| /* GIO - GLib Input, Output and Streaming Library |
| * |
| * Copyright (C) 2006-2007 Red Hat, Inc. |
| * |
| * This library 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. |
| * |
| * This library 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 this library; if not, write to the |
| * Free Software Foundation, Inc., 59 Temple Place, Suite 330, |
| * Boston, MA 02111-1307, USA. |
| * |
| * Author: Alexander Larsson <alexl@redhat.com> |
| */ |
| |
| #include "config.h" |
| #ifdef HAVE_UNISTD_H |
| #include <unistd.h> |
| #endif |
| #include <fcntl.h> |
| #include <gioerror.h> |
| #ifdef G_OS_WIN32 |
| #include <io.h> |
| #ifndef pipe |
| #define pipe(fds) _pipe(fds, 4096, _O_BINARY) |
| #endif |
| #endif |
| #include "gcancellable.h" |
| #include "glibintl.h" |
| |
| #include "gioalias.h" |
| |
| /** |
| * SECTION:gcancellable |
| * @short_description: Thread-safe Operation Cancellation Stack |
| * @include: gio/gio.h |
| * |
| * GCancellable is a thread-safe operation cancellation stack used |
| * throughout GIO to allow for cancellation of synchronous and |
| * asynchronous operations. |
| */ |
| |
| enum { |
| CANCELLED, |
| LAST_SIGNAL |
| }; |
| |
| struct _GCancellable |
| { |
| GObject parent_instance; |
| |
| guint cancelled : 1; |
| guint allocated_pipe : 1; |
| int cancel_pipe[2]; |
| |
| #ifdef G_OS_WIN32 |
| GIOChannel *read_channel; |
| #endif |
| }; |
| |
| static guint signals[LAST_SIGNAL] = { 0 }; |
| |
| G_DEFINE_TYPE (GCancellable, g_cancellable, G_TYPE_OBJECT); |
| |
| static GStaticPrivate current_cancellable = G_STATIC_PRIVATE_INIT; |
| G_LOCK_DEFINE_STATIC(cancellable); |
| |
| static void |
| g_cancellable_finalize (GObject *object) |
| { |
| GCancellable *cancellable = G_CANCELLABLE (object); |
| |
| if (cancellable->cancel_pipe[0] != -1) |
| close (cancellable->cancel_pipe[0]); |
| |
| if (cancellable->cancel_pipe[1] != -1) |
| close (cancellable->cancel_pipe[1]); |
| |
| #ifdef G_OS_WIN32 |
| if (cancellable->read_channel) |
| g_io_channel_unref (cancellable->read_channel); |
| #endif |
| |
| G_OBJECT_CLASS (g_cancellable_parent_class)->finalize (object); |
| } |
| |
| static void |
| g_cancellable_class_init (GCancellableClass *klass) |
| { |
| GObjectClass *gobject_class = G_OBJECT_CLASS (klass); |
| |
| gobject_class->finalize = g_cancellable_finalize; |
| |
| /** |
| * GCancellable::cancelled: |
| * @cancellable: a #GCancellable. |
| * |
| * Emitted when the operation has been cancelled. |
| * |
| * Can be used by implementations of cancellable operations. If the |
| * operation is cancelled from another thread, the signal will be |
| * emitted in the thread that cancelled the operation, not the |
| * thread that is running the operation. |
| * |
| * Note that disconnecting from this signal (or any signal) in a |
| * multi-threaded program is prone to race conditions, and it is |
| * possible that a signal handler may be invoked even |
| * <emphasis>after</emphasis> a call to |
| * g_signal_handler_disconnect() for that handler has already |
| * returned. Therefore, code such as the following is wrong in a |
| * multi-threaded program: |
| * |
| * |[ |
| * my_data = my_data_new (...); |
| * id = g_signal_connect (cancellable, "cancelled", |
| * G_CALLBACK (cancelled_handler), my_data); |
| * |
| * /<!-- -->* cancellable operation here... *<!-- -->/ |
| * |
| * g_signal_handler_disconnect (cancellable, id); |
| * my_data_free (my_data); /<!-- -->* WRONG! *<!-- -->/ |
| * /<!-- -->* if g_cancellable_cancel() is called from another |
| * * thread, cancelled_handler() may be running at this point, |
| * * so it's not safe to free my_data. |
| * *<!-- -->/ |
| * ]| |
| * |
| * The correct way to free data (or otherwise clean up temporary |
| * state) in this situation is to use g_signal_connect_data() (or |
| * g_signal_connect_closure()) to connect to the signal, and do the |
| * cleanup from a #GClosureNotify, which will not be called until |
| * after the signal handler is both removed and not running: |
| * |
| * |[ |
| * static void |
| * cancelled_disconnect_notify (gpointer my_data, GClosure *closure) |
| * { |
| * my_data_free (my_data); |
| * } |
| * |
| * ... |
| * |
| * my_data = my_data_new (...); |
| * id = g_signal_connect_data (cancellable, "cancelled", |
| * G_CALLBACK (cancelled_handler), my_data, |
| * cancelled_disconnect_notify, 0); |
| * |
| * /<!-- -->* cancellable operation here... *<!-- -->/ |
| * |
| * g_signal_handler_disconnect (cancellable, id); |
| * /<!-- -->* cancelled_disconnect_notify() may or may not have |
| * * already been called at this point, so the code has to treat |
| * * my_data as though it has been freed. |
| * *<!-- -->/ |
| * ]| |
| */ |
| signals[CANCELLED] = |
| g_signal_new (I_("cancelled"), |
| G_TYPE_FROM_CLASS (gobject_class), |
| G_SIGNAL_RUN_LAST, |
| G_STRUCT_OFFSET (GCancellableClass, cancelled), |
| NULL, NULL, |
| g_cclosure_marshal_VOID__VOID, |
| G_TYPE_NONE, 0); |
| |
| } |
| |
| static void |
| set_fd_nonblocking (int fd) |
| { |
| #ifdef F_GETFL |
| glong fcntl_flags; |
| fcntl_flags = fcntl (fd, F_GETFL); |
| |
| #ifdef O_NONBLOCK |
| fcntl_flags |= O_NONBLOCK; |
| #else |
| fcntl_flags |= O_NDELAY; |
| #endif |
| |
| fcntl (fd, F_SETFL, fcntl_flags); |
| #endif |
| } |
| |
| static void |
| g_cancellable_open_pipe (GCancellable *cancellable) |
| { |
| if (pipe (cancellable->cancel_pipe) == 0) |
| { |
| /* Make them nonblocking, just to be sure we don't block |
| * on errors and stuff |
| */ |
| set_fd_nonblocking (cancellable->cancel_pipe[0]); |
| set_fd_nonblocking (cancellable->cancel_pipe[1]); |
| } |
| else |
| g_warning ("Failed to create pipe for GCancellable. Out of file descriptors?"); |
| } |
| |
| static void |
| g_cancellable_init (GCancellable *cancellable) |
| { |
| cancellable->cancel_pipe[0] = -1; |
| cancellable->cancel_pipe[1] = -1; |
| } |
| |
| /** |
| * g_cancellable_new: |
| * |
| * Creates a new #GCancellable object. |
| * |
| * Applications that want to start one or more operations |
| * that should be cancellable should create a #GCancellable |
| * and pass it to the operations. |
| * |
| * One #GCancellable can be used in multiple consecutive |
| * operations, but not in multiple concurrent operations. |
| * |
| * Returns: a #GCancellable. |
| **/ |
| GCancellable * |
| g_cancellable_new (void) |
| { |
| return g_object_new (G_TYPE_CANCELLABLE, NULL); |
| } |
| |
| /** |
| * g_cancellable_push_current: |
| * @cancellable: optional #GCancellable object, %NULL to ignore. |
| * |
| * Pushes @cancellable onto the cancellable stack. The current |
| * cancllable can then be recieved using g_cancellable_get_current(). |
| * |
| * This is useful when implementing cancellable operations in |
| * code that does not allow you to pass down the cancellable object. |
| * |
| * This is typically called automatically by e.g. #GFile operations, |
| * so you rarely have to call this yourself. |
| **/ |
| void |
| g_cancellable_push_current (GCancellable *cancellable) |
| { |
| GSList *l; |
| |
| g_return_if_fail (cancellable != NULL); |
| |
| l = g_static_private_get (¤t_cancellable); |
| l = g_slist_prepend (l, cancellable); |
| g_static_private_set (¤t_cancellable, l, NULL); |
| } |
| |
| /** |
| * g_cancellable_pop_current: |
| * @cancellable: optional #GCancellable object, %NULL to ignore. |
| * |
| * Pops @cancellable off the cancellable stack (verifying that @cancellable |
| * is on the top of the stack). |
| **/ |
| void |
| g_cancellable_pop_current (GCancellable *cancellable) |
| { |
| GSList *l; |
| |
| l = g_static_private_get (¤t_cancellable); |
| |
| g_return_if_fail (l != NULL); |
| g_return_if_fail (l->data == cancellable); |
| |
| l = g_slist_delete_link (l, l); |
| g_static_private_set (¤t_cancellable, l, NULL); |
| } |
| |
| /** |
| * g_cancellable_get_current: |
| * |
| * Gets the top cancellable from the stack. |
| * |
| * Returns: a #GCancellable from the top of the stack, or %NULL |
| * if the stack is empty. |
| **/ |
| GCancellable * |
| g_cancellable_get_current (void) |
| { |
| GSList *l; |
| |
| l = g_static_private_get (¤t_cancellable); |
| if (l == NULL) |
| return NULL; |
| |
| return G_CANCELLABLE (l->data); |
| } |
| |
| /** |
| * g_cancellable_reset: |
| * @cancellable: a #GCancellable object. |
| * |
| * Resets @cancellable to its uncancelled state. |
| **/ |
| void |
| g_cancellable_reset (GCancellable *cancellable) |
| { |
| g_return_if_fail (G_IS_CANCELLABLE (cancellable)); |
| |
| G_LOCK(cancellable); |
| /* Make sure we're not leaving old cancel state around */ |
| if (cancellable->cancelled) |
| { |
| char ch; |
| #ifdef G_OS_WIN32 |
| if (cancellable->read_channel) |
| { |
| gsize bytes_read; |
| g_io_channel_read_chars (cancellable->read_channel, &ch, 1, |
| &bytes_read, NULL); |
| } |
| else |
| #endif |
| if (cancellable->cancel_pipe[0] != -1) |
| read (cancellable->cancel_pipe[0], &ch, 1); |
| cancellable->cancelled = FALSE; |
| } |
| G_UNLOCK(cancellable); |
| } |
| |
| /** |
| * g_cancellable_is_cancelled: |
| * @cancellable: a #GCancellable or NULL. |
| * |
| * Checks if a cancellable job has been cancelled. |
| * |
| * Returns: %TRUE if @cancellable is cancelled, |
| * FALSE if called with %NULL or if item is not cancelled. |
| **/ |
| gboolean |
| g_cancellable_is_cancelled (GCancellable *cancellable) |
| { |
| return cancellable != NULL && cancellable->cancelled; |
| } |
| |
| /** |
| * g_cancellable_set_error_if_cancelled: |
| * @cancellable: a #GCancellable object. |
| * @error: #GError to append error state to. |
| * |
| * If the @cancellable is cancelled, sets the error to notify |
| * that the operation was cancelled. |
| * |
| * Returns: %TRUE if @cancellable was cancelled, %FALSE if it was not. |
| **/ |
| gboolean |
| g_cancellable_set_error_if_cancelled (GCancellable *cancellable, |
| GError **error) |
| { |
| if (g_cancellable_is_cancelled (cancellable)) |
| { |
| g_set_error_literal (error, |
| G_IO_ERROR, |
| G_IO_ERROR_CANCELLED, |
| _("Operation was cancelled")); |
| return TRUE; |
| } |
| |
| return FALSE; |
| } |
| |
| /** |
| * g_cancellable_get_fd: |
| * @cancellable: a #GCancellable. |
| * |
| * Gets the file descriptor for a cancellable job. This can be used to |
| * implement cancellable operations on Unix systems. The returned fd will |
| * turn readable when @cancellable is cancelled. |
| * |
| * See also g_cancellable_make_pollfd(). |
| * |
| * Returns: A valid file descriptor. %-1 if the file descriptor |
| * is not supported, or on errors. |
| **/ |
| int |
| g_cancellable_get_fd (GCancellable *cancellable) |
| { |
| int fd; |
| if (cancellable == NULL) |
| return -1; |
| |
| G_LOCK(cancellable); |
| if (!cancellable->allocated_pipe) |
| { |
| cancellable->allocated_pipe = TRUE; |
| g_cancellable_open_pipe (cancellable); |
| } |
| |
| fd = cancellable->cancel_pipe[0]; |
| G_UNLOCK(cancellable); |
| |
| return fd; |
| } |
| |
| /** |
| * g_cancellable_make_pollfd: |
| * @cancellable: a #GCancellable. |
| * @pollfd: a pointer to a #GPollFD |
| * |
| * Creates a #GPollFD corresponding to @cancellable; this can be passed |
| * to g_poll() and used to poll for cancellation. |
| **/ |
| void |
| g_cancellable_make_pollfd (GCancellable *cancellable, GPollFD *pollfd) |
| { |
| g_return_if_fail (G_IS_CANCELLABLE (cancellable)); |
| g_return_if_fail (pollfd != NULL); |
| |
| #ifdef G_OS_WIN32 |
| if (!cancellable->read_channel) |
| { |
| int fd = g_cancellable_get_fd (cancellable); |
| cancellable->read_channel = g_io_channel_win32_new_fd (fd); |
| g_io_channel_set_buffered (cancellable->read_channel, FALSE); |
| g_io_channel_set_flags (cancellable->read_channel, |
| G_IO_FLAG_NONBLOCK, NULL); |
| g_io_channel_set_encoding (cancellable->read_channel, NULL, NULL); |
| } |
| g_io_channel_win32_make_pollfd (cancellable->read_channel, G_IO_IN, pollfd); |
| /* (We need to keep cancellable->read_channel around, because it's |
| * keeping track of state related to the pollfd.) |
| */ |
| #else /* !G_OS_WIN32 */ |
| pollfd->fd = g_cancellable_get_fd (cancellable); |
| pollfd->events = G_IO_IN; |
| #endif /* G_OS_WIN32 */ |
| pollfd->revents = 0; |
| } |
| |
| /** |
| * g_cancellable_cancel: |
| * @cancellable: a #GCancellable object. |
| * |
| * Will set @cancellable to cancelled, and will emit the |
| * #GCancellable::cancelled signal. (However, see the warning about |
| * race conditions in the documentation for that signal if you are |
| * planning to connect to it.) |
| * |
| * This function is thread-safe. In other words, you can safely call |
| * it from a thread other than the one running the operation that was |
| * passed the @cancellable. |
| * |
| * The convention within gio is that cancelling an asynchronous |
| * operation causes it to complete asynchronously. That is, if you |
| * cancel the operation from the same thread in which it is running, |
| * then the operation's #GAsyncReadyCallback will not be invoked until |
| * the application returns to the main loop. |
| **/ |
| void |
| g_cancellable_cancel (GCancellable *cancellable) |
| { |
| gboolean cancel; |
| |
| cancel = FALSE; |
| |
| G_LOCK(cancellable); |
| if (cancellable != NULL && |
| !cancellable->cancelled) |
| { |
| char ch = 'x'; |
| cancel = TRUE; |
| cancellable->cancelled = TRUE; |
| if (cancellable->cancel_pipe[1] != -1) |
| write (cancellable->cancel_pipe[1], &ch, 1); |
| } |
| G_UNLOCK(cancellable); |
| |
| if (cancel) |
| { |
| g_object_ref (cancellable); |
| g_signal_emit (cancellable, signals[CANCELLED], 0); |
| g_object_unref (cancellable); |
| } |
| } |
| |
| #define __G_CANCELLABLE_C__ |
| #include "gioaliasdef.c" |