Allow overriding cache expiry and cache key for cacheable commands

src/Decorators/CachingDecorator.php

@@ -7,6 +7,7 @@
 use Chief\Command;
 use Chief\CommandBus;
 use Chief\Decorator;
+use Chief\HasCacheOptions;
 use Psr\Cache\CacheItemInterface;
 use Psr\Cache\CacheItemPoolInterface;
 
@@ -55,7 +56,7 @@ public function execute(Command $command)
             return $this->innerBus->execute($command);
         }
 
-        $cached = $this->cache->getItem(self::createCacheKey($command));
+        $cached = $this->cache->getItem($this->getCacheKey($command));
         if ($cached->isHit()) {
             return $cached->get();
         }
@@ -76,9 +77,9 @@ public function execute(Command $command)
      */
     private function createCacheItem(CacheableCommand $command, $value)
     {
-        return $this->cache->getItem($this->createCacheKey($command))
-            ->set($value)
-            ->expiresAfter($this->expiresAfter);
+        return $this->cache->getItem($this->getCacheKey($command))
+            ->expiresAfter($this->getCacheExpiry($command))
+            ->set($value);
     }
 
     /**
@@ -91,8 +92,27 @@ private function createCacheItem(CacheableCommand $command, $value)
      * @param CacheableCommand $command
      * @return string
      */
-    private function createCacheKey(CacheableCommand $command)
+    private function getCacheKey(CacheableCommand $command)
     {
+        if ($command instanceof HasCacheOptions && $command->getCacheKey()) {
+            return $command->getCacheKey();
+        }
+
         return md5(serialize($command));
     }
+
+    /**
+     * Determine when this CachableCommand should expire, in terms of seconds from now.
+     *
+     * @param CacheableCommand $command
+     * @return int
+     */
+    private function getCacheExpiry(CacheableCommand $command)
+    {
+        if ($command instanceof HasCacheOptions && $command->getCacheExpiry() > 0) {
+            return $command->getCacheExpiry();
+        }
+
+        return $this->expiresAfter;
+    }
 }

src/HasCacheOptions.php

@@ -0,0 +1,19 @@
+<?php
+
+namespace Chief;
+
+interface HasCacheOptions extends CacheableCommand
+{
+    /**
+     * @return int|null
+     *  In how many seconds from now should this cache item expire. Return null to use the default value specified
+     *  in the CachingDecorator.
+     */
+    public function getCacheExpiry();
+
+    /**
+     * @return string|null
+     *  The cache key used when caching this object. Return null to automatically generate a cache key.
+     */
+    public function getCacheKey();
+}

tests/Decorators/CachingDecoratorTest.php

@@ -7,6 +7,7 @@
 use Chief\Command;
 use Chief\CommandBus;
 use Chief\Decorator;
+use Chief\HasCacheOptions;
 use Prophecy\Argument;
 use Prophecy\Prophecy\ObjectProphecy;
 use Psr\Cache\CacheItemInterface;
@@ -68,6 +69,66 @@ public function test_execution_return_value_is_cached_when_command_implements_ca
         $this->assertEquals(7, $result);
     }
 
+    public function test_cache_expiry_can_be_overridden()
+    {
+        $decorator = $this->getDecorator();
+        $inner = $this->prophesize(CommandBus::class);
+        $decorator->setInnerBus($inner->reveal());
+
+        $commandProphecy = $this->prophesize(HasCacheOptions::class);
+        $commandProphecy->getCacheExpiry()->willReturn(60*60*24*365);
+        $commandProphecy->getCacheKey()->willReturn(null);
+
+        $command = $commandProphecy->reveal();
+
+        $notCachedItem = $this->prophesize(CacheItemInterface::class);
+        $notCachedItem->isHit()->willReturn(false);
+        $notCachedItem->getKey()->willReturn(md5(serialize(($command))));
+        $this->cache->getItem(Argument::any())->willReturn($notCachedItem->reveal());
+
+        $notCachedItem->set(7)->shouldBeCalled()->willReturn($notCachedItem->reveal());
+        $notCachedItem->expiresAfter(60*60*24*365)->shouldBeCalled()->willReturn($notCachedItem->reveal());
+
+        $this->cache->save(Argument::that(function (CacheItemInterface $item) use ($command) {
+            return !empty($item->getKey());
+        }))->shouldBeCalled();
+
+        $inner->execute($command)->shouldBeCalled()->willReturn(7);
+
+        $result = $decorator->execute($command);
+        $this->assertEquals(7, $result);
+    }
+
+    public function test_cache_key_can_be_overridden()
+    {
+        $decorator = $this->getDecorator();
+        $inner = $this->prophesize(CommandBus::class);
+        $decorator->setInnerBus($inner->reveal());
+
+        $commandProphecy = $this->prophesize(HasCacheOptions::class);
+        $commandProphecy->getCacheExpiry()->willReturn(null);
+        $commandProphecy->getCacheKey()->willReturn('custom-cache-key');
+
+        $command = $commandProphecy->reveal();
+
+        $notCachedItem = $this->prophesize(CacheItemInterface::class);
+        $notCachedItem->isHit()->willReturn(false);
+        $notCachedItem->getKey()->willReturn('custom-cache-key');
+        $this->cache->getItem('custom-cache-key')->willReturn($notCachedItem->reveal());
+
+        $notCachedItem->set(7)->shouldBeCalled()->willReturn($notCachedItem->reveal());
+        $notCachedItem->expiresAfter(3600)->shouldBeCalled()->willReturn($notCachedItem->reveal());
+
+        $this->cache->save(Argument::that(function (CacheItemInterface $item) use ($command) {
+            return $item->getKey() === 'custom-cache-key';
+        }))->shouldBeCalled();
+
+        $inner->execute($command)->shouldBeCalled()->willReturn(7);
+
+        $result = $decorator->execute($command);
+        $this->assertEquals(7, $result);
+    }
+
     public function test_cache_item_value_is_returned_if_cached()
     {
         $decorator = $this->getDecorator();