diff options
Diffstat (limited to 'src/pulsecore/fdsem.c')
| -rw-r--r-- | src/pulsecore/fdsem.c | 276 |
1 files changed, 276 insertions, 0 deletions
diff --git a/src/pulsecore/fdsem.c b/src/pulsecore/fdsem.c new file mode 100644 index 00000000..927bf00c --- /dev/null +++ b/src/pulsecore/fdsem.c @@ -0,0 +1,276 @@ +/* $Id$ */ + +/*** + This file is part of PulseAudio. + + Copyright 2006 Lennart Poettering + + PulseAudio 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 2.1 of the + License, or (at your option) any later version. + + PulseAudio 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 + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with PulseAudio; if not, write to the Free Software + Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 + USA. +***/ + +#ifdef HAVE_CONFIG_H +#include <config.h> +#endif + +#ifdef HAVE_SYS_SYSCALL_H +#include <sys/syscall.h> +#endif + +#include <unistd.h> +#include <errno.h> + +#include <pulsecore/atomic.h> +#include <pulsecore/log.h> +#include <pulsecore/thread.h> +#include <pulsecore/macro.h> +#include <pulsecore/core-util.h> +#include <pulse/xmalloc.h> + +#ifndef HAVE_PIPE +#include <pulsecore/pipe.h> +#endif + +#ifdef __linux__ + +#if !defined(__NR_eventfd) && defined(__i386__) +#define __NR_eventfd 323 +#endif + +#if !defined(__NR_eventfd) && defined(__x86_64__) +#define __NR_eventfd 284 +#endif + +#if !defined(SYS_eventfd) && defined(__NR_eventfd) +#define SYS_eventfd __NR_eventfd +#endif + +#ifdef SYS_eventfd +#define HAVE_EVENTFD + +static inline long eventfd(unsigned count) { + return syscall(SYS_eventfd, count); +} + +#endif +#endif + +#include "fdsem.h" + +struct pa_fdsem { + int fds[2]; +#ifdef HAVE_EVENTFD + int efd; +#endif + pa_atomic_t waiting; + pa_atomic_t signalled; + pa_atomic_t in_pipe; +}; + +pa_fdsem *pa_fdsem_new(void) { + pa_fdsem *f; + + f = pa_xnew(pa_fdsem, 1); + +#ifdef HAVE_EVENTFD + if ((f->efd = eventfd(0)) >= 0) { + pa_make_fd_cloexec(f->efd); + f->fds[0] = f->fds[1] = -1; + + } else +#endif + { + if (pipe(f->fds) < 0) { + pa_xfree(f); + return NULL; + } + + pa_make_fd_cloexec(f->fds[0]); + pa_make_fd_cloexec(f->fds[1]); + } + + pa_atomic_store(&f->waiting, 0); + pa_atomic_store(&f->signalled, 0); + pa_atomic_store(&f->in_pipe, 0); + + return f; +} + +void pa_fdsem_free(pa_fdsem *f) { + pa_assert(f); + +#ifdef HAVE_EVENTFD + if (f->efd >= 0) + pa_close(f->efd); +#endif + pa_close_pipe(f->fds); + + pa_xfree(f); +} + +static void flush(pa_fdsem *f) { + ssize_t r; + pa_assert(f); + + if (pa_atomic_load(&f->in_pipe) <= 0) + return; + + do { + char x[10]; + +#ifdef HAVE_EVENTFD + if (f->efd >= 0) { + uint64_t u; + + if ((r = read(f->efd, &u, sizeof(u))) != sizeof(u)) { + pa_assert(r < 0 && errno == EINTR); + continue; + } + r = (ssize_t) u; + } else +#endif + + if ((r = read(f->fds[0], &x, sizeof(x))) <= 0) { + pa_assert(r < 0 && errno == EINTR); + continue; + } + + } while (pa_atomic_sub(&f->in_pipe, r) > r); +} + +void pa_fdsem_post(pa_fdsem *f) { + pa_assert(f); + + if (pa_atomic_cmpxchg(&f->signalled, 0, 1)) { + + if (pa_atomic_load(&f->waiting)) { + ssize_t r; + char x = 'x'; + + pa_atomic_inc(&f->in_pipe); + + for (;;) { + +#ifdef HAVE_EVENTFD + if (f->efd >= 0) { + uint64_t u = 1; + + if ((r = write(f->efd, &u, sizeof(u))) != sizeof(u)) { + pa_assert(r < 0 && errno == EINTR); + continue; + } + } else +#endif + + if ((r = write(f->fds[1], &x, 1)) != 1) { + pa_assert(r < 0 && errno == EINTR); + continue; + } + + break; + } + } + } +} + +void pa_fdsem_wait(pa_fdsem *f) { + pa_assert(f); + + flush(f); + + if (pa_atomic_cmpxchg(&f->signalled, 1, 0)) + return; + + pa_atomic_inc(&f->waiting); + + while (!pa_atomic_cmpxchg(&f->signalled, 1, 0)) { + char x[10]; + ssize_t r; + +#ifdef HAVE_EVENTFD + if (f->efd >= 0) { + uint64_t u; + + if ((r = read(f->efd, &u, sizeof(u))) != sizeof(u)) { + pa_assert(r < 0 && errno == EINTR); + continue; + } + + r = (ssize_t) u; + } else +#endif + + if ((r = read(f->fds[0], &x, sizeof(x))) <= 0) { + pa_assert(r < 0 && errno == EINTR); + continue; + } + + pa_atomic_sub(&f->in_pipe, r); + } + + pa_assert_se(pa_atomic_dec(&f->waiting) >= 1); +} + +int pa_fdsem_try(pa_fdsem *f) { + pa_assert(f); + + flush(f); + + if (pa_atomic_cmpxchg(&f->signalled, 1, 0)) + return 1; + + return 0; +} + +int pa_fdsem_get(pa_fdsem *f) { + pa_assert(f); + +#ifdef HAVE_EVENTFD + if (f->efd >= 0) + return f->efd; +#endif + + return f->fds[0]; +} + +int pa_fdsem_before_poll(pa_fdsem *f) { + pa_assert(f); + + flush(f); + + if (pa_atomic_cmpxchg(&f->signalled, 1, 0)) + return -1; + + pa_atomic_inc(&f->waiting); + + if (pa_atomic_cmpxchg(&f->signalled, 1, 0)) { + pa_assert_se(pa_atomic_dec(&f->waiting) >= 1); + return -1; + } + return 0; +} + +int pa_fdsem_after_poll(pa_fdsem *f) { + pa_assert(f); + + pa_assert_se(pa_atomic_dec(&f->waiting) >= 1); + + flush(f); + + if (pa_atomic_cmpxchg(&f->signalled, 1, 0)) + return 1; + + return 0; +} |