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 (at) 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, write to the Free Software 22 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 23 USA. 24 ***/ 25 26 #include <pulse/sample.h> 27 #include <pulse/def.h> 28 #include <pulse/mainloop-api.h> 29 #include <pulse/cdecl.h> 30 #include <pulse/operation.h> 31 #include <pulse/proplist.h> 32 #include <pulse/version.h> 33 34 /** \page async Asynchronous API 35 * 36 * \section overv_sec Overview 37 * 38 * The asynchronous API is the native interface to the PulseAudio library. 39 * It allows full access to all available functionality. This however means that 40 * it is rather complex and can take some time to fully master. 41 * 42 * \section mainloop_sec Main Loop Abstraction 43 * 44 * The API is based around an asynchronous event loop, or main loop, 45 * abstraction. This abstraction contains three basic elements: 46 * 47 * \li Deferred events - Events that will trigger as soon as possible. Note 48 * that some implementations may block all other events 49 * when a deferred event is active. 50 * \li I/O events - Events that trigger on file descriptor activities. 51 * \li Times events - Events that trigger after a fixed amount of time. 52 * 53 * The abstraction is represented as a number of function pointers in the 54 * pa_mainloop_api structure. 55 * 56 * To actually be able to use these functions, an implementation needs to 57 * be coupled to the abstraction. There are three of these shipped with 58 * PulseAudio, but any other can be used with a minimal amount of work, 59 * provided it supports the three basic events listed above. 60 * 61 * The implementations shipped with PulseAudio are: 62 * 63 * \li \subpage mainloop - A minimal but fast implementation based on poll(). 64 * \li \subpage threaded_mainloop - A special version of the previous 65 * implementation where all of PulseAudio's 66 * internal handling runs in a separate 67 * thread. 68 * \li \subpage glib-mainloop - A wrapper around GLib's main loop. 69 * 70 * UNIX signals may be hooked to a main loop using the functions from 71 * \ref mainloop-signal.h. These rely only on the main loop abstraction 72 * and can therefore be used with any of the implementations. 73 * 74 * \section refcnt_sec Reference Counting 75 * 76 * Almost all objects in PulseAudio are reference counted. What that means 77 * is that you rarely malloc() or free() any objects. Instead you increase 78 * and decrease their reference counts. Whenever an object's reference 79 * count reaches zero, that object gets destroy and any resources it uses 80 * get freed. 81 * 82 * The benefit of this design is that an application need not worry about 83 * whether or not it needs to keep an object around in case the library is 84 * using it internally. If it is, then it has made sure it has its own 85 * reference to it. 86 * 87 * Whenever the library creates an object, it will have an initial 88 * reference count of one. Most of the time, this single reference will be 89 * sufficient for the application, so all required reference count 90 * interaction will be a single call to the objects unref function. 91 * 92 * \section context_sec Context 93 * 94 * A context is the basic object for a connection to a PulseAudio server. 95 * It multiplexes commands, data streams and events through a single 96 * channel. 97 * 98 * There is no need for more than one context per application, unless 99 * connections to multiple servers are needed. 100 * 101 * \subsection ops_subsec Operations 102 * 103 * All operations on the context are performed asynchronously. I.e. the 104 * client will not wait for the server to complete the request. To keep 105 * track of all these in-flight operations, the application is given a 106 * pa_operation object for each asynchronous operation. 107 * 108 * There are only two actions (besides reference counting) that can be 109 * performed on a pa_operation: querying its state with 110 * pa_operation_get_state() and aborting it with pa_operation_cancel(). 111 * 112 * A pa_operation object is reference counted, so an application must 113 * make sure to unreference it, even if it has no intention of using it. 114 * 115 * \subsection conn_subsec Connecting 116 * 117 * A context must be connected to a server before any operation can be 118 * issued. Calling pa_context_connect() will initiate the connection 119 * procedure. Unlike most asynchronous operations, connecting does not 120 * result in a pa_operation object. Instead, the application should 121 * register a callback using pa_context_set_state_callback(). 122 * 123 * \subsection disc_subsec Disconnecting 124 * 125 * When the sound support is no longer needed, the connection needs to be 126 * closed using pa_context_disconnect(). This is an immediate function that 127 * works synchronously. 128 * 129 * Since the context object has references to other objects it must be 130 * disconnected after use or there is a high risk of memory leaks. If the 131 * connection has terminated by itself, then there is no need to explicitly 132 * disconnect the context using pa_context_disconnect(). 133 * 134 * \section Functions 135 * 136 * The sound server's functionality can be divided into a number of 137 * subsections: 138 * 139 * \li \subpage streams 140 * \li \subpage scache 141 * \li \subpage introspect 142 * \li \subpage subscribe 143 */ 144 145 /** \file 146 * Connection contexts for asynchronous communication with a 147 * server. A pa_context object wraps a connection to a PulseAudio 148 * server using its native protocol. 149 * 150 * See also \subpage async 151 */ 152 153 PA_C_DECL_BEGIN 154 155 /** An opaque connection context to a daemon */ 156 typedef struct pa_context pa_context; 157 158 /** Generic notification callback prototype */ 159 typedef void (*pa_context_notify_cb_t)(pa_context *c, void *userdata); 160 161 /** A generic callback for operation completion */ 162 typedef void (*pa_context_success_cb_t) (pa_context *c, int success, void *userdata); 163 164 /** A callback for asynchronous meta/policy event messages. The set 165 * of defined events can be extended at any time. Also, server modules 166 * may introduce additional message types so make sure that your 167 * callback function ignores messages it doesn't know. \since 168 * 0.9.15 */ 169 typedef void (*pa_context_event_cb_t)(pa_context *c, const char *name, pa_proplist *p, void *userdata); 170 171 /** Instantiate a new connection context with an abstract mainloop API 172 * and an application name. It is recommended to use pa_context_new_with_proplist() 173 * instead and specify some initial properties.*/ 174 pa_context *pa_context_new(pa_mainloop_api *mainloop, const char *name); 175 176 /** Instantiate a new connection context with an abstract mainloop API 177 * and an application name, and specify the the initial client property 178 * list. \since 0.9.11 */ 179 pa_context *pa_context_new_with_proplist(pa_mainloop_api *mainloop, const char *name, pa_proplist *proplist); 180 181 /** Decrease the reference counter of the context by one */ 182 void pa_context_unref(pa_context *c); 183 184 /** Increase the reference counter of the context by one */ 185 pa_context* pa_context_ref(pa_context *c); 186 187 /** Set a callback function that is called whenever the context status changes */ 188 void pa_context_set_state_callback(pa_context *c, pa_context_notify_cb_t cb, void *userdata); 189 190 /** Set a callback function that is called whenever a meta/policy 191 * control event is received. \since 0.9.15 */ 192 void pa_context_set_event_callback(pa_context *p, pa_context_event_cb_t cb, void *userdata); 193 194 /** Return the error number of the last failed operation */ 195 int pa_context_errno(pa_context *c); 196 197 /** Return non-zero if some data is pending to be written to the connection */ 198 int pa_context_is_pending(pa_context *c); 199 200 /** Return the current context status */ 201 pa_context_state_t pa_context_get_state(pa_context *c); 202 203 /** Connect the context to the specified server. If server is NULL, 204 connect to the default server. This routine may but will not always 205 return synchronously on error. Use pa_context_set_state_callback() to 206 be notified when the connection is established. If flags doesn't have 207 PA_CONTEXT_NOAUTOSPAWN set and no specific server is specified or 208 accessible a new daemon is spawned. If api is non-NULL, the functions 209 specified in the structure are used when forking a new child 210 process. */ 211 int pa_context_connect(pa_context *c, const char *server, pa_context_flags_t flags, const pa_spawn_api *api); 212 213 /** Terminate the context connection immediately */ 214 void pa_context_disconnect(pa_context *c); 215 216 /** Drain the context. If there is nothing to drain, the function returns NULL */ 217 pa_operation* pa_context_drain(pa_context *c, pa_context_notify_cb_t cb, void *userdata); 218 219 /** Tell the daemon to exit. The returned operation is unlikely to 220 * complete successfully, since the daemon probably died before 221 * returning a success notification */ 222 pa_operation* pa_context_exit_daemon(pa_context *c, pa_context_success_cb_t cb, void *userdata); 223 224 /** Set the name of the default sink. */ 225 pa_operation* pa_context_set_default_sink(pa_context *c, const char *name, pa_context_success_cb_t cb, void *userdata); 226 227 /** Set the name of the default source. */ 228 pa_operation* pa_context_set_default_source(pa_context *c, const char *name, pa_context_success_cb_t cb, void *userdata); 229 230 /** Returns 1 when the connection is to a local daemon. Returns negative when no connection has been made yet. */ 231 int pa_context_is_local(pa_context *c); 232 233 /** Set a different application name for context on the server. */ 234 pa_operation* pa_context_set_name(pa_context *c, const char *name, pa_context_success_cb_t cb, void *userdata); 235 236 /** Return the server name this context is connected to. */ 237 const char* pa_context_get_server(pa_context *c); 238 239 /** Return the protocol version of the library. */ 240 uint32_t pa_context_get_protocol_version(pa_context *c); 241 242 /** Return the protocol version of the connected server. */ 243 uint32_t pa_context_get_server_protocol_version(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 much 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 */ 250 pa_operation *pa_context_proplist_update(pa_context *c, pa_update_mode_t mode, 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 */ 253 pa_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(). \since 0.9.11 */ 258 uint32_t pa_context_get_index(pa_context *s); 259 260 /** Create a new timer event source for the specified time (wrapper 261 * for mainloop->time_new). \since 0.9.16 */ 262 pa_time_event* pa_context_rttime_new(pa_context *c, pa_usec_t usec, pa_time_event_cb_t cb, void *userdata); 263 264 /** Restart a running or expired timer event source (wrapper for 265 * mainloop->time_restart). \since 0.9.16 */ 266 void pa_context_rttime_restart(pa_context *c, pa_time_event *e, pa_usec_t usec); 267 268 /** Return the optimal block size for passing around audio buffers. It 269 * is recommended to allocate buffers of the size returned here when 270 * writing audio data to playback streams, if the latency constraints 271 * permit this. It is not recommended writing larger blocks than this 272 * because usually they will then be split up internally into chunks 273 * of this size. It is not recommended writing smaller blocks than 274 * this (unless required due to latency demands) because this 275 * increases CPU usage. If ss is NULL you will be returned the 276 * byte-exact tile size. If you pass a valid ss, then the tile size 277 * will be rounded down to multiple of the frame size. This is 278 * supposed to be used in a construct such as 279 * pa_context_get_tile_size(pa_stream_get_context(s), 280 * pa_stream_get_sample_spec(ss)); \since 0.9.20 */ 281 size_t pa_context_get_tile_size(pa_context *c, const pa_sample_spec *ss); 282 283 PA_C_DECL_END 284 285 #endif 286
