_create(newname, argc, argv, path, cwd, &env, tiop, idx, sx,
> -         sy, &cause);
> +         sy, wc, &cause);
>       if (s == NULL) {
>               cmdq_error(cmdq, "create session failed: %s", cause);
>               free(cause);
> diff --git a/cmd-new-window.c b/cmd-new-window.c
> index cd0042e..d5987e8 100644
> --- a/cmd-new-window.c
> +++ b/cmd-new-window.c
> @@ -34,8 +34,8 @@ enum cmd_retval     cmd_new_window_exec(struct cmd *, 
> struct cmd_q *);
>  
>  const struct cmd_entry cmd_new_window_entry = {
>       "new-window", "neww",
> -     "ac:dF:kn:Pt:", 0, -1,
> -     "[-adkP] [-c start-directory] [-F format] [-n window-name] "
> +     "ac:dF:kn:Pt:W:", 0, -1,
> +     "[-adkP] [-c start-directory] [-F format] [-n window-name] [-W channel]"
>       CMD_TARGET_WINDOW_USAGE " [command]",
>       0,
>       NULL,
> @@ -54,6 +54,7 @@ cmd_new_window_exec(struct cmd *self, struct cmd_q *cmdq)
>       int                      argc, idx, last, detached, cwd, fd = -1;
>       struct format_tree      *ft;
>       struct environ_entry    *envent;
> +     struct wait_channel *wc = NULL;
>  
>       if (args_has(args, 'a')) {
>               wl = cmd_find_window(cmdq, args_get(args, 't'), &s);
> @@ -152,10 +153,13 @@ cmd_new_window_exec(struct cmd *self, struct cmd_q 
> *cmdq)
>               }
>       }
>  
> +     if (args_has(args, 'W'))
> +             wc = wait_channel_hold_by_name(args_get(args, 'W'));
> +
>       if (idx == -1)
>               idx = -1 - options_get_number(&s->options, "base-index");
>       wl = session_new(s, args_get(args, 'n'), argc, argv, path, cwd, idx,
> -             &cause);
> +             wc, &cause);
>       if (wl == NULL) {
>               cmdq_error(cmdq, "create window failed: %s", cause);
>               free(cause);
> diff --git a/cmd-split-window.c b/cmd-split-window.c
> index ea047a3..9a4fc15 100644
> --- a/cmd-split-window.c
> +++ b/cmd-split-window.c
> @@ -37,6 +37,7 @@ const struct cmd_entry cmd_split_window_entry = {
>       "split-window", "splitw",
>       "c:dF:l:hp:Pt:v", 0, -1,
>       "[-dhvP] [-c start-directory] [-F format] [-p percentage|-l size] "
> +     "[-W channel] "
>       CMD_TARGET_PANE_USAGE " [command]",
>       0,
>       cmd_split_window_key_binding,
> @@ -158,6 +159,10 @@ cmd_split_window_exec(struct cmd *self, struct cmd_q 
> *cmdq)
>       }
>       new_wp = window_add_pane(w, hlimit);
>  
> +     if (args_has(args, 'W'))
> +             new_wp->signal_on_destroy =
> +                     wait_channel_hold_by_name(args_get(args, 'W'));
> +
>       path = NULL;
>       if (cmdq->client != NULL && cmdq->client->session == NULL)
>               envent = environ_find(&cmdq->client->environ, "PATH");
> diff --git a/cmd-wait-for.c b/cmd-wait-for.c
> index e251863..f0dd92b 100644
> --- a/cmd-wait-for.c
> +++ b/cmd-wait-for.c
> @@ -43,6 +43,7 @@ struct wait_channel {
>       const char             *name;
>       int                     locked;
>  
> +     u_int                   holds;
>       TAILQ_HEAD(, cmd_q)     waiters;
>       TAILQ_HEAD(, cmd_q)     lockers;
>  
> @@ -70,6 +71,70 @@ enum cmd_retval    cmd_wait_for_lock(struct cmd_q *, const 
> char *,
>  enum cmd_retval      cmd_wait_for_unlock(struct cmd_q *, const char *,
>                   struct wait_channel *);
>  
> +static struct wait_channel *
> +wait_channel_find_by_name(const char *name) {
> +     struct wait_channel     wc0;
> +
> +     wc0.name = name;
> +     return RB_FIND(wait_channels, &wait_channels, &wc0);
> +}
> +
> +static struct wait_channel *
> +wait_channel_alloc(const char *name) {
> +     struct wait_channel *wc = xmalloc(sizeof *wc);
> +     wc->name = xstrdup(name);
> +     wc->locked = 0;
> +     TAILQ_INIT(&wc->waiters);
> +     TAILQ_INIT(&wc->lockers);
> +     RB_INSERT(wait_channels, &wait_channels, wc);
> +
> +     return wc;
> +}
> +
> +static void
> +wait_channel_try_free(struct wait_channel *wc) {
> +     if (wc->holds > 0)
> +             return;
> +
> +     if (!TAILQ_EMPTY(&wc->waiters))
> +             return;
> +
> +     if (!TAILQ_EMPTY(&wc->lockers)) {
> +             /* Should we assert that wc->locked == 1 ? */
> +             return;
> +     }
> +
> +     /* All references to this wait_channel are gone */
> +     RB_REMOVE(wait_channels, &wait_channels, wc);
> +     free((void*) wc->name);
> +     free(wc);
> +}
> +
> +static void
> +wait_channel_hold(struct wait_channel *wc) {
> +     wc->holds++;
> +}
> +
> +struct wait_channel *
> +wait_channel_hold_by_name(const char *name) {
> +     struct wait_channel *wc = wait_channel_find_by_name(name);
> +
> +     if(!wc)
> +             wc = wait_channel_alloc(name);
> +
> +     wait_channel_hold(wc);
> +
> +     return wc;
> +}
> +
> +void
> +wait_channel_unhold(struct wait_channel *wc) {
> +     if(--wc->holds != 0)
> +             return;
> +
> +     wait_channel_try_free(wc);
> +}
> +
>  enum cmd_retval
>  cmd_wait_for_exec(struct cmd *self, struct cmd_q *cmdq)
>  {
> @@ -89,28 +154,29 @@ cmd_wait_for_exec(struct cmd *self, struct cmd_q *cmdq)
>       return (cmd_wait_for_wait(cmdq, name, wc));
>  }
>  
> +void
> +wait_channel_signal(struct wait_channel *wc) {
> +     struct cmd_q    *wq, *wq1;
> +
> +     TAILQ_FOREACH_SAFE(wq, &wc->waiters, waitentry, wq1) {
> +             TAILQ_REMOVE(&wc->waiters, wq, waitentry);
> +             if (!cmdq_free(wq))
> +                     cmdq_continue(wq);
> +     }
> +}
> +
>  enum cmd_retval
>  cmd_wait_for_signal(struct cmd_q *cmdq, const char *name,
>      struct wait_channel *wc)
>  {
> -     struct cmd_q    *wq, *wq1;
> -
>       if (wc == NULL || TAILQ_EMPTY(&wc->waiters)) {
>               cmdq_error(cmdq, "no waiting clients on %s", name);
>               return (CMD_RETURN_ERROR);
>       }
>  
> -     TAILQ_FOREACH_SAFE(wq, &wc->waiters, waitentry, wq1) {
> -             TAILQ_REMOVE(&wc->waiters, wq, waitentry);
> -             if (!cmdq_free(wq))
> -                     cmdq_continue(wq);
> -     }
> +     wait_channel_signal(wc);
>  
> -     if (!wc->locked) {
> -             RB_REMOVE(wait_channels, &wait_channels, wc);
> -             free((void*) wc->name);
> -             free(wc);
> -     }
> +     wait_channel_try_free(wc);
>  
>       return (CMD_RETURN_NORMAL);
>  }
> @@ -124,14 +190,8 @@ cmd_wait_for_wait(struct cmd_q *cmdq, const char *name,
>               return (CMD_RETURN_ERROR);
>       }
>  
> -     if (wc == NULL) {
> -             wc = xmalloc(sizeof *wc);
> -             wc->name = xstrdup(name);
> -             wc->locked = 0;
> -             TAILQ_INIT(&wc->waiters);
> -             TAILQ_INIT(&wc->lockers);
> -             RB_INSERT(wait_channels, &wait_channels, wc);
> -     }
> +     if (wc == NULL)
> +             wc = wait_channel_alloc(name);
>  
>       TAILQ_INSERT_TAIL(&wc->waiters, cmdq, waitentry);
>       cmdq->references++;
> @@ -184,11 +244,7 @@ cmd_wait_for_unlock(struct cmd_q *cmdq, const char *name,
>                       cmdq_continue(wq);
>       } else {
>               wc->locked = 0;
> -             if (TAILQ_EMPTY(&wc->waiters)) {
> -                     RB_REMOVE(wait_channels, &wait_channels, wc);
> -                     free((void*) wc->name);
> -                     free(wc);
> -             }
> +             wait_channel_try_free(wc);
>       }
>  
>       return (CMD_RETURN_NORMAL);
> diff --git a/session.c b/session.c
> index 2bcb1b9..bd50021 100644
> --- a/session.c
> +++ b/session.c
> @@ -86,7 +86,7 @@ session_find_by_id(u_int id)
>  struct session *
>  session_create(const char *name, int argc, char **argv, const char *path,
>      int cwd, struct environ *env, struct termios *tio, int idx, u_int sx,
> -    u_int sy, char **cause)
> +    u_int sy, struct wait_channel *wc, char **cause)
>  {
>       struct session  *s;
>       struct winlink  *wl;
> @@ -133,7 +133,7 @@ session_create(const char *name, int argc, char **argv, 
> const char *path,
>       RB_INSERT(sessions, &sessions, s);
>  
>       if (argc >= 0) {
> -             wl = session_new(s, NULL, argc, argv, path, cwd, idx, cause);
> +             wl = session_new(s, NULL, argc, argv, path, cwd, idx, wc, 
> cause);
>               if (wl == NULL) {
>                       session_destroy(s);
>                       return (NULL);
> @@ -229,7 +229,7 @@ session_previous_session(struct session *s)
>  /* Create a new window on a session. */
>  struct winlink *
>  session_new(struct session *s, const char *name, int argc, char **argv,
> -    const char *path, int cwd, int idx, char **cause)
> +    const char *path, int cwd, int idx, struct wait_channel *wc, char 
> **cause)
>  {
>       struct window   *w;
>       struct winlink  *wl;
> @@ -253,7 +253,7 @@ session_new(struct session *s, const char *name, int 
> argc, char **argv,
>  
>       hlimit = options_get_number(&s->options, "history-limit");
>       w = window_create(name, argc, argv, path, shell, cwd, &env, s->tio,
> -         s->sx, s->sy, hlimit, cause);
> +         s->sx, s->sy, hlimit, wc, cause);
>       if (w == NULL) {
>               winlink_remove(&s->windows, wl);
>               environ_free(&env);
> diff --git a/tmux.1 b/tmux.1
> index 924157d..1b51cb9 100644
> --- a/tmux.1
> +++ b/tmux.1
> @@ -709,6 +709,7 @@ Lock all clients attached to
>  .Op Fl t Ar target-session
>  .Op Fl x Ar width
>  .Op Fl y Ar height
> +.Op Fl W Ar channel
>  .Op Ar shell-command
>  .Xc
>  .D1 (alias: Ic new )
> @@ -776,6 +777,15 @@ By default, it uses the format
>  .Ql #{session_name}:
>  but a different format may be specified with
>  .Fl F .
> +.Pp
> +The
> +.Fl W
> +option specifies a channel name which will be signaled when the created pane
> +is destroyed.  Clients may use the
> +.Ic wait-for
> +command to suspend until this happens.
> +.Ic new-session
> +does not lock the channel.
>  .It Xo Ic refresh-client
>  .Op Fl S
>  .Op Fl t Ar target-client
> @@ -1498,6 +1508,7 @@ option.
>  .Op Fl F Ar format
>  .Op Fl n Ar window-name
>  .Op Fl t Ar target-window
> +.Op Fl W Ar channel
>  .Op Ar shell-command
>  .Xc
>  .D1 (alias: Ic neww )
> @@ -1553,6 +1564,15 @@ By default, it uses the format
>  .Ql #{session_name}:#{window_index}
>  but a different format may be specified with
>  .Fl F .
> +.Pp
> +The
> +.Fl W
> +option specifies a channel name which will be signaled when the created pane
> +is destroyed.  Clients may use the
> +.Ic wait-for
> +command to suspend until this happens.
> +.Ic new-window
> +does not lock the channel.
>  .It Ic next-layout Op Fl t Ar target-window
>  .D1 (alias: Ic nextl )
>  Move a window to the next layout and rearrange the panes to fit.
> @@ -1754,6 +1774,7 @@ the command behaves like
>  .Ar size |
>  .Fl p Ar percentage Oc
>  .Op Fl t Ar target-pane
> +.Op Fl W Ar channel
>  .Op Ar shell-command
>  .Op Fl F Ar format
>  .Xc
> diff --git a/tmux.h b/tmux.h
> index c4c5236..2c51baa 100644
> --- a/tmux.h
> +++ b/tmux.h
> @@ -954,6 +954,8 @@ struct window_pane {
>  
>       TAILQ_ENTRY(window_pane) entry;
>       RB_ENTRY(window_pane) tree_entry;
> +
> +     struct wait_channel *signal_on_destroy;
>  };
>  TAILQ_HEAD(window_panes, window_pane);
>  RB_HEAD(window_pane_tree, window_pane);
> @@ -1884,6 +1886,11 @@ void            cmdq_flush(struct cmd_q *);
>  int  cmd_string_parse(const char *, struct cmd_list **, const char *,
>           u_int, char **);
>  
> +/* cmd-wait-for.c */
> +struct wait_channel *wait_channel_hold_by_name(const char *);
> +void wait_channel_signal(struct wait_channel *);
> +void wait_channel_unhold(struct wait_channel *);
> +
>  /* client.c */
>  int  client_main(int, char **, int);
>  
> @@ -2148,7 +2155,7 @@ struct window   *window_find_by_id(u_int);
>  struct window        *window_create1(u_int, u_int);
>  struct window        *window_create(const char *, int, char **, const char *,
>                    const char *, int, struct environ *, struct termios *,
> -                  u_int, u_int, u_int, char **);
> +                  u_int, u_int, u_int, struct wait_channel *, char **);
>  void          window_destroy(struct window *);
>  struct window_pane *window_get_active_at(struct window *, u_int, u_int);
>  void          window_set_active_at(struct window *, u_int, u_int);
> @@ -2312,14 +2319,14 @@ struct session        *session_find(const char *);
>  struct session       *session_find_by_id(u_int);
>  struct session       *session_create(const char *, int, char **, const char 
> *,
>                    int, struct environ *, struct termios *, int, u_int,
> -                  u_int, char **);
> +                  u_int, struct wait_channel *, char **);
>  void          session_destroy(struct session *);
>  int           session_check_name(const char *);
>  void          session_update_activity(struct session *);
>  struct session       *session_next_session(struct session *);
>  struct session       *session_previous_session(struct session *);
>  struct winlink       *session_new(struct session *, const char *, int, char 
> **,
> -                  const char *, int, int, char **);
> +                  const char *, int, int, struct wait_channel *, char **);
>  struct winlink       *session_attach(struct session *, struct window *, int,
>                    char **);
>  int           session_detach(struct session *, struct winlink *);
> diff --git a/window.c b/window.c
> index 5b93f93..eecacd9 100644
> --- a/window.c
> +++ b/window.c
> @@ -308,13 +308,14 @@ window_create1(u_int sx, u_int sy)
>  struct window *
>  window_create(const char *name, int argc, char **argv, const char *path,
>      const char *shell, int cwd, struct environ *env, struct termios *tio,
> -    u_int sx, u_int sy, u_int hlimit, char **cause)
> +    u_int sx, u_int sy, u_int hlimit, struct wait_channel *wc, char **cause)
>  {
>       struct window           *w;
>       struct window_pane      *wp;
>  
>       w = window_create1(sx, sy);
>       wp = window_add_pane(w, hlimit);
> +    wp->signal_on_destroy = wc;
>       layout_init(w, wp);
>  
>       if (window_pane_spawn(wp, argc, argv, path, shell, cwd, env, tio,
> @@ -712,6 +713,12 @@ window_pane_create(struct window *w, u_int sx, u_int sy, 
> u_int hlimit)
>  void
>  window_pane_destroy(struct window_pane *wp)
>  {
> +     if(wp->signal_on_destroy) {
> +             wait_channel_signal(wp->signal_on_destroy);
> +             wait_channel_unhold(wp->signal_on_destroy);
> +             wp->signal_on_destroy = NULL;
> +     }
> +
>       window_pane_reset_mode(wp);
>  
>       if (event_initialized(&wp->changes_timer))




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Build a bridge from your legacy apps to the future.
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