Remove _expires cache keys

Apcu and wincache implement ttl - it shouldn't be necessary to set two
cache keys and double-confirm that the cache entry has not expired
before returning the cache hit.

XCache also implements ttl, but uses the request time for all
timestamps, that means cache usage like this doesn't work:

    Cache::write('something', 'value');
    sleep(longer than ttl);
    $result = Cache::read('something'); <- still 'value'

Since XCache support ends soon, this engine is not modified.

src/Cache/Engine/ApcuEngine.php

@@ -59,29 +59,9 @@ public function init(array $config = [])
     public function write($key, $value)
     {
         $key = $this->_key($key);
-
-        $expires = 0;
         $duration = $this->_config['duration'];
-        if ($duration) {
-            $expires = time() + $duration;
-        }
-
-        $values = [
-            $key . '_expires' => $expires,
-            $key => $value,
-        ];
-
-        $errors = apcu_store($values, null, $duration);
-
-        if ($errors !== []) {
-            $this->warning(
-                sprintf('Failed to store %s into APCu cache.', json_encode($errors))
-            );
-
-            return false;
-        }
 
-        return true;
+        return apcu_store($key, $value, $duration);
     }
 
     /**
@@ -96,13 +76,6 @@ public function read($key)
     {
         $key = $this->_key($key);
 
-        $time = time();
-        $success = false;
-        $cachetime = (int)apcu_fetch($key . '_expires', $success);
-        if ($success && $cachetime !== 0 && ($cachetime < $time || ($time + $this->_config['duration']) < $cachetime)) {
-            return false;
-        }
-
         return apcu_fetch($key);
     }
 
@@ -196,15 +169,9 @@ public function clear($check)
     public function add($key, $value)
     {
         $key = $this->_key($key);
-
-        $expires = 0;
         $duration = $this->_config['duration'];
-        if ($duration) {
-            $expires = time() + $duration;
-        }
 
-        return apcu_add($key, $value, $duration) === true
-            && apcu_add($key . '_expires', $expires, $duration) === true;
+        return apcu_add($key, $value, $duration);
     }
 
     /**

src/Cache/Engine/WincacheEngine.php

@@ -61,17 +61,9 @@ public function init(array $config = [])
     public function write($key, $value)
     {
         $key = $this->_key($key);
-
         $duration = $this->_config['duration'];
-        $expires = time() + $duration;
-
-        $data = [
-            $key . '_expires' => $expires,
-            $key => $value
-        ];
-        $result = wincache_ucache_set($data, null, $duration);
 
-        return empty($result);
+        return wincache_ucache_set($key, $value, $duration);
     }
 
     /**
@@ -85,12 +77,6 @@ public function read($key)
     {
         $key = $this->_key($key);
 
-        $time = time();
-        $cachetime = (int)wincache_ucache_get($key . '_expires');
-        if ($cachetime < $time || ($time + $this->_config['duration']) < $cachetime) {
-            return false;
-        }
-
         return wincache_ucache_get($key);
     }