source: trunk/scripts/db-backup-delete @ 1184

#! /usr/bin/env php
<?php

require_once(dirname($argv[0]) . "/utilities.php");

// This script deletes unnecessary backups.
// It assumes that backups are made daily.
// This script should be run after every backup.
// Backups will be held from every 2^x days before(approximately).

// Parameters:  1. The path to the backups directory (compulsory) ex: /backups/
//              2. Normal/Safe mode (optional) ex: safe

// Important: Set the first date when the script will be run.
define('START', mktime(0, 0, 0, 3, 21, 2010));


function compare_by_timestamp($first, $second) {
    if ($first["timestamp"] == $second["timestamp"]) {
        return 0;
    } else {
        return ($first["timestamp"] > $second["timestamp"]) ? -1 : 1;
    }
}

function days_between($timestamp1, $timestamp2) {
    return round(abs($timestamp1 - $timestamp2) / 60 / 60 / 24);
}

// Validate the directory
log_assert(isset($argv[1]), "Specify backup directory!");
$dir_path = $argv[1];
if ($dir_path[strlen($dir_path) - 1] != '/') {
    $dir_path .= "/";
}
log_assert(is_dir($dir_path), "The argument is not a valid directory!\n");
$dir = dir($dir_path);

// Today's timestamp at 00:00
$now = mktime(0, 0, 0);

// Find the existing backups
$backups = array();
$backup_today = false;
while (false !== ($file = $dir->read())) {
    $matches = array();
    if (is_file($dir->path . $file) && is_backup_filename($file, $matches)) {
        $year = $matches[1];
        $month = $matches[2];
        $day = $matches[3];
        $time = mktime(0, 0, 0, $month, $day, $year);
        if ($time >= START) {
            if ($now == $time) {
                $backup_today = true;
            } else {
                $backups[] = array("timestamp" => $time, "filename" => $file);
            }
        }
    }
}
usort($backups, "compare_by_timestamp");

// Verifying previous backups
log_assert($backup_today == true, "There was no backup made today.");
if (count($backups) == 0) {
    log_print("There are no previous backups to delete.");
    exit;
}
for ($index = 1; $index < count($backups); $index++) {
    $dday = days_between($backups[$index]["timestamp"], $now);
    log_assert((pow(2, $index - 1) <= $dday && $dday <= pow(2, $index)),
            "The current backups do not respect the backup schedule.");
}

// Finding any unnecessary backup
$days_passed = days_between($now, START);
if ($days_passed % pow(2, count($backups) - 1) == 0) {
    $dfile = null;
} else {
    for ($index = count($backups) - 1; $index > 0; $index--) {
        if ($days_passed % pow(2, $index - 1) == 0) {
            $dfile = $backups[$index]["filename"];
            break;
        }
    }
}

// Deleting the unnecessary backup
if (isset($dfile)) {
    log_print("Deleting file: ".$dfile);
    if (!(isset($argv[2]) && $argv[2] == "safe")) {
        unlink($dir->path . $dfile);
    } else {
        log_print("No files deleted. (safe mode)");
    }
} else {
    log_print("Not deleting anything.");
}

?>