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 2016-08-01 10:47 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	7
CRAP Score	6.2017

Importance

Changes	2
Bugs	1	Features	1

Metric	Value
c	2
b	1
f	1
dl	0
loc	19
ccs	7
cts	11
cp	0.6364
rs	8.8571
cc	5
eloc	10
nc	5
nop	1
crap	6.2017

<?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. 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);
                $cacheItem
                    ->expiresAfter($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		*/
45	10	public function __construct(CacheItemPoolInterface $pool, StreamFactory $streamFactory, array $config = [])
46		{
47	10	$this->pool = $pool;
48	10	$this->streamFactory = $streamFactory;
49
50	10	$optionsResolver = new OptionsResolver();
51	10	$this->configureOptions($optionsResolver);
52	10	$this->config = $optionsResolver->resolve($config);
53	10	}
54
55		/**
56		* {@inheritdoc}
57		*/
58	8	public function handleRequest(RequestInterface $request, callable $next, callable $first)
59		{
60	8	$method = strtoupper($request->getMethod());
61		// if the request not is cachable, move to $next
62	8	if ($method !== 'GET' && $method !== 'HEAD') {
63	1	return $next($request);
64		}
65
66		// If we can cache the request
67	7	$key = $this->createCacheKey($request);
68	7	$cacheItem = $this->pool->getItem($key);
69
70	7	if ($cacheItem->isHit()) {
71	3	$data = $cacheItem->get();
72	3	if (isset($data['expiresAt']) && time() < $data['expiresAt']) {
73		// This item is still valid according to previous cache headers
74	1	return new FulfilledPromise($this->createResponseFromCacheItem($cacheItem));
75		}
76
77		// Add headers to ask the server if this cache is still valid
78	2	if ($mod = $this->getModifiedAt($cacheItem)) {
79	2	$mod = new \DateTime('@'.$mod);
80	2	$mod->setTimezone(new \DateTimeZone('GMT'));
81	2	$request = $request->withHeader('If-Modified-Since', sprintf('%s GMT', $mod->format('l, d-M-y H:i:s')));
82	2	}
83
84	2	if ($etag = $this->getETag($cacheItem)) {
85	2	$request = $request->withHeader('If-None-Match', $etag);
86	2	}
87	2	}
88
89	6	return $next($request)->then(function (ResponseInterface $response) use ($cacheItem) {
90	6	if (304 === $response->getStatusCode()) {
91	2	if (!$cacheItem->isHit()) {
92		/*
93		* We do not have the item in cache. This plugin did not add If-Modified-Since
94		* or If-None-Match headers. Return the response from server.
95		*/
96	1	return $response;
97		}
98
99		// The cached response we have is still valid
100	1	$data = $cacheItem->get();
101	1	$maxAge = $this->getMaxAge($response);
102	1	$data['expiresAt'] = time() + $maxAge;
103	1	$cacheItem->set($data)->expiresAfter($this->config['cache_lifetime'] + $maxAge);
104	1	$this->pool->save($cacheItem);
105
106	1	return $this->createResponseFromCacheItem($cacheItem);
107		}
108
109	4	if ($this->isCacheable($response)) {
110	3	$bodyStream = $response->getBody();
111	3	$body = $bodyStream->__toString();
112	3	if ($bodyStream->isSeekable()) {
113	3	$bodyStream->rewind();
114	3	} else {
115		$response = $response->withBody($this->streamFactory->createStream($body));
116		}
117
118	3	$maxAge = $this->getMaxAge($response);
119		$cacheItem
120	3	->expiresAfter($this->config['cache_lifetime'] + $maxAge)
121	3	->set([
122	3	'response' => $response,
123	3	'body' => $body,
124	3	'expiresAt' => time() + $maxAge,
125	3	'createdAt' => time(),
126	3	'etag' => $response->getHeader('ETag'),
127	3	]);
128	3	$this->pool->save($cacheItem);
129	3	}
130
131	4	return $response;
132	6	});
133		}
134
135		/**
136		* Verify that we can cache this response.
137		*
138		* @param ResponseInterface $response
139		*
140		* @return bool
141		*/
142	4	protected function isCacheable(ResponseInterface $response)
143		{
144	4	if (!in_array($response->getStatusCode(), [200, 203, 300, 301, 302, 404, 410])) {
145	1	return false;
146		}
147	3	if (!$this->config['respect_cache_headers']) {
148		return true;
149		}
150	3	if ($this->getCacheControlDirective($response, 'no-store') \|\| $this->getCacheControlDirective($response, 'private')) {
151		return false;
152		}
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		*/
165	4	private function getCacheControlDirective(ResponseInterface $response, $name)
166		{
167	4	$headers = $response->getHeader('Cache-Control');
168	4	foreach ($headers as $header) {
169	1	if (preg_match(sprintf('\|%s=?([0-9]+)?\|i', $name), $header, $matches)) {
170
171		// return the value for $name if it exists
172	1	if (isset($matches[1])) {
173	1	return $matches[1];
174		}
175
176		return true;
177		}
178	4	}
179
180	4	return false;
181		}
182
183		/**
184		* @param RequestInterface $request
185		*
186		* @return string
187		*/
188	7	private function createCacheKey(RequestInterface $request)
189		{
190	7	return md5($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		*
196		* @param ResponseInterface $response
197		*
198		* @return int\|null
199		*/
200	4	private function getMaxAge(ResponseInterface $response)
201		{
202	4	if (!$this->config['respect_cache_headers']) {
203		return $this->config['default_ttl'];
204		}
205
206		// check for max age in the Cache-Control header
207	4	$maxAge = $this->getCacheControlDirective($response, 'max-age');
208	4	if (!is_bool($maxAge)) {
209	1	$ageHeaders = $response->getHeader('Age');
210	1	foreach ($ageHeaders as $age) {
211	1	return $maxAge - ((int) $age);
212		}
213
214		return (int) $maxAge;
215		}
216
217		// check for ttl in the Expires header
218	3	$headers = $response->getHeader('Expires');
219	3	foreach ($headers as $header) {
220		return (new \DateTime($header))->getTimestamp() - (new \DateTime())->getTimestamp();
221	3	}
222
223	3	return $this->config['default_ttl'];
224		}
225
226		/**
227		* Configure an options resolver.
228		*
229		* @param OptionsResolver $resolver
230		*/
231	10	private function configureOptions(OptionsResolver $resolver)
232		{
233	10	$resolver->setDefaults([
234	10	'cache_lifetime' => 2592000, // 30 days
235	10	'default_ttl' => null,
236	10	'respect_cache_headers' => true,
237	10	]);
238
239	10	$resolver->setAllowedTypes('cache_lifetime', 'int');
240	10	$resolver->setAllowedTypes('default_ttl', ['int', 'null']);
241	10	$resolver->setAllowedTypes('respect_cache_headers', 'bool');
242	10	}
243
244		/**
245		* @param CacheItemInterface $cacheItem
246		*
247		* @return ResponseInterface
248		*/
249	2	private function createResponseFromCacheItem(CacheItemInterface $cacheItem)
250		{
251	2	$data = $cacheItem->get();
252
253		/** @var ResponseInterface $response */
254	2	$response = $data['response'];
255	2	$response = $response->withBody($this->streamFactory->createStream($data['body']));
256
257	2	return $response;
258		}
259
260		/**
261		* Get the timestamp when the cached response was stored.
262		*
263		* @param CacheItemInterface $cacheItem
264		*
265		* @return int\|null
266		*/
267	2	private function getModifiedAt(CacheItemInterface $cacheItem)
268		{
269	2	$data = $cacheItem->get();
270	2	if (!isset($data['createdAt'])) {
271		return;
272		}
273
274	2	return $data['createdAt'];
275		}
276
277		/**
278		* Get the ETag from the cached response.
279		*
280		* @param CacheItemInterface $cacheItem
281		*
282		* @return string\|null
283		*/
284	2	private function getETag(CacheItemInterface $cacheItem)
285		{
286	2	$data = $cacheItem->get();
287	2	if (!isset($data['etag'])) {
288		return;
289		}
290
291	2	if (is_array($data['etag'])) {
292	2	foreach ($data['etag'] as $etag) {
293	2	if (!empty($etag)) {
294	2	return $etag;
295		}
296		}
297
298		return;
299		}
300
301		return $data['etag'];
302		}
303		}
304

php-http / cache-plugin

Pull Request — master (#8)

CachePlugin::getETag() B

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