Add SQLite cache provider

Author: doekenorg

.gitignore

@@ -21,3 +21,6 @@ phpcs.xml
 .idea/**/.name
 .idea/**/codeStyles
 .idea/**/php.xml
+
+## Tests
+tests/assets/test-sqlite.db

composer.json

@@ -40,6 +40,9 @@
 		"phpcompatibility/phpcompatibility-wp": "^2.1",
 		"overtrue/phplint": "^3.4"
 	},
+	"suggest": {
+		"ext-pdo": "PDO is required to use the SQLite cache provider"
+	},
 	"scripts": {
 		"suite": [
 			"composer test",

src/Cache/ArrayCacheProvider.php

@@ -14,15 +14,15 @@
  *
  * @since $ver$
  */
-final class ArrayCacheProvider implements CacheProvider {
+final class ArrayCacheProvider extends BaseCacheProvider {
 	/**
 	 * The cached items.
 	 *
 	 * @since $ver$
 	 *
 	 * @var CacheItem[]
 	 */
-	private array $items;
+	private array $items = [];
 
 	/**
 	 * Contains the reference to the tags with their tagged cache keys.
@@ -33,26 +33,17 @@ final class ArrayCacheProvider implements CacheProvider {
 	 */
 	private array $tags = [];
 
-	/**
-	 * The clock instance.
-	 *
-	 * @since $ver$
-	 *
-	 * @var Clock
-	 */
-	private Clock $clock;
-
 	/**
 	 * Creates an Array cache provider.
 	 *
 	 * @since $ver$
 	 *
-	 * @param Clock|null  $clock The clock instance.
-	 * @param CacheItem[] $items The pre-filled cache items.
+	 * @param Clock|null $clock The clock instance.
 	 */
-	public function __construct( ?Clock $clock = null, array $items = [] ) {
+	public function __construct( ?Clock $clock = null ) {
+		parent::__construct( $clock );
+
 		$this->clock = $clock ?? new SystemClock();
-		$this->items = $items;
 	}
 
 	/**
@@ -74,41 +65,6 @@ public function set( string $key, $value, ?int $ttl = null, array $tags = [] ):
 		$this->add_tags( $key, $tags );
 	}
 
-	/**
-	 * @inheritDoc
-	 *
-	 * @since $ver$
-	 */
-	public function get( string $key, $fallback = null ) {
-		$item = $this->items[ $key ] ?? null;
-
-		if ( ! $item || $item->is_expired( $this->clock ) ) {
-			unset( $this->items[ $key ] );
-
-			return $fallback;
-		}
-
-		return $item->value();
-	}
-
-	/**
-	 * @inheritDoc
-	 *
-	 * @since $ver$
-	 */
-	public function has( string $key ): bool {
-		if (
-			isset( $this->items[ $key ] )
-			&& ! $this->items[ $key ]->is_expired( $this->clock )
-		) {
-			return true;
-		}
-
-		unset( $this->items[ $key ] );
-
-		return false;
-	}
-
 	/**
 	 * @inheritDoc
 	 *
@@ -168,4 +124,13 @@ private function add_tags( string $key, array $tags ): void {
 			$this->tags[ $tag ] = array_unique( array_merge( $this->tags[ $tag ], [ $key ] ) );
 		}
 	}
+
+	/**
+	 * @inheritDoc
+	 *
+	 * @since $ver$
+	 */
+	protected function doGet( string $key ): ?CacheItem {
+		return $this->items[ $key ] ?? null;
+	}
 }

src/Cache/BaseCacheProvider.php

@@ -0,0 +1,72 @@
+<?php
+
+namespace DataKit\DataViews\Cache;
+
+use DataKit\DataViews\Clock\Clock;
+use DataKit\DataViews\Clock\SystemClock;
+
+/**
+ * An abstract cache provider that implements default logic.
+ *
+ * @since $ver$
+ */
+abstract class BaseCacheProvider implements CacheProvider {
+	/**
+	 * The clock.
+	 *
+	 * @since $ver$
+	 * @var Clock
+	 */
+	protected Clock $clock;
+
+	/**
+	 * Creates the base cache provider.
+	 *
+	 * @since $ver$
+	 *
+	 * @param Clock|null $clock The clock.
+	 */
+	public function __construct( ?Clock $clock = null ) {
+		$this->clock = $clock ?? new SystemClock();
+	}
+
+	/**
+	 * Returns the {@see CacheItem} if found by key.
+	 *
+	 * @param string $key The key.
+	 *
+	 * @return CacheItem|null The cache item.
+	 */
+	abstract protected function doGet( string $key ): ?CacheItem;
+
+	/**
+	 * @inheritDoc
+	 * @since $ver$
+	 */
+	public function get( string $key, $fallback = null ) {
+		$item = $this->doGet( $key );
+		if ( ! $item || $item->is_expired( $this->clock->now() ) ) {
+			$this->delete( $key );
+
+			return $fallback;
+		}
+
+		return $item->value();
+	}
+
+	/**
+	 * @inheritDoc
+	 * @since $ver$
+	 */
+	public function has( string $key ): bool {
+		$item = $this->doGet( $key );
+
+		if ( ! $item || $item->is_expired( $this->clock->now() ) ) {
+			$this->delete( $key );
+
+			return false;
+		}
+
+		return true;
+	}
+}

src/Cache/CacheItem.php

@@ -2,8 +2,7 @@
 
 namespace DataKit\DataViews\Cache;
 
-use DataKit\DataViews\Clock\Clock;
-use DateTime;
+use DateTimeImmutable;
 use DateTimeInterface;
 
 /**
@@ -119,16 +118,16 @@ public function tags(): array {
 	/**
 	 * Returns whether the cache item is expired.
 	 *
-	 * @param Clock $clock The clock to test expiration.
+	 * @param DateTimeImmutable $now The date time to test against.
 	 *
 	 * @return bool Whether the cache item is expired.
 	 */
-	public function is_expired( Clock $clock ): bool {
+	public function is_expired( DateTimeImmutable $now ): bool {
 		if ( null === $this->expires_at ) {
 			return false;
 		}
 
-		return $clock->now() > $this->expires_at;
+		return $now > $this->expires_at;
 	}
 
 	/**