notmuch/lib/messages.c
Carl Worth 70962fabf9 lib/messages.c: Make message searches stream as well.
Xapian provides an interator-based interface to all search results.
So it was natural to make notmuch_messages_t be iterator-based as
well. Which we did originally.

But we ran into a problem when we added two APIs, (_get_replies and
_get_toplevel_messages), that want to return a messages iterator
that's *not* based on a Xapian search result. My original compromise
was to use notmuch_message_list_t as the basis for all returned
messages iterators in the public interface.

This had the problem of introducing extra latency at the beginning
of a search for messages, (the call would block while iterating over
all results from Xapian, converting to a message list).

In this commit, we remove that initial conversion and instead provide
two alternate implementations of notmuch_messages_t (one on top of a
Xapian iterator and one on top of a message list).

With this change, I tested a "notmuch search" returning *many* results
as previously taking about 7 seconds before results started appearing,
and now taking only 2 seconds.
2009-11-24 11:33:09 -08:00

142 lines
3.6 KiB
C

/* messages.c - Iterator for a set of messages
*
* Copyright © 2009 Carl Worth
*
* 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: Carl Worth <cworth@cworth.org>
*/
#include "notmuch-private.h"
/* Create a new notmuch_message_list_t object, with 'ctx' as its
* talloc owner.
*
* This function can return NULL in case of out-of-memory.
*/
notmuch_message_list_t *
_notmuch_message_list_create (const void *ctx)
{
notmuch_message_list_t *list;
list = talloc (ctx, notmuch_message_list_t);
if (unlikely (list == NULL))
return NULL;
list->head = NULL;
list->tail = &list->head;
return list;
}
/* Append 'node' (which can of course point to an arbitrarily long
* list of nodes) to the end of 'list'.
*/
void
_notmuch_message_list_append (notmuch_message_list_t *list,
notmuch_message_node_t *node)
{
*(list->tail) = node;
list->tail = &node->next;
}
/* Allocate a new node for 'message' and append it to the end of
* 'list'.
*/
void
_notmuch_message_list_add_message (notmuch_message_list_t *list,
notmuch_message_t *message)
{
notmuch_message_node_t *node = talloc (list, notmuch_message_node_t);
node->message = message;
node->next = NULL;
_notmuch_message_list_append (list, node);
}
notmuch_messages_t *
_notmuch_messages_create (notmuch_message_list_t *list)
{
notmuch_messages_t *messages;
if (list->head == NULL)
return NULL;
messages = talloc (list, notmuch_messages_t);
if (unlikely (messages == NULL))
return NULL;
messages->is_of_list_type = TRUE;
messages->iterator = list->head;
return messages;
}
/* We're using the "is_of_type_list" to conditionally defer to the
* notmuch_mset_messages_t implementation of notmuch_messages_t in
* query.cc. It's ugly that that's over in query.cc, and it's ugly
* that we're not using a union here. Both of those uglies are due to
* C++:
*
* 1. I didn't want to force a C++ header file onto
* notmuch-private.h and suddenly subject all our code to a
* C++ compiler and its rules.
*
* 2. C++ won't allow me to put C++ objects, (with non-trivial
* constructors) into a union anyway. Even though I'd
* carefully control object construction with placement new
* anyway. *sigh*
*/
notmuch_bool_t
notmuch_messages_has_more (notmuch_messages_t *messages)
{
if (messages == NULL)
return FALSE;
if (! messages->is_of_list_type)
return _notmuch_mset_messages_has_more (messages);
return (messages->iterator != NULL);
}
notmuch_message_t *
notmuch_messages_get (notmuch_messages_t *messages)
{
if (! messages->is_of_list_type)
return _notmuch_mset_messages_get (messages);
if (messages->iterator == NULL)
return NULL;
return messages->iterator->message;
}
void
notmuch_messages_advance (notmuch_messages_t *messages)
{
if (! messages->is_of_list_type)
return _notmuch_mset_messages_advance (messages);
if (messages->iterator == NULL)
return;
messages->iterator = messages->iterator->next;
}
void
notmuch_messages_destroy (notmuch_messages_t *messages)
{
talloc_free (messages);
}