CachePlugin::getETag() - Code Metrics - Inspection of "Added support for Last-Modified and ETag" - php-http/cache-plugin - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Pull Request — master (#8)

by Tobias

created 2016-07-31 14:34 UTC

CachePlugin::getETag() B

↳ Parent: CachePlugin

Complexity

Conditions	5
Paths	5

Size

Total Lines	19
Code Lines	10

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	0
CRAP Score	30

Importance

Changes	2
Bugs	1	Features	1

Metric	Value
c	2
b	1
f	1
dl	0
loc	19
ccs	0
cts	0
cp	0
rs	8.8571
cc	5
eloc	10
nc	5
nop	1
crap	30

<?php

namespace Http\Client\Common\Plugin;

use Http\Client\Common\Plugin;
use Http\Message\StreamFactory;
use Http\Promise\FulfilledPromise;
use Psr\Cache\CacheItemInterface;
use Psr\Cache\CacheItemPoolInterface;
use Psr\Http\Message\RequestInterface;
use Psr\Http\Message\ResponseInterface;
use Symfony\Component\OptionsResolver\OptionsResolver;

/**
 * Allow for caching a response.
 *
 * @author Tobias Nyholm <[email protected]>
 */
final class CachePlugin implements Plugin
{
    /**
     * @var CacheItemPoolInterface
     */
    private $pool;

    /**
     * @var StreamFactory
     */
    private $streamFactory;

    /**
     * @var array
     */
    private $config;

    /**
     * @param CacheItemPoolInterface $pool
     * @param StreamFactory          $streamFactory
     * @param array                  $config        {
     *
     *     @var bool $respect_cache_headers Whether to look at the cache directives or ignore them
     *     @var int $default_ttl If we do not respect cache headers or can't calculate a good ttl, use this value.
     * }
     */
    public function __construct(CacheItemPoolInterface $pool, StreamFactory $streamFactory, array $config = [])
    {
        $this->pool = $pool;
        $this->streamFactory = $streamFactory;

        $optionsResolver = new OptionsResolver();
        $this->configureOptions($optionsResolver);
        $this->config = $optionsResolver->resolve($config);
    }

    /**
     * {@inheritdoc}
     */
    public function handleRequest(RequestInterface $request, callable $next, callable $first)
    {
        $method = strtoupper($request->getMethod());
        // if the request not is cachable, move to $next
        if ($method !== 'GET' && $method !== 'HEAD') {
            return $next($request);
        }

        // If we can cache the request
        $key = $this->createCacheKey($request);
        $cacheItem = $this->pool->getItem($key);

        if ($cacheItem->isHit()) {
            $data = $cacheItem->get();
            if (isset($data['expiresAt']) && time() > $data['expiresAt']) {
                // This item is still valid according to previous cache headers
                return new FulfilledPromise($this->createResponseFromCacheItem($cacheItem));
            }

            // Add headers to ask the server if this cache is still valid
            if ($mod = $this->getModifiedAt($cacheItem)) {
                $mod = new \DateTime('@'.$mod);
                $mod->setTimezone(new \DateTimeZone('GMT'));
                $request = $request->withHeader('If-Modified-Since', sprintf('%s GMT', $mod->format('l, d-M-y H:i:s')));
            }

            if ($etag = $this->getETag($cacheItem)) {
                $request = $request->withHeader('If-None-Match', $etag);
            }
        }

        return $next($request)->then(function (ResponseInterface $response) use ($cacheItem) {
            if (304 === $response->getStatusCode()) {
                if (!$cacheItem->isHit()) {
                    // We do not have the item in cache. We can return the cached response.
                    return $response;
                }

                // The cached response we have is still valid
                $data = $cacheItem->get();
                $maxAge = $this->getMaxAge($response);
                $data['expiresAt'] = time() + $maxAge;
                $cacheItem->set($data)->expiresAfter($this->config['cache_lifetime'] + $maxAge);
                $this->pool->save($cacheItem);

                return $this->createResponseFromCacheItem($cacheItem);
            }

            if ($this->isCacheable($response)) {
                $bodyStream = $response->getBody();
                $body = $bodyStream->__toString();
                if ($bodyStream->isSeekable()) {
                    $bodyStream->rewind();
                } else {
                    $response = $response->withBody($this->streamFactory->createStream($body));
                }

                $maxAge = $this->getMaxAge($response);
                $cacheItem
                    ->expiresAfter($this->config['cache_lifetime'] + $maxAge)
                    ->set([
                    'response' => $response,
                    'body' => $body,
                    'expiresAt' => time() + $maxAge,
                    'createdAt' => time(),
                    'etag' => $response->getHeader('ETag'),
                ]);
                $this->pool->save($cacheItem);
            }

            return $response;
        });
    }

    /**
     * Verify that we can cache this response.
     *
     * @param ResponseInterface $response
     *
     * @return bool
     */
    protected function isCacheable(ResponseInterface $response)
    {
        if (!in_array($response->getStatusCode(), [200, 203, 300, 301, 302, 404, 410])) {
            return false;
        }
        if (!$this->config['respect_cache_headers']) {
            return true;
        }
        if ($this->getCacheControlDirective($response, 'no-store') || $this->getCacheControlDirective($response, 'private')) {
            return false;
        }

        return true;
    }

    /**
     * Get the value of a parameter in the cache control header.
     *
     * @param ResponseInterface $response
     * @param string            $name     The field of Cache-Control to fetch
     *
     * @return bool|string The value of the directive, true if directive without value, false if directive not present
     */
    private function getCacheControlDirective(ResponseInterface $response, $name)
    {
        $headers = $response->getHeader('Cache-Control');
        foreach ($headers as $header) {
            if (preg_match(sprintf('|%s=?([0-9]+)?|i', $name), $header, $matches)) {

                // return the value for $name if it exists
                if (isset($matches[1])) {
                    return $matches[1];
                }

                return true;
            }
        }

        return false;
    }

    /**
     * @param RequestInterface $request
     *
     * @return string
     */
    private function createCacheKey(RequestInterface $request)
    {
        return md5($request->getMethod().' '.$request->getUri());
    }

    /**
     * Get a ttl in seconds. It could return null if we do not respect cache headers and got no defaultTtl.
     *
     * @param ResponseInterface $response
     *
     * @return int|null
     */
    private function getMaxAge(ResponseInterface $response)
    {
        if (!$this->config['respect_cache_headers']) {
            return $this->config['default_ttl'];
        }

        // check for max age in the Cache-Control header
        $maxAge = $this->getCacheControlDirective($response, 'max-age');
        if (!is_bool($maxAge)) {
            $ageHeaders = $response->getHeader('Age');
            foreach ($ageHeaders as $age) {
                return $maxAge - ((int) $age);
            }

            return (int) $maxAge;
        }

        // check for ttl in the Expires header
        $headers = $response->getHeader('Expires');
        foreach ($headers as $header) {
            return (new \DateTime($header))->getTimestamp() - (new \DateTime())->getTimestamp();
        }

        return $this->config['default_ttl'];
    }

    /**
     * Configure an options resolver.
     *
     * @param OptionsResolver $resolver
     */
    private function configureOptions(OptionsResolver $resolver)
    {
        $resolver->setDefaults([
            'cache_lifetime' => 2592000, // 30 days
            'default_ttl' => null,
            'respect_cache_headers' => true,
        ]);

        $resolver->setAllowedTypes('cache_lifetime', 'int');
        $resolver->setAllowedTypes('default_ttl', ['int', 'null']);
        $resolver->setAllowedTypes('respect_cache_headers', 'bool');
    }

    /**
     * @param CacheItemInterface $cacheItem
     *
     * @return ResponseInterface
     */
    private function createResponseFromCacheItem(CacheItemInterface $cacheItem)
    {
        $data = $cacheItem->get();

        /** @var ResponseInterface $response */
        $response = $data['response'];
        $response = $response->withBody($this->streamFactory->createStream($data['body']));

        return $response;
    }

    /**
     * Get the timestamp when the cached response was stored.
     *
     * @param CacheItemInterface $cacheItem
     *
     * @return int|null
     */
    private function getModifiedAt(CacheItemInterface $cacheItem)
    {
        $data = $cacheItem->get();
        if (!isset($data['createdAt'])) {
            return;
        }

        return $data['createdAt'];
    }

    /**
     * Get the ETag from the cached response.
     *
     * @param CacheItemInterface $cacheItem
     *
     * @return string|null
     */
    private function getETag(CacheItemInterface $cacheItem)
    {
        $data = $cacheItem->get();
        if (!isset($data['etag'])) {
            return;
        }

        if (is_array($data['etag'])) {
            foreach ($data['etag'] as $etag) {
                if (!empty($etag)) {
                    return $etag;
                }
            }

            return;
        }

        return $data['etag'];
    }
}


1		<?php
2
3		namespace Http\Client\Common\Plugin;
4
5		use Http\Client\Common\Plugin;
6		use Http\Message\StreamFactory;
7		use Http\Promise\FulfilledPromise;
8		use Psr\Cache\CacheItemInterface;
9		use Psr\Cache\CacheItemPoolInterface;
10		use Psr\Http\Message\RequestInterface;
11		use Psr\Http\Message\ResponseInterface;
12		use Symfony\Component\OptionsResolver\OptionsResolver;
13
14		/**
15		* Allow for caching a response.
16		*
17		* @author Tobias Nyholm <[email protected]>
18		*/
19		final class CachePlugin implements Plugin
20		{
21		/**
22		* @var CacheItemPoolInterface
23		*/
24		private $pool;
25
26		/**
27		* @var StreamFactory
28		*/
29		private $streamFactory;
30
31		/**
32		* @var array
33		*/
34		private $config;
35
36		/**
37		* @param CacheItemPoolInterface $pool
38		* @param StreamFactory $streamFactory
39		* @param array $config {
40		*
41		* @var bool $respect_cache_headers Whether to look at the cache directives or ignore them
42		* @var int $default_ttl If we do not respect cache headers or can't calculate a good ttl, use this value.
43		* }
44	6	*/
45		public function __construct(CacheItemPoolInterface $pool, StreamFactory $streamFactory, array $config = [])
46	6	{
47	6	$this->pool = $pool;
48		$this->streamFactory = $streamFactory;
49	6
50	6	$optionsResolver = new OptionsResolver();
51	6	$this->configureOptions($optionsResolver);
52	6	$this->config = $optionsResolver->resolve($config);
53		}
54
55		/**
56		* {@inheritdoc}
57	4	*/
58		public function handleRequest(RequestInterface $request, callable $next, callable $first)
59	4	{
60		$method = strtoupper($request->getMethod());
61		// if the request not is cachable, move to $next
62	4	if ($method !== 'GET' && $method !== 'HEAD') {
63	1	return $next($request);
64		}
65
66		// If we can cache the request
67	3	$key = $this->createCacheKey($request);
68	3	$cacheItem = $this->pool->getItem($key);
69
70	3	if ($cacheItem->isHit()) {
71		$data = $cacheItem->get();
72		if (isset($data['expiresAt']) && time() > $data['expiresAt']) {
73		// This item is still valid according to previous cache headers
74		return new FulfilledPromise($this->createResponseFromCacheItem($cacheItem));
75		}
76
77		// Add headers to ask the server if this cache is still valid
78		if ($mod = $this->getModifiedAt($cacheItem)) {
79	3	$mod = new \DateTime('@'.$mod);
80	3	$mod->setTimezone(new \DateTimeZone('GMT'));
81	2	$request = $request->withHeader('If-Modified-Since', sprintf('%s GMT', $mod->format('l, d-M-y H:i:s')));
82	2	}
83	2
84	2	if ($etag = $this->getETag($cacheItem)) {
85	2	$request = $request->withHeader('If-None-Match', $etag);
86		}
87		}
88
89	2	return $next($request)->then(function (ResponseInterface $response) use ($cacheItem) {
90	2	if (304 === $response->getStatusCode()) {
91	2	if (!$cacheItem->isHit()) {
92	2	// We do not have the item in cache. We can return the cached response.
93		return $response;
94	3	}
95	3
96		// The cached response we have is still valid
97		$data = $cacheItem->get();
98		$maxAge = $this->getMaxAge($response);
99		$data['expiresAt'] = time() + $maxAge;
100		$cacheItem->set($data)->expiresAfter($this->config['cache_lifetime'] + $maxAge);
101		$this->pool->save($cacheItem);
102
103		return $this->createResponseFromCacheItem($cacheItem);
104		}
105	3
106		if ($this->isCacheable($response)) {
107	3	$bodyStream = $response->getBody();
108	1	$body = $bodyStream->__toString();
109		if ($bodyStream->isSeekable()) {
110	2	$bodyStream->rewind();
111		} else {
112		$response = $response->withBody($this->streamFactory->createStream($body));
113	2	}
114
115		$maxAge = $this->getMaxAge($response);
116		$cacheItem
117	2	->expiresAfter($this->config['cache_lifetime'] + $maxAge)
118		->set([
119		'response' => $response,
120		'body' => $body,
121		'expiresAt' => time() + $maxAge,
122		'createdAt' => time(),
123		'etag' => $response->getHeader('ETag'),
124		]);
125		$this->pool->save($cacheItem);
126		}
127
128	2	return $response;
129		});
130	2	}
131	2
132	1	/**
133		* Verify that we can cache this response.
134		*
135	1	* @param ResponseInterface $response
136	1	*
137		* @return bool
138		*/
139		protected function isCacheable(ResponseInterface $response)
140		{
141	2	if (!in_array($response->getStatusCode(), [200, 203, 300, 301, 302, 404, 410])) {
142		return false;
143	2	}
144		if (!$this->config['respect_cache_headers']) {
145		return true;
146		}
147		if ($this->getCacheControlDirective($response, 'no-store') \|\| $this->getCacheControlDirective($response, 'private')) {
148		return false;
149		}
150
151	3	return true;
152		}
153	3
154		/**
155		* Get the value of a parameter in the cache control header.
156		*
157		* @param ResponseInterface $response
158		* @param string $name The field of Cache-Control to fetch
159		*
160		* @return bool\|string The value of the directive, true if directive without value, false if directive not present
161		*/
162		private function getCacheControlDirective(ResponseInterface $response, $name)
163	2	{
164		$headers = $response->getHeader('Cache-Control');
165	2	foreach ($headers as $header) {
166		if (preg_match(sprintf('\|%s=?([0-9]+)?\|i', $name), $header, $matches)) {
167
168		// return the value for $name if it exists
169		if (isset($matches[1])) {
170	2	return $matches[1];
171	2	}
172	1
173	1	return true;
174	1	}
175		}
176
177		return false;
178		}
179
180		/**
181	1	* @param RequestInterface $request
182	1	*
183		* @return string
184	1	*/
185		private function createCacheKey(RequestInterface $request)
186	1	{
187		return md5($request->getMethod().' '.$request->getUri());
188		}
189
190		/**
191		* Get a ttl in seconds. It could return null if we do not respect cache headers and got no defaultTtl.
192		*
193		* @param ResponseInterface $response
194	6	*
195		* @return int\|null
196	6	*/
197	6	private function getMaxAge(ResponseInterface $response)
198	6	{
199	6	if (!$this->config['respect_cache_headers']) {
200		return $this->config['default_ttl'];
201	6	}
202	6
203	6	// check for max age in the Cache-Control header
204		$maxAge = $this->getCacheControlDirective($response, 'max-age');
205		if (!is_bool($maxAge)) {
206		$ageHeaders = $response->getHeader('Age');
207		foreach ($ageHeaders as $age) {
208		return $maxAge - ((int) $age);
209		}
210
211		return (int) $maxAge;
212		}
213
214		// check for ttl in the Expires header
215		$headers = $response->getHeader('Expires');
216		foreach ($headers as $header) {
217		return (new \DateTime($header))->getTimestamp() - (new \DateTime())->getTimestamp();
218		}
219
220		return $this->config['default_ttl'];
221		}
222
223		/**
224		* Configure an options resolver.
225		*
226		* @param OptionsResolver $resolver
227		*/
228		private function configureOptions(OptionsResolver $resolver)
229		{
230		$resolver->setDefaults([
231		'cache_lifetime' => 2592000, // 30 days
232		'default_ttl' => null,
233		'respect_cache_headers' => true,
234		]);
235
236		$resolver->setAllowedTypes('cache_lifetime', 'int');
237		$resolver->setAllowedTypes('default_ttl', ['int', 'null']);
238		$resolver->setAllowedTypes('respect_cache_headers', 'bool');
239		}
240
241		/**
242		* @param CacheItemInterface $cacheItem
243		*
244		* @return ResponseInterface
245		*/
246		private function createResponseFromCacheItem(CacheItemInterface $cacheItem)
247		{
248		$data = $cacheItem->get();
249
250		/** @var ResponseInterface $response */
251		$response = $data['response'];
252		$response = $response->withBody($this->streamFactory->createStream($data['body']));
253
254		return $response;
255		}
256
257		/**
258		* Get the timestamp when the cached response was stored.
259		*
260		* @param CacheItemInterface $cacheItem
261		*
262		* @return int\|null
263		*/
264		private function getModifiedAt(CacheItemInterface $cacheItem)
265		{
266		$data = $cacheItem->get();
267		if (!isset($data['createdAt'])) {
268		return;
269		}
270
271		return $data['createdAt'];
272		}
273
274		/**
275		* Get the ETag from the cached response.
276		*
277		* @param CacheItemInterface $cacheItem
278		*
279		* @return string\|null
280		*/
281		private function getETag(CacheItemInterface $cacheItem)
282		{
283		$data = $cacheItem->get();
284		if (!isset($data['etag'])) {
285		return;
286		}
287
288		if (is_array($data['etag'])) {
289		foreach ($data['etag'] as $etag) {
290		if (!empty($etag)) {
291		return $etag;
292		}
293		}
294
295		return;
296		}
297
298		return $data['etag'];
299		}
300		}
301

php-http / cache-plugin

Pull Request — master (#8)

CachePlugin::getETag() B

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