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// download_manager.h -*-c++-*-
//
// Copyright (C) 2005, 2008 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_MANAGER_H
#define DOWNLOAD_MANAGER_H
// For RunResult
#include <apt-pkg/acquire.h>
#include <sigc++/slot.h>
#include <sigc++/trackable.h>
/** \brief An abstract interface for download processes, and two implementations.
*
* \file download_manager.h
*/
class OpProgress;
class download_signal_log;
/** The generic interface for a task involving a download and possibly
* some post-download operations. (for instance, downloading and
* installing packages)
*/
class download_manager : public sigc::trackable
{
public:
/** Used to determine what the client should do after a download
* completes.
*/
enum result {success, failure, do_again};
protected:
/** The object doing the actual download. Initialized to \b NULL
* and deleted in the destructor; it is expected that subclasses
* will provide a prepare() routine that sets this to an actual
* value.
*/
pkgAcquire *fetcher;
public:
download_manager();
virtual ~download_manager();
/** Do any preliminary work needed to set up a download.
*
* \param progress a status object used to monitor tasks that
* execute while this method is running.
*
* \param acqlog a pkgAcqStatus object that will be used to do the
* actual download.
*
* \param download_signal_log a signal logger that will be used
* to Complete the download.
*
* \return \b true if the preparation succeeded, \b false otherwise
*/
virtual bool prepare(OpProgress &progress,
pkgAcquireStatus &acqlog,
download_signal_log *signallog) = 0;
/** Perform the actual download. This may execute in a background
* thread.
*/
virtual pkgAcquire::RunResult do_download();
/** Similar, but with a particular pulse interval. */
virtual pkgAcquire::RunResult do_download(int PulseInterval);
/** Perform any post-download tasks that need to be handled. This
* should be called from the main thread.
*
* \param result the result of do_download().
*
* \param progress a progress bar that may be used by the finishing
* process. This should not be destroyed until the
* continuation is invoked.
*
* \param k a continuation to invoke when the post-download
* operations are complete; it is passed the result of finish().
* If the argument is do_again, the frontend should repeat the
* download and post-download tasks. The download manager may
* arrange for finish() to complete early while a long-running task
* executes in a background thread, as long as k() is later invoked
* in a foreground thread.
*
* The reason for passing a continuation is that some download
* managers need to run even more stuff in a background thread;
* this gives them room to do so. The main example of this is the
* download_install_manager. By building this support into the
* download_manager interface, we support generic install harnesses
* like ui_download_manager.
*
* \note Why is prepare() not built using continuations? Simple:
* none of the managers seem to need that.
*/
virtual void finish(pkgAcquire::RunResult result,
OpProgress *progress,
const sigc::slot1<void, download_manager::result> &k) = 0;
};
#endif
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