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1 <?php
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2
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3 namespace Drupal\page_cache\StackMiddleware;
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4
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5 use Drupal\Core\Cache\Cache;
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6 use Drupal\Core\Cache\CacheableResponseInterface;
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7 use Drupal\Core\Cache\CacheBackendInterface;
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8 use Drupal\Core\PageCache\RequestPolicyInterface;
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9 use Drupal\Core\PageCache\ResponsePolicyInterface;
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10 use Drupal\Core\Site\Settings;
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11 use Symfony\Component\HttpFoundation\BinaryFileResponse;
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12 use Symfony\Component\HttpFoundation\Request;
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13 use Symfony\Component\HttpFoundation\Response;
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14 use Symfony\Component\HttpFoundation\StreamedResponse;
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15 use Symfony\Component\HttpKernel\HttpKernelInterface;
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16
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17 /**
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18 * Executes the page caching before the main kernel takes over the request.
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19 */
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20 class PageCache implements HttpKernelInterface {
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21
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22 /**
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23 * The wrapped HTTP kernel.
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24 *
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25 * @var \Symfony\Component\HttpKernel\HttpKernelInterface
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26 */
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27 protected $httpKernel;
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28
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29 /**
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30 * The cache bin.
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31 *
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32 * @var \Drupal\Core\Cache\CacheBackendInterface
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33 */
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34 protected $cache;
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35
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36 /**
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37 * A policy rule determining the cacheability of a request.
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38 *
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39 * @var \Drupal\Core\PageCache\RequestPolicyInterface
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40 */
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41 protected $requestPolicy;
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42
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43 /**
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44 * A policy rule determining the cacheability of the response.
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45 *
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46 * @var \Drupal\Core\PageCache\ResponsePolicyInterface
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47 */
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48 protected $responsePolicy;
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49
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50 /**
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51 * The cache ID for the (master) request.
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52 *
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53 * @var string
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54 */
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55 protected $cid;
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56
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57 /**
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58 * Constructs a PageCache object.
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59 *
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60 * @param \Symfony\Component\HttpKernel\HttpKernelInterface $http_kernel
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61 * The decorated kernel.
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62 * @param \Drupal\Core\Cache\CacheBackendInterface $cache
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63 * The cache bin.
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64 * @param \Drupal\Core\PageCache\RequestPolicyInterface $request_policy
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65 * A policy rule determining the cacheability of a request.
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66 * @param \Drupal\Core\PageCache\ResponsePolicyInterface $response_policy
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67 * A policy rule determining the cacheability of the response.
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68 */
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69 public function __construct(HttpKernelInterface $http_kernel, CacheBackendInterface $cache, RequestPolicyInterface $request_policy, ResponsePolicyInterface $response_policy) {
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70 $this->httpKernel = $http_kernel;
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71 $this->cache = $cache;
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72 $this->requestPolicy = $request_policy;
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73 $this->responsePolicy = $response_policy;
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74 }
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75
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76 /**
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77 * {@inheritdoc}
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78 */
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79 public function handle(Request $request, $type = self::MASTER_REQUEST, $catch = TRUE) {
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80 // Only allow page caching on master request.
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81 if ($type === static::MASTER_REQUEST && $this->requestPolicy->check($request) === RequestPolicyInterface::ALLOW) {
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82 $response = $this->lookup($request, $type, $catch);
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83 }
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84 else {
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85 $response = $this->pass($request, $type, $catch);
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86 }
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87
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88 return $response;
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89 }
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90
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91 /**
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92 * Sidesteps the page cache and directly forwards a request to the backend.
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93 *
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94 * @param \Symfony\Component\HttpFoundation\Request $request
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95 * A request object.
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96 * @param int $type
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97 * The type of the request (one of HttpKernelInterface::MASTER_REQUEST or
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98 * HttpKernelInterface::SUB_REQUEST)
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99 * @param bool $catch
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100 * Whether to catch exceptions or not
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101 *
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102 * @returns \Symfony\Component\HttpFoundation\Response $response
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103 * A response object.
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104 */
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105 protected function pass(Request $request, $type = self::MASTER_REQUEST, $catch = TRUE) {
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106 return $this->httpKernel->handle($request, $type, $catch);
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107 }
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108
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109 /**
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110 * Retrieves a response from the cache or fetches it from the backend.
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111 *
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112 * @param \Symfony\Component\HttpFoundation\Request $request
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113 * A request object.
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114 * @param int $type
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115 * The type of the request (one of HttpKernelInterface::MASTER_REQUEST or
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116 * HttpKernelInterface::SUB_REQUEST)
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117 * @param bool $catch
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118 * Whether to catch exceptions or not
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119 *
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120 * @returns \Symfony\Component\HttpFoundation\Response $response
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121 * A response object.
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122 */
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123 protected function lookup(Request $request, $type = self::MASTER_REQUEST, $catch = TRUE) {
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124 if ($response = $this->get($request)) {
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125 $response->headers->set('X-Drupal-Cache', 'HIT');
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126 }
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127 else {
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128 $response = $this->fetch($request, $type, $catch);
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129 }
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130
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131 // Only allow caching in the browser and prevent that the response is stored
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132 // by an external proxy server when the following conditions apply:
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133 // 1. There is a session cookie on the request.
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134 // 2. The Vary: Cookie header is on the response.
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135 // 3. The Cache-Control header does not contain the no-cache directive.
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136 if ($request->cookies->has(session_name()) &&
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137 in_array('Cookie', $response->getVary()) &&
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138 !$response->headers->hasCacheControlDirective('no-cache')) {
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139
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140 $response->setPrivate();
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141 }
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142
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143 // Perform HTTP revalidation.
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144 // @todo Use Response::isNotModified() as
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145 // per https://www.drupal.org/node/2259489.
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146 $last_modified = $response->getLastModified();
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147 if ($last_modified) {
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148 // See if the client has provided the required HTTP headers.
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149 $if_modified_since = $request->server->has('HTTP_IF_MODIFIED_SINCE') ? strtotime($request->server->get('HTTP_IF_MODIFIED_SINCE')) : FALSE;
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150 $if_none_match = $request->server->has('HTTP_IF_NONE_MATCH') ? stripslashes($request->server->get('HTTP_IF_NONE_MATCH')) : FALSE;
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151
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152 if ($if_modified_since && $if_none_match
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153 // etag must match.
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154 && $if_none_match == $response->getEtag()
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155 // if-modified-since must match.
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156 && $if_modified_since == $last_modified->getTimestamp()) {
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157 $response->setStatusCode(304);
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158 $response->setContent(NULL);
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159
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160 // In the case of a 304 response, certain headers must be sent, and the
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161 // remaining may not (see RFC 2616, section 10.3.5).
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162 foreach (array_keys($response->headers->all()) as $name) {
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163 if (!in_array($name, ['content-location', 'expires', 'cache-control', 'vary'])) {
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164 $response->headers->remove($name);
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165 }
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166 }
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167 }
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168 }
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169
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170 return $response;
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171 }
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172
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173 /**
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174 * Fetches a response from the backend and stores it in the cache.
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175 *
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176 * @see drupal_page_header()
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177 *
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178 * @param \Symfony\Component\HttpFoundation\Request $request
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179 * A request object.
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180 * @param int $type
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181 * The type of the request (one of HttpKernelInterface::MASTER_REQUEST or
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182 * HttpKernelInterface::SUB_REQUEST)
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183 * @param bool $catch
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184 * Whether to catch exceptions or not
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185 *
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186 * @returns \Symfony\Component\HttpFoundation\Response $response
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187 * A response object.
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188 */
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189 protected function fetch(Request $request, $type = self::MASTER_REQUEST, $catch = TRUE) {
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190 /** @var \Symfony\Component\HttpFoundation\Response $response */
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191 $response = $this->httpKernel->handle($request, $type, $catch);
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192
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193 // Only set the 'X-Drupal-Cache' header if caching is allowed for this
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194 // response.
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195 if ($this->storeResponse($request, $response)) {
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196 $response->headers->set('X-Drupal-Cache', 'MISS');
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197 }
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198
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199 return $response;
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200 }
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201
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202 /**
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203 * Stores a response in the page cache.
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204 *
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205 * @param \Symfony\Component\HttpFoundation\Request $request
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206 * A request object.
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207 * @param \Symfony\Component\HttpFoundation\Response $response
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208 * A response object that should be stored in the page cache.
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209 *
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210 * @returns bool
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211 */
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212 protected function storeResponse(Request $request, Response $response) {
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213 // Drupal's primary cache invalidation architecture is cache tags: any
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214 // response that varies by a configuration value or data in a content
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215 // entity should have cache tags, to allow for instant cache invalidation
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216 // when that data is updated. However, HTTP does not standardize how to
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217 // encode cache tags in a response. Different CDNs implement their own
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218 // approaches, and configurable reverse proxies (e.g., Varnish) allow for
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219 // custom implementations. To keep Drupal's internal page cache simple, we
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220 // only cache CacheableResponseInterface responses, since those provide a
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221 // defined API for retrieving cache tags. For responses that do not
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222 // implement CacheableResponseInterface, there's no easy way to distinguish
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223 // responses that truly don't depend on any site data from responses that
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224 // contain invalidation information customized to a particular proxy or
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225 // CDN.
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226 // - Drupal modules are encouraged to use CacheableResponseInterface
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227 // responses where possible and to leave the encoding of that information
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228 // into response headers to the corresponding proxy/CDN integration
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229 // modules.
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230 // - Custom applications that wish to provide internal page cache support
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231 // for responses that do not implement CacheableResponseInterface may do
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232 // so by replacing/extending this middleware service or adding another
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233 // one.
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234 if (!$response instanceof CacheableResponseInterface) {
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235 return FALSE;
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236 }
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237
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238 // Currently it is not possible to cache binary file or streamed responses:
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239 // https://github.com/symfony/symfony/issues/9128#issuecomment-25088678.
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240 // Therefore exclude them, even for subclasses that implement
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241 // CacheableResponseInterface.
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242 if ($response instanceof BinaryFileResponse || $response instanceof StreamedResponse) {
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243 return FALSE;
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244 }
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245
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246 // Allow policy rules to further restrict which responses to cache.
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247 if ($this->responsePolicy->check($response, $request) === ResponsePolicyInterface::DENY) {
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248 return FALSE;
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249 }
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250
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251 $request_time = $request->server->get('REQUEST_TIME');
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252 // The response passes all of the above checks, so cache it. Page cache
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253 // entries default to Cache::PERMANENT since they will be expired via cache
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254 // tags locally. Because of this, page cache ignores max age.
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255 // - Get the tags from CacheableResponseInterface per the earlier comments.
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256 // - Get the time expiration from the Expires header, rather than the
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257 // interface, but see https://www.drupal.org/node/2352009 about possibly
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258 // changing that.
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259 $expire = 0;
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260 // 403 and 404 responses can fill non-LRU cache backends and generally are
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261 // likely to have a low cache hit rate. So do not cache them permanently.
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262 if ($response->isClientError()) {
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263 // Cache for an hour by default. If the 'cache_ttl_4xx' setting is
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264 // set to 0 then do not cache the response.
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265 $cache_ttl_4xx = Settings::get('cache_ttl_4xx', 3600);
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266 if ($cache_ttl_4xx > 0) {
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267 $expire = $request_time + $cache_ttl_4xx;
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268 }
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269 }
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270 // The getExpires method could return NULL if Expires header is not set, so
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271 // the returned value needs to be checked before calling getTimestamp.
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272 elseif ($expires = $response->getExpires()) {
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273 $date = $expires->getTimestamp();
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274 $expire = ($date > $request_time) ? $date : Cache::PERMANENT;
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275 }
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276 else {
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277 $expire = Cache::PERMANENT;
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278 }
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279
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280 if ($expire === Cache::PERMANENT || $expire > $request_time) {
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281 $tags = $response->getCacheableMetadata()->getCacheTags();
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282 $this->set($request, $response, $expire, $tags);
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283 }
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284
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285 return TRUE;
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286 }
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287
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288 /**
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289 * Returns a response object from the page cache.
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290 *
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291 * @param \Symfony\Component\HttpFoundation\Request $request
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292 * A request object.
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293 * @param bool $allow_invalid
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294 * (optional) If TRUE, a cache item may be returned even if it is expired or
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295 * has been invalidated. Such items may sometimes be preferred, if the
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296 * alternative is recalculating the value stored in the cache, especially
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297 * if another concurrent request is already recalculating the same value.
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298 * The "valid" property of the returned object indicates whether the item is
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299 * valid or not. Defaults to FALSE.
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300 *
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301 * @return \Symfony\Component\HttpFoundation\Response|false
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302 * The cached response or FALSE on failure.
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303 */
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304 protected function get(Request $request, $allow_invalid = FALSE) {
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305 $cid = $this->getCacheId($request);
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306 if ($cache = $this->cache->get($cid, $allow_invalid)) {
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307 return $cache->data;
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308 }
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309 return FALSE;
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310 }
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311
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312 /**
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313 * Stores a response object in the page cache.
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314 *
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315 * @param \Symfony\Component\HttpFoundation\Request $request
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316 * A request object.
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317 * @param \Symfony\Component\HttpFoundation\Response $response
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318 * The response to store in the cache.
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319 * @param int $expire
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320 * One of the following values:
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321 * - CacheBackendInterface::CACHE_PERMANENT: Indicates that the item should
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322 * not be removed unless it is deleted explicitly.
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323 * - A Unix timestamp: Indicates that the item will be considered invalid
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324 * after this time, i.e. it will not be returned by get() unless
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325 * $allow_invalid has been set to TRUE. When the item has expired, it may
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326 * be permanently deleted by the garbage collector at any time.
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327 * @param array $tags
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328 * An array of tags to be stored with the cache item. These should normally
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329 * identify objects used to build the cache item, which should trigger
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330 * cache invalidation when updated. For example if a cached item represents
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331 * a node, both the node ID and the author's user ID might be passed in as
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332 * tags. For example array('node' => array(123), 'user' => array(92)).
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333 */
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334 protected function set(Request $request, Response $response, $expire, array $tags) {
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335 $cid = $this->getCacheId($request);
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336 $this->cache->set($cid, $response, $expire, $tags);
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337 }
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338
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339 /**
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340 * Gets the page cache ID for this request.
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341 *
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342 * @param \Symfony\Component\HttpFoundation\Request $request
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343 * A request object.
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344 *
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345 * @return string
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346 * The cache ID for this request.
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347 */
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348 protected function getCacheId(Request $request) {
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349 // Once a cache ID is determined for the request, reuse it for the duration
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350 // of the request. This ensures that when the cache is written, it is only
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351 // keyed on request data that was available when it was read. For example,
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352 // the request format might be NULL during cache lookup and then set during
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353 // routing, in which case we want to key on NULL during writing, since that
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354 // will be the value during lookups for subsequent requests.
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355 if (!isset($this->cid)) {
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356 $cid_parts = [
|
Chris@18
|
357 $request->getSchemeAndHttpHost() . $request->getRequestUri(),
|
Chris@18
|
358 $request->getRequestFormat(NULL),
|
Chris@18
|
359 ];
|
Chris@18
|
360 $this->cid = implode(':', $cid_parts);
|
Chris@18
|
361 }
|
Chris@18
|
362 return $this->cid;
|
Chris@0
|
363 }
|
Chris@0
|
364
|
Chris@0
|
365 }
|