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authorLennart Poettering <lennart@poettering.net>2008-08-09 03:49:42 +0200
committerLennart Poettering <lennart@poettering.net>2008-08-09 03:49:42 +0200
commit15cebbacebf27703848afb18883fad7984349f04 (patch)
tree22f820a7f1cf96b4d0609fbacd044090cc3d3f28 /src/pulse
parentb4a566918cc6fbf2d5e66ae354275d36fbe8d13a (diff)
rework autospawning code to survive multiple pa_contexts in a single process
Diffstat (limited to 'src/pulse')
-rw-r--r--src/pulse/context.c105
-rw-r--r--src/pulse/internal.h7
-rw-r--r--src/pulse/lock-autospawn.c329
-rw-r--r--src/pulse/lock-autospawn.h32
4 files changed, 448 insertions, 25 deletions
diff --git a/src/pulse/context.c b/src/pulse/context.c
index bdd519a6..00236b96 100644
--- a/src/pulse/context.c
+++ b/src/pulse/context.c
@@ -54,6 +54,7 @@
#include <pulse/utf8.h>
#include <pulse/util.h>
#include <pulse/i18n.h>
+#include <pulse/lock-autospawn.h>
#include <pulsecore/winsock.h>
#include <pulsecore/core-error.h>
@@ -81,8 +82,6 @@
#include "context.h"
-#define AUTOSPAWN_LOCK "autospawn.lock"
-
void pa_command_extension(pa_pdispatch *pd, uint32_t command, uint32_t tag, pa_tagstruct *t, void *userdata);
static const pa_pdispatch_cb_t command_table[PA_COMMAND_MAX] = {
@@ -100,20 +99,23 @@ static const pa_pdispatch_cb_t command_table[PA_COMMAND_MAX] = {
[PA_COMMAND_EXTENSION] = pa_command_extension
};
-static void unlock_autospawn_lock_file(pa_context *c) {
+static void unlock_autospawn(pa_context *c) {
pa_assert(c);
- if (c->autospawn_lock_fd >= 0) {
- char *lf;
+ if (c->autospawn_fd >= 0) {
- if (!(lf = pa_runtime_path(AUTOSPAWN_LOCK)))
- pa_log_warn(_("Cannot unlock autospawn because runtime path is no more."));
+ if (c->autospawn_locked)
+ pa_autospawn_lock_release();
- pa_unlock_lockfile(lf, c->autospawn_lock_fd);
- pa_xfree(lf);
+ if (c->autospawn_event)
+ c->mainloop->io_free(c->autospawn_event);
- c->autospawn_lock_fd = -1;
+ pa_autospawn_lock_done(FALSE);
}
+
+ c->autospawn_locked = FALSE;
+ c->autospawn_fd = -1;
+ c->autospawn_event = NULL;
}
static void context_free(pa_context *c);
@@ -174,11 +176,15 @@ pa_context *pa_context_new_with_proplist(pa_mainloop_api *mainloop, const char *
c->is_local = FALSE;
c->server_list = NULL;
c->server = NULL;
- c->autospawn_lock_fd = -1;
- memset(&c->spawn_api, 0, sizeof(c->spawn_api));
- c->do_autospawn = FALSE;
+
c->do_shm = FALSE;
+ c->do_autospawn = FALSE;
+ c->autospawn_fd = -1;
+ c->autospawn_locked = FALSE;
+ c->autospawn_event = NULL;
+ memset(&c->spawn_api, 0, sizeof(c->spawn_api));
+
#ifndef MSG_NOSIGNAL
#ifdef SIGPIPE
pa_check_signal_is_blocked(SIGPIPE);
@@ -246,7 +252,7 @@ static void context_free(pa_context *c) {
context_unlink(c);
- unlock_autospawn_lock_file(c);
+ unlock_autospawn(c);
if (c->record_streams)
pa_dynarray_free(c->record_streams, NULL, NULL);
@@ -674,7 +680,7 @@ static int context_connect_spawn(pa_context *c) {
c->is_local = TRUE;
- unlock_autospawn_lock_file(c);
+ unlock_autospawn(c);
io = pa_iochannel_new(c->mainloop, fds[0], fds[0]);
setup_context(c, io);
@@ -686,7 +692,7 @@ static int context_connect_spawn(pa_context *c) {
fail:
pa_close_pipe(fds);
- unlock_autospawn_lock_file(c);
+ unlock_autospawn(c);
pa_context_unref(c);
@@ -768,13 +774,46 @@ static void on_connection(pa_socket_client *client, pa_iochannel*io, void *userd
goto finish;
}
- unlock_autospawn_lock_file(c);
+ unlock_autospawn(c);
setup_context(c, io);
finish:
pa_context_unref(c);
}
+static void autospawn_cb(pa_mainloop_api*a, pa_io_event *e, int fd, pa_io_event_flags_t events, void *userdata) {
+ pa_context *c = userdata;
+ int k;
+
+ pa_assert(a);
+ pa_assert(e);
+ pa_assert(fd >= 0);
+ pa_assert(events = PA_IO_EVENT_INPUT);
+ pa_assert(c);
+ pa_assert(e == c->autospawn_event);
+ pa_assert(fd == c->autospawn_fd);
+
+ pa_context_ref(c);
+
+ /* Check whether we can get the lock right now*/
+ if ((k = pa_autospawn_lock_acquire(FALSE)) < 0) {
+ pa_context_fail(c, PA_ERR_ACCESS);
+ goto finish;
+ }
+
+ if (k > 0) {
+ /* So we got it, rock on! */
+ c->autospawn_locked = TRUE;
+ try_next_connection(c);
+
+ c->mainloop->io_free(c->autospawn_event);
+ c->autospawn_event = NULL;
+ }
+
+finish:
+
+ pa_context_unref(c);
+}
static char *get_old_legacy_runtime_dir(void) {
char *p, u[128];
@@ -847,6 +886,7 @@ int pa_context_connect(
pa_context_fail(c, PA_ERR_INVALIDSERVER);
goto finish;
}
+
} else {
char *d, *ufn;
static char *legacy_dir;
@@ -895,21 +935,40 @@ int pa_context_connect(
/* Wrap the connection attempts in a single transaction for sane autospawn locking */
if (!(flags & PA_CONTEXT_NOAUTOSPAWN) && c->conf->autospawn) {
- char *lf;
+ int k;
- if (!(lf = pa_runtime_path(AUTOSPAWN_LOCK))) {
+ pa_assert(c->autospawn_fd < 0);
+ pa_assert(!c->autospawn_locked);
+
+ /* Start the locking procedure */
+ if ((c->autospawn_fd = pa_autospawn_lock_init()) < 0) {
pa_context_fail(c, PA_ERR_ACCESS);
goto finish;
}
- pa_assert(c->autospawn_lock_fd <= 0);
- c->autospawn_lock_fd = pa_lock_lockfile(lf);
- pa_xfree(lf);
-
if (api)
c->spawn_api = *api;
c->do_autospawn = TRUE;
+
+ /* Check whether we can get the lock right now*/
+ if ((k = pa_autospawn_lock_acquire(FALSE)) < 0) {
+ pa_context_fail(c, PA_ERR_ACCESS);
+ goto finish;
+ }
+
+ if (k > 0)
+ /* So we got it, rock on! */
+ c->autospawn_locked = TRUE;
+ else {
+ /* Hmm, we didn't get it, so let's wait for it */
+ c->autospawn_event = c->mainloop->io_new(c->mainloop, c->autospawn_fd, PA_IO_EVENT_INPUT, autospawn_cb, c);
+
+ pa_context_set_state(c, PA_CONTEXT_CONNECTING);
+ r = 0;
+ goto finish;
+ }
+
}
}
diff --git a/src/pulse/internal.h b/src/pulse/internal.h
index bfe888ee..26fb04d4 100644
--- a/src/pulse/internal.h
+++ b/src/pulse/internal.h
@@ -75,9 +75,12 @@ struct pa_context {
pa_mempool *mempool;
pa_bool_t is_local:1;
- pa_bool_t do_autospawn:1;
pa_bool_t do_shm:1;
- int autospawn_lock_fd;
+
+ pa_bool_t do_autospawn:1;
+ pa_bool_t autospawn_locked:1;
+ int autospawn_fd;
+ pa_io_event *autospawn_event;
pa_spawn_api spawn_api;
pa_strlist *server_list;
diff --git a/src/pulse/lock-autospawn.c b/src/pulse/lock-autospawn.c
new file mode 100644
index 00000000..33a53113
--- /dev/null
+++ b/src/pulse/lock-autospawn.c
@@ -0,0 +1,329 @@
+/***
+ This file is part of PulseAudio.
+
+ Copyright 2008 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 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
+ 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
+
+#include <fcntl.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/poll.h>
+#include <signal.h>
+#include <pthread.h>
+
+#include <pulse/i18n.h>
+#include <pulse/xmalloc.h>
+
+#include <pulsecore/mutex.h>
+#include <pulsecore/thread.h>
+#include <pulsecore/core-util.h>
+
+#include "lock-autospawn.h"
+
+/* So, why do we have this complex code here with threads and pipes
+ * and stuff? For two reasons: POSIX file locks are per-process, not
+ * per-file descriptor. That means that two contexts within the same
+ * process that try to create the autospawn lock might end up assuming
+ * they both managed to lock the file. And then, POSIX locking
+ * operations are synchronous. If two contexts run from the same event
+ * loop it must be made sure that they do not block each other, but
+ * that the locking operation can happen asynchronously. */
+
+#define AUTOSPAWN_LOCK "autospawn.lock"
+
+static pa_mutex *mutex;
+
+static unsigned n_ref = 0;
+static int lock_fd = -1;
+static pa_mutex *lock_fd_mutex = NULL;
+static pa_bool_t taken = FALSE;
+static pa_thread *thread;
+static int pipe_fd[2] = { -1, -1 };
+
+static void destroy_mutex(void) PA_GCC_DESTRUCTOR;
+
+static int ref(void) {
+
+ if (n_ref > 0) {
+
+ pa_assert(pipe_fd[0] >= 0);
+ pa_assert(pipe_fd[1] >= 0);
+
+ n_ref++;
+
+ return 0;
+ }
+
+ pa_assert(lock_fd < 0);
+ pa_assert(!lock_fd_mutex);
+ pa_assert(!taken);
+ pa_assert(!thread);
+ pa_assert(pipe_fd[0] < 0);
+ pa_assert(pipe_fd[1] < 0);
+
+ if (pipe(pipe_fd) < 0)
+ return -1;
+
+ lock_fd_mutex = pa_mutex_new(FALSE, FALSE);
+
+ pa_make_fd_cloexec(pipe_fd[0]);
+ pa_make_fd_cloexec(pipe_fd[1]);
+
+ pa_make_fd_nonblock(pipe_fd[1]);
+ pa_make_fd_nonblock(pipe_fd[0]);
+
+ n_ref = 1;
+ return 0;
+}
+
+static void unref(pa_bool_t after_fork) {
+
+ pa_assert(n_ref > 0);
+ pa_assert(pipe_fd[0] >= 0);
+ pa_assert(pipe_fd[1] >= 0);
+ pa_assert(lock_fd_mutex);
+
+ n_ref--;
+
+ if (n_ref > 0)
+ return;
+
+ pa_assert(!taken);
+
+ if (thread) {
+ pa_thread_free(thread);
+ thread = NULL;
+ }
+
+ pa_mutex_lock(lock_fd_mutex);
+ if (lock_fd >= 0) {
+
+ if (after_fork)
+ pa_close(lock_fd);
+ else {
+ char *lf;
+
+ if (!(lf = pa_runtime_path(AUTOSPAWN_LOCK)))
+ pa_log_warn(_("Cannot access autospawn lock."));
+
+ pa_unlock_lockfile(lf, lock_fd);
+ pa_xfree(lf);
+
+ lock_fd = -1;
+ }
+ }
+ pa_mutex_unlock(lock_fd_mutex);
+
+ pa_mutex_free(lock_fd_mutex);
+
+ pa_close(pipe_fd[0]);
+ pa_close(pipe_fd[1]);
+ pipe_fd[0] = pipe_fd[1] = -1;
+}
+
+static void ping(void) {
+ ssize_t s;
+
+ pa_assert(pipe_fd[1] >= 0);
+
+ for (;;) {
+ char x = 'x';
+
+ if ((s = write(pipe_fd[1], &x, 1)) == 1)
+ break;
+
+ pa_assert(s < 0);
+
+ if (errno == EAGAIN)
+ break;
+
+ pa_assert(errno == EINTR);
+ }
+}
+
+static void wait_for_ping(void) {
+ ssize_t s;
+ char x;
+ struct pollfd pfd;
+ int k;
+
+ pa_assert(pipe_fd[0] >= 0);
+
+ memset(&pfd, 0, sizeof(pfd));
+ pfd.fd = pipe_fd[0];
+ pfd.events = POLLIN;
+
+ if ((k = poll(&pfd, 1, -1)) != 1) {
+ pa_assert(k < 0);
+ pa_assert(errno == EINTR);
+ } else if ((s = read(pipe_fd[0], &x, 1)) != 1) {
+ pa_assert(s < 0);
+ pa_assert(errno == EAGAIN);
+ }
+}
+
+static void empty_pipe(void) {
+ char x[16];
+ ssize_t s;
+
+ pa_assert(pipe_fd[0] >= 0);
+
+ if ((s = read(pipe_fd[0], &x, sizeof(x))) < 1) {
+ pa_assert(s < 0);
+ pa_assert(errno == EAGAIN);
+ }
+}
+
+static void thread_func(void *u) {
+ int fd;
+ char *lf;
+ sigset_t fullset;
+
+ /* No signals in this thread please */
+ sigfillset(&fullset);
+ pthread_sigmask(SIG_BLOCK, &fullset, NULL);
+
+ if (!(lf = pa_runtime_path(AUTOSPAWN_LOCK))) {
+ pa_log_warn(_("Cannot access autospawn lock."));
+ goto finish;
+ }
+
+ if ((fd = pa_lock_lockfile(lf)) < 0)
+ goto finish;
+
+ pa_mutex_lock(lock_fd_mutex);
+ pa_assert(lock_fd < 0);
+ lock_fd = fd;
+ pa_mutex_unlock(lock_fd_mutex);
+
+finish:
+ pa_xfree(lf);
+
+ ping();
+}
+
+static int start_thread(void) {
+
+ if (!thread)
+ if (!(thread = pa_thread_new(thread_func, NULL)))
+ return -1;
+
+ return 0;
+}
+
+static void create_mutex(void) {
+ PA_ONCE_BEGIN {
+ mutex = pa_mutex_new(FALSE, FALSE);
+ } PA_ONCE_END;
+}
+
+static void destroy_mutex(void) {
+
+ if (mutex)
+ pa_mutex_free(mutex);
+}
+
+
+int pa_autospawn_lock_init(void) {
+ int ret = -1;
+
+ create_mutex();
+ pa_mutex_lock(mutex);
+
+ if (ref() < 0)
+ ret = -1;
+ else
+ ret = pipe_fd[0];
+
+ pa_mutex_unlock(mutex);
+
+ return ret;
+}
+
+int pa_autospawn_lock_acquire(pa_bool_t block) {
+ int ret = -1;
+
+ create_mutex();
+ pa_mutex_lock(mutex);
+ pa_assert(n_ref >= 1);
+
+ pa_mutex_lock(lock_fd_mutex);
+
+ for (;;) {
+
+ empty_pipe();
+
+ if (lock_fd >= 0 && !taken) {
+ taken = TRUE;
+ ret = 1;
+ break;
+ }
+
+ if (lock_fd < 0)
+ if (start_thread() < 0)
+ break;
+
+ if (!block) {
+ ret = 0;
+ break;
+ }
+
+ pa_mutex_unlock(lock_fd_mutex);
+ pa_mutex_unlock(mutex);
+
+ wait_for_ping();
+
+ pa_mutex_lock(mutex);
+ pa_mutex_lock(lock_fd_mutex);
+ }
+
+ pa_mutex_unlock(lock_fd_mutex);
+
+ pa_mutex_unlock(mutex);
+
+ return ret;
+}
+
+void pa_autospawn_lock_release(void) {
+
+ create_mutex();
+ pa_mutex_lock(mutex);
+ pa_assert(n_ref >= 1);
+
+ pa_assert(taken);
+ taken = FALSE;
+
+ ping();
+
+ pa_mutex_unlock(mutex);
+}
+
+void pa_autospawn_lock_done(pa_bool_t after_fork) {
+
+ create_mutex();
+ pa_mutex_lock(mutex);
+ pa_assert(n_ref >= 1);
+
+ unref(after_fork);
+
+ pa_mutex_unlock(mutex);
+}
diff --git a/src/pulse/lock-autospawn.h b/src/pulse/lock-autospawn.h
new file mode 100644
index 00000000..c04c4bd1
--- /dev/null
+++ b/src/pulse/lock-autospawn.h
@@ -0,0 +1,32 @@
+#ifndef foopulselockautospawnhfoo
+#define foopulselockautospawnhfoo
+
+/***
+ This file is part of PulseAudio.
+
+ Copyright 2008 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.
+***/
+
+#include <pulsecore/macro.h>
+
+int pa_autospawn_lock_init(void);
+int pa_autospawn_lock_acquire(pa_bool_t block);
+void pa_autospawn_lock_release(void);
+void pa_autospawn_lock_done(pa_bool_t after_fork);
+
+#endif