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/*
* Asterisk -- An open source telephony toolkit.
*
* Copyright (C) 2013, Digium, Inc.
*
* David M. Lee, II <dlee@digium.com>
*
* See http://www.asterisk.org for more information about
* the Asterisk project. Please do not directly contact
* any of the maintainers of this project for assistance;
* the project provides a web site, mailing lists and IRC
* channels for your use.
*
* This program is free software, distributed under the terms of
* the GNU General Public License Version 2. See the LICENSE file
* at the top of the source tree.
*/
#ifndef _ASTERISK_STASIS_MESSAGE_ROUTER_H
#define _ASTERISK_STASIS_MESSAGE_ROUTER_H
/*!
* \brief A simplistic router for \ref stasis_message's.
*
* Often times, when subscribing to a topic, one wants to handle different
* message types differently. While one could cascade if/else statements through
* the subscription handler, it is much cleaner to specify a different callback
* for each message type. The \ref stasis_message_router is here to help!
*
* A \ref stasis_message_router is constructed for a particular \ref
* stasis_topic, which is subscribes to. Call
* stasis_message_router_unsubscribe() to cancel that subscription.
*
* Once constructed, routes can be added using stasis_message_router_add() (or
* stasis_message_router_set_default() for any messages not handled by other
* routes). There may be only one route per \ref stasis_message_type. The
* route's \a callback is invoked just as if it were a callback for a
* subscription; but it only gets called for messages of the specified type.
*
* \since 12
*/
#include "asterisk/stasis.h"
/*! \brief Stasis message routing object */
struct stasis_message_router;
/*!
* \brief Create a new message router object.
*
* \param topic Topic to subscribe route to.
*
* \return New \ref stasis_message_router.
* \return \c NULL on error.
*
* \since 12
*/
struct stasis_message_router *stasis_message_router_create(
struct stasis_topic *topic);
/*!
* \brief Create a new message router object.
*
* The subscription created for this message router will dispatch
* callbacks on a thread pool.
*
* \param topic Topic to subscribe route to.
*
* \return New \ref stasis_message_router.
* \return \c NULL on error.
*
* \since 12.8.0
*/
struct stasis_message_router *stasis_message_router_create_pool(
struct stasis_topic *topic);
/*!
* \brief Unsubscribe the router from the upstream topic.
*
* \param router Router to unsubscribe.
*
* \since 12
*/
void stasis_message_router_unsubscribe(struct stasis_message_router *router);
/*!
* \brief Unsubscribe the router from the upstream topic, blocking until the
* final message has been processed.
*
* See stasis_unsubscribe_and_join() for info on when to use this
* vs. stasis_message_router_unsubscribe().
*
* \param router Router to unsubscribe.
*
* \since 12
*/
void stasis_message_router_unsubscribe_and_join(
struct stasis_message_router *router);
/*!
* \brief Returns whether \a router has received its final message.
*
* \param router Router.
*
* \return True (non-zero) if stasis_subscription_final_message() has been
* received.
* \return False (zero) if waiting for the end.
*/
int stasis_message_router_is_done(struct stasis_message_router *router);
/*!
* \brief Publish a message to a message router's subscription synchronously
*
* \param router Router
* \param message The \ref stasis message
*
* This should be used when a message needs to be published synchronously to
* the underlying subscription created by a message router. This is analagous
* to \ref stasis_publish_sync.
*
* Note that the caller will be blocked until the thread servicing the message
* on the message router's subscription completes handling of the message.
*
* \since 12.1.0
*/
void stasis_message_router_publish_sync(struct stasis_message_router *router,
struct stasis_message *message);
/*!
* \brief Set the high and low alert water marks of the stasis message router.
* \since 13.10.0
*
* \param router Pointer to a stasis message router
* \param low_water New queue low water mark. (-1 to set as 90% of high_water)
* \param high_water New queue high water mark.
*
* \retval 0 on success.
* \retval -1 on error (water marks not changed).
*/
int stasis_message_router_set_congestion_limits(struct stasis_message_router *router,
long low_water, long high_water);
/*!
* \brief Add a route to a message router.
*
* A particular \a message_type may have at most one route per \a router. If
* you route \ref stasis_cache_update messages, the callback will only receive
* updates for types not handled by routes added with
* stasis_message_router_add_cache_update().
*
* Adding multiple routes for the same message type results in undefined
* behavior.
*
* \param router Router to add the route to.
* \param message_type Type of message to route.
* \param callback Callback to forard messages of \a message_type to.
* \param data Data pointer to pass to \a callback.
*
* \retval 0 on success
* \retval -1 on failure
*
* \since 12
*/
int stasis_message_router_add(struct stasis_message_router *router,
struct stasis_message_type *message_type,
stasis_subscription_cb callback, void *data);
/*!
* \brief Add a route for \ref stasis_cache_update messages to a message router.
*
* A particular \a message_type may have at most one cache route per \a router.
* These are distinct from regular routes, so one could have both a regular
* route and a cache route for the same \a message_type.
*
* Adding multiple routes for the same message type results in undefined
* behavior.
*
* \param router Router to add the route to.
* \param message_type Subtype of cache update to route.
* \param callback Callback to forard messages of \a message_type to.
* \param data Data pointer to pass to \a callback.
*
* \retval 0 on success
* \retval -1 on failure
*
* \since 12
*/
int stasis_message_router_add_cache_update(struct stasis_message_router *router,
struct stasis_message_type *message_type,
stasis_subscription_cb callback, void *data);
/*!
* \brief Remove a route from a message router.
*
* If a route is removed from another thread, there is no notification that
* all messages using this route have been processed. This typically means that
* the associated \c data pointer for this route must be kept until the
* route itself is disposed of.
*
* \param router Router to remove the route from.
* \param message_type Type of message to route.
*
* \since 12
*/
void stasis_message_router_remove(struct stasis_message_router *router,
struct stasis_message_type *message_type);
/*!
* \brief Remove a cache route from a message router.
*
* If a route is removed from another thread, there is no notification that
* all messages using this route have been processed. This typically means that
* the associated \c data pointer for this route must be kept until the
* route itself is disposed of.
*
* \param router Router to remove the route from.
* \param message_type Type of message to route.
*
* \since 12
*/
void stasis_message_router_remove_cache_update(
struct stasis_message_router *router,
struct stasis_message_type *message_type);
/*!
* \brief Sets the default route of a router.
*
* \param router Router to set the default route of.
* \param callback Callback to forard messages which otherwise have no home.
* \param data Data pointer to pass to \a callback.
*
* \retval 0 on success
* \retval -1 on failure
*
* \since 12
*/
int stasis_message_router_set_default(struct stasis_message_router *router,
stasis_subscription_cb callback,
void *data);
#endif /* _ASTERISK_STASIS_MESSAGE_ROUTER_H */
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