emacs/show: introduce notmuch-show-height-limit

Analogous to notmuch-show-depth-limit, it requires a bit more
calculation, but that cost seems dominated by the rendering cost.

doc/notmuch-emacs.rst

@@ -280,6 +280,9 @@ Display of messages can be controlled by the following variables
 :index:`notmuch-show-depth-limit`
        |docstring::notmuch-show-depth-limit|
 
+:index:`notmuch-show-height-limit`
+       |docstring::notmuch-show-height-limit|
+
 :index:`notmuch-show-max-text-part-size`
        |docstring::notmuch-show-max-text-part-size|
 

emacs/notmuch-show.el

@@ -123,6 +123,19 @@ insertion is done."
                  (number :tag "Limit" 10))
   :group 'notmuch-show)
 
+(defcustom notmuch-show-height-limit nil
+  "Height (from leaves) beyond which message bodies are displayed lazily.
+
+If bound to an integer, any message with height in the message
+tree greater than this will have its body displayed lazily,
+initially only a button.
+
+If this variable is set to nil (the default) no such lazy
+display is done."
+  :type '(choice (const :tag "No limit" nil)
+                 (number :tag "Limit" 10))
+  :group 'notmuch-show)
+
 (defcustom notmuch-show-relative-dates t
   "Display relative dates in the message summary line."
   :type 'boolean
@@ -505,6 +518,18 @@ Return unchanged ADDRESS if parsing fails."
       ;; Otherwise format the name and address together.
       (concat p-name " <" p-address ">"))))
 
+(defun notmuch-show--mark-height (tree)
+  "Calculate and cache height (distance from deepest descendent)"
+  (let* ((msg (car tree))
+	 (children (cadr tree))
+	 (cached-height (plist-get msg :height)))
+    (or cached-height
+	(let ((height
+	       (if (null children) 0
+		 (1+ (apply #'max (mapcar #'notmuch-show--mark-height children))))))
+	  (plist-put msg :height height)
+	  height))))
+
 (defun notmuch-show-insert-headerline (headers date tags depth)
   "Insert a notmuch style headerline based on HEADERS for a
 message at DEPTH in the current thread."
@@ -1039,16 +1064,19 @@ is t, hide the part initially and show the button."
   (let* ((content-type (plist-get part :content-type))
 	 (mime-type (notmuch-show-mime-type part))
 	 (nth (plist-get part :id))
+	 (height (plist-get msg :height))
 	 (long (and (notmuch-match-content-type mime-type "text/*")
 		    (> notmuch-show-max-text-part-size 0)
 		    (> (length (plist-get part :content))
 		       notmuch-show-max-text-part-size)))
 	 (deep (and notmuch-show-depth-limit
 		    (> depth notmuch-show-depth-limit)))
+	 (high (and notmuch-show-height-limit
+		    (> height notmuch-show-height-limit)))
 	 (beg (point))
 	 ;; This default header-p function omits the part button for
 	 ;; the first (or only) part if this is text/plain.
-	 (button (and (or deep long
+	 (button (and (or deep long high
 			  (funcall notmuch-show-insert-header-p-function part hide))
 		      (notmuch-show-insert-part-header
 		       nth mime-type
@@ -1058,6 +1086,7 @@ is t, hide the part initially and show the button."
 	 ;; and we have a button to allow toggling.
 	 (show-part (not (or (equal hide t)
 			     (and deep button)
+			     (and high button)
 			     (and long button))))
 	 (content-beg (point)))
     ;; Store the computed mime-type for later use (e.g. by attachment handlers).
@@ -1201,6 +1230,7 @@ is t, hide the part initially and show the button."
 	(replies (cadr tree)))
     ;; We test whether there is a message or just some replies.
     (when msg
+      (notmuch-show--mark-height tree)
       (notmuch-show-insert-msg msg depth))
     (notmuch-show-insert-thread replies (1+ depth))))
 

test/T450-emacs-show.sh

@@ -100,6 +100,26 @@ test_emacs '(let ((notmuch-show-depth-limit -1))
 	(test-visible-output))'
 test_expect_equal_file $EXPECTED/notmuch-show-depth OUTPUT
 
+
+test_begin_subtest "Hide bodies of messages by height"
+test_emacs '(let ((notmuch-show-height-limit -1))
+	(notmuch-search "thread:{id:87ocn0qh6d.fsf@yoom.home.cworth.org}")
+	(notmuch-test-wait)
+	(notmuch-search-show-thread)
+	(notmuch-test-wait)
+	(test-visible-output))'
+# folding all messages by height or depth should look the same
+test_expect_equal_file $EXPECTED/notmuch-show-depth OUTPUT
+
+test_begin_subtest "Hide bodies of messages; show only leaves."
+test_emacs '(let ((notmuch-show-height-limit 0))
+	(notmuch-search "thread:{id:87ocn0qh6d.fsf@yoom.home.cworth.org}")
+	(notmuch-test-wait)
+	(notmuch-search-show-thread)
+	(notmuch-test-wait)
+	(test-visible-output))'
+test_expect_equal_file $EXPECTED/notmuch-show-height-0 OUTPUT
+
 test_begin_subtest "Hide bodies of messages (depth > 1)"
 test_emacs '(let ((notmuch-show-depth-limit 1))
 	(notmuch-search "thread:{id:87ocn0qh6d.fsf@yoom.home.cworth.org}")

test/emacs-show.expected-output/notmuch-show-height-0

@@ -0,0 +1,97 @@
+Lars Kellogg-Stedman <lars@seas.harvard.edu> (2009-11-17) (inbox signed)
+Subject: [notmuch] Working with Maildir storage?
+To: notmuch@notmuchmail.org
+Date: Tue, 17 Nov 2009 14:00:54 -0500
+
+[ multipart/mixed (hidden) ]
+ Mikhail Gusarov <dottedmag@dottedmag.net> (2009-11-17) (inbox signed unread)
+ Subject: Re: [notmuch] Working with Maildir storage?
+ To: notmuch@notmuchmail.org
+ Date: Wed, 18 Nov 2009 01:02:38 +0600
+
+ [ multipart/mixed (hidden) ]
+  Lars Kellogg-Stedman <lars@seas.harvard.edu> (2009-11-17) (inbox signed)
+  Subject: Re: [notmuch] Working with Maildir storage?
+  To: Mikhail Gusarov <dottedmag@dottedmag.net>
+  Cc: notmuch@notmuchmail.org
+  Date: Tue, 17 Nov 2009 15:33:01 -0500
+
+  [ multipart/mixed (hidden) ]
+   Mikhail Gusarov <dottedmag@dottedmag.net> (2009-11-17) (inbox unread)
+   Subject: [notmuch] Working with Maildir storage?
+   To: notmuch@notmuchmail.org
+   Date: Wed, 18 Nov 2009 02:50:48 +0600
+
+   Twas brillig at 15:33:01 17.11.2009 UTC-05 when lars at seas.harvard.edu
+   did gyre and gimble:
+
+    LK> Is the list archived anywhere?  The obvious archives
+    LK> (http://notmuchmail.org/pipermail/notmuch/) aren't available, and I
+    LK> think I subscribed too late to get the patch (I only just saw the
+    LK> discussion about it).
+
+    LK> It doesn't look like the patch is in git yet.
+
+   Just has been pushed
+
+   [ 10-line signature. Click/Enter to show. ]
+   Keith Packard <keithp@keithp.com> (2009-11-17) (inbox unread)
+   Subject: [notmuch] Working with Maildir storage?
+   To: notmuch@notmuchmail.org
+   Date: Tue, 17 Nov 2009 13:24:13 -0800
+
+   [ text/plain (hidden) ]
+    Lars Kellogg-Stedman <lars@seas.harvard.edu> (2009-11-18) (inbox signed unread)
+    Subject: Re: [notmuch] Working with Maildir storage?
+    To: Keith Packard <keithp@keithp.com>
+    Cc: notmuch@notmuchmail.org
+    Date: Tue, 17 Nov 2009 19:50:40 -0500
+
+    [ multipart/mixed ]
+    [ multipart/signed ]
+    [ Unknown key ID 0xD74695063141ACD8 or unsupported algorithm ]
+    [ text/plain ]
+    > I've also pushed a slightly more complicated (and complete) fix to my
+    > private notmuch repository
+
+    The version of lib/messages.cc in your repo doesn't build because it's
+    missing "#include <stdint.h>" (for the uint32_t on line 466).
+
+    [ 4-line signature. Click/Enter to show. ]
+    [ application/pgp-signature ]
+    [ text/plain ]
+    [ 4-line signature. Click/Enter to show. ]
+ Carl Worth <cworth@cworth.org> (2009-11-18) (inbox unread)
+ Subject: [notmuch] Working with Maildir storage?
+ To: notmuch@notmuchmail.org
+ Date: Wed, 18 Nov 2009 02:08:10 -0800
+
+ On Tue, 17 Nov 2009 14:00:54 -0500, Lars Kellogg-Stedman <lars at
+ seas.harvard.edu> wrote:
+ > I saw the LWN article and decided to take a look at notmuch.  I'm
+ > currently using mutt and mairix to index and read a collection of
+ > Maildir mail folders (around 40,000 messages total).
+
+ Welcome, Lars!
+
+ I hadn't even seen that Keith's blog post had been picked up by lwn.net.
+ That's very interesting. So, thanks for coming and trying out notmuch.
+
+ >   Error opening
+ > /home/lars/Mail/read-messages.2008/cur/1246413773.24928_27334.hostname,U=3026:2,S:
+ >   Too many open files
+
+ Sadly, the lwn article coincided with me having just introduced this
+ bug, and then getting on a Trans-Atlantic flight. So I fixed the bug
+ fairly quickly, but there was quite a bit of latency before I could push
+ the fix out. It should be fixed now.
+
+ > I'm curious if this is expected behavior (i.e., notmuch does not work
+ > with Maildir) or if something else is going on.
+
+ Notmuch works just fine with maildir---it's one of the things that it
+ likes the best.
+
+ Happy hacking,
+
+ -Carl