[screen-devel] screen: Implement dead/zombie window polling

[Thomas Renninger]

Hello,

please CC me in the answer, as I am not subscribed on this list.

I based the patch on a screen-4.0.4 tarball with some additional
dist patches on top.
Please tell me if and against which version/repository I should
update the patch if needed.

If the patch is acceptable it would be great if it gets applied
to the latest mainline repo/tarball.

Thanks,

   Thomas


screen: Implement dead/zombie window polling

Currently if zombie keys are defined, one needs to explicitly
hit a key to tell screen to try to reconnect a window.
This is rather unfortunte if you for example have dozens of screens
connected to foreign machines through network connections.
Once the network connection is cut for a while, all windows will
enter the dead/zombie state and one has to go through all windows
manually and hit the zombie resurrect key, once the network got
set up again.

This patch implements auto-reconnecting via zombie_timeout
(in seconds) variable. By default it is set to 0 which complies
to current behavior (no polling is done).

Signed-off-by: Thomas Renninger <address@hidden>

---
 comm.c             |    3 ++-
 comm.h.dist        |    3 ++-
 doc/screen.1       |    9 +++++++++
 doc/screen.texinfo |    9 +++++++++
 process.c          |   12 ++++++++++++
 screen.c           |    7 +++++++
 window.c           |   29 ++++++++++++++++++++++++++++-
 window.h           |    3 +++
 8 files changed, 72 insertions(+), 3 deletions(-)

Index: screen-4.0.4/comm.c
===================================================================
--- screen-4.0.4.orig/comm.c
+++ screen-4.0.4/comm.c
@@ -339,5 +339,6 @@ struct comm comms[RC_LAST + 1] =
 #ifdef ZMODEM
   { "zmodem",          ARGS_012 },
 #endif
-  { "zombie",          ARGS_012 }
+  { "zombie",          ARGS_012 },
+  { "zombie_timeout", ARGS_1 }
 };
Index: screen-4.0.4/doc/screen.1
===================================================================
--- screen-4.0.4.orig/doc/screen.1
+++ screen-4.0.4/doc/screen.1
@@ -3545,6 +3545,15 @@ Optionally you can put the word \*Qonerr
 to monitor exit status of the process running in the window. If it exits 
normally ('0'), 
 the window disappears. Any other exit value causes the window to become a 
zombie.
 
+.BR "zombie_timeout" [\fIseconds\fP]
+.PP
+Per default
+.I screen
+windows are removed from the window list as soon as
+the windows process (e.g. shell) exits. If \fBzombie\fP keys are defined
+(compare with above \fBzombie\fP command), it is possible to also set a
+timeout when screen tries to automatically reconnect a dead screen window.
+
 .SH "THE MESSAGE LINE"
 .I Screen
 displays informational messages and other diagnostics in a \fImessage line\fP.
Index: screen-4.0.4/doc/screen.texinfo
===================================================================
--- screen-4.0.4.orig/doc/screen.texinfo
+++ screen-4.0.4/doc/screen.texinfo
@@ -1238,6 +1238,8 @@ Send an XON character.  @xref{XON/XOFF}.
 Define how screen treats zmodem requests.  @xref{Zmodem}.
 @item zombie address@hidden [onerror] ]
 Keep dead windows.  @xref{Zombie}.
address@hidden zombie_timeout address@hidden
+Try to reconnect dead windows after timeout.  @xref{Zombie}.
 @end table
 
 @node New Window, Selecting, Commands, Top
@@ -5222,6 +5224,8 @@ Display the version and modification dat
 @section Zombie
 @deffn Command zombie address@hidden [onerror] ]
 @deffnx Command defzombie address@hidden
address@hidden Command zombie_timeout address@hidden
address@hidden deffn
 (none)@*
 Per default windows are removed from the window list as soon as the
 windows process (e.g. shell) exits. When a string of two keys is
@@ -5241,6 +5245,11 @@ Optionally you can put the word @code{on
 cause screen to monitor exit status of the process running in the window.
 If it exits normally ('0'), the window disappears. Any other exit value
 causes the window to become a zombie.
+
+Additionally the @code{zombie_timeout} command exists.
+If a window is declared ``dead'', screen will automatically try to
+resurrect the window after the timeout.
+It only works if zombie keys are defined via @code{zombie} command.
 @end deffn
 
 @node Printcmd, Rendition, Zombie, Miscellaneous
Index: screen-4.0.4/process.c
===================================================================
--- screen-4.0.4.orig/process.c
+++ screen-4.0.4/process.c
@@ -3067,6 +3067,18 @@ int key;
        }
       WindowChanged((struct win *)0, 0);
       break;
+    case RC_ZOMBIE_TIMEOUT:
+      if (argc != 1)
+       {
+         Msg(0, "Setting zombie polling needs a timeout arg\n");
+         break;
+       }
+      nwin_default.poll_zombie_timeout = atoi(args[0]);
+      if (fore)
+         fore->w_poll_zombie_timeout = nwin_default.poll_zombie_timeout;
+
+      debug1("Setting zombie polling to %d\n", 
nwin_default.poll_zombie_timeout);
+      break;
     case RC_SILENCE:
       n = fore->w_silence != 0;
       i = fore->w_silencewait;
Index: screen-4.0.4/screen.c
===================================================================
--- screen-4.0.4.orig/screen.c
+++ screen-4.0.4/screen.c
@@ -1557,6 +1557,13 @@ int wstat_valid;
       p->w_y = MFindUsedLine(p, p->w_bot, 1);
       sprintf(buf, "\n\r=== Command %s (%s) ===", reason, s ? s : "?");
       WriteString(p, buf, strlen(buf));
+      if (p->w_poll_zombie_timeout)
+       {
+         debug2("Set zombie poll timeout for window %s to %d\n", p->w_title,
+                p->w_poll_zombie_timeout);
+         SetTimeout(&p->w_zombieev, p->w_poll_zombie_timeout * 1000);
+         evenq(&p->w_zombieev);
+       }
       WindowChanged(p, 'f');
     }
   else
Index: screen-4.0.4/window.c
===================================================================
--- screen-4.0.4.orig/window.c
+++ screen-4.0.4/window.c
@@ -87,6 +87,7 @@ static int  DoAutolf __P((char *, int *,
 static void ZombieProcess __P((char **, int *));
 static void win_readev_fn __P((struct event *, char *));
 static void win_writeev_fn __P((struct event *, char *));
+static void win_resurrect_zombie_fn __P((struct event *, char *));
 static int  muchpending __P((struct win *, struct event *));
 #ifdef COPY_PASTE
 static void paste_slowev_fn __P((struct event *, char *));
@@ -164,7 +165,8 @@ struct NewWindow nwin_default =
   0,           /* bce */
   0,           /* encoding */
   (char *)0,   /* hstatus */
-  (char *)0    /* charset */
+  (char *)0,   /* charset */
+  0            /* poll_zombie_timeout */
 };
 
 struct NewWindow nwin_options;
@@ -198,6 +200,7 @@ struct NewWindow *def, *new, *res;
   COMPOSE(encoding);
   COMPOSE(hstatus);
   COMPOSE(charset);
+  COMPOSE(poll_zombie_timeout);
 #undef COMPOSE
 }
 
@@ -838,6 +841,14 @@ struct NewWindow *newwin;
       DoStartLog(p, buf, sizeof(buf));
     }
 
+  /* Is this all where I have to init window poll timeout? */
+  if (nwin.poll_zombie_timeout)
+    p->w_poll_zombie_timeout = nwin.poll_zombie_timeout;
+
+  p->w_zombieev.type = EV_TIMEOUT;
+  p->w_zombieev.data = (char *)p;
+  p->w_zombieev.handler = win_resurrect_zombie_fn;
+
   p->w_readev.fd = p->w_writeev.fd = p->w_ptyfd;
   p->w_readev.type = EV_READ;
   p->w_writeev.type = EV_WRITE;
@@ -1060,6 +1071,7 @@ struct win *wp;
   evdeq(&wp->w_readev);                /* just in case */
   evdeq(&wp->w_writeev);       /* just in case */
   evdeq(&wp->w_silenceev);
+  evdeq(&wp->w_zombieev);
   evdeq(&wp->w_destroyev);
 #ifdef COPY_PASTE
   FreePaster(&wp->w_paster);
@@ -1941,6 +1953,21 @@ char *data;
   return;
 }
 
+static void
+win_resurrect_zombie_fn(ev, data)
+struct event *ev;
+char *data;
+{
+  struct win *p = (struct win *)data;
+  debug2("Try to resurrecting Zombie event: %d [%s]\n",
+        p->w_number, p->w_title);
+  /* Already reconnected? */
+  if (p->w_deadpid != p->w_pid)
+         return;
+  debug1("Resurrecting Zombie: %d\n", p->w_number);
+  WriteString(p, "\r\n", 2);
+  RemakeWindow(p);
+}
 
 static void
 win_writeev_fn(ev, data)
Index: screen-4.0.4/window.h
===================================================================
--- screen-4.0.4.orig/window.h
+++ screen-4.0.4/window.h
@@ -57,6 +57,7 @@ struct NewWindow
   int   encoding;
   char *hstatus;
   char *charset;
+  int  poll_zombie_timeout;
 };
 
 #ifdef PSEUDOS
@@ -150,6 +151,8 @@ struct win
   struct event w_readev;
   struct event w_writeev;
   struct event w_silenceev;    /* silence event */
+  struct event w_zombieev;     /* event to try to resurrect window */
+  int   w_poll_zombie_timeout;
   int   w_ptyfd;               /* fd of the master pty */
   char  w_inbuf[IOSIZE];
   int   w_inlen;

screen-poll-zombies.patch
Description: Text Data