#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
+#include <errno.h>
#include <fcntl.h>
#include <gioerror.h>
#ifdef G_OS_WIN32
#include "gcancellable.h"
#include "glibintl.h"
-#include "gioalias.h"
/**
* SECTION:gcancellable
struct _GCancellablePrivate
{
- GObject parent_instance;
-
guint cancelled : 1;
- guint allocated_pipe : 1;
guint cancelled_running : 1;
guint cancelled_running_waiting : 1;
+
+ guint fd_refcount;
int cancel_pipe[2];
#ifdef G_OS_WIN32
static GCond *cancellable_cond = NULL;
static void
-g_cancellable_finalize (GObject *object)
+g_cancellable_close_pipe (GCancellable *cancellable)
{
- GCancellable *cancellable = G_CANCELLABLE (object);
GCancellablePrivate *priv;
-
+
priv = cancellable->priv;
if (priv->cancel_pipe[0] != -1)
- close (priv->cancel_pipe[0]);
+ {
+ close (priv->cancel_pipe[0]);
+ priv->cancel_pipe[0] = -1;
+ }
if (priv->cancel_pipe[1] != -1)
- close (priv->cancel_pipe[1]);
+ {
+ close (priv->cancel_pipe[1]);
+ priv->cancel_pipe[1] = -1;
+ }
#ifdef G_OS_WIN32
if (priv->event)
- CloseHandle (priv->event);
+ {
+ CloseHandle (priv->event);
+ priv->event = NULL;
+ }
#endif
+}
+
+static void
+g_cancellable_finalize (GObject *object)
+{
+ GCancellable *cancellable = G_CANCELLABLE (object);
+
+ g_cancellable_close_pipe (cancellable);
G_OBJECT_CLASS (g_cancellable_parent_class)->finalize (object);
}
set_fd_nonblocking (priv->cancel_pipe[1]);
set_fd_close_exec (priv->cancel_pipe[0]);
set_fd_close_exec (priv->cancel_pipe[1]);
+
+ if (priv->cancelled)
+ {
+ const char ch = 'x';
+ gssize c;
+
+ do
+ c = write (priv->cancel_pipe[1], &ch, 1);
+ while (c == -1 && errno == EINTR);
+ }
}
- else
- g_warning ("Failed to create pipe for GCancellable. Out of file descriptors?");
}
#endif
*
* Gets the top cancellable from the stack.
*
- * Returns: a #GCancellable from the top of the stack, or %NULL
+ * Returns: (transfer none): a #GCancellable from the top of the stack, or %NULL
* if the stack is empty.
**/
GCancellable *
if (priv->cancelled)
{
- char ch;
-
/* Make sure we're not leaving old cancel state around */
#ifdef G_OS_WIN32
if (priv->event)
ResetEvent (priv->event);
- else
#endif
if (priv->cancel_pipe[0] != -1)
- read (priv->cancel_pipe[0], &ch, 1);
+ {
+ gssize c;
+ char ch;
+
+ do
+ c = read (priv->cancel_pipe[0], &ch, 1);
+ while (c == -1 && errno == EINTR);
+ }
+
priv->cancelled = FALSE;
}
G_UNLOCK(cancellable);
* readable status. Reading to unset the readable status is done
* with g_cancellable_reset().
*
+ * After a successful return from this function, you should use
+ * g_cancellable_release_fd() to free up resources allocated for
+ * the returned file descriptor.
+ *
* See also g_cancellable_make_pollfd().
*
* Returns: A valid file descriptor. %-1 if the file descriptor
g_cancellable_get_fd (GCancellable *cancellable)
{
GCancellablePrivate *priv;
-
int fd;
+
if (cancellable == NULL)
return -1;
return -1;
#else
G_LOCK(cancellable);
- if (!priv->allocated_pipe)
- {
- priv->allocated_pipe = TRUE;
- g_cancellable_open_pipe (cancellable);
- }
-
+ if (priv->cancel_pipe[0] == -1)
+ g_cancellable_open_pipe (cancellable);
fd = priv->cancel_pipe[0];
+ if (fd != -1)
+ priv->fd_refcount++;
G_UNLOCK(cancellable);
#endif
/**
* g_cancellable_make_pollfd:
- * @cancellable: a #GCancellable.
+ * @cancellable: a #GCancellable or %NULL
* @pollfd: a pointer to a #GPollFD
*
* Creates a #GPollFD corresponding to @cancellable; this can be passed
* for unix systems without a native poll and for portability to
* windows.
*
+ * When this function returns %TRUE, you should use
+ * g_cancellable_release_fd() to free up resources allocated for the
+ * @pollfd. After a %FALSE return, do not call g_cancellable_release_fd().
+ *
+ * If this function returns %FALSE, either no @cancellable was given or
+ * resource limits prevent this function from allocating the necessary
+ * structures for polling. (On Linux, you will likely have reached
+ * the maximum number of file descriptors.) The suggested way to handle
+ * these cases is to ignore the @cancellable.
+ *
* You are not supposed to read from the fd yourself, just check for
* readable status. Reading to unset the readable status is done
* with g_cancellable_reset().
+ *
+ * Returns: %TRUE if @pollfd was successfully initialized, %FALSE on
+ * failure to prepare the cancellable.
*
+ * Since: 2.22
**/
-void
+gboolean
g_cancellable_make_pollfd (GCancellable *cancellable, GPollFD *pollfd)
{
- GCancellablePrivate *priv;
-
- g_return_if_fail (G_IS_CANCELLABLE (cancellable));
- g_return_if_fail (pollfd != NULL);
-
- priv = cancellable->priv;
+ g_return_val_if_fail (pollfd != NULL, FALSE);
+ if (cancellable == NULL)
+ return FALSE;
+ g_return_val_if_fail (G_IS_CANCELLABLE (cancellable), FALSE);
+ {
#ifdef G_OS_WIN32
- if (!priv->event)
- {
- /* A manual reset anonymous event, starting unset */
- priv->event = CreateEvent (NULL, TRUE, FALSE, NULL);
- }
- pollfd->fd = (gintptr)priv->event;
+ GCancellablePrivate *priv;
+
+ priv = cancellable->priv;
+ G_LOCK(cancellable);
+ if (priv->event == NULL)
+ {
+ /* A manual reset anonymous event, starting unset */
+ priv->event = CreateEvent (NULL, TRUE, FALSE, NULL);
+ if (priv->event == NULL)
+ {
+ G_UNLOCK(cancellable);
+ return FALSE;
+ }
+ if (priv->cancelled)
+ SetEvent(priv->event);
+ }
+ priv->fd_refcount++;
+ G_UNLOCK(cancellable);
+
+ pollfd->fd = (gintptr)priv->event;
#else /* !G_OS_WIN32 */
- pollfd->fd = g_cancellable_get_fd (cancellable);
+ int fd = g_cancellable_get_fd (cancellable);
+
+ if (fd == -1)
+ return FALSE;
+ pollfd->fd = fd;
#endif /* G_OS_WIN32 */
+ }
+
pollfd->events = G_IO_IN;
pollfd->revents = 0;
+
+ return TRUE;
+}
+
+/**
+ * g_cancellable_release_fd:
+ * @cancellable: a #GCancellable
+ *
+ * Releases a resources previously allocated by g_cancellable_get_fd()
+ * or g_cancellable_make_pollfd().
+ *
+ * For compatibility reasons with older releases, calling this function
+ * is not strictly required, the resources will be automatically freed
+ * when the @cancellable is finalized. However, the @cancellable will
+ * block scarce file descriptors until it is finalized if this function
+ * is not called. This can cause the application to run out of file
+ * descriptors when many #GCancellables are used at the same time.
+ *
+ * Since: 2.22
+ **/
+void
+g_cancellable_release_fd (GCancellable *cancellable)
+{
+ GCancellablePrivate *priv;
+
+ if (cancellable == NULL)
+ return;
+
+ g_return_if_fail (G_IS_CANCELLABLE (cancellable));
+ g_return_if_fail (cancellable->priv->fd_refcount > 0);
+
+ priv = cancellable->priv;
+
+ G_LOCK (cancellable);
+ priv->fd_refcount--;
+ if (priv->fd_refcount == 0)
+ g_cancellable_close_pipe (cancellable);
+ G_UNLOCK (cancellable);
}
/**
void
g_cancellable_cancel (GCancellable *cancellable)
{
- static const char ch = 'x';
- gboolean cancel;
GCancellablePrivate *priv;
if (cancellable == NULL ||
- priv->cancelled)
+ cancellable->priv->cancelled)
return;
priv = cancellable->priv;
- cancel = FALSE;
G_LOCK(cancellable);
- cancel = TRUE;
+ if (priv->cancelled)
+ {
+ G_UNLOCK (cancellable);
+ return;
+ }
+
priv->cancelled = TRUE;
priv->cancelled_running = TRUE;
#ifdef G_OS_WIN32
if (priv->event)
- SetEvent(priv->event);
+ SetEvent (priv->event);
#endif
if (priv->cancel_pipe[1] != -1)
- write (priv->cancel_pipe[1], &ch, 1);
+ {
+ const char ch = 'x';
+ gssize c;
+
+ do
+ c = write (priv->cancel_pipe[1], &ch, 1);
+ while (c == -1 && errno == EINTR);
+ }
G_UNLOCK(cancellable);
- if (cancel)
- {
- g_object_ref (cancellable);
- g_signal_emit (cancellable, signals[CANCELLED], 0);
+ g_object_ref (cancellable);
+ g_signal_emit (cancellable, signals[CANCELLED], 0);
- G_LOCK(cancellable);
+ G_LOCK(cancellable);
- priv->cancelled_running = FALSE;
- if (priv->cancelled_running_waiting)
- g_cond_broadcast (cancellable_cond);
- priv->cancelled_running_waiting = FALSE;
+ priv->cancelled_running = FALSE;
+ if (priv->cancelled_running_waiting)
+ g_cond_broadcast (cancellable_cond);
+ priv->cancelled_running_waiting = FALSE;
- G_UNLOCK(cancellable);
+ G_UNLOCK(cancellable);
- g_object_unref (cancellable);
- }
+ g_object_unref (cancellable);
}
/**
* @cancellable: A #GCancellable or %NULL.
* @handler_id: Handler id of the handler to be disconnected, or %0.
*
- * Disconnects a handler from an cancellable instance similar to
- * g_signal_handler_disconnect() but ensures that once this
- * function returns the handler will not run anymore in any thread.
+ * Disconnects a handler from a cancellable instance similar to
+ * g_signal_handler_disconnect(). Additionally, in the event that a
+ * signal handler is currently running, this call will block until the
+ * handler has finished. Calling this function from a
+ * #GCancellable::cancelled signal handler will therefore result in a
+ * deadlock.
*
* This avoids a race condition where a thread cancels at the
* same time as the cancellable operation is finished and the
g_signal_handler_disconnect (cancellable, handler_id);
G_UNLOCK (cancellable);
}
-
-#define __G_CANCELLABLE_C__
-#include "gioaliasdef.c"
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