mu4e: handle xapian single-threaded operation

Provide user feedback when we need to wait for the indexing to finish.

Suffix the version with "-st" when this is the case.

mu4e/meson.build

@@ -16,6 +16,11 @@
 
 
 # generate some build data for use in mu4e
+version_extra=''
+if get_option('xapian-single-threaded')
+  version_extra='-st'
+endif
+
 mu4e_meta = configure_file(
   input: 'mu4e-config.el.in',
   output: 'mu4e-config.el',
@@ -23,6 +28,7 @@ mu4e_meta = configure_file(
   install_dir: mu4e_lispdir,
   configuration: {
       'VERSION'           : meson.project_version(),
+      'MU_VERSION_EXTRA'  : version_extra,
       'MU_DOC_DIR'        : join_paths(datadir, 'doc', 'mu'),
     })
 

mu4e/mu4e-main.el

@@ -1,6 +1,6 @@
 ;;; mu4e-main.el --- The Main interface for mu4e -*- lexical-binding: t -*-
 
-;; Copyright (C) 2011-2023 Dirk-Jan C. Binnema
+;; Copyright (C) 2011-2024 Dirk-Jan C. Binnema
 
 ;; Author: Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
 ;; Maintainer: Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
@@ -299,7 +299,9 @@ Otherwise, do nothing."
          "* "
          (propertize "mu4e" 'face 'mu4e-header-key-face)
          (propertize " - mu for emacs version " 'face 'mu4e-title-face)
-         (propertize  mu4e-mu-version 'face 'mu4e-header-key-face)
+         (propertize  (concat mu4e-mu-version
+                              (if (mu4e--server-xapian-single-threaded-p) "-st" ""))
+                      'face 'mu4e-header-key-face)
          "\n\n"
          (propertize "  Basics\n\n" 'face 'mu4e-title-face)
          (mu4e--main-action

mu4e/mu4e-server.el

@@ -188,6 +188,11 @@ for bookmarks and maildirs.")
   "Get the latest server query items."
   mu4e--server-query-items)
 
+;; temporary
+(defun mu4e--server-xapian-single-threaded-p()
+  "Are we using Xapian in single-threaded mode?"
+  (plist-get mu4e--server-props :xapian-single-threaded))
+
 
 ;;; Handling raw server data
 
@@ -210,6 +215,9 @@ for bookmarks and maildirs.")
           mu4e--server-cookie-post)
   "Regular expression matching the length cookie.
 Match 1 will be the length (in hex).")
+
+(defvar mu4e--server-indexing nil "Currently indexing?")
+
 
 (defun mu4e-running-p ()
   "Whether mu4e is running.
@@ -383,6 +391,11 @@ The server output is as follows:
 
          ;; get some info
          ((plist-get sexp :info)
+          ;; when indexing is finished, remove the block
+          (when (and (eq (plist-get sexp :info) 'index)
+                     (eq (plist-get sexp :status) 'complete))
+            (setq mu4e--server-indexing nil))
+
           (funcall mu4e-info-func sexp))
 
          ;; get some data
@@ -486,6 +499,7 @@ You cannot run the repl when mu4e is running (or vice-versa)."
          (proc (and (buffer-live-p buf) (get-buffer-process buf))))
     (when proc
       (mu4e-message "shutting down")
+      (setq mu4e--server-indexing nil)
       (set-process-filter mu4e--server-process nil)
       (set-process-sentinel mu4e--server-process nil)
       (let ((delete-exited-processes t))
@@ -526,7 +540,11 @@ You cannot run the repl when mu4e is running (or vice-versa)."
 
 (defun mu4e--server-call-mu (form)
   "Call the mu server with some command FORM."
-  (unless (mu4e-running-p) (mu4e--server-start))
+  (unless (mu4e-running-p)
+    (mu4e--server-start))
+  ;; in single-threaded mode, mu can't accept our command right now.
+  (when (and (mu4e--server-xapian-single-threaded-p) mu4e--server-indexing)
+    (mu4e-warn "Cannot handle command while indexing, please retry later."))
   (let* ((print-length nil) (print-level nil)
          (cmd (format "%S" form)))
     (mu4e-log 'to-server "%s" cmd)
@@ -600,7 +618,8 @@ added or removed), since merely editing a message does not update
 the directory time stamp."
   (mu4e--server-call-mu
    `(index :cleanup ,(and cleanup t)
-           :lazy-check ,(and lazy-check t))))
+           :lazy-check ,(and lazy-check t)))
+  (setq mu4e--server-indexing t)) ;; remember we're indexing.
 
 (defun mu4e--server-mkdir (path &optional update)
   "Create a new maildir-directory at filesystem PATH.