driver: break up cache drivers

inc/Data/Driver/FsCachedriver.php

@@ -0,0 +1,150 @@
+<?php
+namespace Vichan\Data\Driver;
+
+defined('TINYBOARD') or exit;
+
+
+class FsCacheDriver implements CacheDriver {
+	private string $prefix;
+	private string $base_path;
+	private mixed $lock_fd;
+	private int|false $collect_chance_den;
+
+
+	private function prepareKey(string $key): string {
+		$key = \str_replace('/', '::', $key);
+		$key = \str_replace("\0", '', $key);
+		return $this->prefix . $key;
+	}
+
+	private function sharedLockCache(): void {
+		\flock($this->lock_fd, LOCK_SH);
+	}
+
+	private function exclusiveLockCache(): void {
+		\flock($this->lock_fd, LOCK_EX);
+	}
+
+	private function unlockCache(): void {
+		\flock($this->lock_fd, LOCK_UN);
+	}
+
+	private function collectImpl(): int {
+		// A read lock is ok, since it's alright if we delete expired items from under the feet of other processes.
+		$files = \glob($this->base_path . $this->prefix . '*', \GLOB_NOSORT);
+		$count = 0;
+		foreach ($files as $file) {
+			$data = \file_get_contents($file);
+			$wrapped = \json_decode($data, true, 512, \JSON_THROW_ON_ERROR);
+			if ($wrapped['expires'] !== false && $wrapped['expires'] <= \time()) {
+				if (@\unlink($file)) {
+					$count++;
+				}
+			}
+		}
+		return $count;
+	}
+
+	private function maybeCollect(): void {
+		if ($this->collect_chance_den !== false && \mt_rand(0, $this->collect_chance_den - 1) === 0) {
+			$this->collect_chance_den = false; // Collect only once per instance (aka process).
+			$this->collectImpl();
+		}
+	}
+
+	public function __construct(string $prefix, string $base_path, string $lock_file, int|false $collect_chance_den) {
+		if ($base_path[\strlen($base_path) - 1] !== '/') {
+			$base_path = "$base_path/";
+		}
+
+		if (!\is_dir($base_path)) {
+			throw new \RuntimeException("$base_path is not a directory!");
+		}
+
+		if (!\is_writable($base_path)) {
+			throw new \RuntimeException("$base_path is not writable!");
+		}
+
+		$this->lock_fd = \fopen($base_path . $lock_file, 'w');
+		if ($this->lock_fd === false) {
+			throw new \RuntimeException('Unable to open the lock file!');
+		}
+
+		$this->prefix = $prefix;
+		$this->base_path = $base_path;
+		$this->collect_chance_den = $collect_chance_den;
+	}
+
+	public function __destruct() {
+		$this->close();
+	}
+
+	public function get(string $key): mixed {
+		$key = $this->prepareKey($key);
+
+		$this->sharedLockCache();
+
+		$fd = \fopen($this->base_path . $key, 'r');
+		if ($fd === false) {
+			$this->unlockCache();
+			return null;
+		}
+
+		$data = \stream_get_contents($fd);
+		\fclose($fd);
+		$this->maybeCollect();
+		$this->unlockCache();
+		$wrapped = \json_decode($data, true, 512, \JSON_THROW_ON_ERROR);
+
+		if ($wrapped['expires'] !== false && $wrapped['expires'] <= \time()) {
+			// Already expired, leave it there since we already released the lock and pretend it doesn't exist.
+			return null;
+		} else {
+			return $wrapped['inner'];
+		}
+	}
+
+	public function set(string $key, mixed $value, mixed $expires = false): void {
+		$key = $this->prepareKey($key);
+
+		$wrapped = [
+			'expires' => $expires ? \time() + $expires : false,
+			'inner' => $value
+		];
+
+		$data = \json_encode($wrapped);
+		$this->exclusiveLockCache();
+		\file_put_contents($this->base_path . $key, $data);
+		$this->maybeCollect();
+		$this->unlockCache();
+	}
+
+	public function delete(string $key): void {
+		$key = $this->prepareKey($key);
+
+		$this->exclusiveLockCache();
+		@\unlink($this->base_path . $key);
+		$this->maybeCollect();
+		$this->unlockCache();
+	}
+
+	public function collect(): int {
+		$this->sharedLockCache();
+		$count = $this->collectImpl();
+		$this->unlockCache();
+		return $count;
+	}
+
+	public function flush(): void {
+		$this->exclusiveLockCache();
+		$files = \glob($this->base_path . $this->prefix . '*', \GLOB_NOSORT);
+		foreach ($files as $file) {
+			@\unlink($file);
+		}
+		$this->unlockCache();
+	}
+
+	public function close(): void {
+		\fclose($this->lock_fd);
+	}
+}