initial version

lib/DebugLockingProvider.php

@@ -0,0 +1,144 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * @copyright Copyright (c) 2022 Robin Appelman <robin@icewind.nl>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\LockPick;
+
+use OCP\IRequest;
+use OCP\Lock\ILockingProvider;
+use OCP\Lock\LockedException;
+
+class DebugLockingProvider implements ILockingProvider {
+	private ILockingProvider $inner;
+	private TraceStore $store;
+	private IRequest $request;
+	private array $openTraces = [];
+	private array $pathMap = [];
+
+	public function __construct(ILockingProvider $inner, IRequest $request, TraceStore $store) {
+		$this->inner = $inner;
+		$this->request = $request;
+		$this->store = $store;
+	}
+
+	/**
+	 * Normalize path to the "readable" form if possible
+	 */
+	private function getPath(string $path, string $readablePath = null): string {
+		if ($readablePath) {
+			$this->pathMap[$path] = $readablePath;
+			return $readablePath;
+		} elseif (isset($this->pathMap[$path])) {
+			return $this->pathMap[$path];
+		} else {
+			return $path;
+		}
+	}
+
+	private function openTrace(string $path, int $type): void {
+		$trace = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS);
+		$trace = $this->unwindTrace($trace);
+		if (!isset($this->openTraces[$path])) {
+			$this->openTraces[$path] = [];
+		}
+		$this->openTraces[$path][] = [
+			'trace' => $trace,
+			'type' => $type,
+		];
+	}
+
+	/**
+	 * Remove the bits from the backtrace that are from this debug handling
+	 */
+	private function unwindTrace(array $backtrace): array {
+		while($backtrace[0]['class'] === self::class) {
+			array_shift($backtrace);
+		}
+		return $backtrace;
+	}
+
+	private function closeTrace(string $path, int $type): void {
+		// todo find a way to better link acquire/release pairs
+
+
+		if (!isset($this->openTraces[$path])) {
+			return;
+		}
+
+		foreach ($this->openTraces[$path] as $id => $trace) {
+			if ($trace['type'] === $type) {
+				unset($this->openTraces[$path][$id]);
+				break;
+			}
+		}
+		$this->openTraces[$path] = array_values($this->openTraces[$path]);
+	}
+
+	private function logConflict(string $path, int $type): void {
+		$path = $this->getPath($path);
+
+		// conflict comes from other request
+		// todo store traces in memcache so we can debug cross-requests conflicts
+		if (!isset($this->openTraces[$path])) {
+			return;
+		}
+
+		$this->openTrace($path, $type);
+
+		$this->store->store($this->request->getId(), $this->openTraces[$path]);
+	}
+
+	public function acquireLock(string $path, int $type, ?string $readablePath = null): void {
+		try {
+			$this->inner->acquireLock($path, $type, $readablePath);
+			$this->openTrace($this->getPath($path, $readablePath), $type);
+		} catch (LockedException $e) {
+			$this->logConflict($path, $type);
+			throw $e;
+		}
+	}
+
+	public function changeLock(string $path, int $targetType): void {
+		try {
+			$this->inner->changeLock($path, $targetType);
+			$this->closeTrace($this->getPath($path), 3 - $targetType);
+			$this->openTrace($this->getPath($path), $targetType);
+		} catch (LockedException $e) {
+			$this->logConflict($path, $targetType);
+			throw $e;
+		}
+	}
+
+	public function releaseLock(string $path, int $type): void {
+		$this->inner->releaseLock($path, $type);
+		$this->closeTrace($this->getPath($path), $type);
+	}
+
+	public function releaseAll(): void {
+		$this->inner->releaseAll();
+		$this->openTraces = [];
+	}
+
+	public function isLocked(string $path, int $type): bool {
+		return $this->inner->isLocked($path, $type);
+	}
+}