notmuch search: Return first 100 results as quickly as possible.

This is one of those cases where total time is not the metric of
interest. We increase the total time of the search, (by doing some
redundant work for the initial threads). But more significantly, we
give the user *some* results nearly instantaneously, (so that the user
might see the result of interest without ever even waiting for the
complete results to come in).

1 files changed, 64 insertions, 39 deletions

diff --git a/notmuch-search.c b/notmuch-search.c
index 8db09c77..59ffb038 100644
--- a/notmuch-search.c
+++ b/notmuch-search.c
@@ -20,18 +20,69 @@
 
 #include "notmuch-client.h"
 
+/* If the user asks for a *lot* of threads, lets give some results as
+ * quickly as possible and let the user read those while we compute
+ * the remainder. */
+#define NOTMUCH_SHOW_INITIAL_BURST 100
+
+static void
+do_search_threads (const void *ctx,
+		   notmuch_query_t *query,
+		   notmuch_sort_t sort,
+		   int first, int max_threads)
+{
+    notmuch_thread_t *thread;
+    notmuch_threads_t *threads;
+    notmuch_tags_t *tags;
+    time_t date;
+    const char *relative_date;
+
+    for (threads = notmuch_query_search_threads (query, first, max_threads);
+	 notmuch_threads_has_more (threads);
+	 notmuch_threads_advance (threads))
+    {
+	int first_tag = 1;
+
+	thread = notmuch_threads_get (threads);
+
+	if (sort == NOTMUCH_SORT_DATE)
+	    date = notmuch_thread_get_oldest_date (thread);
+	else
+	    date = notmuch_thread_get_newest_date (thread);
+
+	relative_date = notmuch_time_relative_date (ctx, date);
+
+	printf ("thread:%s %12s [%d/%d] %s; %s",
+		notmuch_thread_get_thread_id (thread),
+		relative_date,
+		notmuch_thread_get_matched_messages (thread),
+		notmuch_thread_get_total_messages (thread),
+		notmuch_thread_get_authors (thread),
+		notmuch_thread_get_subject (thread));
+
+	printf (" (");
+	for (tags = notmuch_thread_get_tags (thread);
+	     notmuch_tags_has_more (tags);
+	     notmuch_tags_advance (tags))
+	{
+	    if (! first_tag)
+		printf (" ");
+	    printf ("%s", notmuch_tags_get (tags));
+	    first_tag = 0;
+	}
+	printf (")\n");
+
+	notmuch_thread_destroy (thread);
+    }
+}
+
 int
 notmuch_search_command (void *ctx, int argc, char *argv[])
 {
     notmuch_config_t *config;
     notmuch_database_t *notmuch;
     notmuch_query_t *query;
-    notmuch_threads_t *threads;
-    notmuch_thread_t *thread;
-    notmuch_tags_t *tags;
     char *query_str;
-    const char *relative_date;
-    time_t date;
     int i, first = 0, max_threads = -1;
     char *opt, *end;
     notmuch_sort_t sort = NOTMUCH_SORT_DATE;
@@ -88,44 +139,18 @@ notmuch_search_command (void *ctx, int argc, char *argv[])
 
     notmuch_query_set_sort (query, sort);
 
-    for (threads = notmuch_query_search_threads (query, first, max_threads);
-	 notmuch_threads_has_more (threads);
-	 notmuch_threads_advance (threads))
+    if (max_threads < 0 || max_threads > NOTMUCH_SHOW_INITIAL_BURST)
     {
-	int first = 1;
-
-	thread = notmuch_threads_get (threads);
-
-	if (sort == NOTMUCH_SORT_DATE)
-	    date = notmuch_thread_get_oldest_date (thread);
-	else
-	    date = notmuch_thread_get_newest_date (thread);
-
-	relative_date = notmuch_time_relative_date (ctx, date);
+	do_search_threads (ctx, query, sort,
+			   first, NOTMUCH_SHOW_INITIAL_BURST);
 
-	printf ("thread:%s %12s [%d/%d] %s; %s",
-		notmuch_thread_get_thread_id (thread),
-		relative_date,
-		notmuch_thread_get_matched_messages (thread),
-		notmuch_thread_get_total_messages (thread),
-		notmuch_thread_get_authors (thread),
-		notmuch_thread_get_subject (thread));
-
-	printf (" (");
-	for (tags = notmuch_thread_get_tags (thread);
-	     notmuch_tags_has_more (tags);
-	     notmuch_tags_advance (tags))
-	{
-	    if (! first)
-		printf (" ");
-	    printf ("%s", notmuch_tags_get (tags));
-	    first = 0;
-	}
-	printf (")\n");
-
-	notmuch_thread_destroy (thread);
+	first += NOTMUCH_SHOW_INITIAL_BURST;
+	if (max_threads > 0)
+	    max_threads -= NOTMUCH_SHOW_INITIAL_BURST;
     }
 
+    do_search_threads (ctx, query, sort, first, max_threads);
+
     notmuch_query_destroy (query);
     notmuch_database_close (notmuch);