1#ifndef foocontexthfoo
2#define foocontexthfoo
3
4/***
5 This file is part of PulseAudio.
6
7 Copyright 2004-2006 Lennart Poettering
8 Copyright 2006 Pierre Ossman <ossman@cendio.se> for Cendio AB
9
10 PulseAudio is free software; you can redistribute it and/or modify
11 it under the terms of the GNU Lesser General Public License as published
12 by the Free Software Foundation; either version 2.1 of the License,
13 or (at your option) any later version.
14
15 PulseAudio is distributed in the hope that it will be useful, but
16 WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 General Public License for more details.
19
20 You should have received a copy of the GNU Lesser General Public License
21 along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.
22***/
23
24#include <pulse/sample.h>
25#include <pulse/def.h>
26#include <pulse/mainloop-api.h>
27#include <pulse/cdecl.h>
28#include <pulse/operation.h>
29#include <pulse/proplist.h>
30#include <pulse/version.h>
31
32/** \page async Asynchronous API
33 *
34 * \section overv_sec Overview
35 *
36 * The asynchronous API is the native interface to the PulseAudio library.
37 * It allows full access to all available functionality. This however means that
38 * it is rather complex and can take some time to fully master.
39 *
40 * \section mainloop_sec Main Loop Abstraction
41 *
42 * The API is based around an asynchronous event loop, or main loop,
43 * abstraction. This abstraction contains three basic elements:
44 *
45 * \li Deferred events - Events that will trigger as soon as possible. Note
46 * that some implementations may block all other events
47 * when a deferred event is active.
48 * \li I/O events - Events that trigger on file descriptor activities.
49 * \li Timer events - Events that trigger after a fixed amount of time.
50 *
51 * The abstraction is represented as a number of function pointers in the
52 * pa_mainloop_api structure.
53 *
54 * To actually be able to use these functions, an implementation needs to
55 * be coupled to the abstraction. There are three of these shipped with
56 * PulseAudio, but any other can be used with a minimal amount of work,
57 * provided it supports the three basic events listed above.
58 *
59 * The implementations shipped with PulseAudio are:
60 *
61 * \li \subpage mainloop - A minimal but fast implementation based on poll().
62 * \li \subpage threaded_mainloop - A special version of the previous
63 * implementation where all of PulseAudio's
64 * internal handling runs in a separate
65 * thread.
66 * \li \subpage glib-mainloop - A wrapper around GLib's main loop.
67 *
68 * UNIX signals may be hooked to a main loop using the functions from
69 * \ref mainloop-signal.h. These rely only on the main loop abstraction
70 * and can therefore be used with any of the implementations.
71 *
72 * \section refcnt_sec Reference Counting
73 *
74 * Almost all objects in PulseAudio are reference counted. What that means
75 * is that you rarely malloc() or free() any objects. Instead you increase
76 * and decrease their reference counts. Whenever an object's reference
77 * count reaches zero, that object gets destroy and any resources it uses
78 * get freed.
79 *
80 * The benefit of this design is that an application need not worry about
81 * whether or not it needs to keep an object around in case the library is
82 * using it internally. If it is, then it has made sure it has its own
83 * reference to it.
84 *
85 * Whenever the library creates an object, it will have an initial
86 * reference count of one. Most of the time, this single reference will be
87 * sufficient for the application, so all required reference count
88 * interaction will be a single call to the object's unref function.
89 *
90 * \section context_sec Context
91 *
92 * A context is the basic object for a connection to a PulseAudio server.
93 * It multiplexes commands, data streams and events through a single
94 * channel.
95 *
96 * There is no need for more than one context per application, unless
97 * connections to multiple servers are needed.
98 *
99 * \subsection ops_subsec Operations
100 *
101 * All operations on the context are performed asynchronously. I.e. the
102 * client will not wait for the server to complete the request. To keep
103 * track of all these in-flight operations, the application is given a
104 * pa_operation object for each asynchronous operation.
105 *
106 * There are only two actions (besides reference counting) that can be
107 * performed on a pa_operation: querying its state with
108 * pa_operation_get_state() and aborting it with pa_operation_cancel().
109 *
110 * A pa_operation object is reference counted, so an application must
111 * make sure to unreference it, even if it has no intention of using it.
112 *
113 * \subsection conn_subsec Connecting
114 *
115 * A context must be connected to a server before any operation can be
116 * issued. Calling pa_context_connect() will initiate the connection
117 * procedure. Unlike most asynchronous operations, connecting does not
118 * result in a pa_operation object. Instead, the application should
119 * register a callback using pa_context_set_state_callback().
120 *
121 * \subsection disc_subsec Disconnecting
122 *
123 * When the sound support is no longer needed, the connection needs to be
124 * closed using pa_context_disconnect(). This is an immediate function that
125 * works synchronously.
126 *
127 * Since the context object has references to other objects it must be
128 * disconnected after use or there is a high risk of memory leaks. If the
129 * connection has terminated by itself, then there is no need to explicitly
130 * disconnect the context using pa_context_disconnect().
131 *
132 * \section Functions
133 *
134 * The sound server's functionality can be divided into a number of
135 * subsections:
136 *
137 * \li \subpage streams
138 * \li \subpage scache
139 * \li \subpage introspect
140 * \li \subpage subscribe
141 */
142
143/** \file
144 * Connection contexts for asynchronous communication with a
145 * server. A pa_context object wraps a connection to a PulseAudio
146 * server using its native protocol.
147 *
148 * See also \subpage async
149 */
150
151PA_C_DECL_BEGIN
152
153/** An opaque connection context to a daemon */
154typedef struct pa_context pa_context;
155
156/** Generic notification callback prototype */
157typedef void (*pa_context_notify_cb_t)(pa_context *c, void *userdata);
158
159/** A generic callback for operation completion */
160typedef void (*pa_context_success_cb_t) (pa_context *c, int success, void *userdata);
161
162/** A callback for asynchronous meta/policy event messages. The set
163 * of defined events can be extended at any time. Also, server modules
164 * may introduce additional message types so make sure that your
165 * callback function ignores messages it doesn't know. \since
166 * 0.9.15 */
167typedef void (*pa_context_event_cb_t)(pa_context *c, const char *name, pa_proplist *p, void *userdata);
168
169/** Instantiate a new connection context with an abstract mainloop API
170 * and an application name. It is recommended to use pa_context_new_with_proplist()
171 * instead and specify some initial properties.*/
172pa_context *pa_context_new(pa_mainloop_api *mainloop, const char *name);
173
174/** Instantiate a new connection context with an abstract mainloop API
175 * and an application name, and specify the initial client property
176 * list. \since 0.9.11 */
177pa_context *pa_context_new_with_proplist(pa_mainloop_api *mainloop, const char *name, const pa_proplist *proplist);
178
179/** Decrease the reference counter of the context by one */
180void pa_context_unref(pa_context *c);
181
182/** Increase the reference counter of the context by one */
183pa_context* pa_context_ref(pa_context *c);
184
185/** Set a callback function that is called whenever the context status changes */
186void pa_context_set_state_callback(pa_context *c, pa_context_notify_cb_t cb, void *userdata);
187
188/** Set a callback function that is called whenever a meta/policy
189 * control event is received. \since 0.9.15 */
190void pa_context_set_event_callback(pa_context *p, pa_context_event_cb_t cb, void *userdata);
191
192/** Return the error number of the last failed operation */
193int pa_context_errno(const pa_context *c);
194
195/** Return non-zero if some data is pending to be written to the connection */
196int pa_context_is_pending(const pa_context *c);
197
198/** Return the current context status */
199pa_context_state_t pa_context_get_state(const pa_context *c);
200
201/** Connect the context to the specified server. If server is NULL,
202 * connect to the default server. This routine may but will not always
203 * return synchronously on error. Use pa_context_set_state_callback() to
204 * be notified when the connection is established. If flags doesn't have
205 * PA_CONTEXT_NOAUTOSPAWN set and no specific server is specified or
206 * accessible a new daemon is spawned. If api is non-NULL, the functions
207 * specified in the structure are used when forking a new child
208 * process. Returns negative on certain errors such as invalid state
209 * or parameters. */
210int pa_context_connect(pa_context *c, const char *server, pa_context_flags_t flags, const pa_spawn_api *api);
211
212/** Terminate the context connection immediately */
213void pa_context_disconnect(pa_context *c);
214
215/** Drain the context. If there is nothing to drain, the function returns NULL */
216pa_operation* pa_context_drain(pa_context *c, pa_context_notify_cb_t cb, void *userdata);
217
218/** Tell the daemon to exit. The returned operation is unlikely to
219 * complete successfully, since the daemon probably died before
220 * returning a success notification */
221pa_operation* pa_context_exit_daemon(pa_context *c, pa_context_success_cb_t cb, void *userdata);
222
223/** Set the name of the default sink. */
224pa_operation* pa_context_set_default_sink(pa_context *c, const char *name, pa_context_success_cb_t cb, void *userdata);
225
226/** Set the name of the default source. */
227pa_operation* pa_context_set_default_source(pa_context *c, const char *name, pa_context_success_cb_t cb, void *userdata);
228
229/** Returns 1 when the connection is to a local daemon. Returns negative when no connection has been made yet. */
230int pa_context_is_local(const pa_context *c);
231
232/** Set a different application name for context on the server. */
233pa_operation* pa_context_set_name(pa_context *c, const char *name, pa_context_success_cb_t cb, void *userdata);
234
235/** Return the server name this context is connected to. */
236const char* pa_context_get_server(const pa_context *c);
237
238/** Return the protocol version of the library. */
239uint32_t pa_context_get_protocol_version(const pa_context *c);
240
241/** Return the protocol version of the connected server.
242 * Returns PA_INVALID_INDEX on error. */
243uint32_t pa_context_get_server_protocol_version(const pa_context *c);
244
245/** Update the property list of the client, adding new entries. Please
246 * note that it is highly recommended to set as many properties
247 * initially via pa_context_new_with_proplist() as possible instead a
248 * posteriori with this function, since that information may then be
249 * used to route streams of the client to the right device. \since 0.9.11 */
250pa_operation *pa_context_proplist_update(pa_context *c, pa_update_mode_t mode, const pa_proplist *p, pa_context_success_cb_t cb, void *userdata);
251
252/** Update the property list of the client, remove entries. \since 0.9.11 */
253pa_operation *pa_context_proplist_remove(pa_context *c, const char *const keys[], pa_context_success_cb_t cb, void *userdata);
254
255/** Return the client index this context is
256 * identified in the server with. This is useful for usage with the
257 * introspection functions, such as pa_context_get_client_info().
258 * Returns PA_INVALID_INDEX on error. \since 0.9.11 */
259uint32_t pa_context_get_index(const pa_context *s);
260
261/** Create a new timer event source for the specified time (wrapper
262 * for mainloop->time_new). \since 0.9.16 */
263pa_time_event* pa_context_rttime_new(const pa_context *c, pa_usec_t usec, pa_time_event_cb_t cb, void *userdata);
264
265/** Restart a running or expired timer event source (wrapper for
266 * mainloop->time_restart). \since 0.9.16 */
267void pa_context_rttime_restart(const pa_context *c, pa_time_event *e, pa_usec_t usec);
268
269/** Return the optimal block size for passing around audio buffers. It
270 * is recommended to allocate buffers of the size returned here when
271 * writing audio data to playback streams, if the latency constraints
272 * permit this. It is not recommended writing larger blocks than this
273 * because usually they will then be split up internally into chunks
274 * of this size. It is not recommended writing smaller blocks than
275 * this (unless required due to latency demands) because this
276 * increases CPU usage. If ss is NULL you will be returned the
277 * byte-exact tile size. if ss is invalid, (size_t) -1 will be
278 * returned. If you pass a valid ss, then the tile size
279 * will be rounded down to multiple of the frame size. This is
280 * supposed to be used in a construct such as
281 * pa_context_get_tile_size(pa_stream_get_context(s),
282 * pa_stream_get_sample_spec(ss)); \since 0.9.20 */
283size_t pa_context_get_tile_size(const pa_context *c, const pa_sample_spec *ss);
284
285/** Load the authentication cookie from a file. This function is primarily
286 * meant for PulseAudio's own tunnel modules, which need to load the cookie
287 * from a custom location. Applications don't usually need to care about the
288 * cookie at all, but if it happens that you know what the authentication
289 * cookie is and your application needs to load it from a non-standard
290 * location, feel free to use this function. \since 5.0 */
291int pa_context_load_cookie_from_file(pa_context *c, const char *cookie_file_path);
292
293PA_C_DECL_END
294
295#endif
296

source code of include/pulse/context.h