#ifdef G_OS_WIN32
GPollFD poll;
#else /* G_OS_WIN32 */
- gint count;
gboolean child_exited;
#endif /* G_OS_WIN32 */
};
GPollFD *fd);
static void g_main_context_wakeup_unlocked (GMainContext *context);
-static void _g_main_wake_up_all_contexts (void);
-
static gboolean g_timeout_prepare (GSource *source,
gint *timeout);
static gboolean g_timeout_check (GSource *source);
static gboolean g_child_watch_dispatch (GSource *source,
GSourceFunc callback,
gpointer user_data);
+static void g_child_watch_finalize (GSource *source);
#ifdef G_OS_UNIX
-static gpointer unix_signal_helper_thread (gpointer data) G_GNUC_NORETURN;
static void g_unix_signal_handler (int signum);
static gboolean g_unix_signal_watch_prepare (GSource *source,
gint *timeout);
#ifndef G_OS_WIN32
-/* The UNIX signal pipe contains a single byte specifying which
- * signal was received.
- */
-#define _UNIX_SIGNAL_PIPE_SIGCHLD_CHAR 'C'
-#define _UNIX_SIGNAL_PIPE_SIGHUP_CHAR 'H'
-#define _UNIX_SIGNAL_PIPE_SIGINT_CHAR 'I'
-#define _UNIX_SIGNAL_PIPE_SIGTERM_CHAR 'T'
-/* Guards all the data below */
-G_LOCK_DEFINE_STATIC (unix_signal_lock);
-static gboolean unix_signal_initialized;
-static sigset_t unix_signal_mask;
-static gint unix_signal_wake_up_pipe[2];
-GSList *unix_signal_watches;
-/* Not guarded ( FIXME should it be? ) */
-static gint child_watch_count = 1;
+/* UNIX signals work by marking one of these variables then waking the
+ * worker context to check on them and dispatch accordingly.
+ */
+static volatile gchar unix_signal_pending[NSIG];
+static volatile gboolean any_unix_signal_pending;
+
+/* Guards all the data below */
+G_LOCK_DEFINE_STATIC (unix_signal_lock);
+static GSList *unix_signal_watches;
+static GSList *unix_child_watches;
static GSourceFuncs g_unix_signal_funcs =
{
g_child_watch_prepare,
g_child_watch_check,
g_child_watch_dispatch,
- NULL
+ g_child_watch_finalize
};
GSourceFuncs g_idle_funcs =
return result;
}
-static void
-_g_main_wake_up_all_contexts (void)
-{
- GSList *list;
-
- /* We were woken up. Wake up all other contexts in all other threads */
- G_LOCK (main_context_list);
- for (list = main_context_list; list; list = list->next)
- {
- GMainContext *context = list->data;
-
- LOCK_CONTEXT (context);
- g_main_context_wakeup_unlocked (context);
- UNLOCK_CONTEXT (context);
- }
- G_UNLOCK (main_context_list);
-}
-
-
/* HOLDS: context's lock */
/* Wake the main loop up from a poll() */
static void
#else /* G_OS_WIN32 */
-static gboolean
-check_for_child_exited (GSource *source)
+static void
+wake_source (GSource *source)
{
- GChildWatchSource *child_watch_source;
- gint count;
+ GMainContext *context;
+
+ /* This should be thread-safe:
+ *
+ * - if the source is currently being added to a context, that
+ * context will be woken up anyway
+ *
+ * - if the source is currently being destroyed, we simply need not
+ * to crash:
+ *
+ * - the memory for the source will remain valid until after the
+ * source finalize function was called (which would remove the
+ * source from the global list which we are currently holding the
+ * lock for)
+ *
+ * - the GMainContext will either be NULL or point to a live
+ * GMainContext
+ *
+ * - the GMainContext will remain valid since we hold the
+ * main_context_list lock
+ *
+ * Since we are holding a lot of locks here, don't try to enter any
+ * more GMainContext functions for fear of dealock -- just hit the
+ * GWakeup and run. Even if that's safe now, it could easily become
+ * unsafe with some very minor changes in the future, and signal
+ * handling is not the most well-tested codepath.
+ */
+ G_LOCK(main_context_list);
+ context = source->context;
+ if (context)
+ g_wakeup_signal (context->wakeup);
+ G_UNLOCK(main_context_list);
+}
- /* protect against another SIGCHLD in the middle of this call */
- count = child_watch_count;
+static void
+dispatch_unix_signals (void)
+{
+ GSList *node;
- child_watch_source = (GChildWatchSource *) source;
+ /* clear this first incase another one arrives while we're processing */
+ any_unix_signal_pending = FALSE;
+
+ G_LOCK(unix_signal_lock);
- if (child_watch_source->child_exited)
- return TRUE;
+ /* handle GChildWatchSource instances */
+ if (unix_signal_pending[SIGCHLD])
+ {
+ unix_signal_pending[SIGCHLD] = FALSE;
+
+ /* The only way we can do this is to scan all of the children.
+ *
+ * The docs promise that we will not reap children that we are not
+ * explicitly watching, so that ties our hands from calling
+ * waitpid(-1). We also can't use siginfo's si_pid field since if
+ * multiple SIGCHLD arrive at the same time, one of them can be
+ * dropped (since a given UNIX signal can only be pending once).
+ */
+ for (node = unix_child_watches; node; node = node->next)
+ {
+ GChildWatchSource *source = node->data;
+
+ if (!source->child_exited)
+ {
+ if (waitpid (source->pid, &source->child_status, WNOHANG) > 0)
+ {
+ source->child_exited = TRUE;
- if (child_watch_source->count < count)
+ wake_source ((GSource *) source);
+ }
+ }
+ }
+ }
+
+ /* handle GUnixSignalWatchSource instances */
+ for (node = unix_signal_watches; node; node = node->next)
{
- gint child_status;
+ GUnixSignalWatchSource *source = node->data;
- if (waitpid (child_watch_source->pid, &child_status, WNOHANG) > 0)
- {
- child_watch_source->child_status = child_status;
- child_watch_source->child_exited = TRUE;
- }
- child_watch_source->count = count;
+ if (!source->pending)
+ {
+ if (unix_signal_pending[source->signum])
+ {
+ unix_signal_pending[source->signum] = FALSE;
+ source->pending = TRUE;
+
+ wake_source ((GSource *) source);
+ }
+ }
}
- return child_watch_source->child_exited;
+ G_UNLOCK(unix_signal_lock);
}
static gboolean
g_child_watch_prepare (GSource *source,
gint *timeout)
{
- *timeout = -1;
+ GChildWatchSource *child_watch_source;
- return check_for_child_exited (source);
-}
+ child_watch_source = (GChildWatchSource *) source;
-static gboolean
-g_child_watch_check (GSource *source)
-{
- return check_for_child_exited (source);
+ return child_watch_source->child_exited;
}
static gboolean
-check_for_signal_delivery (GSource *source)
+g_child_watch_check (GSource *source)
{
- GUnixSignalWatchSource *unix_signal_source = (GUnixSignalWatchSource*) source;
- gboolean delivered;
+ GChildWatchSource *child_watch_source;
- G_LOCK (unix_signal_lock);
- g_assert (unix_signal_initialized);
- delivered = unix_signal_source->pending;
- G_UNLOCK (unix_signal_lock);
+ child_watch_source = (GChildWatchSource *) source;
- return delivered;
+ return child_watch_source->child_exited;
}
static gboolean
g_unix_signal_watch_prepare (GSource *source,
gint *timeout)
{
- *timeout = -1;
+ GUnixSignalWatchSource *unix_signal_source;
- return check_for_signal_delivery (source);
+ unix_signal_source = (GUnixSignalWatchSource *) source;
+
+ return unix_signal_source->pending;
}
-static gboolean
+static gboolean
g_unix_signal_watch_check (GSource *source)
{
- return check_for_signal_delivery (source);
+ GUnixSignalWatchSource *unix_signal_source;
+
+ unix_signal_source = (GUnixSignalWatchSource *) source;
+
+ return unix_signal_source->pending;
}
static gboolean
(callback) (user_data);
- G_LOCK (unix_signal_lock);
- g_assert (unix_signal_initialized);
unix_signal_source->pending = FALSE;
- G_UNLOCK (unix_signal_lock);
return TRUE;
}
static void
ensure_unix_signal_handler_installed_unlocked (int signum)
{
+ static sigset_t installed_signal_mask;
+ static gboolean initialized;
struct sigaction action;
- GError *error = NULL;
- if (!unix_signal_initialized)
+ if (!initialized)
{
- sigemptyset (&unix_signal_mask);
-
- if (!g_unix_open_pipe (unix_signal_wake_up_pipe, FD_CLOEXEC, &error))
- g_error ("Cannot create UNIX signal wake up pipe: %s\n", error->message);
- g_unix_set_fd_nonblocking (unix_signal_wake_up_pipe[1], TRUE, NULL);
-
- /* We create a helper thread that polls on the wakeup pipe indefinitely */
- if (g_thread_create (unix_signal_helper_thread, NULL, FALSE, &error) == NULL)
- g_error ("Cannot create a thread to monitor UNIX signals: %s\n", error->message);
-
- unix_signal_initialized = TRUE;
+ sigemptyset (&installed_signal_mask);
+ glib_get_worker_context ();
+ initialized = TRUE;
}
- if (sigismember (&unix_signal_mask, signum))
+ if (sigismember (&installed_signal_mask, signum))
return;
- sigaddset (&unix_signal_mask, signum);
+ sigaddset (&installed_signal_mask, signum);
action.sa_handler = g_unix_signal_handler;
sigemptyset (&action.sa_mask);
G_LOCK (unix_signal_lock);
ensure_unix_signal_handler_installed_unlocked (signum);
unix_signal_watches = g_slist_prepend (unix_signal_watches, unix_signal_source);
+ if (unix_signal_pending[signum])
+ unix_signal_source->pending = TRUE;
+ unix_signal_pending[signum] = FALSE;
G_UNLOCK (unix_signal_lock);
return source;
#endif /* G_OS_WIN32 */
+static void
+g_child_watch_finalize (GSource *source)
+{
+ G_LOCK (unix_signal_lock);
+ unix_child_watches = g_slist_remove (unix_child_watches, source);
+ G_UNLOCK (unix_signal_lock);
+}
+
static gboolean
g_child_watch_dispatch (GSource *source,
GSourceFunc callback,
static void
g_unix_signal_handler (int signum)
{
- if (signum == SIGCHLD)
- child_watch_count ++;
-
- char buf[1];
- switch (signum)
- {
- case SIGCHLD:
- buf[0] = _UNIX_SIGNAL_PIPE_SIGCHLD_CHAR;
- break;
- case SIGHUP:
- buf[0] = _UNIX_SIGNAL_PIPE_SIGHUP_CHAR;
- break;
- case SIGINT:
- buf[0] = _UNIX_SIGNAL_PIPE_SIGINT_CHAR;
- break;
- case SIGTERM:
- buf[0] = _UNIX_SIGNAL_PIPE_SIGTERM_CHAR;
- break;
- default:
- /* Shouldn't happen */
- return;
- }
-
- write (unix_signal_wake_up_pipe[1], buf, 1);
-}
-
-static void
-deliver_unix_signal (int signum)
-{
- GSList *iter;
- g_assert (signum == SIGHUP || signum == SIGINT || signum == SIGTERM);
-
- G_LOCK (unix_signal_lock);
- for (iter = unix_signal_watches; iter; iter = iter->next)
- {
- GUnixSignalWatchSource *source = iter->data;
-
- if (source->signum != signum)
- continue;
-
- source->pending = TRUE;
- }
- G_UNLOCK (unix_signal_lock);
-}
-
-/*
- * This thread is created whenever anything in GLib needs
- * to deal with UNIX signals; at present, just SIGCHLD
- * from g_child_watch_source_new().
- *
- * Note: We could eventually make this thread a more public interface
- * and allow e.g. GDBus to use it instead of its own worker thread.
- */
-static gpointer
-unix_signal_helper_thread (gpointer data)
-{
- while (1)
- {
- gchar b[128];
- ssize_t i, bytes_read;
- gboolean sigterm_received = FALSE;
- gboolean sigint_received = FALSE;
- gboolean sighup_received = FALSE;
-
- bytes_read = read (unix_signal_wake_up_pipe[0], b, sizeof (b));
- if (bytes_read < 0)
- {
- g_warning ("Failed to read from child watch wake up pipe: %s",
- strerror (errno));
- /* Not much we can do here sanely; just wait a second and hope
- * it was transient.
- */
- g_usleep (G_USEC_PER_SEC);
- continue;
- }
- for (i = 0; i < bytes_read; i++)
- {
- switch (b[i])
- {
- case _UNIX_SIGNAL_PIPE_SIGCHLD_CHAR:
- /* The child watch source will call waitpid() in its
- * prepare() and check() methods; however, we don't
- * know which pid exited, so we need to wake up
- * all contexts. Note: actually we could get the pid
- * from the "siginfo_t" via the handler, but to pass
- * that info down the pipe would require a more structured
- * data stream (as opposed to a single byte).
- */
- break;
- case _UNIX_SIGNAL_PIPE_SIGTERM_CHAR:
- sigterm_received = TRUE;
- break;
- case _UNIX_SIGNAL_PIPE_SIGHUP_CHAR:
- sighup_received = TRUE;
- break;
- case _UNIX_SIGNAL_PIPE_SIGINT_CHAR:
- sigint_received = TRUE;
- break;
- default:
- g_warning ("Invalid char '%c' read from child watch pipe", b[i]);
- break;
- }
- }
- if (sigterm_received)
- deliver_unix_signal (SIGTERM);
- if (sigint_received)
- deliver_unix_signal (SIGINT);
- if (sighup_received)
- deliver_unix_signal (SIGHUP);
- _g_main_wake_up_all_contexts ();
- }
-}
+ unix_signal_pending[signum] = TRUE;
+ any_unix_signal_pending = TRUE;
-static void
-g_child_watch_source_init (void)
-{
- G_LOCK (unix_signal_lock);
- ensure_unix_signal_handler_installed_unlocked (SIGCHLD);
- G_UNLOCK (unix_signal_lock);
+ g_wakeup_signal (glib_worker_context->wakeup);
}
#endif /* !G_OS_WIN32 */
GSource *source = g_source_new (&g_child_watch_funcs, sizeof (GChildWatchSource));
GChildWatchSource *child_watch_source = (GChildWatchSource *)source;
+ child_watch_source->pid = pid;
+
#ifdef G_OS_WIN32
child_watch_source->poll.fd = (gintptr) pid;
child_watch_source->poll.events = G_IO_IN;
g_source_add_poll (source, &child_watch_source->poll);
#else /* G_OS_WIN32 */
- g_child_watch_source_init ();
+ G_LOCK (unix_signal_lock);
+ ensure_unix_signal_handler_installed_unlocked (SIGCHLD);
+ unix_child_watches = g_slist_prepend (unix_child_watches, child_watch_source);
+ if (waitpid (pid, &child_watch_source->child_status, WNOHANG) > 0)
+ child_watch_source->child_exited = TRUE;
+ G_UNLOCK (unix_signal_lock);
#endif /* G_OS_WIN32 */
- child_watch_source->pid = pid;
-
return source;
}
static gpointer
glib_worker_main (gpointer data)
{
- LOCK_CONTEXT (glib_worker_context);
-
while (TRUE)
- g_main_context_iterate (glib_worker_context, TRUE, TRUE, G_THREAD_SELF);
+ {
+ g_main_context_iteration (glib_worker_context, TRUE);
+
+ if (any_unix_signal_pending)
+ dispatch_unix_signals ();
+ }
return NULL; /* worst GCC warning message ever... */
}
GMainContext *
glib_get_worker_context (void)
{
- gsize initialised;
+ static gsize initialised;
g_thread_init_glib ();
projects / platform / upstream / glib.git / commitdiff