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/** \file download_queue.h */ // -*-c++-*-
// Copyright (C) 2009-2010 Daniel Burrows
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of the
// License, or (at your option) any later version.
//
// This program 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 General Public License
// along with this program; see the file COPYING. If not, write to
// the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
// Boston, MA 02111-1307, USA.
#ifndef DOWNLOAD_QUEUE_H
#define DOWNLOAD_QUEUE_H
#include <boost/shared_ptr.hpp>
#include <generic/util/post_thunk.h>
#include <generic/util/temp.h>
#include <sigc++/slot.h>
namespace aptitude
{
/** \brief The callbacks that should be invoked in response to
* events that occur during the download of a particular item.
*/
class download_callbacks
{
public:
download_callbacks()
{
}
virtual ~download_callbacks()
{
}
/** \brief The callback invoked when the download completes
* successfully.
*
* \param filename The file into which the item was downloaded.
*/
virtual void success(const temp::name &filename) = 0;
/** \brief The callback invoked when the download fails.
*
* \param msg A message describing what happened.
*
* The default implementation does nothing.
*/
virtual void failure(const std::string &msg)
{
}
/** \brief Invoked when the item is partly downloaded.
*
* \param filename The file name that the download is
* being written to.
* \param currentSize The current size of the file.
* \param totalSize The total size of the file.
*
* The default implementation does nothing.
*/
virtual void partial_download(const temp::name &filename,
unsigned long long currentSize,
unsigned long long totalSize)
{
}
/** \brief Invoked when the item is canceled. */
virtual void canceled()
{
}
};
/** \brief Handle to a screenshot download request; can be used to
* cancel the request after it has been enqueued.
*
* download_request objects are guaranteed to not store strong
* references (via shared_ptr, RefPtr, ref_ptr, etc) to any
* objects.
*/
class download_request
{
public:
virtual ~download_request();
/** \brief Cancel this download request.
*
* This is safe to call from any thread. There is no guarantee
* that the download won't complete anyway, but if it hasn't
* completed by the next call to Pulse() (once a second or so),
* it will be canceled. Even if it does complete, the callbacks
* won't be invoked.
*/
virtual void cancel() = 0;
};
/** \brief Add a new download to the background thread's queue.
*
* \param uri The URI to download.
*
* \param short_description A brief description of this item;
* used to generate log messages.
*
* \param callbacks A callback object used to respond to events
* on the download.
*
* \param post_thunk A function used to pass download events to
* the main thread.
*
* \return a handle that can be used to cancel the download.
*/
boost::shared_ptr<download_request>
queue_download(const std::string &uri,
const std::string &short_description,
const boost::shared_ptr<download_callbacks> &callbacks,
post_thunk_f post_thunk);
/** \brief Shut down the background thread and clear its data
* structures; used to abort all processing when the program is
* terminating.
*
* We need to do this because otherwise, the objects in the queue
* might be destroyed when global destructors are called, and some
* of them access things that are destroyed at the same time,
* causing crashes and other bad behavior.
*
* This function blocks until the queue is fully shut down.
*/
void shutdown_download_queue();
}
#endif // DOWNLOAD_QUEUE_H
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