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authorLennart Poettering <lennart@poettering.net>2006-06-19 21:53:48 +0000
committerLennart Poettering <lennart@poettering.net>2006-06-19 21:53:48 +0000
commitf44ba092651aa75055e109e04b4164ea92ae7fdc (patch)
tree5dfe076191b32946e78edf64d584d0a65f320013 /src/polyp/thread-mainloop.h
parentdd21f11deda64e65a6f75817496534c2c9dda1a8 (diff)
big s/polyp/pulse/g
git-svn-id: file:///home/lennart/svn/public/pulseaudio/trunk@1033 fefdeb5f-60dc-0310-8127-8f9354f1896f
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diff --git a/src/polyp/thread-mainloop.h b/src/polyp/thread-mainloop.h
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-#ifndef foothreadmainloophfoo
-#define foothreadmainloophfoo
-
-/* $Id$ */
-
-/***
- This file is part of polypaudio.
-
- polypaudio 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.
-
- polypaudio 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 polypaudio; if not, write to the Free Software
- Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
- USA.
-***/
-
-#include <polyp/mainloop-api.h>
-#include <polyp/cdecl.h>
-
-PA_C_DECL_BEGIN
-
-/** \page threaded_mainloop Threaded Main Loop
- *
- * \section overv_sec Overview
- *
- * The threaded main loop implementation is a special version of the primary
- * main loop implementation (see \ref mainloop). For the basic design, see
- * its documentation.
- *
- * The added feature in the threaded main loop is that it spawns a new thread
- * that runs the real main loop. This allows a synchronous application to use
- * the asynchronous API without risking to stall the Polypaudio library.
- *
- * \section creat_sec Creation
- *
- * A pa_threaded_mainloop object is created using pa_threaded_mainloop_new().
- * This will only allocate the required structures though, so to use it the
- * thread must also be started. This is done through
- * pa_threaded_mainloop_start(), after which you can start using the main loop.
- *
- * \section destr_sec Destruction
- *
- * When the Polypaudio connection has been terminated, the thread must be
- * stopped and the resources freed. Stopping the thread is done using
- * pa_threaded_mainloop_stop(), which must be called without the lock (see
- * below) held. When that function returns, the thread is stopped and the
- * pa_threaded_mainloop object can be freed using pa_threaded_mainloop_free().
- *
- * \section lock_sec Locking
- *
- * Since the Polypaudio API doesn't allow concurrent accesses to objects,
- * a locking scheme must be used to guarantee safe usage. The threaded main
- * loop API provides such a scheme through the functions
- * pa_threaded_mainloop_lock() and pa_threaded_mainloop_unlock().
- *
- * The lock is recursive, so it's safe to use it multiple times from the same
- * thread. Just make sure you call pa_threaded_mainloop_unlock() the same
- * number of times you called pa_threaded_mainloop_lock().
- *
- * The lock needs to be held whenever you call any Polypaudio function that
- * uses an object associated with this main loop. Make sure you do not hold
- * on to the lock more than necessary though, as the threaded main loop stops
- * while the lock is held.
- *
- * Example:
- *
- * \code
- * void my_check_stream_func(pa_threaded_mainloop *m, pa_stream *s) {
- * pa_stream_state_t state;
- *
- * pa_threaded_mainloop_lock(m);
- *
- * state = pa_stream_get_state(s);
- *
- * pa_threaded_mainloop_unlock(m);
- *
- * if (state == PA_STREAM_READY)
- * printf("Stream is ready!");
- * else
- * printf("Stream is not ready!");
- * }
- * \endcode
- *
- * \section cb_sec Callbacks
- *
- * Callbacks in Polypaudio are asynchronous, so they require extra care when
- * using them together with a threaded main loop.
- *
- * The easiest way to turn the callback based operations into synchronous
- * ones, is to simply wait for the callback to be called and continue from
- * there. This is the approach chosen in Polypaudio's threaded API.
- *
- * \subsection basic_subsec Basic callbacks
- *
- * For the basic case, where all that is required is to wait for the callback
- * to be invoked, the code should look something like this:
- *
- * Example:
- *
- * \code
- * static void my_drain_callback(pa_stream*s, int success, void *userdata) {
- * pa_threaded_mainloop *m;
- *
- * m = (pa_threaded_mainloop*)userdata;
- * assert(m);
- *
- * pa_threaded_mainloop_signal(m, 0);
- * }
- *
- * void my_drain_stream_func(pa_threaded_mainloop *m, pa_stream *s) {
- * pa_operation *o;
- *
- * pa_threaded_mainloop_lock(m);
- *
- * o = pa_stream_drain(s, my_drain_callback, m);
- * assert(o);
- *
- * while (pa_operation_get_state(o) != OPERATION_DONE)
- * pa_threaded_mainloop_wait(m);
- *
- * pa_operation_unref(o);
- *
- * pa_threaded_mainloop_unlock(m);
- * }
- * \endcode
- *
- * The main function, my_drain_stream_func(), will wait for the callback to
- * be called using pa_threaded_mainloop_wait().
- *
- * If your application is multi-threaded, then this waiting must be done
- * inside a while loop. The reason for this is that multiple threads might be
- * using pa_threaded_mainloop_wait() at the same time. Each thread must
- * therefore verify that it was its callback that was invoked.
- *
- * The callback, my_drain_callback(), indicates to the main function that it
- * has been called using pa_threaded_mainloop_signal().
- *
- * As you can see, both pa_threaded_mainloop_wait() may only be called with
- * the lock held. The same thing is true for pa_threaded_mainloop_signal(),
- * but as the lock is held before the callback is invoked, you do not have to
- * deal with that.
- *
- * The functions will not dead lock because the wait function will release
- * the lock before waiting and then regrab it once it has been signaled.
- * For those of you familiar with threads, the behaviour is that of a
- * condition variable.
- *
- * \subsection data_subsec Data callbacks
- *
- * For many callbacks, simply knowing that they have been called is
- * insufficient. The callback also receives some data that is desired. To
- * access this data safely, we must extend our example a bit:
- *
- * \code
- * static int *drain_result;
- *
- * static void my_drain_callback(pa_stream*s, int success, void *userdata) {
- * pa_threaded_mainloop *m;
- *
- * m = (pa_threaded_mainloop*)userdata;
- * assert(m);
- *
- * drain_result = &success;
- *
- * pa_threaded_mainloop_signal(m, 1);
- * }
- *
- * void my_drain_stream_func(pa_threaded_mainloop *m, pa_stream *s) {
- * pa_operation *o;
- *
- * pa_threaded_mainloop_lock(m);
- *
- * o = pa_stream_drain(s, my_drain_callback, m);
- * assert(o);
- *
- * while (pa_operation_get_state(o) != OPERATION_DONE)
- * pa_threaded_mainloop_wait(m);
- *
- * pa_operation_unref(o);
- *
- * if (*drain_result)
- * printf("Success!");
- * else
- * printf("Bitter defeat...");
- *
- * pa_threaded_mainloop_accept(m);
- *
- * pa_threaded_mainloop_unlock(m);
- * }
- * \endcode
- *
- * The example is a bit silly as it would probably have been easier to just
- * copy the contents of success, but for larger data structures this can be
- * wasteful.
- *
- * The difference here compared to the basic callback is the 1 sent to
- * pa_threaded_mainloop_signal() and the call to
- * pa_threaded_mainloop_accept(). What will happen is that
- * pa_threaded_mainloop_signal() will signal the main function and then stop.
- * The main function is then free to use the data in the callback until
- * pa_threaded_mainloop_accept() is called, which will allow the callback
- * to continue.
- *
- * Note that pa_threaded_mainloop_accept() must be called some time between
- * exiting the while loop and unlocking the main loop! Failure to do so will
- * result in a race condition. I.e. it is not ok to release the lock and
- * regrab it before calling pa_threaded_mainloop_accept().
- *
- * \subsection async_subsec Asynchronous callbacks
- *
- * Polypaudio also has callbacks that are completely asynchronous, meaning
- * that they can be called at any time. The threading main loop API provides
- * the locking mechanism to handle concurrent accesses, but nothing else.
- * Applications will have to handle communication from the callback to the
- * main program through some own system.
- *
- * The callbacks that are completely asynchronous are:
- *
- * \li State callbacks for contexts, streams, etc.
- * \li Subscription notifications
- */
-
-/** \file
- *
- * A thread based event loop implementation based on pa_mainloop. The
- * event loop is run in a helper thread in the background. A few
- * synchronization primitives are available to access the objects
- * attached to the event loop safely. */
-
-/** An opaque threaded main loop object */
-typedef struct pa_threaded_mainloop pa_threaded_mainloop;
-
-/** Allocate a new threaded main loop object. You have to call
- * pa_threaded_mainloop_start() before the event loop thread starts
- * running. */
-pa_threaded_mainloop *pa_threaded_mainloop_new(void);
-
-/** Free a threaded main loop object. If the event loop thread is
- * still running, it is terminated using pa_threaded_mainloop_stop()
- * first. */
-void pa_threaded_mainloop_free(pa_threaded_mainloop* m);
-
-/** Start the event loop thread. */
-int pa_threaded_mainloop_start(pa_threaded_mainloop *m);
-
-/** Terminate the event loop thread cleanly. Make sure to unlock the
- * mainloop object before calling this function. */
-void pa_threaded_mainloop_stop(pa_threaded_mainloop *m);
-
-/** Lock the event loop object, effectively blocking the event loop
- * thread from processing events. You can use this to enforce
- * exclusive access to all objects attached to the event loop. This
- * lock is recursive. This function may not be called inside the event
- * loop thread. Events that are dispatched from the event loop thread
- * are executed with this lock held. */
-void pa_threaded_mainloop_lock(pa_threaded_mainloop *m);
-
-/** Unlock the event loop object, inverse of pa_threaded_mainloop_lock() */
-void pa_threaded_mainloop_unlock(pa_threaded_mainloop *m);
-
-/** Wait for an event to be signalled by the event loop thread. You
- * can use this to pass data from the event loop thread to the main
- * thread in synchronized fashion. This function may not be called
- * inside the event loop thread. Prior to this call the event loop
- * object needs to be locked using pa_threaded_mainloop_lock(). While
- * waiting the lock will be released, immediately before returning it
- * will be acquired again. */
-void pa_threaded_mainloop_wait(pa_threaded_mainloop *m);
-
-/** Signal all threads waiting for a signalling event in
- * pa_threaded_mainloop_wait(). If wait_for_release is non-zero, do
- * not return before the signal was accepted by a
- * pa_threaded_mainloop_accept() call. While waiting for that condition
- * the event loop object is unlocked. */
-void pa_threaded_mainloop_signal(pa_threaded_mainloop *m, int wait_for_accept);
-
-/** Accept a signal from the event thread issued with
- * pa_threaded_mainloop_signal(). This call should only be used in
- * conjunction with pa_threaded_mainloop_signal() with a non-zero
- * wait_for_accept value. */
-void pa_threaded_mainloop_accept(pa_threaded_mainloop *m);
-
-/** Return the return value as specified with the main loop's quit() routine. */
-int pa_threaded_mainloop_get_retval(pa_threaded_mainloop *m);
-
-/** Return the abstract main loop abstraction layer vtable for this main loop. */
-pa_mainloop_api* pa_threaded_mainloop_get_api(pa_threaded_mainloop*m);
-
-PA_C_DECL_END
-
-#endif