On Wed, 19 Feb 2014, Mark Walters <markwalters1009@gmail.com> wrote:
> From: Austin Clements <amdragon@MIT.EDU>
>
> This patch switches notmuch-tag-formats to use regexps with caching
> for performance.
>
> We have to clear the cache somehow on changes to notmuch-tag-formats.
> This version takes the simplest approach: search/show/tree all clear
> the cache whenever they start loading.
>
> We cannot use assoc-default since there's no way to distinguish a
> missing key from a present key with a null cdr: thus, we use assoc*
> from cl instead.
>
> Performance-wise, the caching of regexp lookup makes this at least as
> fast as the previous code using assoc (see
> id:1392226351-31440-1-git-send-email-amdragon@mit.edu for timing
> details).
How about this for a commit message?
- 8< -
This modifies `notmuch-tag-format-tag' to treat the keys of
`notmuch-tag-formats' as (anchored) regexps, rather than literal
strings. This is clearly more flexible, as it allows for prefix
matching, defining a fallback format, etc. This may cause compatibility
problems if people have customized `notmuch-tag-formats' to match tags
that contain regexp specials, but this seems unlikely.
Regular expression matching has quite a performance hit over string
lookup, so this also introduces a simple cache from exact tags to
formatted strings. The number of unique tags is likely to be quite
small, so this cache should have a high hit rate. In addition to
eliminating the regexp lookup in the common case, this cache stores
fully formatted tags, eliminating the repeated evaluation of potentially
expensive, user-specified formatting code. This makes regexp lookup at
least as fast as assoc for unformatted tags (e.g., inbox) and *faster*
than the current code for formatted tags (e.g., unread):
inbox (usec) unread (usec)
assoc: 0.4 2.8
regexp: 3.2 7.2
regexp+caching: 0.4 0.4
(Though even at 7.2 usec, tag formatting is not our top bottleneck.)
This cache must be explicitly cleared to keep it coherent, so this adds
the appropriate clearing calls.
- >8 -
> ---
> emacs/notmuch-show.el | 1 +
> emacs/notmuch-tag.el | 70 +++++++++++++++++++++++++++++++++---------------
> emacs/notmuch-tree.el | 1 +
> emacs/notmuch.el | 1 +
> 4 files changed, 51 insertions(+), 22 deletions(-)
>
> diff --git a/emacs/notmuch-show.el b/emacs/notmuch-show.el
> index 1ac80ca..4bddf6c 100644
> --- a/emacs/notmuch-show.el
> +++ b/emacs/notmuch-show.el
> @@ -1145,6 +1145,7 @@ function is used."
> ;; Don't track undo information for this buffer
> (set 'buffer-undo-list t)
>
> + (notmuch-tag-clear-cache)
> (erase-buffer)
> (goto-char (point-min))
> (save-excursion
> diff --git a/emacs/notmuch-tag.el b/emacs/notmuch-tag.el
> index 908e7ad..47e0205 100644
> --- a/emacs/notmuch-tag.el
> +++ b/emacs/notmuch-tag.el
> @@ -28,23 +28,39 @@
> (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.)
This is no longer true, so this comment can be removed and the following
two defs can be moved to a more natural location further down in the
file.
> +
> +(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'."
Likewise, this sentence is out of date. I would just omit it and add
the doc I suggest below.
> + (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
> @@ -56,7 +72,7 @@ with images."
>
> :group 'notmuch-search
> :group 'notmuch-show
> - :type '(alist :key-type (string :tag "Tag")
> + :type '(alist :key-type (regexp :tag "Tag")
> :extra-offset -3
> :value-type
> (radio :format "%v"
> @@ -137,16 +153,26 @@ This can be used with `notmuch-tag-format-image-data'."
>
> (defun notmuch-tag-format-tag (tag)
> "Format TAG by looking into `notmuch-tag-formats'."
This would be a great place to mention that modes need to call
`notmuch-tag-clear-cache' if they intent to use formatted tags.
"Format TAG according to `notmuch-tag-formats'.
Callers must ensure that the tag format cache has been recently cleared
via `notmuch-tag-clear-cache' before using this function. For example,
it would be appropriate to clear the cache just prior to filling a
buffer that uses formatted tags."
> - (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
This is a better place for the comment about assoc* that's currently in
the commit message.
;; Don't use assoc-default since there's no way to distinguish a missing
;; key from a present key with a null cdr:.
> + (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."
> diff --git a/emacs/notmuch-tree.el b/emacs/notmuch-tree.el
> index 4f2ac02..a106e09 100644
> --- a/emacs/notmuch-tree.el
> +++ b/emacs/notmuch-tree.el
> @@ -881,6 +881,7 @@ the same as for the function notmuch-tree."
> (message-arg "--entire-thread"))
> (if (equal (car (process-lines notmuch-command "count" search-args)) "0")
> (setq search-args basic-query))
> + (notmuch-tag-clear-cache)
> (let ((proc (notmuch-start-notmuch
> "notmuch-tree" (current-buffer) #'notmuch-tree-process-sentinel
> "show" "--body=false" "--format=sexp"
> diff --git a/emacs/notmuch.el b/emacs/notmuch.el
> index 0471750..0c767f7 100644
> --- a/emacs/notmuch.el
> +++ b/emacs/notmuch.el
> @@ -888,6 +888,7 @@ the configured default sort order."
> (set 'notmuch-search-oldest-first oldest-first)
> (set 'notmuch-search-target-thread target-thread)
> (set 'notmuch-search-target-line target-line)
> + (notmuch-tag-clear-cache)
> (let ((proc (get-buffer-process (current-buffer)))
> (inhibit-read-only t))
> (if proc
> --
> 1.7.9.1