feat: Give more control over caching

lib/private/Memcache/Factory.php

@@ -31,6 +31,7 @@
  */
 namespace OC\Memcache;
 
+use OCP\Cache\CappedMemoryCache;
 use OCP\Profiler\IProfiler;
 use OCP\ICache;
 use OCP\ICacheFactory;
@@ -115,7 +116,7 @@ public function __construct(string $globalPrefix, LoggerInterface $logger, IProf
 	 * @param string $prefix
 	 * @return IMemcache
 	 */
-	public function createLocking(string $prefix = ''): IMemcache {
+	public function createLocking(string $prefix = ''): ?IMemcache {
 		assert($this->lockingCacheClass !== null);
 		$cache = new $this->lockingCacheClass($this->globalPrefix . '/' . $prefix);
 		if ($this->lockingCacheClass === Redis::class && $this->profiler->isEnabled()) {
@@ -137,7 +138,7 @@ public function createLocking(string $prefix = ''): IMemcache {
 	 * @param string $prefix
 	 * @return ICache
 	 */
-	public function createDistributed(string $prefix = ''): ICache {
+	public function createDistributed(string $prefix = ''): ?ICache {
 		assert($this->distributedCacheClass !== null);
 		$cache = new $this->distributedCacheClass($this->globalPrefix . '/' . $prefix);
 		if ($this->distributedCacheClass === Redis::class && $this->profiler->isEnabled()) {
@@ -159,7 +160,7 @@ public function createDistributed(string $prefix = ''): ICache {
 	 * @param string $prefix
 	 * @return ICache
 	 */
-	public function createLocal(string $prefix = ''): ICache {
+	public function createLocal(string $prefix = ''): ?ICache {
 		assert($this->localCacheClass !== null);
 		$cache = new $this->localCacheClass($this->globalPrefix . '/' . $prefix);
 		if ($this->localCacheClass === Redis::class && $this->profiler->isEnabled()) {
@@ -184,6 +185,10 @@ public function isAvailable(): bool {
 		return $this->distributedCacheClass !== self::NULL_CACHE;
 	}
 
+	public function createInMemory(int $capacity = 512): ICache {
+		return new CappedMemoryCache($capacity);
+	}
+
 	/**
 	 * @see \OC\Memcache\Factory::createLocal()
 	 * @param string $prefix

lib/public/ICacheFactory.php

@@ -53,26 +53,43 @@ public function isLocalCacheAvailable(): bool;
 	 * create a cache instance for storing locks
 	 *
 	 * @param string $prefix
-	 * @return IMemcache
+	 * @return IMemcache|null
 	 * @since 13.0.0
+	 * @since 28.0.0 return type is nullable but the method will continue to return an object for backwards compatibility. Future versions will only return an object if distributed cache is available.
 	 */
-	public function createLocking(string $prefix = ''): IMemcache;
+	public function createLocking(string $prefix = ''): ?IMemcache;
 
 	/**
 	 * create a distributed cache instance
 	 *
 	 * @param string $prefix
-	 * @return ICache
+	 * @return ICache|null a cache implementation
 	 * @since 13.0.0
+	 * @since 28.0.0 return type is nullable but the method will continue to return an object for backwards compatibility. Future versions will only return an object if distributed cache is available.
 	 */
-	public function createDistributed(string $prefix = ''): ICache;
+	public function createDistributed(string $prefix = ''): ?ICache;
 
 	/**
-	 * create a local cache instance
+	 * Create a local cache instance
 	 *
 	 * @param string $prefix
-	 * @return ICache
+	 *
+	 * @return ICache|null a cache implementation
 	 * @since 13.0.0
+	 * @since 28.0.0 return type is nullable but the method will continue to return an object for backwards compatibility. Future versions will only return an object if local cache is available.
+	 */
+	public function createLocal(string $prefix = ''): ?ICache;
+
+	/**
+	 * Create an in-memory cache instance
+	 *
+	 * Useful for remembering values inside one process. Cache memory is cleared
+	 * when the object is garbage-collected. Implementation may also expire keys
+	 * earlier when the TTL is reached or too much memory is consumed.
+	 *
+	 * @param int $capacity
+	 * @return ICache
+	 * @since 28.0.0
 	 */
-	public function createLocal(string $prefix = ''): ICache;
+	public function createInMemory(int $capacity = 512): ICache;
 }