code.delx.au - pulseaudio/blob - src/pulse/context.h

   1 #ifndef foocontexthfoo
   2 #define foocontexthfoo
   3
   4 /* $Id$ */
   5
   6 /***
   7   This file is part of PulseAudio.
   8
   9   Copyright 2004-2006 Lennart Poettering
  10   Copyright 2006 Pierre Ossman <ossman@cendio.se> for Cendio AB
  11
  12   PulseAudio is free software; you can redistribute it and/or modify
  13   it under the terms of the GNU Lesser General Public License as published
  14   by the Free Software Foundation; either version 2 of the License,
  15   or (at your option) any later version.
  16
  17   PulseAudio is distributed in the hope that it will be useful, but
  18   WITHOUT ANY WARRANTY; without even the implied warranty of
  19   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  20   General Public License for more details.
  21
  22   You should have received a copy of the GNU Lesser General Public License
  23   along with PulseAudio; if not, write to the Free Software
  24   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  25   USA.
  26 ***/
  27
  28 #include <pulse/sample.h>
  29 #include <pulse/def.h>
  30 #include <pulse/mainloop-api.h>
  31 #include <pulse/cdecl.h>
  32 #include <pulse/operation.h>
  33 #include <pulse/proplist.h>
  34
  35 /** \page async Asynchronous API
  36  *
  37  * \section overv_sec Overview
  38  *
  39  * The asynchronous API is the native interface to the PulseAudio library.
  40  * It allows full access to all available functions. This also means that
  41  * it is rather complex and can take some time to fully master.
  42  *
  43  * \section mainloop_sec Main Loop Abstraction
  44  *
  45  * The API is based around an asynchronous event loop, or main loop,
  46  * abstraction. This abstraction contains three basic elements:
  47  *
  48  * \li Deferred events - Events that will trigger as soon as possible. Note
  49  *                       that some implementations may block all other events
  50  *                       when a deferred event is active.
  51  * \li I/O events - Events that trigger on file descriptor activities.
  52  * \li Times events - Events that trigger after a fixed ammount of time.
  53  *
  54  * The abstraction is represented as a number of function pointers in the
  55  * pa_mainloop_api structure.
  56  *
  57  * To actually be able to use these functions, an implementation needs to
  58  * be coupled to the abstraction. There are three of these shipped with
  59  * PulseAudio, but any other can be used with a minimal ammount of work,
  60  * provided it supports the three basic events listed above.
  61  *
  62  * The implementations shipped with PulseAudio are:
  63  *
  64  * \li \subpage mainloop - A minimal but fast implementation based on poll().
  65  * \li \subpage threaded_mainloop - A special version of the previous
  66  *                                  implementation where all of PulseAudio's
  67  *                                  internal handling runs in a separate
  68  *                                  thread.
  69  * \li \subpage glib-mainloop - A wrapper around GLIB's main loop. Available
  70  *                              for both GLIB 1.2 and GLIB 2.x.
  71  *
  72  * UNIX signals may be hooked to a main loop using the functions from
  73  * \ref mainloop-signal.h. These rely only on the main loop abstraction
  74  * and can therefore be used with any of the implementations.
  75  *
  76  * \section refcnt_sec Reference Counting
  77  *
  78  * Almost all objects in PulseAudio are reference counted. What that means
  79  * is that you rarely malloc() or free() any objects. Instead you increase
  80  * and decrease their reference counts. Whenever an object's reference
  81  * count reaches zero, that object gets destroy and any resources it uses
  82  * get freed.
  83  *
  84  * The benefit of this design is that an application need not worry about
  85  * whether or not it needs to keep an object around in case the library is
  86  * using it internally. If it is, then it has made sure it has its own
  87  * reference to it.
  88  *
  89  * Whenever the library creates an object, it will have an initial
  90  * reference count of one. Most of the time, this single reference will be
  91  * sufficient for the application, so all required reference count
  92  * interaction will be a single call to the objects unref function.
  93  *
  94  * \section context_sec Context
  95  *
  96  * A context is the basic object for a connection to a PulseAudio server.
  97  * It multiplexes commands, data streams and events through a single
  98  * channel.
  99  *
 100  * There is no need for more than one context per application, unless
 101  * connections to multiple servers are needed.
 102  *
 103  * \subsection ops_subsec Operations
 104  *
 105  * All operations on the context are performed asynchronously. I.e. the
 106  * client will not wait for the server to complete the request. To keep
 107  * track of all these in-flight operations, the application is given a
 108  * pa_operation object for each asynchronous operation.
 109  *
 110  * There are only two actions (besides reference counting) that can be
 111  * performed on a pa_operation: querying its state with
 112  * pa_operation_get_state() and aborting it with pa_operation_cancel().
 113  *
 114  * A pa_operation object is reference counted, so an application must
 115  * make sure to unreference it, even if it has no intention of using it.
 116  *
 117  * \subsection conn_subsec Connecting
 118  *
 119  * A context must be connected to a server before any operation can be
 120  * issued. Calling pa_context_connect() will initiate the connection
 121  * procedure. Unlike most asynchronous operations, connecting does not
 122  * result in a pa_operation object. Instead, the application should
 123  * register a callback using pa_context_set_state_callback().
 124  *
 125  * \subsection disc_subsec Disconnecting
 126  *
 127  * When the sound support is no longer needed, the connection needs to be
 128  * closed using pa_context_disconnect(). This is an immediate function that
 129  * works synchronously.
 130  *
 131  * Since the context object has references to other objects it must be
 132  * disconnected after use or there is a high risk of memory leaks. If the
 133  * connection has terminated by itself, then there is no need to explicitly
 134  * disconnect the context using pa_context_disconnect().
 135  *
 136  * \section Functions
 137  *
 138  * The sound server's functionality can be divided into a number of
 139  * subsections:
 140  *
 141  * \li \subpage streams
 142  * \li \subpage scache
 143  * \li \subpage introspect
 144  * \li \subpage subscribe
 145  */
 146
 147 /** \file
 148  * Connection contexts for asynchrononous communication with a
 149  * server. A pa_context object wraps a connection to a PulseAudio
 150  * server using its native protocol. */
 151
 152 /** \example pacat.c
 153  * A playback and recording tool using the asynchronous API */
 154
 155 /** \example paplay.c
 156  * A sound file playback tool using the asynchronous API, based on libsndfile */
 157
 158 PA_C_DECL_BEGIN
 159
 160 /** An opaque connection context to a daemon */
 161 typedef struct pa_context pa_context;
 162
 163 /** Generic notification callback prototype */
 164 typedef void (*pa_context_notify_cb_t)(pa_context *c, void *userdata);
 165
 166 /** A generic callback for operation completion */
 167 typedef void (*pa_context_success_cb_t) (pa_context *c, int success, 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.*/
 172 pa_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 the initial client property
 176  * list. \since 0.9.10 */
 177 pa_context *pa_context_new_with_proplist(pa_mainloop_api *mainloop, const char *name, pa_proplist *proplist);
 178
 179 /** Decrease the reference counter of the context by one */
 180 void pa_context_unref(pa_context *c);
 181
 182 /** Increase the reference counter of the context by one */
 183 pa_context* pa_context_ref(pa_context *c);
 184
 185 /** Set a callback function that is called whenever the context status changes */
 186 void pa_context_set_state_callback(pa_context *c, pa_context_notify_cb_t cb, void *userdata);
 187
 188 /** Return the error number of the last failed operation */
 189 int pa_context_errno(pa_context *c);
 190
 191 /** Return non-zero if some data is pending to be written to the connection */
 192 int pa_context_is_pending(pa_context *c);
 193
 194 /** Return the current context status */
 195 pa_context_state_t pa_context_get_state(pa_context *c);
 196
 197 /** Connect the context to the specified server. If server is NULL,
 198 connect to the default server. This routine may but will not always
 199 return synchronously on error. Use pa_context_set_state_callback() to
 200 be notified when the connection is established. If flags doesn't have
 201 PA_NOAUTOSPAWN set and no specific server is specified or accessible a
 202 new daemon is spawned. If api is non-NULL, the functions specified in
 203 the structure are used when forking a new child process. */
 204 int pa_context_connect(pa_context *c, const char *server, pa_context_flags_t flags, const pa_spawn_api *api);
 205
 206 /** Terminate the context connection immediately */
 207 void pa_context_disconnect(pa_context *c);
 208
 209 /** Drain the context. If there is nothing to drain, the function returns NULL */
 210 pa_operation* pa_context_drain(pa_context *c, pa_context_notify_cb_t cb, void *userdata);
 211
 212 /** Tell the daemon to exit. The returned operation is unlikely to
 213  * complete succesfully, since the daemon probably died before
 214  * returning a success notification */
 215 pa_operation* pa_context_exit_daemon(pa_context *c, pa_context_success_cb_t cb, void *userdata);
 216
 217 /** Set the name of the default sink. \since 0.4 */
 218 pa_operation* pa_context_set_default_sink(pa_context *c, const char *name, pa_context_success_cb_t cb, void *userdata);
 219
 220 /** Set the name of the default source. \since 0.4 */
 221 pa_operation* pa_context_set_default_source(pa_context *c, const char *name, pa_context_success_cb_t cb, void *userdata);
 222
 223 /** Returns 1 when the connection is to a local daemon. Returns negative when no connection has been made yet. \since 0.5 */
 224 int pa_context_is_local(pa_context *c);
 225
 226 /** Set a different application name for context on the server. \since 0.5 */
 227 pa_operation* pa_context_set_name(pa_context *c, const char *name, pa_context_success_cb_t cb, void *userdata);
 228
 229 /** Return the server name this context is connected to. \since 0.7 */
 230 const char* pa_context_get_server(pa_context *c);
 231
 232 /** Return the protocol version of the library. \since 0.8 */
 233 uint32_t pa_context_get_protocol_version(pa_context *c);
 234
 235 /** Return the protocol version of the connected server. \since 0.8 */
 236 uint32_t pa_context_get_server_protocol_version(pa_context *c);
 237
 238 /* Update the property list of the client, adding new entries. Please
 239  * note that it is highly recommended to set as much properties
 240  * initially via pa_context_new_with_proplist() as possible instead a
 241  * posteriori with this function, since that information may then be
 242  * used to route streams of the client to the right device. \since 0.9.10 */
 243 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);
 244
 245 /* Update the property list of the client, remove entries. \since 0.9.10 */
 246 pa_operation *pa_context_proplist_remove(pa_context *c, const char *const keys[], pa_context_success_cb_t cb, void *userdata);
 247
 248 /** Return the client index this context is
 249  * identified in the server with. This is useful for usage with the
 250  * introspection functions, such as pa_context_get_client_info(). \since 0.9.10 */
 251 uint32_t pa_context_get_index(pa_context *s);
 252
 253 PA_C_DECL_END
 254
 255 #endif