[WIP Patch 1/7] Make keys of notmuch-tag-formats regexps and use caching
Mark Walters
markwalters1009 at gmail.com
Fri Feb 14 01:15:13 PST 2014
From: Austin Clements <amdragon at MIT.EDU>
This was a little hack to test the feasibility of switching
notmuch-tag-formats to use regexps with caching for performance. In
the end it works fine and isn't particularly complex, though there
were a few gotchas:
1) We have to clear the cache somehow on changes to
notmuch-tag-formats. I opted to use a defcustom :set plus some
documentation telling people what to do if they change it directly
from Elisp. This is less automatic than I would like, but I doubt
people are changing this very often and I concluded that any machinery
to automatically detect changes to notmuch-tag-formats would probably
outweigh the benefits of caching. Alternatively, we could require
search/show/tree buffers to "opt in" to caching when they start
building.
2) I spent way too long trying to use assoc-default before realizing
this it just wouldn't work, since there's no way to distinguish a
missing key from a present key with a null cdr. assoc* from cl works
fine.
Performance-wise, the caching of regexp lookup makes this just as fast
as assoc for unformatted tags (it would probably be faster if someone
had a really big `notmuch-tag-formats') and the caching of eval
results makes this much *faster* than the current code for formatted
tags.
inbox (usec) unread (usec)
assoc: 0.4 2.8
regexp: 3.2 7.2
regexp+caching: 0.4 0.4
That said, even at 7.2 usec, tag formatting is still *very* fast
(though regexp matching may get noticeably slower with larger
`notmuch-tag-formats'). Tag formatting is nowhere near our top
bottleneck.
---
emacs/notmuch-tag.el | 75 +++++++++++++++++++++++++++++++++++--------------
1 files changed, 53 insertions(+), 22 deletions(-)
diff --git a/emacs/notmuch-tag.el b/emacs/notmuch-tag.el
index 908e7ad..cb88fd5 100644
--- a/emacs/notmuch-tag.el
+++ b/emacs/notmuch-tag.el
@@ -28,35 +28,56 @@
(require 'crm)
(require 'notmuch-lib)
+;; (notmuch-tag-clear-cache will be called by the defcustom
+;; notmuch-tag-formats, so it has to be defined first.)
+
+(defvar notmuch-tag--format-cache (make-hash-table :test 'equal)
+ "Cache of tag format lookup. Internal to `notmuch-tag-format-tag'.")
+
+(defun notmuch-tag-clear-cache ()
+ "Clear the internal cache of tag formats.
+
+This must be called after changes to `notmuch-tag-formats'."
+ (clrhash notmuch-tag--format-cache))
+
(defcustom notmuch-tag-formats
'(("unread" (propertize tag 'face '(:foreground "red")))
("flagged" (propertize tag 'face '(:foreground "blue"))
(notmuch-tag-format-image-data tag (notmuch-tag-star-icon))))
"Custom formats for individual tags.
-This gives a list that maps from tag names to lists of formatting
-expressions. The car of each element gives a tag name and the
-cdr gives a list of Elisp expressions that modify the tag. If
-the list is empty, the tag will simply be hidden. Otherwise,
-each expression will be evaluated in order: for the first
-expression, the variable `tag' will be bound to the tag name; for
-each later expression, the variable `tag' will be bound to the
-result of the previous expression. In this way, each expression
-can build on the formatting performed by the previous expression.
-The result of the last expression will displayed in place of the
-tag.
+This is an association list that maps from tag name regexps to
+lists of formatting expressions. The first entry whose car
+regexp-matches a tag will be used to format that tag. The regexp
+is implicitly anchored, so to match a literal tag name, just use
+that tag name (if it contains special regexp characters like
+\".\" or \"*\", these have to be escaped). The cdr of the
+matching entry gives a list of Elisp expressions that modify the
+tag. If the list is empty, the tag will simply be hidden.
+Otherwise, each expression will be evaluated in order: for the
+first expression, the variable `tag' will be bound to the tag
+name; for each later expression, the variable `tag' will be bound
+to the result of the previous expression. In this way, each
+expression can build on the formatting performed by the previous
+expression. The result of the last expression will displayed in
+place of the tag.
For example, to replace a tag with another string, simply use
that string as a formatting expression. To change the foreground
of a tag to red, use the expression
(propertize tag 'face '(:foreground \"red\"))
+After modifying this variable in Elisp, be sure to call
+`notmuch-tag-clear-cache'. Modifying this via customize does
+this automatically.
+
See also `notmuch-tag-format-image', which can help replace tags
with images."
:group 'notmuch-search
:group 'notmuch-show
- :type '(alist :key-type (string :tag "Tag")
+ :set (lambda (var val) (set-default var val) (notmuch-tag-clear-cache))
+ :type '(alist :key-type (regexp :tag "Tag")
:extra-offset -3
:value-type
(radio :format "%v"
@@ -137,16 +158,26 @@ This can be used with `notmuch-tag-format-image-data'."
(defun notmuch-tag-format-tag (tag)
"Format TAG by looking into `notmuch-tag-formats'."
- (let ((formats (assoc tag notmuch-tag-formats)))
- (cond
- ((null formats) ;; - Tag not in `notmuch-tag-formats',
- tag) ;; the format is the tag itself.
- ((null (cdr formats)) ;; - Tag was deliberately hidden,
- nil) ;; no format must be returned
- (t ;; - Tag was found and has formats,
- (let ((tag tag)) ;; we must apply all the formats.
- (dolist (format (cdr formats) tag)
- (setq tag (eval format))))))))
+ (let ((formatted (gethash tag notmuch-tag--format-cache 'missing)))
+ (when (eq formatted 'missing)
+ (let* ((formats
+ (save-match-data
+ (assoc* tag notmuch-tag-formats
+ :test (lambda (tag key)
+ (and (eq (string-match key tag) 0)
+ (= (match-end 0) (length tag))))))))
+ (setq formatted
+ (cond
+ ((null formats) ;; - Tag not in `notmuch-tag-formats',
+ tag) ;; the format is the tag itself.
+ ((null (cdr formats)) ;; - Tag was deliberately hidden,
+ nil) ;; no format must be returned
+ (t ;; - Tag was found and has formats,
+ (let ((tag tag)) ;; we must apply all the formats.
+ (dolist (format (cdr formats) tag)
+ (setq tag (eval format)))))))
+ (puthash tag formatted notmuch-tag--format-cache)))
+ formatted))
(defun notmuch-tag-format-tags (tags &optional face)
"Return a string representing formatted TAGS."
--
1.7.9.1
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