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+ id 1YF56p-0003m9-3E; Sat, 24 Jan 2015 13:06:59 -0500\r
+From: Austin Clements <amdragon@mit.edu>\r
+To: Mark Walters <markwalters1009@gmail.com>\r
+Subject: Re: [PATCH 08/11] emacs: Support caching in\r
+ notmuch-get-bodypart-{binary, text}\r
+In-Reply-To: <87d2g5uczr.fsf@qmul.ac.uk>\r
+References: <1398105468-14317-1-git-send-email-amdragon@mit.edu>\r
+ <1398105468-14317-9-git-send-email-amdragon@mit.edu>\r
+ <87sip3t37f.fsf@qmul.ac.uk> <20140424181216.GO25817@mit.edu>\r
+ <87d2g5uczr.fsf@qmul.ac.uk>\r
+User-Agent: Notmuch/0.18.1+86~gef5e66a (http://notmuchmail.org) Emacs/24.4.1\r
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+Date: Sat, 24 Jan 2015 13:06:59 -0500\r
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+\r
+On Fri, 25 Apr 2014, Mark Walters <markwalters1009@gmail.com> wrote:\r
+> On Thu, 24 Apr 2014, Austin Clements <amdragon@MIT.EDU> wrote:\r
+>> Quoth Mark Walters on Apr 24 at 11:46 am:\r
+>>> \r
+>>> On Mon, 21 Apr 2014, Austin Clements <amdragon@MIT.EDU> wrote:\r
+>>> > (The actual code change here is small, but requires re-indenting\r
+>>> > existing code.)\r
+>>> > ---\r
+>>> > emacs/notmuch-lib.el | 52 ++++++++++++++++++++++++++++++----------------------\r
+>>> > 1 file changed, 30 insertions(+), 22 deletions(-)\r
+>>> >\r
+>>> > diff --git a/emacs/notmuch-lib.el b/emacs/notmuch-lib.el\r
+>>> > index fc67b14..fee8512 100644\r
+>>> > --- a/emacs/notmuch-lib.el\r
+>>> > +++ b/emacs/notmuch-lib.el\r
+>>> > @@ -503,33 +503,39 @@ (defun notmuch-parts-filter-by-type (parts type)\r
+>>> > (lambda (part) (notmuch-match-content-type (plist-get part :content-type) type))\r
+>>> > parts))\r
+>>> > \r
+>>> > -(defun notmuch-get-bodypart-binary (msg part process-crypto)\r
+>>> > +(defun notmuch-get-bodypart-binary (msg part process-crypto &optional cache)\r
+>>> > "Return the unprocessed content of PART in MSG as a unibyte string.\r
+>>> > \r
+>>> > This returns the \"raw\" content of the given part after content\r
+>>> > transfer decoding, but with no further processing (see the\r
+>>> > discussion of --format=raw in man notmuch-show). In particular,\r
+>>> > this does no charset conversion."\r
+>>> > - (let ((args `("show" "--format=raw"\r
+>>> > - ,(format "--part=%d" (plist-get part :id))\r
+>>> > - ,@(when process-crypto '("--decrypt"))\r
+>>> > - ,(notmuch-id-to-query (plist-get msg :id)))))\r
+>>> > - (with-temp-buffer\r
+>>> > - ;; Emacs internally uses a UTF-8-like multibyte string\r
+>>> > - ;; representation by default (regardless of the coding system,\r
+>>> > - ;; which only affects how it goes from outside data to this\r
+>>> > - ;; internal representation). This *almost* never matters.\r
+>>> > - ;; Annoyingly, it does matter if we use this data in an image\r
+>>> > - ;; descriptor, since Emacs will use its internal data buffer\r
+>>> > - ;; directly and this multibyte representation corrupts binary\r
+>>> > - ;; image formats. Since the caller is asking for binary data, a\r
+>>> > - ;; unibyte string is a more appropriate representation anyway.\r
+>>> > - (set-buffer-multibyte nil)\r
+>>> > - (let ((coding-system-for-read 'no-conversion))\r
+>>> > - (apply #'call-process notmuch-command nil '(t nil) nil args)\r
+>>> > - (buffer-string)))))\r
+>>> > -\r
+>>> > -(defun notmuch-get-bodypart-text (msg part process-crypto)\r
+>>> > + (let ((data (plist-get part :binary-content)))\r
+>>> > + (when (not data)\r
+>>> > + (let ((args `("show" "--format=raw"\r
+>>> > + ,(format "--part=%d" (plist-get part :id))\r
+>>> > + ,@(when process-crypto '("--decrypt"))\r
+>>> > + ,(notmuch-id-to-query (plist-get msg :id)))))\r
+>>> > + (with-temp-buffer\r
+>>> > + ;; Emacs internally uses a UTF-8-like multibyte string\r
+>>> > + ;; representation by default (regardless of the coding\r
+>>> > + ;; system, which only affects how it goes from outside data\r
+>>> > + ;; to this internal representation). This *almost* never\r
+>>> > + ;; matters. Annoyingly, it does matter if we use this data\r
+>>> > + ;; in an image descriptor, since Emacs will use its internal\r
+>>> > + ;; data buffer directly and this multibyte representation\r
+>>> > + ;; corrupts binary image formats. Since the caller is\r
+>>> > + ;; asking for binary data, a unibyte string is a more\r
+>>> > + ;; appropriate representation anyway.\r
+>>> > + (set-buffer-multibyte nil)\r
+>>> > + (let ((coding-system-for-read 'no-conversion))\r
+>>> > + (apply #'call-process notmuch-command nil '(t nil) nil args)\r
+>>> > + (setq data (buffer-string)))))\r
+>>> > + (when cache\r
+>>> > + (plist-put part :binary-content data)))\r
+>>> > + data))\r
+>>> \r
+>>> I am a little puzzled by this but that could be lack of familiarity with\r
+>>> elisp. As far as I can see plist-put will sometimes modify the original\r
+>>> plist and sometimes return a new plist. If the latter happens then I\r
+>>> think it works out as if we hadn't cached anything as the part passed to\r
+>>> the function is unmodified. That might not matter in this case (though I\r
+>>> find the lack of determinism disturbing).\r
+>>> \r
+>>> Or is something else going on?\r
+>>\r
+>> No, your familiarity with Elisp serves you well. I'm completely\r
+>> cheating here. According to the specification of plist-put, it's\r
+>> allowed to return a new list but in reality this only happens when the\r
+>> original plist is nil. We lean on this already all over the\r
+>> notmuch-emacs code, but maybe that doesn't excuse me adding one more\r
+>> cheat.\r
+>>\r
+>> I could add a comment here explaining what's going on, I could\r
+>> manually do the list insertion in a way that's guaranteed to mutate it\r
+>> in place, or I could add a nil :binary-content property when parts are\r
+>> created (since plist-put is guaranteed to mutate existing keys in\r
+>> place).\r
+>\r
+> I think a comment is fine. \r
+\r
+Done.\r
+\r
+> (Incidentally what is the best way of telling if emacs has changed an\r
+> object or returned a new one for other commands? Something like (setq\r
+> oldobject object) (setq object (operation-on object)) (if (eq object\r
+> oldobject) ... ))\r
+\r
+If `eq' returns t, it definitely returned the original object, though it\r
+may or may not have modified it. If `eq' returns nil, there's no\r
+guarantee that it *didn't* modify the object you passed in (maybe it\r
+modified it and tacked a new cons on the beginning). In short, there's\r
+really no way of knowing.\r
+\r
+> Also, I think the function should have a comment about the lifetime of\r
+> the caching. I think in some cases the addition of :binary-content could\r
+> occur on load and thus the plist with binary content added would get\r
+> saved in the buffer when the msg plist was saved as a\r
+> text-property. However, maybe in other cases this gets called after the\r
+> initial insertion and thus the cached value is just used during this\r
+> operation on msg? Sorry that is a little incoherent as I haven't checked\r
+> all callers.\r
+\r
+I believe the caching will always last as long as the buffer. We only\r
+have one instance of each message plist. This plist goes in to the text\r
+properties and caching works by mutating this same plist.\r
+\r
+However, I updated the docstring to clarify that the cache is stored in\r
+MSG. These functions don't ultimately control the lifetime of MSG, but\r
+this gives the caller enough information to know the lifetime of the\r
+cache if it knows the lifetime of MSG.\r
+\r
+> Best wishes\r
+>\r
+> Mark\r
+>\r
+>\r
+>\r
+>>> Best wishes\r
+>>> \r
+>>> Mark\r
+>>> \r
+>>> \r
+>>> \r
+>>> > +\r
+>>> > +(defun notmuch-get-bodypart-text (msg part process-crypto &optional cache)\r
+>>> > "Return the text content of PART in MSG.\r
+>>> > \r
+>>> > This returns the content of the given part as a multibyte Lisp\r
+>>> > @@ -546,7 +552,9 @@ (defun notmuch-get-bodypart-text (msg part process-crypto)\r
+>>> > (npart (apply #'notmuch-call-notmuch-sexp args)))\r
+>>> > (setq content (plist-get npart :content))\r
+>>> > (when (not content)\r
+>>> > - (error "Internal error: No :content from %S" args))))\r
+>>> > + (error "Internal error: No :content from %S" args)))\r
+>>> > + (when cache\r
+>>> > + (plist-put part :content content)))\r
+>>> > content))\r
+>>> > \r
+>>> > ;; Workaround: The call to `mm-display-part' below triggers a bug in\r
projects / notmuch-archives.git / commitdiff