mirror of
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5effc83479
FSF addresses used in PA sources are no longer valid and rpmlint generates numerous warnings during packaging because of this. This patch changes all FSF addresses to FSF web page according to the GPL how-to: https://www.gnu.org/licenses/gpl-howto.en.html Done automatically by sed-ing through sources.
100 lines
3.1 KiB
C
100 lines
3.1 KiB
C
#ifndef foopulsecoreaupdatehfoo
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#define foopulsecoreaupdatehfoo
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/***
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This file is part of PulseAudio.
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Copyright 2009 Lennart Poettering
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PulseAudio is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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PulseAudio is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.
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***/
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typedef struct pa_aupdate pa_aupdate;
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pa_aupdate *pa_aupdate_new(void);
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void pa_aupdate_free(pa_aupdate *a);
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/* Will return 0, or 1, depending on which copy of the data the caller
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* should look at */
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unsigned pa_aupdate_read_begin(pa_aupdate *a);
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void pa_aupdate_read_end(pa_aupdate *a);
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/* Will return 0, or 1, depending which copy of the data the caller
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* should modify */
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unsigned pa_aupdate_write_begin(pa_aupdate *a);
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void pa_aupdate_write_end(pa_aupdate *a);
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/* Will return 0, or 1, depending which copy of the data the caller
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* should modify. Each time called this will return the opposite of
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* the previous pa_aupdate_write_begin() / pa_aupdate_write_swap()
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* call. Should only be called between pa_aupdate_write_begin() and
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* pa_aupdate_write_end() */
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unsigned pa_aupdate_write_swap(pa_aupdate *a);
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/*
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* This infrastructure allows lock-free updates of arbitrary data
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* structures in an rcu'ish way: two copies of the data structure
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* should be existing. One side ('the reader') has read access to one
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* of the two data structure at a time. It does not have to lock it,
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* however it needs to signal that it is using it/stopped using
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* it. The other side ('the writer') modifies the second data structure,
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* and then atomically swaps the two data structures, followed by a
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* modification of the other one.
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*
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* This is intended to be used for cases where the reader side needs
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* to be fast while the writer side can be slow.
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*
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* The reader side is signal handler safe.
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*
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* The writer side lock is not recursive. The reader side is.
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*
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* There may be multiple readers and multiple writers at the same
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* time.
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*
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* Usage is like this:
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*
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* static struct foo bar[2];
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* static pa_aupdate *a;
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*
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* reader() {
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* unsigned j;
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*
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* j = pa_update_read_begin(a);
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*
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* ... read the data structure bar[j] ...
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*
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* pa_update_read_end(a);
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* }
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*
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* writer() {
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* unsigned j;
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*
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* j = pa_update_write_begin(a);
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*
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* ... update the data structure bar[j] ...
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*
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* j = pa_update_write_swap(a);
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*
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* ... update the data structure bar[j], the same way as above ...
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*
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* pa_update_write_end(a)
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* }
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*
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* In some cases keeping both structures up-to-date might not be
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* necessary, since they are fully rebuilt on each iteration
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* anyway. In that case you may leave the _write_swap() call out, it
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* will then be done implicitly in the _write_end() invocation.
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*/
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#endif
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