|author||Lennart Poettering <firstname.lastname@example.org>||2006-06-19 21:53:48 +0000|
|committer||Lennart Poettering <email@example.com>||2006-06-19 21:53:48 +0000|
git-svn-id: file:///home/lennart/svn/public/pulseaudio/trunk@1033 fefdeb5f-60dc-0310-8127-8f9354f1896f
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+/* $Id$ */
+ This file is part of PulseAudio.
+ PulseAudio is free software; you can redistribute it and/or modify
+ it under the terms of the GNU Lesser General Public License as published
+ by the Free Software Foundation; either version 2 of the License,
+ or (at your option) any later version.
+ PulseAudio 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 Lesser General Public License
+ along with PulseAudio; if not, write to the Free Software
+ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+/** \page async Asynchronous API
+ * \section overv_sec Overview
+ * The asynchronous API is the native interface to the pulseaudio library.
+ * It allows full access to all available functions. This also means that
+ * it is rather complex and can take some time to fully master.
+ * \section mainloop_sec Main Loop Abstraction
+ * The API is based around an asynchronous event loop, or main loop,
+ * abstraction. This abstraction contains three basic elements:
+ * \li Deferred events - Events that will trigger as soon as possible. Note
+ * that some implementations may block all other events
+ * when a deferred event is active.
+ * \li I/O events - Events that trigger on file descriptor activities.
+ * \li Times events - Events that trigger after a fixed ammount of time.
+ * The abstraction is represented as a number of function pointers in the
+ * pa_mainloop_api structure.
+ * To actually be able to use these functions, an implementation needs to
+ * be coupled to the abstraction. There are three of these shipped with
+ * pulseaudio, but any other can be used with a minimal ammount of work,
+ * provided it supports the three basic events listed above.
+ * The implementations shipped with pulseaudio are:
+ * \li \subpage mainloop - A minimal but fast implementation based on poll().
+ * \li \subpage threaded_mainloop - A special version of the previous
+ * implementation where all of Polypaudio's
+ * internal handling runs in a separate
+ * thread.
+ * \li \subpage glib-mainloop - A wrapper around GLIB's main loop. Available
+ * for both GLIB 1.2 and GLIB 2.x.
+ * UNIX signals may be hooked to a main loop using the functions from
+ * \ref mainloop-signal.h. These rely only on the main loop abstraction
+ * and can therefore be used with any of the implementations.
+ * \section refcnt_sec Reference Counting
+ * Almost all objects in pulseaudio are reference counted. What that means
+ * is that you rarely malloc() or free() any objects. Instead you increase
+ * and decrease their reference counts. Whenever an object's reference
+ * count reaches zero, that object gets destroy and any resources it uses
+ * get freed.
+ * The benefit of this design is that an application need not worry about
+ * whether or not it needs to keep an object around in case the library is
+ * using it internally. If it is, then it has made sure it has its own
+ * reference to it.
+ * Whenever the library creates an object, it will have an initial
+ * reference count of one. Most of the time, this single reference will be
+ * sufficient for the application, so all required reference count
+ * interaction will be a single call to the objects unref function.
+ * \section context_sec Context
+ * A context is the basic object for a connection to a pulseaudio server.
+ * It multiplexes commands, data streams and events through a single
+ * channel.
+ * There is no need for more than one context per application, unless
+ * connections to multiple servers are needed.
+ * \subsection ops_subsec Operations
+ * All operations on the context are performed asynchronously. I.e. the
+ * client will not wait for the server to complete the request. To keep
+ * track of all these in-flight operations, the application is given a
+ * pa_operation object for each asynchronous operation.
+ * There are only two actions (besides reference counting) that can be
+ * performed on a pa_operation: querying its state with
+ * pa_operation_get_state() and aborting it with pa_operation_cancel().
+ * A pa_operation object is reference counted, so an application must
+ * make sure to unreference it, even if it has no intention of using it.
+ * \subsection conn_subsec Connecting
+ * A context must be connected to a server before any operation can be
+ * issued. Calling pa_context_connect() will initiate the connection
+ * procedure. Unlike most asynchronous operations, connecting does not
+ * result in a pa_operation object. Instead, the application should
+ * register a callback using pa_context_set_state_callback().
+ * \subsection disc_subsec Disconnecting
+ * When the sound support is no longer needed, the connection needs to be
+ * closed using pa_context_disconnect(). This is an immediate function that
+ * works synchronously.
+ * Since the context object has references to other objects it must be
+ * disconnected after use or there is a high risk of memory leaks. If the
+ * connection has terminated by itself, then there is no need to explicitly
+ * disconnect the context using pa_context_disconnect().
+ * \section Functions
+ * The sound server's functionality can be divided into a number of
+ * subsections:
+ * \li \subpage streams
+ * \li \subpage scache
+ * \li \subpage introspect
+ * \li \subpage subscribe
+ * Connection contexts for asynchrononous communication with a
+ * server. A pa_context object wraps a connection to a pulseaudio
+ * server using its native protocol. */
+/** \example pacat.c
+ * A playback and recording tool using the asynchronous API */
+/** \example paplay.c
+ * A sound file playback tool using the asynchronous API, based on libsndfile */
+/** An opaque connection context to a daemon */
+typedef struct pa_context pa_context;
+/** Generic notification callback prototype */
+typedef void (*pa_context_notify_cb_t)(pa_context *c, void *userdata);
+/** A generic callback for operation completion */
+typedef void (*pa_context_success_cb_t) (pa_context *c, int success, void *userdata);
+/** Instantiate a new connection context with an abstract mainloop API
+ * and an application name */
+pa_context *pa_context_new(pa_mainloop_api *mainloop, const char *name);
+/** Decrease the reference counter of the context by one */
+void pa_context_unref(pa_context *c);
+/** Increase the reference counter of the context by one */
+pa_context* pa_context_ref(pa_context *c);
+/** Set a callback function that is called whenever the context status changes */
+void pa_context_set_state_callback(pa_context *c, pa_context_notify_cb_t cb, void *userdata);
+/** Return the error number of the last failed operation */
+int pa_context_errno(pa_context *c);
+/** Return non-zero if some data is pending to be written to the connection */
+int pa_context_is_pending(pa_context *c);
+/** Return the current context status */
+pa_context_state_t pa_context_get_state(pa_context *c);
+/** Connect the context to the specified server. If server is NULL,
+connect to the default server. This routine may but will not always
+return synchronously on error. Use pa_context_set_state_callback() to
+be notified when the connection is established. If flags doesn't have
+PA_NOAUTOSPAWN set and no specific server is specified or accessible a
+new daemon is spawned. If api is non-NULL, the functions specified in
+the structure are used when forking a new child process. */
+int pa_context_connect(pa_context *c, const char *server, pa_context_flags_t flags, const pa_spawn_api *api);
+/** Terminate the context connection immediately */
+void pa_context_disconnect(pa_context *c);
+/** Drain the context. If there is nothing to drain, the function returns NULL */
+pa_operation* pa_context_drain(pa_context *c, pa_context_notify_cb_t cb, void *userdata);
+/** Tell the daemon to exit. The returned operation is unlikely to
+ * complete succesfully, since the daemon probably died before
+ * returning a success notification */
+pa_operation* pa_context_exit_daemon(pa_context *c, pa_context_success_cb_t cb, void *userdata);
+/** Set the name of the default sink. \since 0.4 */
+pa_operation* pa_context_set_default_sink(pa_context *c, const char *name, pa_context_success_cb_t cb, void *userdata);
+/** Set the name of the default source. \since 0.4 */
+pa_operation* pa_context_set_default_source(pa_context *c, const char *name, pa_context_success_cb_t cb, void *userdata);
+/** Returns 1 when the connection is to a local daemon. Returns negative when no connection has been made yet. \since 0.5 */
+int pa_context_is_local(pa_context *c);
+/** Set a different application name for context on the server. \since 0.5 */
+pa_operation* pa_context_set_name(pa_context *c, const char *name, pa_context_success_cb_t cb, void *userdata);
+/** Return the server name this context is connected to. \since 0.7 */
+const char* pa_context_get_server(pa_context *c);
+/** Return the protocol version of the library. \since 0.8 */
+uint32_t pa_context_get_protocol_version(pa_context *c);
+/** Return the protocol version of the connected server. \since 0.8 */
+uint32_t pa_context_get_server_protocol_version(pa_context *c);