Improve prompts for reusing dead REPLs

CHANGELOG.md

@@ -2,9 +2,14 @@
 
 ## master (unreleased)
 
+### New features
+
+- [#3354](https://github.com/clojure-emacs/cider/issues/3354): Add new customization variable `cider-reuse-dead-repls` to control how dead REPL buffers are reused on new connections.
+
 ### Bugs fixed
 
 - [#3341](https://github.com/clojure-emacs/cider/issues/3341): Escape clojure-cli args on MS-Windows on non powershell invocations.
+- [#3353](https://github.com/clojure-emacs/cider/issues/3353): Fix regression which caused new connections to prompt for reusing dead REPLs.
 
 ## 1.7.0 (2023-03-23)
 

cider-connection.el

@@ -61,19 +61,40 @@ available) and the matching REPL buffer."
   :safe #'booleanp
   :package-version '(cider . "0.9.0"))
 
-;;;###autoload
 (defcustom cider-merge-sessions nil
   "Controls session combination behaviour.
 
 Symbol `host' combines all sessions of a project associated with the same host.
 Symbol `project' combines all sessions of a project.
 
 All other values do not combine any sessions."
-  :type 'symbol
+  :type '(choice (const :tag "Combine all sessions with the same host" host)
+                 (const :tag "Combine all sessions from the same project" project)
+                 (other :tag "Do not combine any sessions"))
   :group 'cider
   :safe #'symbolp
   :package-version '(cider . "1.5"))
 
+(defcustom cider-reuse-dead-repls 'prompt
+  "How to deal with existing dead REPL buffers when initializing a connection.
+
+Possible choices are `prompt', `auto', `any', and nil.
+- `prompt' means to always ask the user for a decision.
+- `auto' means to automatically reuse a dead REPL without prompting the user
+  if it is the only available option.  When there are multiple buffers to
+  choose from, the user is is prompted for a choice.
+- `any' (or any other non-nil value) means to reuse any dead REPL buffer
+  available, by default the most relevant according to various heuristics,
+  and never prompt the user.
+- nil means to start a new REPL each time, ignoring existing buffers."
+  :type '(choice (const :tag "Always prompt for what to do with dead REPLs" prompt)
+                 (const :tag "Reuse dead REPL, prompting only for multiple choice" auto)
+                 (const :tag "Reuse any available dead REPL and never prompt" any)
+                 (const :tag "Never reuse dead REPLs" nil))
+  :group 'cider
+  :safe #'symbolp
+  :package-version '(cider . "1.8"))
+
 (defconst cider-required-nrepl-version "0.6.0"
   "The minimum nREPL version that's known to work properly with CIDER.")
 
@@ -819,28 +840,27 @@ PARAMS is a plist as received by `cider-repl-create'."
     (let* ((proj-dir (plist-get params :project-dir))
            (host (plist-get params :host))
            (port (plist-get params :port))
-           (cljsp (eq (plist-get params :repl-type) 'cljs))
+           (type (plist-get params :repl-type))
            (scored-repls
-            (delq nil
-                  (mapcar (lambda (b)
-                            (let ((bparams (cider--gather-connect-params nil b)))
-                              (when (and cljsp
-                                         (eq (plist-get bparams :repl-type)
-                                             'cljs))
-                                (cons (buffer-name b)
-                                      (+
-                                       (if (equal proj-dir (plist-get bparams :project-dir)) 8 0)
-                                       (if (equal host (plist-get bparams :host)) 4 0)
-                                       (if (equal port (plist-get bparams :port)) 2 0))))))
-                          repls))))
-      (when scored-repls
-        (if (> (length scored-repls) 1)
-            (when (y-or-n-p "Dead REPLs exist.  Reuse? ")
-              (let ((sorted-repls (seq-sort (lambda (a b) (> (cdr a) (cdr b))) scored-repls)))
-                (get-buffer (completing-read "REPL to reuse: "
-                                             (mapcar #'car sorted-repls) nil t nil nil (caar sorted-repls)))))
-          (when (y-or-n-p (format "A dead REPL %s exists.  Reuse? " (caar scored-repls)))
-            (get-buffer (caar scored-repls))))))))
+            (mapcar (lambda (b)
+                      (let ((bparams (cider--gather-connect-params nil b)))
+                        (when (eq type (plist-get bparams :repl-type))
+                          (cons b (+
+                                   (if (equal proj-dir (plist-get bparams :project-dir)) 8 0)
+                                   (if (equal host (plist-get bparams :host)) 4 0)
+                                   (if (equal port (plist-get bparams :port)) 2 0))))))
+                    repls))
+           (sorted-repls (mapcar #'car (seq-sort-by #'cdr #'> (delq nil scored-repls)))))
+      (when sorted-repls
+        (cond ((eq 'any cider-reuse-dead-repls)
+               (car sorted-repls))
+              ((= 1 (length sorted-repls))
+               (when (or (eq 'auto cider-reuse-dead-repls)
+                         (y-or-n-p (format "A dead REPL %s exists.  Reuse buffer? " (car sorted-repls))))
+                 (car sorted-repls)))
+              ((y-or-n-p "Dead REPL buffers exist.  Select one to reuse? ")
+               (get-buffer (completing-read "REPL buffer to reuse: " (mapcar #'buffer-name sorted-repls)
+                                            nil t nil nil (car sorted-repls)))))))))
 
 (declare-function cider-default-err-handler "cider-eval")
 (declare-function cider-repl-mode "cider-repl")
@@ -858,7 +878,8 @@ function with the repl buffer set as current."
   ;; Connection might not have been set as yet. Please don't send requests in
   ;; this function, but use cider--connected-handler instead.
   (let ((buffer (or (plist-get params :repl-buffer)
-                    (cider--choose-reusable-repl-buffer params)
+                    (and cider-reuse-dead-repls
+                         (cider--choose-reusable-repl-buffer params))
                     (get-buffer-create (generate-new-buffer-name "*cider-uninitialized-repl*"))))
         (ses-name (or (plist-get params :session-name)
                       (cider-make-session-name params))))

doc/modules/ROOT/pages/usage/managing_connections.adoc

@@ -192,3 +192,18 @@ name and the REPL type specification post-fix
 You can customize session names with `cider-session-name-template` and REPL
 names with `nrepl-repl-buffer-name-template`. See also
 `cider-format-connection-params` for available formats.
+
+== Reusing dead REPLs
+
+Under normal circumstances, CIDER automatically kills the REPL buffers and cleans up after itself when ending a session.
+However, when a session is terminated unexpectedly, e.g. when it crashes or is disconnected from an external server process, the REPL buffer is left without an active connection and outputs a log:
+
+[source]
+----
+*** Closed on < date/time > ***
+----
+
+Upon starting a new connection, CIDER can detect these "dead REPLs" and offer to reuse the buffer for the new connection.
+By default, it prompts for confirmation whenever a dead REPL buffer is available for reuse, but you can customize this behaviour via the variable `cider-reuse-dead-repls`.
+Setting it to `auto` reuses a dead REPL buffer automatically, and only displays a prompt when there are multiple options to choose from.
+To suppress the prompt entirely, set it to `nil` to always start a new REPL buffer, or `any` to reuse the most relevant dead REPL.