[PATCH] lib: make notmuch_query_count_messages exact

[Jani Nikula]

Our tests have expected this to be exact all along, but maybe
inaccuracies only show up with big databases.
---
 devel/TODO    | 5 -----
 lib/notmuch.h | 6 +++---
 lib/query.cc  | 7 ++++++-
 3 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/devel/TODO b/devel/TODO
index 1cf4089f1d93..116194d82ad1 100644
--- a/devel/TODO
+++ b/devel/TODO
@@ -188,11 +188,6 @@ into the shared-library interface.
 Audit all libnotmuch entry points to ensure that all Xapian calls are
 wrapped in a try/catch block.
 
-Fix the "count" functionality to be exact as Olly explained in IRC:
-
-	ojwb> cworth: if you set the check_at_least parameter to the
-	database size, get_matches_estimated() will be exact
-
 Fix the threading of a message that has a References: header but no
 In-Reply-To: header (see id:"87lixxnxpb.fsf at yoom.home.cworth.org").
 
diff --git a/lib/notmuch.h b/lib/notmuch.h
index dae041640fdb..6091082617e7 100644
--- a/lib/notmuch.h
+++ b/lib/notmuch.h
@@ -893,10 +893,10 @@ void
 notmuch_threads_destroy (notmuch_threads_t *threads);
 
 /**
- * Return an estimate of the number of messages matching a search.
+ * Return the number of messages matching a search.
  *
- * This function performs a search and returns Xapian's best
- * guess as to number of matching messages.
+ * This function performs a search and returns the number of matching
+ * messages.
  *
  * If a Xapian exception occurs, this function may return 0 (after
  * printing a message).
diff --git a/lib/query.cc b/lib/query.cc
index 60ff8bd9a39e..ce26e3f3e4ed 100644
--- a/lib/query.cc
+++ b/lib/query.cc
@@ -557,7 +557,12 @@ notmuch_query_count_messages (notmuch_query_t *query)
 
 	enquire.set_query (final_query);
 
-	mset = enquire.get_mset (0, notmuch->xapian_db->get_doccount ());
+	/*
+	 * Set the checkatleast parameter to the number of documents
+	 * in the database to make get_matches_estimated() exact.
+	 */
+	mset = enquire.get_mset (0, notmuch->xapian_db->get_doccount (),
+				 notmuch->xapian_db->get_doccount ());
 
 	count = mset.get_matches_estimated();
 
-- 
2.1.1