[PATCH] Allow ERC to re-connect in the background properly

[Victor Orlikowski]

In my experience, the existing code for re-connecting to a
disconnected server forces ERC into the foreground.

The following patch changes ERC so that reconnection attempts
proceed in the background, without interrupting the user's workflow.

>From 7a64c15406225a14dca6863342da3d90569baf49 Mon Sep 17 00:00:00 2001
From: "Victor J. Orlikowski" <address@hidden>
Date: Sun, 3 Feb 2019 12:32:12 -0500
Subject: [PATCH] Handle reconnection attempts in the background, rather than
 forcing to the foreground.

---
 lisp/erc/erc-backend.el | 38 +++++++++++++++++++++-----------------
 1 file changed, 21 insertions(+), 17 deletions(-)

diff --git a/lisp/erc/erc-backend.el b/lisp/erc/erc-backend.el
index 2fd3d454bf..57f34073be 100644
--- a/lisp/erc/erc-backend.el
+++ b/lisp/erc/erc-backend.el
@@ -613,11 +613,6 @@ Make sure you are in an ERC buffer when running this."
         (erc-open erc-session-server erc-session-port erc-server-current-nick
                   erc-session-user-full-name t erc-session-password)))))
 
-(defun erc-server-delayed-reconnect (buffer)
-  (if (buffer-live-p buffer)
-    (with-current-buffer buffer
-      (erc-server-reconnect))))
-
 (defun erc-server-filter-function (process string)
   "The process filter for the ERC server."
   (with-current-buffer (process-buffer process)
@@ -667,6 +662,25 @@ EVENT is the message received from the closed connection 
process."
               ;; open-network-stream-nowait error for connection refused
               (if (string-match "^failed with code 111" ,event) 'nonblocking 
t))))))
 
+(defun erc-server-background-reconnect (buffer)
+  (let ((process nil))
+    (condition-case err
+        (progn
+          (setq erc-server-reconnecting nil
+                erc-server-reconnect-count (1+ erc-server-reconnect-count))
+          (if (buffer-live-p buffer)
+              (with-current-buffer buffer
+                (setq process (get-buffer-process (erc-server-buffer)))
+                (erc-server-reconnect))))
+      (error (unless (integerp erc-server-reconnect-attempts)
+               (message "%s ... %s"
+                        "Reconnecting until we succeed"
+                        "kill the ERC server buffer to stop"))
+             (run-at-time erc-server-reconnect-timeout nil
+                          #'erc-server-background-reconnect buffer)))
+    (if process
+        (delete-process process))))
+
 (defun erc-process-sentinel-2 (event buffer)
   "Called when `erc-process-sentinel-1' has detected an unexpected disconnect."
   (if (not (buffer-live-p buffer))
@@ -684,18 +698,8 @@ EVENT is the message received from the closed connection 
process."
               (erc-update-mode-line)
               (set-buffer-modified-p nil))
           ;; reconnect
-          (condition-case nil
-              (progn
-                (setq erc-server-reconnecting   nil
-                      erc-server-reconnect-count (1+ 
erc-server-reconnect-count))
-                (setq delay erc-server-reconnect-timeout)
-                (run-at-time delay nil
-                             #'erc-server-delayed-reconnect buffer))
-            (error (unless (integerp erc-server-reconnect-attempts)
-                     (message "%s ... %s"
-                              "Reconnecting until we succeed"
-                              "kill the ERC server buffer to stop"))
-                   (erc-server-delayed-reconnect buffer))))))))
+          (run-at-time erc-server-reconnect-timeout nil
+                       #'erc-server-background-reconnect buffer))))))
 
 (defun erc-process-sentinel-1 (event buffer)
   "Called when `erc-process-sentinel' has decided that we're disconnecting.

Best,
Victor
-- 
Victor J. Orlikowski <> vjo@(ee.|cs.)?duke.edu