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glib/gio/giostream.c
Ryan Lortie c2c0a6ae5c GIOStream: support for unemulated async close() 
Add an implementation of non-thread-emulated async close of a GIOStream
if either of the underlying stream objects support it.

This prevents us from calling close() functions from another thread on
an object that may not be expecting that.  It also allows us to skip the
thread entirely in case our objects support a pure async close.

https://bugzilla.gnome.org/show_bug.cgi?id=741630
2015-02-17 16:17:01 -05:00

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/* GIO - GLib Input, Output and Streaming Library
*
* Copyright © 2008 codethink
* Copyright © 2009 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, see <http://www.gnu.org/licenses/>.
*
* Authors: Ryan Lortie <desrt@desrt.ca>
* Alexander Larsson <alexl@redhat.com>
*/
#include "config.h"
#include <glib.h>
#include "glibintl.h"
#include "giostream.h"
#include "gasyncresult.h"
#include "gioprivate.h"
#include "gtask.h"
/**
* SECTION:giostream
* @short_description: Base class for implementing read/write streams
* @include: gio/gio.h
* @see_also: #GInputStream, #GOutputStream
*
* GIOStream represents an object that has both read and write streams.
* Generally the two streams acts as separate input and output streams,
* but they share some common resources and state. For instance, for
* seekable streams they may use the same position in both streams.
*
* Examples of #GIOStream objects are #GSocketConnection which represents
* a two-way network connection, and #GFileIOStream which represent a
* file handle opened in read-write mode.
*
* To do the actual reading and writing you need to get the substreams
* with g_io_stream_get_input_stream() and g_io_stream_get_output_stream().
*
* The #GIOStream object owns the input and the output streams, not the other
* way around, so keeping the substreams alive will not keep the #GIOStream
* object alive. If the #GIOStream object is freed it will be closed, thus
* closing the substream, so even if the substreams stay alive they will
* always just return a %G_IO_ERROR_CLOSED for all operations.
*
* To close a stream use g_io_stream_close() which will close the common
* stream object and also the individual substreams. You can also close
* the substreams themselves. In most cases this only marks the
* substream as closed, so further I/O on it fails but common state in the
* #GIOStream may still be open. However, some streams may support
* "half-closed" states where one direction of the stream is actually shut down.
*
* Since: 2.22
*/
enum
{
PROP_0,
PROP_INPUT_STREAM,
PROP_OUTPUT_STREAM,
PROP_CLOSED
};
struct _GIOStreamPrivate {
guint closed : 1;
guint pending : 1;
};
static gboolean g_io_stream_real_close (GIOStream *stream,
GCancellable *cancellable,
GError **error);
static void g_io_stream_real_close_async (GIOStream *stream,
int io_priority,
GCancellable *cancellable,
GAsyncReadyCallback callback,
gpointer user_data);
static gboolean g_io_stream_real_close_finish (GIOStream *stream,
GAsyncResult *result,
GError **error);
G_DEFINE_ABSTRACT_TYPE_WITH_PRIVATE (GIOStream, g_io_stream, G_TYPE_OBJECT)
static void
g_io_stream_dispose (GObject *object)
{
GIOStream *stream;
stream = G_IO_STREAM (object);
if (!stream->priv->closed)
g_io_stream_close (stream, NULL, NULL);
G_OBJECT_CLASS (g_io_stream_parent_class)->dispose (object);
}
static void
g_io_stream_init (GIOStream *stream)
{
stream->priv = g_io_stream_get_instance_private (stream);
}
static void
g_io_stream_get_property (GObject *object,
guint prop_id,
GValue *value,
GParamSpec *pspec)
{
GIOStream *stream = G_IO_STREAM (object);
switch (prop_id)
{
case PROP_CLOSED:
g_value_set_boolean (value, stream->priv->closed);
break;
case PROP_INPUT_STREAM:
g_value_set_object (value, g_io_stream_get_input_stream (stream));
break;
case PROP_OUTPUT_STREAM:
g_value_set_object (value, g_io_stream_get_output_stream (stream));
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
}
}
static void
g_io_stream_class_init (GIOStreamClass *klass)
{
GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
gobject_class->dispose = g_io_stream_dispose;
gobject_class->get_property = g_io_stream_get_property;
klass->close_fn = g_io_stream_real_close;
klass->close_async = g_io_stream_real_close_async;
klass->close_finish = g_io_stream_real_close_finish;
g_object_class_install_property (gobject_class, PROP_CLOSED,
g_param_spec_boolean ("closed",
P_("Closed"),
P_("Is the stream closed"),
FALSE,
G_PARAM_READABLE | G_PARAM_STATIC_STRINGS));
g_object_class_install_property (gobject_class, PROP_INPUT_STREAM,
g_param_spec_object ("input-stream",
P_("Input stream"),
P_("The GInputStream to read from"),
G_TYPE_INPUT_STREAM,
G_PARAM_READABLE | G_PARAM_STATIC_STRINGS));
g_object_class_install_property (gobject_class, PROP_OUTPUT_STREAM,
g_param_spec_object ("output-stream",
P_("Output stream"),
P_("The GOutputStream to write to"),
G_TYPE_OUTPUT_STREAM,
G_PARAM_READABLE | G_PARAM_STATIC_STRINGS));
}
/**
* g_io_stream_is_closed:
* @stream: a #GIOStream
*
* Checks if a stream is closed.
*
* Returns: %TRUE if the stream is closed.
*
* Since: 2.22
*/
gboolean
g_io_stream_is_closed (GIOStream *stream)
{
g_return_val_if_fail (G_IS_IO_STREAM (stream), TRUE);
return stream->priv->closed;
}
/**
* g_io_stream_get_input_stream:
* @stream: a #GIOStream
*
* Gets the input stream for this object. This is used
* for reading.
*
* Returns: (transfer none): a #GInputStream, owned by the #GIOStream.
* Do not free.
*
* Since: 2.22
*/
GInputStream *
g_io_stream_get_input_stream (GIOStream *stream)
{
GIOStreamClass *klass;
klass = G_IO_STREAM_GET_CLASS (stream);
g_assert (klass->get_input_stream != NULL);
return klass->get_input_stream (stream);
}
/**
* g_io_stream_get_output_stream:
* @stream: a #GIOStream
*
* Gets the output stream for this object. This is used for
* writing.
*
* Returns: (transfer none): a #GOutputStream, owned by the #GIOStream.
* Do not free.
*
* Since: 2.22
*/
GOutputStream *
g_io_stream_get_output_stream (GIOStream *stream)
{
GIOStreamClass *klass;
klass = G_IO_STREAM_GET_CLASS (stream);
g_assert (klass->get_output_stream != NULL);
return klass->get_output_stream (stream);
}
/**
* g_io_stream_has_pending:
* @stream: a #GIOStream
*
* Checks if a stream has pending actions.
*
* Returns: %TRUE if @stream has pending actions.
*
* Since: 2.22
**/
gboolean
g_io_stream_has_pending (GIOStream *stream)
{
g_return_val_if_fail (G_IS_IO_STREAM (stream), FALSE);
return stream->priv->pending;
}
/**
* g_io_stream_set_pending:
* @stream: a #GIOStream
* @error: a #GError location to store the error occurring, or %NULL to
* ignore
*
* Sets @stream to have actions pending. If the pending flag is
* already set or @stream is closed, it will return %FALSE and set
* @error.
*
* Returns: %TRUE if pending was previously unset and is now set.
*
* Since: 2.22
*/
gboolean
g_io_stream_set_pending (GIOStream *stream,
GError **error)
{
g_return_val_if_fail (G_IS_IO_STREAM (stream), FALSE);
if (stream->priv->closed)
{
g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_CLOSED,
_("Stream is already closed"));
return FALSE;
}
if (stream->priv->pending)
{
g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_PENDING,
/* Translators: This is an error you get if there is
* already an operation running against this stream when
* you try to start one */
_("Stream has outstanding operation"));
return FALSE;
}
stream->priv->pending = TRUE;
return TRUE;
}
/**
* g_io_stream_clear_pending:
* @stream: a #GIOStream
*
* Clears the pending flag on @stream.
*
* Since: 2.22
*/
void
g_io_stream_clear_pending (GIOStream *stream)
{
g_return_if_fail (G_IS_IO_STREAM (stream));
stream->priv->pending = FALSE;
}
static gboolean
g_io_stream_real_close (GIOStream *stream,
GCancellable *cancellable,
GError **error)
{
gboolean res;
res = g_output_stream_close (g_io_stream_get_output_stream (stream),
cancellable, error);
/* If this errored out, unset error so that we don't report
further errors, but still do the following ops */
if (error != NULL && *error != NULL)
error = NULL;
res &= g_input_stream_close (g_io_stream_get_input_stream (stream),
cancellable, error);
return res;
}
/**
* g_io_stream_close:
* @stream: a #GIOStream
* @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore
* @error: location to store the error occurring, or %NULL to ignore
*
* Closes the stream, releasing resources related to it. This will also
* closes the individual input and output streams, if they are not already
* closed.
*
* Once the stream is closed, all other operations will return
* %G_IO_ERROR_CLOSED. Closing a stream multiple times will not
* return an error.
*
* Closing a stream will automatically flush any outstanding buffers
* in the stream.
*
* Streams will be automatically closed when the last reference
* is dropped, but you might want to call this function to make sure
* resources are released as early as possible.
*
* Some streams might keep the backing store of the stream (e.g. a file
* descriptor) open after the stream is closed. See the documentation for
* the individual stream for details.
*
* On failure the first error that happened will be reported, but the
* close operation will finish as much as possible. A stream that failed
* to close will still return %G_IO_ERROR_CLOSED for all operations.
* Still, it is important to check and report the error to the user,
* otherwise there might be a loss of data as all data might not be written.
*
* If @cancellable is not NULL, then the operation can be cancelled by
* triggering the cancellable object from another thread. If the operation
* was cancelled, the error %G_IO_ERROR_CANCELLED will be returned.
* Cancelling a close will still leave the stream closed, but some streams
* can use a faster close that doesn't block to e.g. check errors.
*
* The default implementation of this method just calls close on the
* individual input/output streams.
*
* Returns: %TRUE on success, %FALSE on failure
*
* Since: 2.22
*/
gboolean
g_io_stream_close (GIOStream *stream,
GCancellable *cancellable,
GError **error)
{
GIOStreamClass *class;
gboolean res;
g_return_val_if_fail (G_IS_IO_STREAM (stream), FALSE);
class = G_IO_STREAM_GET_CLASS (stream);
if (stream->priv->closed)
return TRUE;
if (!g_io_stream_set_pending (stream, error))
return FALSE;
if (cancellable)
g_cancellable_push_current (cancellable);
res = TRUE;
if (class->close_fn)
res = class->close_fn (stream, cancellable, error);
if (cancellable)
g_cancellable_pop_current (cancellable);
stream->priv->closed = TRUE;
g_io_stream_clear_pending (stream);
return res;
}
static void
async_ready_close_callback_wrapper (GObject *source_object,
GAsyncResult *res,
gpointer user_data)
{
GIOStream *stream = G_IO_STREAM (source_object);
GIOStreamClass *klass = G_IO_STREAM_GET_CLASS (stream);
GTask *task = user_data;
GError *error = NULL;
gboolean success;
stream->priv->closed = TRUE;
g_io_stream_clear_pending (stream);
if (g_async_result_legacy_propagate_error (res, &error))
success = FALSE;
else
success = klass->close_finish (stream, res, &error);
if (error)
g_task_return_error (task, error);
else
g_task_return_boolean (task, success);
g_object_unref (task);
}
/**
* g_io_stream_close_async:
* @stream: a #GIOStream
* @io_priority: the io priority of the request
* @cancellable: (allow-none): optional cancellable object
* @callback: (scope async): callback to call when the request is satisfied
* @user_data: (closure): the data to pass to callback function
*
* Requests an asynchronous close of the stream, releasing resources
* related to it. When the operation is finished @callback will be
* called. You can then call g_io_stream_close_finish() to get
* the result of the operation.
*
* For behaviour details see g_io_stream_close().
*
* The asynchronous methods have a default fallback that uses threads
* to implement asynchronicity, so they are optional for inheriting
* classes. However, if you override one you must override all.
*
* Since: 2.22
*/
void
g_io_stream_close_async (GIOStream *stream,
int io_priority,
GCancellable *cancellable,
GAsyncReadyCallback callback,
gpointer user_data)
{
GIOStreamClass *class;
GError *error = NULL;
GTask *task;
g_return_if_fail (G_IS_IO_STREAM (stream));
task = g_task_new (stream, cancellable, callback, user_data);
if (stream->priv->closed)
{
g_task_return_boolean (task, TRUE);
g_object_unref (task);
return;
}
if (!g_io_stream_set_pending (stream, &error))
{
g_task_return_error (task, error);
g_object_unref (task);
return;
}
class = G_IO_STREAM_GET_CLASS (stream);
class->close_async (stream, io_priority, cancellable,
async_ready_close_callback_wrapper, task);
}
/**
* g_io_stream_close_finish:
* @stream: a #GIOStream
* @result: a #GAsyncResult
* @error: a #GError location to store the error occurring, or %NULL to
* ignore
*
* Closes a stream.
*
* Returns: %TRUE if stream was successfully closed, %FALSE otherwise.
*
* Since: 2.22
*/
gboolean
g_io_stream_close_finish (GIOStream *stream,
GAsyncResult *result,
GError **error)
{
g_return_val_if_fail (G_IS_IO_STREAM (stream), FALSE);
g_return_val_if_fail (g_task_is_valid (result, stream), FALSE);
return g_task_propagate_boolean (G_TASK (result), error);
}
static void
close_async_thread (GTask *task,
gpointer source_object,
gpointer task_data,
GCancellable *cancellable)
{
GIOStream *stream = source_object;
GIOStreamClass *class;
GError *error = NULL;
gboolean result;
class = G_IO_STREAM_GET_CLASS (stream);
if (class->close_fn)
{
result = class->close_fn (stream,
g_task_get_cancellable (task),
&error);
if (!result)
{
g_task_return_error (task, error);
return;
}
}
g_task_return_boolean (task, TRUE);
}
typedef struct
{
GError *error;
gint pending;
} CloseAsyncData;
static void
stream_close_complete (GObject *source,
GAsyncResult *result,
gpointer user_data)
{
GTask *task = user_data;
CloseAsyncData *data;
data = g_task_get_task_data (task);
data->pending--;
if (G_IS_OUTPUT_STREAM (source))
{
GError *error = NULL;
/* Match behaviour with the sync route and give precedent to the
* error returned from closing the output stream.
*/
g_output_stream_close_finish (G_OUTPUT_STREAM (source), result, &error);
if (error)
{
if (data->error)
g_error_free (data->error);
data->error = error;
}
}
else
g_input_stream_close_finish (G_INPUT_STREAM (source), result, data->error ? NULL : &data->error);
if (data->pending == 0)
{
if (data->error)
g_task_return_error (task, data->error);
else
g_task_return_boolean (task, TRUE);
g_slice_free (CloseAsyncData, data);
g_object_unref (task);
}
}
static void
g_io_stream_real_close_async (GIOStream *stream,
int io_priority,
GCancellable *cancellable,
GAsyncReadyCallback callback,
gpointer user_data)
{
GInputStream *input;
GOutputStream *output;
GTask *task;
task = g_task_new (stream, cancellable, callback, user_data);
g_task_set_check_cancellable (task, FALSE);
g_task_set_priority (task, io_priority);
input = g_io_stream_get_input_stream (stream);
output = g_io_stream_get_output_stream (stream);
if (g_input_stream_async_close_is_via_threads (input) && g_output_stream_async_close_is_via_threads (output))
{
/* No sense in dispatching to the thread twice -- just do it all
* in one go.
*/
g_task_run_in_thread (task, close_async_thread);
g_object_unref (task);
}
else
{
CloseAsyncData *data;
/* We should avoid dispatching to another thread in case either
* object that would not do it for itself because it may not be
* threadsafe.
*/
data = g_slice_new (CloseAsyncData);
data->error = NULL;
data->pending = 2;
g_task_set_task_data (task, data, NULL);
g_input_stream_close_async (input, io_priority, cancellable, stream_close_complete, task);
g_output_stream_close_async (output, io_priority, cancellable, stream_close_complete, task);
}
}
static gboolean
g_io_stream_real_close_finish (GIOStream *stream,
GAsyncResult *result,
GError **error)
{
g_return_val_if_fail (g_task_is_valid (result, stream), FALSE);
return g_task_propagate_boolean (G_TASK (result), error);
}
typedef struct
{
GIOStream *stream1;
GIOStream *stream2;
GIOStreamSpliceFlags flags;
gint io_priority;
GCancellable *cancellable;
gulong cancelled_id;
GCancellable *op1_cancellable;
GCancellable *op2_cancellable;
guint completed;
GError *error;
} SpliceContext;
static void
splice_context_free (SpliceContext *ctx)
{
g_object_unref (ctx->stream1);
g_object_unref (ctx->stream2);
if (ctx->cancellable != NULL)
g_object_unref (ctx->cancellable);
g_object_unref (ctx->op1_cancellable);
g_object_unref (ctx->op2_cancellable);
g_clear_error (&ctx->error);
g_slice_free (SpliceContext, ctx);
}
static void
splice_complete (GTask *task,
SpliceContext *ctx)
{
if (ctx->cancelled_id != 0)
g_cancellable_disconnect (ctx->cancellable, ctx->cancelled_id);
ctx->cancelled_id = 0;
if (ctx->error != NULL)
{
g_task_return_error (task, ctx->error);
ctx->error = NULL;
}
else
g_task_return_boolean (task, TRUE);
}
static void
splice_close_cb (GObject *iostream,
GAsyncResult *res,
gpointer user_data)
{
GTask *task = user_data;
SpliceContext *ctx = g_task_get_task_data (task);
GError *error = NULL;
g_io_stream_close_finish (G_IO_STREAM (iostream), res, &error);
ctx->completed++;
/* Keep the first error that occurred */
if (error != NULL && ctx->error == NULL)
ctx->error = error;
else
g_clear_error (&error);
/* If all operations are done, complete now */
if (ctx->completed == 4)
splice_complete (task, ctx);
g_object_unref (task);
}
static void
splice_cb (GObject *ostream,
GAsyncResult *res,
gpointer user_data)
{
GTask *task = user_data;
SpliceContext *ctx = g_task_get_task_data (task);
GError *error = NULL;
g_output_stream_splice_finish (G_OUTPUT_STREAM (ostream), res, &error);
ctx->completed++;
/* ignore cancellation error if it was not requested by the user */
if (error != NULL &&
g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED) &&
(ctx->cancellable == NULL ||
!g_cancellable_is_cancelled (ctx->cancellable)))
g_clear_error (&error);
/* Keep the first error that occurred */
if (error != NULL && ctx->error == NULL)
ctx->error = error;
else
g_clear_error (&error);
if (ctx->completed == 1 &&
(ctx->flags & G_IO_STREAM_SPLICE_WAIT_FOR_BOTH) == 0)
{
/* We don't want to wait for the 2nd operation to finish, cancel it */
g_cancellable_cancel (ctx->op1_cancellable);
g_cancellable_cancel (ctx->op2_cancellable);
}
else if (ctx->completed == 2)
{
if (ctx->cancellable == NULL ||
!g_cancellable_is_cancelled (ctx->cancellable))
{
g_cancellable_reset (ctx->op1_cancellable);
g_cancellable_reset (ctx->op2_cancellable);
}
/* Close the IO streams if needed */
if ((ctx->flags & G_IO_STREAM_SPLICE_CLOSE_STREAM1) != 0)
{
g_io_stream_close_async (ctx->stream1,
g_task_get_priority (task),
ctx->op1_cancellable,
splice_close_cb, g_object_ref (task));
}
else
ctx->completed++;
if ((ctx->flags & G_IO_STREAM_SPLICE_CLOSE_STREAM2) != 0)
{
g_io_stream_close_async (ctx->stream2,
g_task_get_priority (task),
ctx->op2_cancellable,
splice_close_cb, g_object_ref (task));
}
else
ctx->completed++;
/* If all operations are done, complete now */
if (ctx->completed == 4)
splice_complete (task, ctx);
}
g_object_unref (task);
}
static void
splice_cancelled_cb (GCancellable *cancellable,
GTask *task)
{
SpliceContext *ctx;
ctx = g_task_get_task_data (task);
g_cancellable_cancel (ctx->op1_cancellable);
g_cancellable_cancel (ctx->op2_cancellable);
}
/**
* g_io_stream_splice_async:
* @stream1: a #GIOStream.
* @stream2: a #GIOStream.
* @flags: a set of #GIOStreamSpliceFlags.
* @io_priority: the io priority of the request.
* @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
* @callback: (scope async): a #GAsyncReadyCallback.
* @user_data: (closure): user data passed to @callback.
*
* Asyncronously splice the output stream of @stream1 to the input stream of
* @stream2, and splice the output stream of @stream2 to the input stream of
* @stream1.
*
* When the operation is finished @callback will be called.
* You can then call g_io_stream_splice_finish() to get the
* result of the operation.
*
* Since: 2.28
**/
void
g_io_stream_splice_async (GIOStream *stream1,
GIOStream *stream2,
GIOStreamSpliceFlags flags,
gint io_priority,
GCancellable *cancellable,
GAsyncReadyCallback callback,
gpointer user_data)
{
GTask *task;
SpliceContext *ctx;
GInputStream *istream;
GOutputStream *ostream;
if (cancellable != NULL && g_cancellable_is_cancelled (cancellable))
{
g_task_report_new_error (NULL, callback, user_data,
g_io_stream_splice_async,
G_IO_ERROR, G_IO_ERROR_CANCELLED,
"Operation has been cancelled");
return;
}
ctx = g_slice_new0 (SpliceContext);
ctx->stream1 = g_object_ref (stream1);
ctx->stream2 = g_object_ref (stream2);
ctx->flags = flags;
ctx->op1_cancellable = g_cancellable_new ();
ctx->op2_cancellable = g_cancellable_new ();
ctx->completed = 0;
task = g_task_new (NULL, cancellable, callback, user_data);
g_task_set_task_data (task, ctx, (GDestroyNotify) splice_context_free);
if (cancellable != NULL)
{
ctx->cancellable = g_object_ref (cancellable);
ctx->cancelled_id = g_cancellable_connect (cancellable,
G_CALLBACK (splice_cancelled_cb), g_object_ref (task),
g_object_unref);
}
istream = g_io_stream_get_input_stream (stream1);
ostream = g_io_stream_get_output_stream (stream2);
g_output_stream_splice_async (ostream, istream, G_OUTPUT_STREAM_SPLICE_NONE,
io_priority, ctx->op1_cancellable, splice_cb,
g_object_ref (task));
istream = g_io_stream_get_input_stream (stream2);
ostream = g_io_stream_get_output_stream (stream1);
g_output_stream_splice_async (ostream, istream, G_OUTPUT_STREAM_SPLICE_NONE,
io_priority, ctx->op2_cancellable, splice_cb,
g_object_ref (task));
g_object_unref (task);
}
/**
* g_io_stream_splice_finish:
* @result: a #GAsyncResult.
* @error: a #GError location to store the error occurring, or %NULL to
* ignore.
*
* Finishes an asynchronous io stream splice operation.
*
* Returns: %TRUE on success, %FALSE otherwise.
*
* Since: 2.28
**/
gboolean
g_io_stream_splice_finish (GAsyncResult *result,
GError **error)
{
g_return_val_if_fail (g_task_is_valid (result, NULL), FALSE);
return g_task_propagate_boolean (G_TASK (result), error);
}
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