Add 'notmuch count' command to show the count of matching messages

Getting the count of matching threads or messages is a fairly
expensive operation. Xapian provides a very efficient mechanism that
returns an approximate value, so use that for this new command.

This returns the number of matching messages, not threads, as that is
cheap to compute.

Signed-off-by: Keith Packard <keithp@keithp.com>

Makefile.local

@@ -7,6 +7,7 @@ notmuch_client_srcs =		\
 	gmime-filter-reply.c	\
 	notmuch.c		\
 	notmuch-config.c	\
+	notmuch-count.c		\
 	notmuch-dump.c		\
 	notmuch-new.c		\
 	notmuch-reply.c		\

lib/notmuch.h

@@ -468,6 +468,14 @@ notmuch_threads_advance (notmuch_threads_t *threads);
 void
 notmuch_threads_destroy (notmuch_threads_t *threads);
 
+/* Return an estimate of the number of messages matching a search
+ *
+ * This function performs a search and returns Xapian's best
+ * guess as to number of matching messages.
+ */
+unsigned
+notmuch_query_count_messages (notmuch_query_t *query);
+ 
 /* Get the thread ID of 'thread'.
  *
  * The returned string belongs to 'thread' and as such, should not be

lib/query.cc

@@ -279,3 +279,55 @@ notmuch_threads_destroy (notmuch_threads_t *threads)
 {
     talloc_free (threads);
 }
+
+unsigned
+notmuch_query_count_messages (notmuch_query_t *query)
+{
+    notmuch_database_t *notmuch = query->notmuch;
+    const char *query_string = query->query_string;
+    Xapian::doccount count;
+
+    try {
+	Xapian::Enquire enquire (*notmuch->xapian_db);
+	Xapian::Query mail_query (talloc_asprintf (query, "%s%s",
+						   _find_prefix ("type"),
+						   "mail"));
+	Xapian::Query string_query, final_query;
+	Xapian::MSet mset;
+	unsigned int flags = (Xapian::QueryParser::FLAG_BOOLEAN |
+			      Xapian::QueryParser::FLAG_PHRASE |
+			      Xapian::QueryParser::FLAG_LOVEHATE |
+			      Xapian::QueryParser::FLAG_BOOLEAN_ANY_CASE |
+			      Xapian::QueryParser::FLAG_WILDCARD |
+			      Xapian::QueryParser::FLAG_PURE_NOT);
+
+	if (strcmp (query_string, "") == 0) {
+	    final_query = mail_query;
+	} else {
+	    string_query = notmuch->query_parser->
+		parse_query (query_string, flags);
+	    final_query = Xapian::Query (Xapian::Query::OP_AND,
+					 mail_query, string_query);
+	}
+
+	enquire.set_weighting_scheme(Xapian::BoolWeight());
+	enquire.set_docid_order(Xapian::Enquire::ASCENDING);
+
+#if DEBUG_QUERY
+	fprintf (stderr, "Final query is:\n%s\n", final_query.get_description().c_str());
+#endif
+
+	enquire.set_query (final_query);
+
+	mset = enquire.get_mset (0, notmuch->xapian_db->get_doccount ());
+
+	count = mset.get_matches_estimated();
+
+    } catch (const Xapian::Error &error) {
+	fprintf (stderr, "A Xapian exception occurred: %s\n",
+		 error.get_msg().c_str());
+	fprintf (stderr, "Query string was: %s\n", query->query_string);
+    }
+
+    return count;
+}

notmuch-client.h

@@ -92,6 +92,9 @@ chomp_newline (char *str)
 	str[strlen(str)-1] = '\0';
 }
 
+int
+notmuch_count_command (void *ctx, int argc, char *argv[]);
+
 int
 notmuch_dump_command (void *ctx, int argc, char *argv[]);
 

notmuch-count.c

@@ -0,0 +1,110 @@
+/* notmuch - Not much of an email program, (just index and search)
+ *
+ * Copyright © 2009 Carl Worth
+ * Copyright © 2009 Keith Packard
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see http://www.gnu.org/licenses/ .
+ *
+ * Author: Keith Packard <keithp@keithp.com>
+ */
+
+#include "notmuch-client.h"
+
+int
+notmuch_count_command (void *ctx, int argc, char *argv[])
+{
+    notmuch_config_t *config;
+    notmuch_database_t *notmuch;
+    notmuch_query_t *query;
+    char *query_str;
+    int i;
+#if 0
+    char *opt, *end;
+    int i, first = 0, max_threads = -1;
+    notmuch_sort_t sort = NOTMUCH_SORT_NEWEST_FIRST;
+#endif
+
+    for (i = 0; i < argc && argv[i][0] == '-'; i++) {
+	if (strcmp (argv[i], "--") == 0) {
+	    i++;
+	    break;
+	}
+#if 0
+	if (STRNCMP_LITERAL (argv[i], "--first=") == 0) {
+	    opt = argv[i] + sizeof ("--first=") - 1;
+	    first = strtoul (opt, &end, 10);
+	    if (*opt == '\0' || *end != '\0') {
+		fprintf (stderr, "Invalid value for --first: %s\n", opt);
+		return 1;
+	    }
+	} else if (STRNCMP_LITERAL (argv[i], "--max-threads=") == 0) {
+	    opt = argv[i] + sizeof ("--max-threads=") - 1;
+	    max_threads = strtoul (opt, &end, 10);
+	    if (*opt == '\0' || *end != '\0') {
+		fprintf (stderr, "Invalid value for --max-threads: %s\n", opt);
+		return 1;
+	    }
+	} else if (STRNCMP_LITERAL (argv[i], "--sort=") == 0) {
+	    opt = argv[i] + sizeof ("--sort=") - 1;
+	    if (strcmp (opt, "oldest-first") == 0) {
+		sort = NOTMUCH_SORT_OLDEST_FIRST;
+	    } else if (strcmp (opt, "newest-first") == 0) {
+		sort = NOTMUCH_SORT_NEWEST_FIRST;
+	    } else {
+		fprintf (stderr, "Invalid value for --sort: %s\n", opt);
+		return 1;
+	    }
+	} else
+#endif
+	{
+	    fprintf (stderr, "Unrecognized option: %s\n", argv[i]);
+	    return 1;
+	}
+    }
+
+    argc -= i;
+    argv += i;
+
+    config = notmuch_config_open (ctx, NULL, NULL);
+    if (config == NULL)
+	return 1;
+
+    notmuch = notmuch_database_open (notmuch_config_get_database_path (config),
+				     NOTMUCH_DATABASE_MODE_READ_ONLY);
+    if (notmuch == NULL)
+	return 1;
+
+    query_str = query_string_from_args (ctx, argc, argv);
+    if (query_str == NULL) {
+	fprintf (stderr, "Out of memory.\n");
+	return 1;
+    }
+    if (*query_str == '\0') {
+	fprintf (stderr, "Error: notmuch count requires at least one count term.\n");
+	return 1;
+    }
+
+    query = notmuch_query_create (notmuch, query_str);
+    if (query == NULL) {
+	fprintf (stderr, "Out of memory\n");
+	return 1;
+    }
+
+    printf ("%u\n", notmuch_query_count_messages(query));
+
+    notmuch_query_destroy (query);
+    notmuch_database_close (notmuch);
+
+    return 0;
+}

notmuch.c

@@ -187,6 +187,17 @@ command_t commands[] = {
       "\n"
       "\t\tSee \"notmuch help search-terms\" for details of the search\n"
       "\t\tterms syntax." },
+    { "count", notmuch_count_command,
+      "<search-terms> [...]",
+      "\t\tCount messages matching the search terms.",
+      "\t\tThe number of matching messages is output to stdout.\n"
+      "\n"
+      "\t\tA common use of \"notmuch count\" is to display the count\n"
+      "\t\tof messages matching both a specific tag and either inbox\n"
+      "\t\tor unread\n"
+      "\n"
+      "\t\tSee \"notmuch help search-terms\" for details of the search\n"
+      "\t\tterms syntax." },
     { "reply", notmuch_reply_command,
       "<search-terms> [...]",
       "\t\tConstruct a reply template for a set of messages.",