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<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle 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 3 of the License, or
// (at your option) any later version.
//
// Moodle 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 Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* Simple interface for receiving progress during long-running file
* operations.
*
* In some cases progress can be reported precisely. In other cases,
* progress is indeterminate which means that the progress function is called
* periodically but without information on completion.
*
* @package core_files
* @copyright 2013 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
interface file_progress {
/**
* @var int Constant used for indeterminate progress.
*/
const INDETERMINATE = -1;
/**
* Called during a file processing operation that reports progress.
*
* This function will be called periodically during the operation, assuming
* it is successful.
*
* The $max value will be the same for each call to progress() within an
* operation.
*
* If numbers (rather than INDETERMINATE) are provided, then:
* - The $progress value will either be the same as last call, or increased
* by some value (not necessarily 1)
* - The $progress value will be less than or equal to the $max value.
*
* There is no guarantee that this function will be called for every value
* in the range, or that it will be called with $progress == $max.
*
* The function may be called very frequently (e.g. after each file) or
* quite rarely (e.g. after each large file).
*
* When creating an implementation of this function, you probably want to
* do the following:
*
* 1. Check the current time and do not do anything if it's less than a
* second since the last time you reported something.
* 2. Update the PHP timeout (i.e. set it back to 2 minutes or whatever)
* so that the system will not time out.
* 3. If the progress is unchanged since last second, still display some
* output to the user. (Setting PHP timeout is not sufficient; some
* front-end servers require that data is output to the browser every
* minute or so, or they will time out on their own.)
*
* @param int $progress Current progress, or INDETERMINATE if unknown
* @param int $max Max progress, or INDETERMINATE if unknown
*/
public function progress($progress = self::INDETERMINATE, $max = self::INDETERMINATE);
}