1 #ifndef foocontexthfoo 2 #define foocontexthfoo 3 4 /* $Id: context.h 1426 2007-02-13 15:35:19Z ossman $ */ 5 6 /*** 7 This file is part of PulseAudio. 8 9 Copyright 2004-2006 Lennart Poettering 10 Copyright 2006 Pierre Ossman <ossman (at) 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 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 functions. This also 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 ammount 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 ammount 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. Available 69 * for both GLIB 1.2 and GLIB 2.x. 70 * 71 * UNIX signals may be hooked to a main loop using the functions from 72 * \ref mainloop-signal.h. These rely only on the main loop abstraction 73 * and can therefore be used with any of the implementations. 74 * 75 * \section refcnt_sec Reference Counting 76 * 77 * Almost all objects in PulseAudio are reference counted. What that means 78 * is that you rarely malloc() or free() any objects. Instead you increase 79 * and decrease their reference counts. Whenever an object's reference 80 * count reaches zero, that object gets destroy and any resources it uses 81 * get freed. 82 * 83 * The benefit of this design is that an application need not worry about 84 * whether or not it needs to keep an object around in case the library is 85 * using it internally. If it is, then it has made sure it has its own 86 * reference to it. 87 * 88 * Whenever the library creates an object, it will have an initial 89 * reference count of one. Most of the time, this single reference will be 90 * sufficient for the application, so all required reference count 91 * interaction will be a single call to the objects unref function. 92 * 93 * \section context_sec Context 94 * 95 * A context is the basic object for a connection to a PulseAudio server. 96 * It multiplexes commands, data streams and events through a single 97 * channel. 98 * 99 * There is no need for more than one context per application, unless 100 * connections to multiple servers are needed. 101 * 102 * \subsection ops_subsec Operations 103 * 104 * All operations on the context are performed asynchronously. I.e. the 105 * client will not wait for the server to complete the request. To keep 106 * track of all these in-flight operations, the application is given a 107 * pa_operation object for each asynchronous operation. 108 * 109 * There are only two actions (besides reference counting) that can be 110 * performed on a pa_operation: querying its state with 111 * pa_operation_get_state() and aborting it with pa_operation_cancel(). 112 * 113 * A pa_operation object is reference counted, so an application must 114 * make sure to unreference it, even if it has no intention of using it. 115 * 116 * \subsection conn_subsec Connecting 117 * 118 * A context must be connected to a server before any operation can be 119 * issued. Calling pa_context_connect() will initiate the connection 120 * procedure. Unlike most asynchronous operations, connecting does not 121 * result in a pa_operation object. Instead, the application should 122 * register a callback using pa_context_set_state_callback(). 123 * 124 * \subsection disc_subsec Disconnecting 125 * 126 * When the sound support is no longer needed, the connection needs to be 127 * closed using pa_context_disconnect(). This is an immediate function that 128 * works synchronously. 129 * 130 * Since the context object has references to other objects it must be 131 * disconnected after use or there is a high risk of memory leaks. If the 132 * connection has terminated by itself, then there is no need to explicitly 133 * disconnect the context using pa_context_disconnect(). 134 * 135 * \section Functions 136 * 137 * The sound server's functionality can be divided into a number of 138 * subsections: 139 * 140 * \li \subpage streams 141 * \li \subpage scache 142 * \li \subpage introspect 143 * \li \subpage subscribe 144 */ 145 146 /** \file 147 * Connection contexts for asynchrononous communication with a 148 * server. A pa_context object wraps a connection to a PulseAudio 149 * server using its native protocol. */ 150 151 /** \example pacat.c 152 * A playback and recording tool using the asynchronous API */ 153 154 /** \example paplay.c 155 * A sound file playback tool using the asynchronous API, based on libsndfile */ 156 157 PA_C_DECL_BEGIN 158 159 /** An opaque connection context to a daemon */ 160 typedef struct pa_context pa_context; 161 162 /** Generic notification callback prototype */ 163 typedef void (*pa_context_notify_cb_t)(pa_context *c, void *userdata); 164 165 /** A generic callback for operation completion */ 166 typedef void (*pa_context_success_cb_t) (pa_context *c, int success, void *userdata); 167 168 /** Instantiate a new connection context with an abstract mainloop API 169 * and an application name */ 170 pa_context *pa_context_new(pa_mainloop_api *mainloop, const char *name); 171 172 /** Decrease the reference counter of the context by one */ 173 void pa_context_unref(pa_context *c); 174 175 /** Increase the reference counter of the context by one */ 176 pa_context* pa_context_ref(pa_context *c); 177 178 /** Set a callback function that is called whenever the context status changes */ 179 void pa_context_set_state_callback(pa_context *c, pa_context_notify_cb_t cb, void *userdata); 180 181 /** Return the error number of the last failed operation */ 182 int pa_context_errno(pa_context *c); 183 184 /** Return non-zero if some data is pending to be written to the connection */ 185 int pa_context_is_pending(pa_context *c); 186 187 /** Return the current context status */ 188 pa_context_state_t pa_context_get_state(pa_context *c); 189 190 /** Connect the context to the specified server. If server is NULL, 191 connect to the default server. This routine may but will not always 192 return synchronously on error. Use pa_context_set_state_callback() to 193 be notified when the connection is established. If flags doesn't have 194 PA_NOAUTOSPAWN set and no specific server is specified or accessible a 195 new daemon is spawned. If api is non-NULL, the functions specified in 196 the structure are used when forking a new child process. */ 197 int pa_context_connect(pa_context *c, const char *server, pa_context_flags_t flags, const pa_spawn_api *api); 198 199 /** Terminate the context connection immediately */ 200 void pa_context_disconnect(pa_context *c); 201 202 /** Drain the context. If there is nothing to drain, the function returns NULL */ 203 pa_operation* pa_context_drain(pa_context *c, pa_context_notify_cb_t cb, void *userdata); 204 205 /** Tell the daemon to exit. The returned operation is unlikely to 206 * complete succesfully, since the daemon probably died before 207 * returning a success notification */ 208 pa_operation* pa_context_exit_daemon(pa_context *c, pa_context_success_cb_t cb, void *userdata); 209 210 /** Set the name of the default sink. \since 0.4 */ 211 pa_operation* pa_context_set_default_sink(pa_context *c, const char *name, pa_context_success_cb_t cb, void *userdata); 212 213 /** Set the name of the default source. \since 0.4 */ 214 pa_operation* pa_context_set_default_source(pa_context *c, const char *name, pa_context_success_cb_t cb, void *userdata); 215 216 /** Returns 1 when the connection is to a local daemon. Returns negative when no connection has been made yet. \since 0.5 */ 217 int pa_context_is_local(pa_context *c); 218 219 /** Set a different application name for context on the server. \since 0.5 */ 220 pa_operation* pa_context_set_name(pa_context *c, const char *name, pa_context_success_cb_t cb, void *userdata); 221 222 /** Return the server name this context is connected to. \since 0.7 */ 223 const char* pa_context_get_server(pa_context *c); 224 225 /** Return the protocol version of the library. \since 0.8 */ 226 uint32_t pa_context_get_protocol_version(pa_context *c); 227 228 /** Return the protocol version of the connected server. \since 0.8 */ 229 uint32_t pa_context_get_server_protocol_version(pa_context *c); 230 231 PA_C_DECL_END 232 233 #endif 234
