Drupal 8.0.0 beta 12. More info: https://www.drupal.org/node/2514176

core/lib/Drupal/Core/PageCache/ChainRequestPolicy.php

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+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\PageCache\ChainRequestPolicy.
+ */
+
+namespace Drupal\Core\PageCache;
+
+use Symfony\Component\HttpFoundation\Request;
+
+/**
+ * Implements a compound request policy.
+ *
+ * When evaluating the compound policy, all of the contained rules are applied
+ * to the request. The overall result is computed according to the following
+ * rules:
+ *
+ * <ol>
+ *   <li>Returns static::DENY if any of the rules evaluated to static::DENY</li>
+ *   <li>Returns static::ALLOW if at least one of the rules evaluated to
+ *       static::ALLOW and none to static::DENY</li>
+ *   <li>Otherwise returns NULL</li>
+ * </ol>
+ */
+class ChainRequestPolicy implements ChainRequestPolicyInterface {
+
+  /**
+   * A list of policy rules to apply when this policy is evaluated.
+   *
+   * @var \Drupal\Core\PageCache\RequestPolicyInterface[]
+   */
+  protected $rules = [];
+
+  /**
+   * {@inheritdoc}
+   */
+  public function check(Request $request) {
+    $final_result = NULL;
+
+    foreach ($this->rules as $rule) {
+      $result = $rule->check($request);
+      if ($result === static::DENY) {
+        return $result;
+      }
+      elseif ($result === static::ALLOW) {
+        $final_result = $result;
+      }
+      elseif (isset($result)) {
+        throw new \UnexpectedValueException('Return value of RequestPolicyInterface::check() must be one of RequestPolicyInterface::ALLOW, RequestPolicyInterface::DENY or NULL');
+      }
+    }
+
+    return $final_result;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function addPolicy(RequestPolicyInterface $policy) {
+    $this->rules[] = $policy;
+    return $this;
+  }
+
+}

core/lib/Drupal/Core/PageCache/ChainRequestPolicyInterface.php

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+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\PageCache\ChainRequestPolicyInterface.
+ */
+
+namespace Drupal\Core\PageCache;
+
+/**
+ * Defines the interface for compound request policies.
+ */
+interface ChainRequestPolicyInterface extends RequestPolicyInterface {
+
+  /**
+   * Add a policy to the list of policy rules.
+   *
+   * @param \Drupal\Core\PageCache\RequestPolicyInterface $policy
+   *   The request policy rule to add.
+   *
+   * @return $this
+   */
+  public function addPolicy(RequestPolicyInterface $policy);
+
+}

core/lib/Drupal/Core/PageCache/ChainResponsePolicy.php

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+<?php
+/**
+ * @file
+ * Contains \Drupal\Core\PageCache\ChainResponsePolicy.
+ */
+
+namespace Drupal\Core\PageCache;
+
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Response;
+
+/**
+ * Implements a compound response policy.
+ *
+ * When evaluating the compound policy, all of the contained rules are applied
+ * to the response. The overall result is computed according to the following
+ * rules:
+ *
+ * <ol>
+ *   <li>Returns static::DENY if any of the rules evaluated to static::DENY</li>
+ *   <li>Otherwise returns NULL</li>
+ * </ol>
+ */
+class ChainResponsePolicy implements ChainResponsePolicyInterface {
+
+  /**
+   * A list of policy rules to apply when this policy is checked.
+   *
+   * @var \Drupal\Core\PageCache\ResponsePolicyInterface[]
+   */
+  protected $rules = [];
+
+  /**
+   * {@inheritdoc}
+   */
+  public function check(Response $response, Request $request) {
+    foreach ($this->rules as $rule) {
+      $result = $rule->check($response, $request);
+      if ($result === static::DENY) {
+        return $result;
+      }
+      elseif (isset($result)) {
+        throw new \UnexpectedValueException('Return value of ResponsePolicyInterface::check() must be one of ResponsePolicyInterface::DENY or NULL');
+      }
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function addPolicy(ResponsePolicyInterface $policy) {
+    $this->rules[] = $policy;
+    return $this;
+  }
+
+}

core/lib/Drupal/Core/PageCache/ChainResponsePolicyInterface.php

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+<?php
+/**
+ * @file
+ * Contains \Drupal\Core\PageCache\ChainResponsePolicyInterface.
+ */
+
+namespace Drupal\Core\PageCache;
+
+/**
+ * Defines the interface for compound request policies.
+ */
+interface ChainResponsePolicyInterface extends ResponsePolicyInterface {
+
+  /**
+   * Add a policy to the list of policy rules.
+   *
+   * @param \Drupal\Core\PageCache\ResponsePolicyInterface $policy
+   *   The request policy rule to add.
+   *
+   * @return $this
+   */
+  public function addPolicy(ResponsePolicyInterface $policy);
+
+}

core/lib/Drupal/Core/PageCache/DefaultRequestPolicy.php

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+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\PageCache\DefaultRequestPolicy.
+ */
+
+namespace Drupal\Core\PageCache;
+
+use Drupal\Core\Session\SessionConfigurationInterface;
+
+/**
+ * The default page cache request policy.
+ *
+ * Delivery of cached pages is denied if either the application is running from
+ * the command line or the request was not initiated with a safe method (GET or
+ * HEAD). Also caching is only allowed for requests without a session cookie.
+ */
+class DefaultRequestPolicy extends ChainRequestPolicy {
+
+  /**
+   * Constructs the default page cache request policy.
+   *
+   * @param \Drupal\Core\Session\SessionConfigurationInterface $session_configuration
+   *   The session configuration.
+   */
+  public function __construct(SessionConfigurationInterface $session_configuration) {
+    $this->addPolicy(new RequestPolicy\CommandLineOrUnsafeMethod());
+    $this->addPolicy(new RequestPolicy\NoSessionOpen($session_configuration));
+  }
+
+}

core/lib/Drupal/Core/PageCache/RequestPolicy/CommandLineOrUnsafeMethod.php

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+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\PageCache\RequestPolicy\CommandLineOrUnsafeMethod.
+ */
+
+namespace Drupal\Core\PageCache\RequestPolicy;
+
+use Drupal\Core\PageCache\RequestPolicyInterface;
+use Symfony\Component\HttpFoundation\Request;
+
+/**
+ * Reject when running from the command line or when HTTP method is not safe.
+ *
+ * The policy denies caching if the request was initiated from the command line
+ * interface (drush) or the request method is neither GET nor HEAD (see RFC
+ * 2616, section 9.1.1 - Safe Methods).
+ */
+class CommandLineOrUnsafeMethod implements RequestPolicyInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function check(Request $request) {
+    if ($this->isCli() || !$request->isMethodSafe()) {
+      return static::DENY;
+    }
+  }
+
+  /**
+   * Indicates whether this is a CLI request.
+   */
+  protected function isCli() {
+    return PHP_SAPI === 'cli';
+  }
+
+}

core/lib/Drupal/Core/PageCache/RequestPolicy/NoSessionOpen.php

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+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\PageCache\RequestPolicy\NoSessionOpen.
+ */
+
+namespace Drupal\Core\PageCache\RequestPolicy;
+
+use Drupal\Core\PageCache\RequestPolicyInterface;
+use Drupal\Core\Session\SessionConfigurationInterface;
+use Symfony\Component\HttpFoundation\Request;
+
+/**
+ * A policy allowing delivery of cached pages when there is no session open.
+ *
+ * Do not serve cached pages to authenticated users, or to anonymous users when
+ * $_SESSION is non-empty. $_SESSION may contain status messages from a form
+ * submission, the contents of a shopping cart, or other userspecific content
+ * that should not be cached and displayed to other users.
+ */
+class NoSessionOpen implements RequestPolicyInterface {
+
+  /**
+   * The session configuration.
+   *
+   * @var \Drupal\Core\Session\SessionConfigurationInterface
+   */
+  protected $sessionConfiguration;
+
+  /**
+   * Constructs a new page cache session policy.
+   *
+   * @param \Drupal\Core\Session\SessionConfigurationInterface $session_configuration
+   *   The session configuration.
+   */
+  public function __construct(SessionConfigurationInterface $session_configuration) {
+    $this->sessionConfiguration = $session_configuration;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function check(Request $request) {
+    if (!$this->sessionConfiguration->hasSession($request)) {
+      return static::ALLOW;
+    }
+  }
+
+}

core/lib/Drupal/Core/PageCache/RequestPolicyInterface.php

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+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\PageCache\RequestPolicyInterface.
+ */
+
+namespace Drupal\Core\PageCache;
+
+use Symfony\Component\HttpFoundation\Request;
+
+/**
+ * Defines the interface for request policy implementations.
+ *
+ * The request policy is evaluated in order to determine whether delivery of a
+ * cached page should be attempted. The caller should do so if static::ALLOW is
+ * returned from the check() method.
+ */
+interface RequestPolicyInterface {
+
+  /**
+   * Allow delivery of cached pages.
+   */
+  const ALLOW = 'allow';
+
+  /**
+   * Deny delivery of cached pages.
+   */
+  const DENY = 'deny';
+
+  /**
+   * Determines whether delivery of a cached page should be attempted.
+   *
+   * Note that the request-policy check runs very early. In particular it is
+   * not possible to determine the logged in user. Also the current route match
+   * is not yet present when the check runs. Therefore, request-policy checks
+   * need to be designed in a way such that they do not depend on any other
+   * service and only take in account the information present on the incoming
+   * request.
+   *
+   * When matching against the request path, special attention is needed to
+   * support path prefixes which are often used on multilingual sites.
+   *
+   * @param \Symfony\Component\HttpFoundation\Request $request
+   *   The incoming request object.
+   *
+   * @return string|NULL
+   *   One of static::ALLOW, static::DENY or NULL. Calling code may attempt to
+   *   deliver a cached page if static::ALLOW is returned. Returns NULL if the
+   *   policy is not specified for the given request.
+   */
+  public function check(Request $request);
+
+}

core/lib/Drupal/Core/PageCache/ResponsePolicy/DenyNoCacheRoutes.php

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+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\PageCache\ResponsePolicy\DenyNoCacheRoutes.
+ */
+
+namespace Drupal\Core\PageCache\ResponsePolicy;
+
+use Drupal\Core\PageCache\ResponsePolicyInterface;
+use Drupal\Core\Routing\RouteMatchInterface;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Response;
+
+/**
+ * Cache policy for routes with the 'no_cache' option set.
+ *
+ * This policy rule denies caching of responses generated for routes that have
+ * the 'no_cache' option set to TRUE.
+ */
+class DenyNoCacheRoutes implements ResponsePolicyInterface {
+
+  /**
+   * The current route match.
+   *
+   * @var \Drupal\Core\Routing\RouteMatchInterface
+   */
+  protected $routeMatch;
+
+  /**
+   * Constructs a deny node preview page cache policy.
+   *
+   * @param \Drupal\Core\Routing\RouteMatchInterface $route_match
+   *   The current route match.
+   */
+  public function __construct(RouteMatchInterface $route_match) {
+    $this->routeMatch = $route_match;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function check(Response $response, Request $request) {
+    if (($route = $this->routeMatch->getRouteObject()) && $route->getOption('no_cache')) {
+      return static::DENY;
+    }
+  }
+
+}
+

core/lib/Drupal/Core/PageCache/ResponsePolicy/KillSwitch.php

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+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\PageCache\ResponsePolicy\KillSwitch.
+ */
+
+namespace Drupal\Core\PageCache\ResponsePolicy;
+
+use Drupal\Core\PageCache\ResponsePolicyInterface;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Response;
+
+/**
+ * A policy evaluating to static::DENY when the kill switch was triggered.
+ */
+class KillSwitch implements ResponsePolicyInterface {
+
+  /**
+   * A flag indicating whether the kill switch was triggered.
+   *
+   * @var bool
+   */
+  protected $kill = FALSE;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function check(Response $response, Request $request) {
+    if ($this->kill) {
+      return static::DENY;
+    }
+  }
+
+  /**
+   * Deny any page caching on the current request.
+   */
+  public function trigger() {
+    $this->kill = TRUE;
+  }
+
+}

core/lib/Drupal/Core/PageCache/ResponsePolicy/NoServerError.php

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+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\PageCache\ResponsePolicy\NoServerError.
+ */
+
+namespace Drupal\Core\PageCache\ResponsePolicy;
+
+use Drupal\Core\PageCache\ResponsePolicyInterface;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Response;
+
+/**
+ * A policy denying caching of a server error (HTTP 5xx) responses.
+ */
+class NoServerError implements ResponsePolicyInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function check(Response $response, Request $request) {
+    if ($response->isServerError()) {
+      return static::DENY;
+    }
+  }
+
+}

core/lib/Drupal/Core/PageCache/ResponsePolicyInterface.php

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+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\PageCache\ResponsePolicyInterface.
+ */
+
+namespace Drupal\Core\PageCache;
+
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Response;
+
+/**
+ * Defines the interface for response policy implementations.
+ *
+ * The response policy is evaluated in order to determine whether a page should
+ * be stored a in the cache. Calling code should do so unless static::DENY is
+ * returned from the check() method.
+ */
+interface ResponsePolicyInterface {
+
+  /**
+   * Deny storage of a page in the cache.
+   */
+  const DENY = 'deny';
+
+  /**
+   * Determines whether it is save to store a page in the cache.
+   *
+   * @param \Symfony\Component\HttpFoundation\Response $response
+   *   The response which is about to be sent to the client.
+   * @param \Symfony\Component\HttpFoundation\Request $request
+   *   The request object.
+   *
+   * @return string|NULL
+   *   Either static::DENY or NULL. Calling code may attempt to store a page in
+   *   the cache unless static::DENY is returned. Returns NULL if the policy
+   *   policy is not specified for the given response.
+   */
+  public function check(Response $response, Request $request);
+
+}