[PATCH 1/4] lib: add versions of notmuch_query_count_{message,threads} with status return

[David Bremner]

Although I think it's a pretty bad idea to continue using the old API,
this allows both a more gentle transition for clients of the library,
and allows us to break one monolithic change into a series
---
 lib/database.cc |  8 +++++++-
 lib/notmuch.h   | 34 ++++++++++++++++++++++++++++++----
 lib/query.cc    | 36 +++++++++++++++++++++++++++++-------
 3 files changed, 66 insertions(+), 12 deletions(-)

diff --git a/lib/database.cc b/lib/database.cc
index 3974e2e..d92eec0 100644
--- a/lib/database.cc
+++ b/lib/database.cc
@@ -1275,7 +1275,13 @@ notmuch_database_upgrade (notmuch_database_t *notmuch,
     if (new_features &
 	(NOTMUCH_FEATURE_FILE_TERMS | NOTMUCH_FEATURE_BOOL_FOLDER)) {
 	notmuch_query_t *query = notmuch_query_create (notmuch, "");
-	total += notmuch_query_count_messages (query);
+	unsigned msg_count;
+
+	status = notmuch_query_count_messages_st (query, &msg_count);
+	if (status)
+	    goto DONE;
+
+	total += msg_count;
 	notmuch_query_destroy (query);
     }
     if (new_features & NOTMUCH_FEATURE_DIRECTORY_DOCS) {
diff --git a/lib/notmuch.h b/lib/notmuch.h
index 3e326bf..a0fc276 100644
--- a/lib/notmuch.h
+++ b/lib/notmuch.h
@@ -914,12 +914,23 @@ notmuch_threads_destroy (notmuch_threads_t *threads);
  * This function performs a search and returns Xapian's best
  * guess as to number of matching messages.
  *
- * If a Xapian exception occurs, this function may return 0 (after
- * printing a message).
+ * The version returning the count directly instead of a status value 
+ * is deprecated.
+ *
+ * Return value (of the _st) version:
+ *
+ * NOTMUCH_STATUS_SUCCESS: query complete successfully.
+ *
+ * NOTMUCH_STATUS_XAPIAN_EXCEPTION: a Xapian exception occured. The
+ *      value of *count is not defined.
  */
+
 unsigned
 notmuch_query_count_messages (notmuch_query_t *query);
 
+notmuch_status_t
+notmuch_query_count_messages_st (notmuch_query_t *query, unsigned *count);
+
 /**
  * Return the number of threads matching a search.
  *
@@ -928,13 +939,28 @@ notmuch_query_count_messages (notmuch_query_t *query);
  * search.
  *
  * Note that this is a significantly heavier operation than
- * notmuch_query_count_messages().
+ * notmuch_query_count_messages{_st}().
+ *
+ * The version returning the count directly instead of a status value 
+ * is deprecated.
  *
- * If an error occurs, this function may return 0.
+ * Return values (of the _st version):
+ *
+ * NOTMUCH_STATUS_OUT_OF_MEMORY: Memory allocation failed. The value
+ *      of *count is not defined
+
+ * NOTMUCH_STATUS_SUCCESS: query complete successfully.
+ *
+ * NOTMUCH_STATUS_XAPIAN_EXCEPTION: a Xapian exception occured. The
+ *      value of *count is not defined.
  */
+
 unsigned
 notmuch_query_count_threads (notmuch_query_t *query);
 
+notmuch_status_t
+notmuch_query_count_threads_st (notmuch_query_t *query, unsigned *count);
+
 /**
  * Get the thread ID of 'thread'.
  *
diff --git a/lib/query.cc b/lib/query.cc
index 9279915..883d128 100644
--- a/lib/query.cc
+++ b/lib/query.cc
@@ -541,6 +541,16 @@ notmuch_threads_destroy (notmuch_threads_t *threads)
 unsigned
 notmuch_query_count_messages (notmuch_query_t *query)
 {
+    notmuch_status_t status;
+    unsigned count;
+
+    status = notmuch_query_count_messages_st (query, &count);
+    return status ? 0 : count;
+}
+
+notmuch_status_t
+notmuch_query_count_messages_st (notmuch_query_t *query, unsigned *count_out)
+{
     notmuch_database_t *notmuch = query->notmuch;
     const char *query_string = query->query_string;
     Xapian::doccount count = 0;
@@ -595,30 +605,42 @@ notmuch_query_count_messages (notmuch_query_t *query)
 	fprintf (stderr, "A Xapian exception occurred: %s\n",
 		 error.get_msg().c_str());
 	fprintf (stderr, "Query string was: %s\n", query->query_string);
+	return NOTMUCH_STATUS_XAPIAN_EXCEPTION;
     }
 
-    return count;
+    *count_out=count;
+    return NOTMUCH_STATUS_SUCCESS;
 }
 
 unsigned
 notmuch_query_count_threads (notmuch_query_t *query)
 {
+    notmuch_status_t status;
+    unsigned count;
+
+    status = notmuch_query_count_threads_st (query, &count);
+    return status ? 0 : count;
+}
+    
+notmuch_status_t
+notmuch_query_count_threads_st (notmuch_query_t *query, unsigned *count)
+{
     notmuch_messages_t *messages;
     GHashTable *hash;
-    unsigned int count;
     notmuch_sort_t sort;
+    notmuch_status_t ret = NOTMUCH_STATUS_SUCCESS;
 
     sort = query->sort;
     query->sort = NOTMUCH_SORT_UNSORTED;
     messages = notmuch_query_search_messages (query);
     query->sort = sort;
     if (messages == NULL)
-	return 0;
+	return NOTMUCH_STATUS_XAPIAN_EXCEPTION;
 
     hash = g_hash_table_new_full (g_str_hash, g_str_equal, NULL, NULL);
     if (hash == NULL) {
 	talloc_free (messages);
-	return 0;
+	return NOTMUCH_STATUS_OUT_OF_MEMORY;
     }
 
     while (notmuch_messages_valid (messages)) {
@@ -627,7 +649,7 @@ notmuch_query_count_threads (notmuch_query_t *query)
 	char *thread_id_copy = talloc_strdup (messages, thread_id);
 	if (unlikely (thread_id_copy == NULL)) {
 	    notmuch_message_destroy (message);
-	    count = 0;
+	    ret = NOTMUCH_STATUS_OUT_OF_MEMORY;
 	    goto DONE;
 	}
 	g_hash_table_insert (hash, thread_id_copy, NULL);
@@ -635,11 +657,11 @@ notmuch_query_count_threads (notmuch_query_t *query)
 	notmuch_messages_move_to_next (messages);
     }
 
-    count = g_hash_table_size (hash);
+    *count = g_hash_table_size (hash);
 
   DONE:
     g_hash_table_unref (hash);
     talloc_free (messages);
 
-    return count;
+    return ret;
 }
-- 
2.1.4