diff --git a/src/Symfony/Component/Cache/Adapter/AbstractAdapter.php b/src/Symfony/Component/Cache/Adapter/AbstractAdapter.php
index a1f0de7dcaefd..fc6ebbd66c102 100644
--- a/src/Symfony/Component/Cache/Adapter/AbstractAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/AbstractAdapter.php
@@ -16,11 +16,13 @@
 use Psr\Log\LoggerAwareTrait;
 use Psr\Log\LoggerInterface;
 use Symfony\Component\Cache\CacheItem;
+use Symfony\Component\Cache\Exception\CacheException;
+use Symfony\Component\Cache\Exception\InvalidArgumentException;
 
 /**
  * @author Nicolas Grekas <p@tchwork.com>
  */
-abstract class AbstractAdapter implements AdapterInterface, LoggerAwareInterface
+abstract class AbstractAdapter implements ContextAwareAdapterInterface, LoggerAwareInterface
 {
     use LoggerAwareTrait;
 
@@ -32,9 +34,17 @@ abstract class AbstractAdapter implements AdapterInterface, LoggerAwareInterface
     private $createCacheItem;
     private $mergeByLifetime;
 
+    /**
+     * @var int|null The maximum length to enforce for identifiers or null when no limit applies
+     */
+    protected $maxIdLength;
+
     protected function __construct($namespace = '', $defaultLifetime = 0)
     {
-        $this->namespace = '' === $namespace ? '' : $this->getId($namespace);
+        $this->namespace = '' === $namespace ? '' : $this->getId($namespace).':';
+        if (null !== $this->maxIdLength && strlen($namespace) > $this->maxIdLength - 24) {
+            throw new InvalidArgumentException(sprintf('Namespace must be %d chars max, %d given ("%s")', $this->maxIdLength - 24, strlen($namespace), $namespace));
+        }
         $this->createCacheItem = \Closure::bind(
             function ($key, $value, $isHit) use ($defaultLifetime) {
                 $item = new CacheItem();
@@ -363,6 +373,22 @@ public function commit()
         return $ok;
     }
 
+    /**
+     * {@inheritdoc}
+     */
+    public function withContext($context)
+    {
+        $fork = clone $this;
+        $fork->deferred = array();
+        $fork->namespace .= $this->getId($context).':';
+
+        if (null !== $this->maxIdLength && strlen($fork->namespace) > $this->maxIdLength - 23) {
+            throw new CacheException(sprintf('Full namespace must be %d chars max, %d reached ("%s")', $this->maxIdLength - 24, strlen($fork->namespace), substr($fork->namespace, 0, -1)));
+        }
+
+        return $fork;
+    }
+
     public function __destruct()
     {
         if ($this->deferred) {
@@ -401,7 +427,14 @@ private function getId($key)
     {
         CacheItem::validateKey($key);
 
-        return $this->namespace.$key;
+        if (null === $this->maxIdLength) {
+            return $this->namespace.$key;
+        }
+        if (strlen($id = $this->namespace.$key) > $this->maxIdLength) {
+            $id = $this->namespace.substr_replace(base64_encode(md5($key, true)), ':', -2);
+        }
+
+        return $id;
     }
 
     private function generateItems($items, &$keys)
diff --git a/src/Symfony/Component/Cache/Adapter/ApcuAdapter.php b/src/Symfony/Component/Cache/Adapter/ApcuAdapter.php
index d0af11395700d..67afd5c72a89e 100644
--- a/src/Symfony/Component/Cache/Adapter/ApcuAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/ApcuAdapter.php
@@ -37,9 +37,9 @@ public function __construct($namespace = '', $defaultLifetime = 0, $version = nu
         if (null !== $version) {
             CacheItem::validateKey($version);
 
-            if (!apcu_exists($version.':'.$namespace)) {
+            if (!apcu_exists($version.'@'.$namespace)) {
                 $this->clear($namespace);
-                apcu_add($version.':'.$namespace, null);
+                apcu_add($version.'@'.$namespace, null);
             }
         }
     }
diff --git a/src/Symfony/Component/Cache/Adapter/ArrayAdapter.php b/src/Symfony/Component/Cache/Adapter/ArrayAdapter.php
index 2898ba50cdc9a..bf1af03dd2869 100644
--- a/src/Symfony/Component/Cache/Adapter/ArrayAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/ArrayAdapter.php
@@ -19,7 +19,7 @@
 /**
  * @author Nicolas Grekas <p@tchwork.com>
  */
-class ArrayAdapter implements AdapterInterface, LoggerAwareInterface
+class ArrayAdapter implements ContextAwareAdapterInterface, LoggerAwareInterface
 {
     use LoggerAwareTrait;
 
@@ -27,6 +27,7 @@ class ArrayAdapter implements AdapterInterface, LoggerAwareInterface
     private $values = array();
     private $expiries = array();
     private $createCacheItem;
+    private $forks = array();
 
     /**
      * @param int  $defaultLifetime
@@ -115,6 +116,9 @@ public function hasItem($key)
     public function clear()
     {
         $this->values = $this->expiries = array();
+        foreach ($this->forks as $fork) {
+            $fork->clear();
+        }
 
         return true;
     }
@@ -197,6 +201,24 @@ public function commit()
         return true;
     }
 
+    /**
+     * {@inheritdoc}
+     */
+    public function withContext($context)
+    {
+        CacheItem::validateKey($context);
+
+        if (isset($this->forks[$context])) {
+            return $this->forks[$context];
+        }
+
+        $fork = clone $this;
+        $fork->values = $fork->expiries = array();
+        $this->forks[$context] = $fork;
+
+        return $fork;
+    }
+
     private function generateItems(array $keys, $now)
     {
         $f = $this->createCacheItem;
diff --git a/src/Symfony/Component/Cache/Adapter/ChainAdapter.php b/src/Symfony/Component/Cache/Adapter/ChainAdapter.php
index c731e47ddd808..4874e96824e4e 100644
--- a/src/Symfony/Component/Cache/Adapter/ChainAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/ChainAdapter.php
@@ -14,6 +14,7 @@
 use Psr\Cache\CacheItemInterface;
 use Psr\Cache\CacheItemPoolInterface;
 use Symfony\Component\Cache\CacheItem;
+use Symfony\Component\Cache\Exception\CacheException;
 use Symfony\Component\Cache\Exception\InvalidArgumentException;
 
 /**
@@ -24,7 +25,7 @@
  *
  * @author Kévin Dunglas <dunglas@gmail.com>
  */
-class ChainAdapter implements AdapterInterface
+class ChainAdapter implements ContextAwareAdapterInterface
 {
     private $adapters = array();
     private $saveUp;
@@ -223,4 +224,22 @@ public function commit()
 
         return $committed;
     }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function withContext($context)
+    {
+        $fork = clone $this;
+        $fork->adapters = array();
+
+        foreach ($this->adapters as $adapter) {
+            if (!$adapter instanceof ContextAwareAdapterInterface) {
+                throw new CacheException(sprintf('%s does not implement ContextAwareAdapterInterface.', get_class($adapter)));
+            }
+            $fork->adapters[] = $adapter->withContext($context);
+        }
+
+        return $fork;
+    }
 }
diff --git a/src/Symfony/Component/Cache/Adapter/ContextAwareAdapterInterface.php b/src/Symfony/Component/Cache/Adapter/ContextAwareAdapterInterface.php
new file mode 100644
index 0000000000000..f6ea3a655d0d3
--- /dev/null
+++ b/src/Symfony/Component/Cache/Adapter/ContextAwareAdapterInterface.php
@@ -0,0 +1,39 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Cache\Adapter;
+
+use Psr\Cache\CacheException;
+use Psr\Cache\InvalidArgumentException;
+
+/**
+ * Interface for creating contextualized key spaces from existing pools.
+ *
+ * @author Nicolas Grekas <p@tchwork.com>
+ */
+interface ContextAwareAdapterInterface extends AdapterInterface
+{
+    /**
+     * Derivates a new cache pool from an existing one by contextualizing its key space.
+     *
+     * Contexts add to each others.
+     * Clearing a parent also clears all its derivated
+     * pools (but not necessarily their deferred items).
+     *
+     * @param string $context A context identifier.
+     *
+     * @return self A clone of the current instance, where cache keys are isolated from its parent
+     *
+     * @throws InvalidArgumentException When $context contains invalid characters
+     * @throws CacheException           When the adapter can't be forked
+     */
+    public function withContext($context);
+}
diff --git a/src/Symfony/Component/Cache/Adapter/DoctrineAdapter.php b/src/Symfony/Component/Cache/Adapter/DoctrineAdapter.php
index ed91bf56cd0e5..8197885a68514 100644
--- a/src/Symfony/Component/Cache/Adapter/DoctrineAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/DoctrineAdapter.php
@@ -12,6 +12,7 @@
 namespace Symfony\Component\Cache\Adapter;
 
 use Doctrine\Common\Cache\CacheProvider;
+use Symfony\Component\Cache\Exception\CacheException;
 
 /**
  * @author Nicolas Grekas <p@tchwork.com>
@@ -27,6 +28,14 @@ public function __construct(CacheProvider $provider, $namespace = '', $defaultLi
         $provider->setNamespace($namespace);
     }
 
+    /**
+     * @inheritdoc}
+     */
+    public function withContext($context)
+    {
+        throw new CacheException(sprintf('%s does not implement ContextAwareAdapterInterface.', get_class($this)));
+    }
+
     /**
      * {@inheritdoc}
      */
diff --git a/src/Symfony/Component/Cache/Adapter/FilesystemAdapterTrait.php b/src/Symfony/Component/Cache/Adapter/FilesystemAdapterTrait.php
index 809ec15dfb0ae..f72dee95a82ac 100644
--- a/src/Symfony/Component/Cache/Adapter/FilesystemAdapterTrait.php
+++ b/src/Symfony/Component/Cache/Adapter/FilesystemAdapterTrait.php
@@ -11,6 +11,7 @@
 
 namespace Symfony\Component\Cache\Adapter;
 
+use Symfony\Component\Cache\CacheItem;
 use Symfony\Component\Cache\Exception\InvalidArgumentException;
 
 /**
@@ -79,6 +80,19 @@ protected function doDelete(array $ids)
         return $ok;
     }
 
+    /**
+     * {@inheritdoc}
+     */
+    public function withContext($context)
+    {
+        CacheItem::validateKey($context);
+
+        $fork = clone $this;
+        $fork->init($context, $this->directory);
+
+        return $fork;
+    }
+
     private function write($file, $data, $expiresAt = null)
     {
         if (false === @file_put_contents($this->tmp, $data)) {
diff --git a/src/Symfony/Component/Cache/Adapter/NullAdapter.php b/src/Symfony/Component/Cache/Adapter/NullAdapter.php
index f58f81e5b8960..4ed3639134528 100644
--- a/src/Symfony/Component/Cache/Adapter/NullAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/NullAdapter.php
@@ -17,7 +17,7 @@
 /**
  * @author Titouan Galopin <galopintitouan@gmail.com>
  */
-class NullAdapter implements AdapterInterface
+class NullAdapter implements ContextAwareAdapterInterface
 {
     private $createCacheItem;
 
@@ -110,6 +110,14 @@ public function commit()
         return false;
     }
 
+    /**
+     * {@inheritdoc}
+     */
+    public function withContext($context)
+    {
+        return clone $this;
+    }
+
     private function generateItems(array $keys)
     {
         $f = $this->createCacheItem;
diff --git a/src/Symfony/Component/Cache/Adapter/TagAwareAdapter.php b/src/Symfony/Component/Cache/Adapter/TagAwareAdapter.php
index 6f349ab433ef8..dcb017d1b4741 100644
--- a/src/Symfony/Component/Cache/Adapter/TagAwareAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/TagAwareAdapter.php
@@ -14,11 +14,12 @@
 use Psr\Cache\CacheItemInterface;
 use Psr\Cache\InvalidArgumentException;
 use Symfony\Component\Cache\CacheItem;
+use Symfony\Component\Cache\Exception\CacheException;
 
 /**
  * @author Nicolas Grekas <p@tchwork.com>
  */
-class TagAwareAdapter implements TagAwareAdapterInterface
+class TagAwareAdapter implements ContextAwareAdapterInterface, TagAwareAdapterInterface
 {
     const TAGS_PREFIX = "\0tags\0";
 
@@ -242,6 +243,22 @@ public function commit()
         return $this->itemsAdapter->commit() && $ok;
     }
 
+    /**
+     * {@inheritdoc}
+     */
+    public function withContext($context)
+    {
+        if (!$this->itemsAdapter instanceof ContextAwareAdapterInterface) {
+            throw new CacheException(sprintf('%s does not implement ContextAwareAdapterInterface.', get_class($this->itemsAdapter)));
+        }
+
+        $fork = clone $this;
+        $fork->itemsAdapter = $this->itemsAdapter->withContext($context);
+        $fork->deferred = array();
+
+        return $fork;
+    }
+
     public function __destruct()
     {
         $this->commit();
diff --git a/src/Symfony/Component/Cache/Tests/Adapter/AdapterTestCase.php b/src/Symfony/Component/Cache/Tests/Adapter/AdapterTestCase.php
index 4bc80ee30022e..d649b08581cb9 100644
--- a/src/Symfony/Component/Cache/Tests/Adapter/AdapterTestCase.php
+++ b/src/Symfony/Component/Cache/Tests/Adapter/AdapterTestCase.php
@@ -12,6 +12,7 @@
 namespace Symfony\Component\Cache\Tests\Adapter;
 
 use Cache\IntegrationTests\CachePoolTest;
+use Symfony\Component\Cache\Adapter\ContextAwareAdapterInterface;
 
 abstract class AdapterTestCase extends CachePoolTest
 {
@@ -71,6 +72,59 @@ public function testNotUnserializable()
         }
         $this->assertFalse($item->isHit());
     }
+
+    public function testContext()
+    {
+        if (isset($this->skippedTests[__FUNCTION__])) {
+            $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
+
+            return;
+        }
+        $cache = $this->createCachePool();
+
+        if (!$cache instanceof ContextAwareAdapterInterface) {
+            $this->markTestSkipped('ContextAwareAdapterInterface not implemented.');
+        }
+
+        $item = $cache->getItem('foo');
+        $cache->save($item->set('foo'));
+
+        $fork = $cache->withContext('ns');
+        $item = $fork->getItem('foo');
+        $this->assertFalse($item->isHit());
+
+        $fork->save($item->set('bar'));
+        $item = $cache->getItem('bar');
+        $this->assertFalse($item->isHit());
+
+        $fork = $cache->withContext('ns');
+        $item = $fork->getItem('foo');
+        $this->assertTrue($item->isHit());
+
+        $cache->clear();
+        $item = $fork->getItem('foo');
+        $this->assertFalse($item->isHit());
+    }
+
+    /**
+     * @expectedException \Psr\Cache\InvalidArgumentException
+     * @dataProvider invalidKeys
+     */
+    public function testBadContext($context)
+    {
+        if (isset($this->skippedTests[__FUNCTION__])) {
+            $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
+
+            return;
+        }
+        $cache = $this->createCachePool();
+
+        if (!$cache instanceof ContextAwareAdapterInterface) {
+            $this->markTestSkipped('ContextAwareAdapterInterface not implemented.');
+        }
+
+        $cache->withContext($context);
+    }
 }
 
 class NotUnserializable implements \Serializable
diff --git a/src/Symfony/Component/Cache/Tests/Adapter/ChainAdapterTest.php b/src/Symfony/Component/Cache/Tests/Adapter/ChainAdapterTest.php
index b80913c6e089c..d29d9f08df3a6 100644
--- a/src/Symfony/Component/Cache/Tests/Adapter/ChainAdapterTest.php
+++ b/src/Symfony/Component/Cache/Tests/Adapter/ChainAdapterTest.php
@@ -22,6 +22,10 @@
  */
 class ChainAdapterTest extends AdapterTestCase
 {
+    protected $skippedTests = array(
+        'testBadContext' => 'ContextAwareAdapterInterface not implemented by ExternalAdapter.',
+    );
+
     public function createCachePool($defaultLifetime = 0)
     {
         return new ChainAdapter(array(new ArrayAdapter($defaultLifetime), new ExternalAdapter(), new FilesystemAdapter('', $defaultLifetime)), $defaultLifetime);
@@ -44,4 +48,13 @@ public function testInvalidAdapterException()
     {
         new ChainAdapter(array(new \stdClass()));
     }
+
+    /**
+     * @expectedException Symfony\Component\Cache\Exception\CacheException
+     * @expectedExceptionMessage Symfony\Component\Cache\Adapter\ProxyAdapter does not implement ContextAwareAdapterInterface.
+     */
+    public function testContext()
+    {
+        parent::testContext();
+    }
 }
diff --git a/src/Symfony/Component/Cache/Tests/Adapter/DoctrineAdapterTest.php b/src/Symfony/Component/Cache/Tests/Adapter/DoctrineAdapterTest.php
index 93ec9824388e1..ea6cdeea17203 100644
--- a/src/Symfony/Component/Cache/Tests/Adapter/DoctrineAdapterTest.php
+++ b/src/Symfony/Component/Cache/Tests/Adapter/DoctrineAdapterTest.php
@@ -23,10 +23,20 @@ class DoctrineAdapterTest extends AdapterTestCase
         'testDeferredSaveWithoutCommit' => 'Assumes a shared cache which ArrayCache is not.',
         'testSaveWithoutExpire' => 'Assumes a shared cache which ArrayCache is not.',
         'testNotUnserializable' => 'ArrayCache does not use serialize/unserialize',
+        'testBadContext' => 'ContextAwareAdapterInterface not implemented.',
     );
 
     public function createCachePool($defaultLifetime = 0)
     {
         return new DoctrineAdapter(new ArrayCache($defaultLifetime), '', $defaultLifetime);
     }
+
+    /**
+     * @expectedException Symfony\Component\Cache\Exception\CacheException
+     * @expectedExceptionMessage Symfony\Component\Cache\Adapter\DoctrineAdapter does not implement ContextAwareAdapterInterface.
+     */
+    public function testContext()
+    {
+        parent::testContext();
+    }
 }
diff --git a/src/Symfony/Component/Cache/Tests/Adapter/TagAwareAdapterTest.php b/src/Symfony/Component/Cache/Tests/Adapter/TagAwareAdapterTest.php
index fc824ede58868..2b8335f1d27e1 100644
--- a/src/Symfony/Component/Cache/Tests/Adapter/TagAwareAdapterTest.php
+++ b/src/Symfony/Component/Cache/Tests/Adapter/TagAwareAdapterTest.php
@@ -97,4 +97,30 @@ public function testTagsAreCleanedOnDelete()
 
         $this->assertTrue($pool->getItem('k')->isHit());
     }
+
+    public function testTagsImpactSubContexts()
+    {
+        $pool = $this->createCachePool();
+        $fork = $pool->withContext('ns');
+
+        $poolItem = $pool->getItem('i1');
+        $forkItem = $fork->getItem('i2');
+
+        $poolItem->tag('foo');
+        $forkItem->tag('foo');
+
+        $pool->save($poolItem);
+        $fork->save($forkItem);
+
+        $this->assertTrue($pool->hasItem('i1'));
+        $this->assertTrue($fork->hasItem('i2'));
+
+        $this->assertTrue($fork->invalidateTags('foo'));
+
+        $this->assertFalse($pool->hasItem('i1'));
+        $this->assertFalse($fork->hasItem('i2'));
+
+        $this->assertFalse($pool->getItem('i1')->isHit());
+        $this->assertFalse($fork->getItem('i2')->isHit());
+    }
 }