dillard
9cefea019d
TreeWalker walks one or more roots in a stable segment-wise order with exclusions and resumes after a cursor; ParentCursor merge-joins the previous snapshot in the same order. BackupRun no longer keeps a file list or the parent's entries in memory or in its state.
103 lines
3.1 KiB
PHP
103 lines
3.1 KiB
PHP
<?php
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declare(strict_types=1);
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// SPDX-FileCopyrightText: 2026 Dillard Blom
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// SPDX-License-Identifier: AGPL-3.0-or-later
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namespace OCA\NgBackup\Job;
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/**
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* Walks one or more source roots in a stable depth-first order (entries of a directory sorted
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* by name, children right after their directory), yielding "<root>/<relative path>" for files.
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*
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* The same order is used for comparing paths (compare()), so a walk can resume after a cursor
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* and be merge-joined with the previous snapshot without holding any list in memory.
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*/
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final class TreeWalker {
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/**
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* @param array<string, string> $roots name => absolute directory, walked in this order
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* @param list<string> $exclude path prefixes ("<root>/<relative>") that are skipped entirely
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*/
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public function __construct(
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private array $roots,
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private array $exclude = [],
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) {
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}
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/** @return \Generator<string, string> logical path => absolute path, strictly after $after */
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public function walk(?string $after = null): \Generator {
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foreach ($this->roots as $name => $dir) {
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$name = (string)$name;
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if ($name !== '' && $after !== null && self::compare($name, self::firstSegment($after)) < 0) {
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continue; // whole root lies before the cursor
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}
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yield from $this->walkDir(rtrim($dir, '/'), $name, $after);
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}
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}
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/** Order used everywhere: segment by segment, byte-wise. */
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public static function compare(string $a, string $b): int {
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$sa = explode('/', $a);
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$sb = explode('/', $b);
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$n = min(count($sa), count($sb));
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for ($i = 0; $i < $n; $i++) {
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$c = strcmp($sa[$i], $sb[$i]);
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if ($c !== 0) {
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return $c < 0 ? -1 : 1;
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}
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}
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return count($sa) <=> count($sb);
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}
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private function walkDir(string $abs, string $logical, ?string $after): \Generator {
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foreach ($this->exclude as $prefix) {
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if ($logical !== '' && ($logical === $prefix || str_starts_with($logical, $prefix . '/'))) {
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return;
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}
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}
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$names = @scandir($abs);
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if ($names === false) {
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return;
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}
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$names = array_values(array_diff($names, ['.', '..']));
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sort($names, SORT_STRING);
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foreach ($names as $name) {
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$childLogical = $logical === '' ? $name : $logical . '/' . $name;
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$childAbs = $abs . '/' . $name;
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if (is_link($childAbs)) {
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continue; // never follow symlinks out of the data directory
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}
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if (is_dir($childAbs)) {
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// Skip a directory entirely if everything in it sorts before the cursor.
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if ($after !== null && self::compare($childLogical, $after) < 0 && !self::isPrefix($childLogical, $after)) {
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continue;
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}
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yield from $this->walkDir($childAbs, $childLogical, $after);
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} elseif (is_file($childAbs)) {
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if ($after !== null && self::compare($childLogical, $after) <= 0) {
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continue;
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}
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$excluded = false;
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foreach ($this->exclude as $prefix) {
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if ($childLogical === $prefix) {
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$excluded = true;
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break;
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}
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}
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if (!$excluded) {
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yield $childLogical => $childAbs;
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}
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}
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}
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}
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private static function isPrefix(string $dir, string $path): bool {
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return str_starts_with($path, $dir . '/');
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}
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private static function firstSegment(string $path): string {
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return explode('/', $path, 2)[0];
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}
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}
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