[elpa] externals/detached 8cbfca00bd 20/22: Improve support for multiple Emacs sessions

[ELPA Syncer]

branch: externals/detached
commit 8cbfca00bd9831378952dd936e05b59e54868ebd
Author: Niklas Eklund <niklas.eklund@posteo.net>
Commit: Niklas Eklund <niklas.eklund@posteo.net>

    Improve support for multiple Emacs sessions
---
 CHANGELOG.org |  1 +
 detached.el   | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 52 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.org b/CHANGELOG.org
index 08e37bbedf..28bfbf9d74 100644
--- a/CHANGELOG.org
+++ b/CHANGELOG.org
@@ -3,6 +3,7 @@
 #+language: en
 
 * Development
+- Improve support for Emacsen. The PID of all detached Emacsen are registered, 
this is done to be able to promote one Emacs to primary, which has the 
responsibility to update the database.
 - Add command to open a session's log file in =dired=.
 - Remove the need for =detached-shell-history-file=, the advice is updated to 
figure out the history file based on the shell program.
 - Remove the need for external =detached-env= script, the logic of the script 
is moved into the package instead.
diff --git a/detached.el b/detached.el
index 1f7b18bd47..deebce7329 100644
--- a/detached.el
+++ b/detached.el
@@ -701,6 +701,7 @@ Optionally SUPPRESS-OUTPUT."
     (unless (file-exists-p detached-db-directory)
       (make-directory detached-db-directory t))
     (detached--db-initialize)
+    (detached--register-detached-emacs )
     (setq detached--db-watch
       (file-notify-add-watch detached-db-directory
                              '(change attribute-change)
@@ -982,7 +983,7 @@ Optionally CONCAT the command return command into a string."
     (seq-reverse reverse-sessions)))
 
 (defun detached--decode-session (item)
-  "Return the session assicated with ITEM."
+  "Return the session associated with ITEM."
   (cdr (assoc item detached--session-candidates)))
 
 (defun detached--validate-unknown-sessions ()
@@ -1111,6 +1112,42 @@ Optionally make the path LOCAL to host."
       (insert (format ";; Detached Session Version: %s\n\n" 
detached-session-version))
       (prin1 detached--sessions (current-buffer)))))
 
+(defun detached--read-detached-emacsen ()
+  "Read the PIDs of detached Emacsen."
+  (let ((file (expand-file-name "detached-emacsen" detached-db-directory)))
+    (when (file-exists-p file)
+      (with-temp-buffer
+        (insert-file-contents file)
+        (cl-assert (bobp))
+        (read (current-buffer))))))
+
+(defun detached--register-detached-emacs ()
+  "Register Emacs PID."
+  (let* ((file (expand-file-name "detached-emacsen" detached-db-directory))
+         (emacsen
+          (seq-uniq (append (detached--read-detached-emacsen)
+                            `(,(emacs-pid))))))
+    (with-temp-file file
+      (insert (format ";; Detached Emacsen\n\n"))
+      (prin1 emacsen (current-buffer)))))
+
+(defun detached--primary-detached-emacs-p ()
+  "Return t if `(emacs-pid)' is the primary detached Emacs."
+  (let ((emacsen (detached--read-detached-emacsen))
+        (system-processes (list-system-processes)))
+    (thread-last emacsen
+                 (seq-find (lambda (emacs-pid) (member emacs-pid 
system-processes)))
+                 (= (emacs-pid)))))
+
+(defun detached--remove-detached-emacsen ()
+  "Remove terminated Emacsen from the list."
+  (let* ((system-processes (list-system-processes))
+         (emacses (thread-last (detached--read-detached-emacsen)
+                               (seq-filter (lambda (it) (member it 
system-processes))))))
+    (with-temp-file (expand-file-name "detached-emacsen" detached-db-directory)
+      (insert (format ";; Detached Emacsen\n\n"))
+      (prin1 emacses (current-buffer)))))
+
 ;;;;; Other
 
 (defun detached--dtach-arg ()
@@ -1254,11 +1291,14 @@ session and trigger a state transition."
                (string= "socket" (file-name-extension file)))
       (when-let* ((id (intern (file-name-base file)))
                   (session (detached--db-get-session id))
-                  (session-directory (detached--session-directory session)))
-
+                  (session-directory (detached--session-directory session))
+                  (is-primary (detached--primary-detached-emacs-p)))
         ;; Update session
         (detached--session-state-transition-update session)
 
+        ;; Update Emacsen
+        (detached--remove-detached-emacsen)
+
         ;; Remove session directory from `detached--watch-session-directory'
         ;; if there is no active session associated with the directory
         (unless
@@ -1282,7 +1322,14 @@ If event is cased by an update to the `detached' 
database, re-initialize
                                       (or (eq 'attribute-changed action)
                                           (eq 'changed action)))))
     (when database-updated
-      (detached--db-initialize))))
+      ;; Re-initialize the sessions
+      (detached--db-initialize)
+      ;; Make sure to watch session directories
+      (thread-last (detached--db-get-sessions)
+                   (seq-filter (lambda (it) (eq 'active 
(detached--session-state it))))
+                   (seq-map #'detached--session-directory)
+                   (seq-uniq)
+                   (seq-do #'detached--watch-session-directory)))))
 
 (defun detached--annotation-widths (sessions annotation-format)
   "Return widths for ANNOTATION-FORMAT based on SESSIONS."