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