[clojure-emacs/cider#2281] Cache the results of clojure-project-dir

Author: bbatsov

CHANGELOG.md

@@ -2,7 +2,10 @@
 
 ## master (unreleased)
 
+### Changes
+
 * Indent `fdef` (clojure.spec) like a `def`.
+* The results of `clojure-project-dir` are cached by default to optimize performance.
 
 ## 5.7.0 (2018-04-29)
 

clojure-mode.el

@@ -1629,12 +1629,30 @@ nil."
 
 
 
+(defcustom clojure-cache-project-dir t
+  "Whether to cache the results of `clojure-project-dir'."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '(clojure-mode . "5.8.0"))
+
+(defvar-local clojure-cached-project-dir nil
+  "A project dir cache used to speed up related operations.")
+
 (defun clojure-project-dir (&optional dir-name)
   "Return the absolute path to the project's root directory.
 
 Call is delegated down to `clojure-project-root-function' with
-optional DIR-NAME as argument."
-  (funcall clojure-project-root-function dir-name))
+optional DIR-NAME as argument.
+
+When `clojure-cache-project-dir' is t the results of the command
+are cached in a buffer local variable (`clojure-cached-project-dir')."
+  (let ((project-dir (or clojure-cached-project-dir
+                         (funcall clojure-project-root-function dir-name))))
+    (when (and clojure-cache-project-dir
+               (derived-mode-p 'clojure-mode)
+               (not clojure-cached-project-dir))
+      (setq clojure-cached-project-dir project-dir))
+    project-dir))
 
 (defun clojure-project-root-path (&optional dir-name)
   "Return the absolute path to the project's root directory.

test/clojure-mode-util-test.el

@@ -29,7 +29,8 @@
 (let ((project-dir "/home/user/projects/my-project/")
       (clj-file-path "/home/user/projects/my-project/src/clj/my_project/my_ns/my_file.clj")
       (project-relative-clj-file-path "src/clj/my_project/my_ns/my_file.clj")
-      (clj-file-ns "my-project.my-ns.my-file"))
+      (clj-file-ns "my-project.my-ns.my-file")
+      (clojure-cache-project nil))
 
   (ert-deftest project-relative-path ()
     :tags '(utils)