From fcfd701f57fcb6e22162292df3ac61f89a29b5d1 Mon Sep 17 00:00:00 2001
From: Yuan Fu <casouri@gmail.com>
Date: Wed, 12 Dec 2018 01:58:56 -0500
Subject: [PATCH] Manager the global timer gracefully

Don't cancel and create new timers naively.
Only cancel timer (and set to nil) when there is no live buffer
with eldoc-box-hover-mode enabled;
and only create new timer when none exists.
---
 eldoc-box.el | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/eldoc-box.el b/eldoc-box.el
index f15ffe7..806d4d1 100644
--- a/eldoc-box.el
+++ b/eldoc-box.el
@@ -198,6 +198,16 @@ Checkout `lsp-ui-doc--make-frame', `lsp-ui-doc--move-frame'."
     (when (frame-parameter eldoc-box--frame 'visibility)
       (eldoc-box-quit-frame))))
 
+(defvar eldoc-box--enabled-buffer-list nil
+  "A list of buffers that enabled `eldoc-box-hover-mode'.")
+
+(defun eldoc-box--maybe-cancel-timer ()
+  "Cancel `eldoc-box--cleanup-timer' there is no live buffer with `eldoc-box-hover-mode' enabled left."
+  (when (and eldoc-box--cleanup-timer
+             (eq (cl-count-if #'buffer-live-p eldoc-box--enabled-buffer-list) 0))
+    (cancel-timer eldoc-box--cleanup-timer)
+    (setq eldoc-box--cleanup-timer nil)))
+
 (defun eldoc-box--eldoc-message-function (str &rest args)
   "Frontend for eldoc. Display STR in childframe and ARGS works like `message'."
   (if (stringp str)
@@ -215,10 +225,15 @@ Checkout `lsp-ui-doc--make-frame', `lsp-ui-doc--move-frame'."
         ;; Why a timer? ElDoc is mainly use in minibuffer,
         ;; where the text is constantly being flushed by other commands
         ;; so ElDoc doesn't try very hard to cleanup
-        (setq eldoc-box--cleanup-timer (run-with-idle-timer 1 t #'eldoc-box--maybe-cleanup))
+        (unless eldoc-box--cleanup-timer
+          (setq eldoc-box--cleanup-timer (run-with-idle-timer 1 t #'eldoc-box--maybe-cleanup)))
+        (add-to-list 'eldoc-box--enabled-buffer-list (current-buffer))
         (setq-local eldoc-message-function #'eldoc-box--eldoc-message-function))
     (setq-local eldoc-message-function #'eldoc-minibuffer-message)
-    (when eldoc-box--cleanup-timer (cancel-timer eldoc-box--cleanup-timer))
+    (delete (current-buffer) eldoc-box--enabled-buffer-list)
+    ;; this function has to be called after the current buffer is
+    ;; removed from buffer list
+    (eldoc-box--maybe-cancel-timer)
     ;; if minor mode is turned off when childframe is visible
     ;; hide it
     (eldoc-box-quit-frame)))