CachePlugin::getModifiedSinceHeaderValue() - 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 2016-08-02 09:37 UTC

CachePlugin::getModifiedSinceHeaderValue() A

↳ Parent: CachePlugin

Complexity

Conditions	2
Paths	2

Size

Total Lines	12
Code Lines	7

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	0
CRAP Score	6

Importance

Changes	1
Bugs	0	Features	0

Metric	Value
c	1
b	0
f	0
dl	0
loc	12
ccs	0
cts	0
cp	0
rs	9.4285
cc	2
eloc	7
nc	2
nop	1
crap	6

<?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
     *     @var string $hash_algo The hashing algorithm to use when generating cache keys.
     * }
     */
    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 ($modifiedSinceValue = $this->getModifiedSinceHeaderValue($cacheItem)) {
                $request = $request->withHeader('If-Modified-Since', $modifiedSinceValue);
            }

            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. This plugin did not add If-Modified-Since
                     * or If-None-Match headers. Return the response from server.
                     */
                    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);
                $currentTime = time();
                $cacheItem
                    ->expiresAfter($this->config['cache_lifetime'] + $maxAge)
                    ->set([
                    'response' => $response,
                    'body' => $body,
                    'expiresAt' => $currentTime + $maxAge,
                    'createdAt' => $currentTime,
                    '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 $request)
    {
        return hash($this->config['hash_algo'], $request->getMethod().' '.$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' => 86400 * 30, // 30 days
            'default_ttl' => null,
            'respect_cache_headers' => true,
            'hash_algo' => 'sha1',
        ]);

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

    /**
     * @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 value of the "If-Modified-Since" header.
     *
     * @param CacheItemInterface $cacheItem
     *
     * @return string|null
     */
    private function getModifiedSinceHeaderValue(CacheItemInterface $cacheItem)
    {
        $data = $cacheItem->get();
        if (!isset($data['createdAt'])) {
            return;
        }

        $modified = new \DateTime('@'.$data['createdAt']);
        $modified->setTimezone(new \DateTimeZone('GMT'));

        return sprintf('%s GMT', $modified->format('l, d-M-y H:i:s'));
    }

    /**
     * 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		* @var string $hash_algo The hashing algorithm to use when generating cache keys.
44		* }
45	6	*/
46		public function __construct(CacheItemPoolInterface $pool, StreamFactory $streamFactory, array $config = [])
47	6	{
48	6	$this->pool = $pool;
49		$this->streamFactory = $streamFactory;
50	6
51	6	$optionsResolver = new OptionsResolver();
52	6	$this->configureOptions($optionsResolver);
53	6	$this->config = $optionsResolver->resolve($config);
54		}
55
56		/**
57		* {@inheritdoc}
58	4	*/
59		public function handleRequest(RequestInterface $request, callable $next, callable $first)
60	4	{
61		$method = strtoupper($request->getMethod());
62		// if the request not is cachable, move to $next
63	4	if ($method !== 'GET' && $method !== 'HEAD') {
64	1	return $next($request);
65		}
66
67		// If we can cache the request
68	3	$key = $this->createCacheKey($request);
69	3	$cacheItem = $this->pool->getItem($key);
70
71	3	if ($cacheItem->isHit()) {
72		$data = $cacheItem->get();
73		if (isset($data['expiresAt']) && time() < $data['expiresAt']) {
74		// This item is still valid according to previous cache headers
75		return new FulfilledPromise($this->createResponseFromCacheItem($cacheItem));
76		}
77
78		// Add headers to ask the server if this cache is still valid
79		if ($modifiedSinceValue = $this->getModifiedSinceHeaderValue($cacheItem)) {
80	3	$request = $request->withHeader('If-Modified-Since', $modifiedSinceValue);
81	3	}
82	2
83	2	if ($etag = $this->getETag($cacheItem)) {
84	2	$request = $request->withHeader('If-None-Match', $etag);
85	2	}
86	2	}
87
88		return $next($request)->then(function (ResponseInterface $response) use ($cacheItem) {
89		if (304 === $response->getStatusCode()) {
90	2	if (!$cacheItem->isHit()) {
91	2	/*
92	2	* We do not have the item in cache. This plugin did not add If-Modified-Since
93	2	* or If-None-Match headers. Return the response from server.
94		*/
95	3	return $response;
96	3	}
97
98		// The cached response we have is still valid
99		$data = $cacheItem->get();
100		$maxAge = $this->getMaxAge($response);
101		$data['expiresAt'] = time() + $maxAge;
102		$cacheItem->set($data)->expiresAfter($this->config['cache_lifetime'] + $maxAge);
103		$this->pool->save($cacheItem);
104
105		return $this->createResponseFromCacheItem($cacheItem);
106	3	}
107
108	3	if ($this->isCacheable($response)) {
109	1	$bodyStream = $response->getBody();
110		$body = $bodyStream->__toString();
111	2	if ($bodyStream->isSeekable()) {
112		$bodyStream->rewind();
113		} else {
114	2	$response = $response->withBody($this->streamFactory->createStream($body));
115		}
116
117		$maxAge = $this->getMaxAge($response);
118	2	$currentTime = time();
119		$cacheItem
120		->expiresAfter($this->config['cache_lifetime'] + $maxAge)
121		->set([
122		'response' => $response,
123		'body' => $body,
124		'expiresAt' => $currentTime + $maxAge,
125		'createdAt' => $currentTime,
126		'etag' => $response->getHeader('ETag'),
127		]);
128		$this->pool->save($cacheItem);
129	2	}
130
131	2	return $response;
132	2	});
133	1	}
134
135		/**
136	1	* Verify that we can cache this response.
137	1	*
138		* @param ResponseInterface $response
139		*
140		* @return bool
141		*/
142	2	protected function isCacheable(ResponseInterface $response)
143		{
144	2	if (!in_array($response->getStatusCode(), [200, 203, 300, 301, 302, 404, 410])) {
145		return false;
146		}
147		if (!$this->config['respect_cache_headers']) {
148		return true;
149		}
150		if ($this->getCacheControlDirective($response, 'no-store') \|\| $this->getCacheControlDirective($response, 'private')) {
151		return false;
152	3	}
153
154	3	return true;
155		}
156
157		/**
158		* Get the value of a parameter in the cache control header.
159		*
160		* @param ResponseInterface $response
161		* @param string $name The field of Cache-Control to fetch
162		*
163		* @return bool\|string The value of the directive, true if directive without value, false if directive not present
164	2	*/
165		private function getCacheControlDirective(ResponseInterface $response, $name)
166	2	{
167		$headers = $response->getHeader('Cache-Control');
168		foreach ($headers as $header) {
169		if (preg_match(sprintf('\|%s=?([0-9]+)?\|i', $name), $header, $matches)) {
170
171	2	// return the value for $name if it exists
172	2	if (isset($matches[1])) {
173	1	return $matches[1];
174	1	}
175	1
176		return true;
177		}
178		}
179
180		return false;
181		}
182	1
183	1	/**
184		* @param RequestInterface $request
185	1	*
186		* @return string
187	1	*/
188		private function createCacheKey(RequestInterface $request)
189		{
190		return hash($this->config['hash_algo'], $request->getMethod().' '.$request->getUri());
191		}
192
193		/**
194		* Get a ttl in seconds. It could return null if we do not respect cache headers and got no defaultTtl.
195	6	*
196		* @param ResponseInterface $response
197	6	*
198	6	* @return int\|null
199	6	*/
200	6	private function getMaxAge(ResponseInterface $response)
201	6	{
202		if (!$this->config['respect_cache_headers']) {
203	6	return $this->config['default_ttl'];
204	6	}
205	6
206	6	// check for max age in the Cache-Control header
207		$maxAge = $this->getCacheControlDirective($response, 'max-age');
208		if (!is_bool($maxAge)) {
209		$ageHeaders = $response->getHeader('Age');
210		foreach ($ageHeaders as $age) {
211		return $maxAge - ((int) $age);
212		}
213
214		return (int) $maxAge;
215		}
216
217		// check for ttl in the Expires header
218		$headers = $response->getHeader('Expires');
219		foreach ($headers as $header) {
220		return (new \DateTime($header))->getTimestamp() - (new \DateTime())->getTimestamp();
221		}
222
223		return $this->config['default_ttl'];
224		}
225
226		/**
227		* Configure an options resolver.
228		*
229		* @param OptionsResolver $resolver
230		*/
231		private function configureOptions(OptionsResolver $resolver)
232		{
233		$resolver->setDefaults([
234		'cache_lifetime' => 86400 * 30, // 30 days
235		'default_ttl' => null,
236		'respect_cache_headers' => true,
237		'hash_algo' => 'sha1',
238		]);
239
240		$resolver->setAllowedTypes('cache_lifetime', 'int');
241		$resolver->setAllowedTypes('default_ttl', ['int', 'null']);
242		$resolver->setAllowedTypes('respect_cache_headers', 'bool');
243		$resolver->setAllowedValues('hash_algo', hash_algos());
244		}
245
246		/**
247		* @param CacheItemInterface $cacheItem
248		*
249		* @return ResponseInterface
250		*/
251		private function createResponseFromCacheItem(CacheItemInterface $cacheItem)
252		{
253		$data = $cacheItem->get();
254
255		/** @var ResponseInterface $response */
256		$response = $data['response'];
257		$response = $response->withBody($this->streamFactory->createStream($data['body']));
258
259		return $response;
260		}
261
262		/**
263		* Get the value of the "If-Modified-Since" header.
264		*
265		* @param CacheItemInterface $cacheItem
266		*
267		* @return string\|null
268		*/
269		private function getModifiedSinceHeaderValue(CacheItemInterface $cacheItem)
270		{
271		$data = $cacheItem->get();
272		if (!isset($data['createdAt'])) {
273		return;
274		}
275
276		$modified = new \DateTime('@'.$data['createdAt']);
277		$modified->setTimezone(new \DateTimeZone('GMT'));
278
279		return sprintf('%s GMT', $modified->format('l, d-M-y H:i:s'));
280		}
281
282		/**
283		* Get the ETag from the cached response.
284		*
285		* @param CacheItemInterface $cacheItem
286		*
287		* @return string\|null
288		*/
289		private function getETag(CacheItemInterface $cacheItem)
290		{
291		$data = $cacheItem->get();
292		if (!isset($data['etag'])) {
293		return;
294		}
295
296		if (is_array($data['etag'])) {
297		foreach ($data['etag'] as $etag) {
298		if (!empty($etag)) {
299		return $etag;
300		}
301		}
302
303		return;
304		}
305
306		return $data['etag'];
307		}
308		}
309

php-http / cache-plugin

Pull Request — master (#8)

CachePlugin::getModifiedSinceHeaderValue() A

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