emacs: Use streaming S-expr parser for search

In addition to being the Right Thing to do, this noticeably improves
the time taken to display the first page of search results, since it's
roughly an order of magnitude faster than the JSON parser.
Interestingly, it does *not* significantly improve the time to
completely fill a large search buffer because for large search
buffers, the cost of creating author invisibility overlays and
inserting text (which slows down with more overlays) dominates.
However, the time required to display the first page of results is
generally more important to the user experience.

2 files changed, 6 insertions, 17 deletions

diff --git a/emacs/notmuch.el b/emacs/notmuch.el
index b8d9c444..5a8c9570 100644
--- a/emacs/notmuch.el
+++ b/emacs/notmuch.el
@@ -58,6 +58,7 @@
 (require 'notmuch-hello)
 (require 'notmuch-maildir-fcc)
 (require 'notmuch-message)
+(require 'notmuch-parser)
 
 (defcustom notmuch-search-result-format
   `(("date" . "%12s ")
@@ -809,13 +810,6 @@ non-authors is found, assume that all of the authors match."
 	(setq notmuch-search-target-thread "found")
 	(goto-char beg)))))
 
-(defun notmuch-search-show-error (string &rest objects)
-  (save-excursion
-    (goto-char (point-max))
-    (insert "Error: Unexpected output from notmuch search:\n")
-    (insert (apply #'format string objects))
-    (insert "\n")))
-
 (defun notmuch-search-process-filter (proc string)
   "Process and filter the output of \"notmuch search\""
   (let ((results-buf (process-buffer proc))
@@ -829,8 +823,7 @@ non-authors is found, assume that all of the authors match."
 	(save-excursion
 	  (goto-char (point-max))
 	  (insert string))
-	(notmuch-json-parse-partial-list 'notmuch-search-show-result
-					 'notmuch-search-show-error
+	(notmuch-sexp-parse-partial-list 'notmuch-search-show-result
 					 results-buf)))))
 
 (defun notmuch-search-tag-all (&optional tag-changes)
@@ -933,7 +926,7 @@ Other optional parameters are used as follows:
       (save-excursion
 	(let ((proc (notmuch-start-notmuch
 		     "notmuch-search" buffer #'notmuch-search-process-sentinel
-		     "search" "--format=json" "--format-version=1"
+		     "search" "--format=sexp" "--format-version=1"
 		     (if oldest-first
 			 "--sort=oldest-first"
 		       "--sort=newest-first")
diff --git a/test/emacs b/test/emacs
index e3cf4690..5bc3efcc 100755
--- a/test/emacs
+++ b/test/emacs
@@ -858,7 +858,7 @@ test_expect_success "Rendering HTML mail with images" \
 test_begin_subtest "Search handles subprocess error exit codes"
 cat > notmuch_fail <<EOF
 #!/bin/sh
-echo This is output
+echo '()'
 exit 1
 EOF
 chmod a+x notmuch_fail
@@ -873,21 +873,19 @@ test_emacs "(let ((notmuch-command \"$PWD/notmuch_fail\"))
 	       (test-output))"
 sed -i -e 's/^\[.*\]$/[XXX]/' ERROR
 test_expect_equal "$(cat OUTPUT; echo ---; cat MESSAGES; echo ---; cat ERROR)" "\
-Error: Unexpected output from notmuch search:
-This is output
 End of search results.
 ---
 $PWD/notmuch_fail exited with status 1 (see *Notmuch errors* for more details)
 ---
 [XXX]
 $PWD/notmuch_fail exited with status 1
-command: $PWD/notmuch_fail search --format\=json --format-version\=1 --sort\=newest-first tag\:inbox
+command: $PWD/notmuch_fail search --format\=sexp --format-version\=1 --sort\=newest-first tag\:inbox
 exit status: 1"
 
 test_begin_subtest "Search handles subprocess warnings"
 cat > notmuch_fail <<EOF
 #!/bin/sh
-echo This is output
+echo '()'
 echo This is a warning >&2
 echo This is another warning >&2
 exit 0
@@ -905,8 +903,6 @@ test_emacs "(let ((notmuch-command \"$PWD/notmuch_fail\"))
 	       (test-output))"
 sed -i -e 's/^\[.*\]$/[XXX]/' ERROR
 test_expect_equal "$(cat OUTPUT; echo ---; cat MESSAGES; echo ---; cat ERROR)" "\
-Error: Unexpected output from notmuch search:
-This is output
 End of search results.
 ---
 This is a warning (see *Notmuch errors* for more details)