CachePlugin::getETag() - Code Metrics - Inspection of "Optionally enable caching of any request method (#..." - php-http/cache-plugin - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Push — master ( 9ea171...c8dfcc )

by David

created 2017-02-20 07:42 UTC

CachePlugin::getETag() B

↳ Parent: CachePlugin

Complexity

Conditions	5
Paths	5

Size

Total Lines	18
Code Lines	9

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	7
CRAP Score	6.2017

Importance

Changes

Metric	Value
dl	0
loc	18
ccs	7
cts	11
cp	0.6364
rs	8.8571
c	0
b	0
f	0
cc	5
eloc	9
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 (seconds) 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
     *     @var int $cache_lifetime (seconds) To support serving a previous stale response when the server answers 304
     *              we have to store the cache for a longer time than the server originally says it is valid for.
     *              We store a cache item for $cache_lifetime + max age of the response.
     *     @var array $methods list of request methods which can be cached.
     * }
     */
    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 $next
        if (!in_array($method, $this->config['methods'])) {
            return $next($request);
        }

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

        if ($cacheItem->isHit()) {
            $data = $cacheItem->get();
            // The array_key_exists() is to be removed in 2.0.
            if (array_key_exists('expiresAt', $data) && ($data['expiresAt'] === null || 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'] = $this->calculateResponseExpiresAt($maxAge);
                $cacheItem->set($data)->expiresAfter($this->calculateCacheItemExpiresAfter($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->calculateCacheItemExpiresAfter($maxAge))
                    ->set([
                        'response' => $response,
                        'body' => $body,
                        'expiresAt' => $this->calculateResponseExpiresAt($maxAge),
                        'createdAt' => time(),
                        'etag' => $response->getHeader('ETag'),
                    ]);
                $this->pool->save($cacheItem);
            }

            return $response;
        });
    }

    /**
     * Calculate the timestamp when this cache item should be dropped from the cache. The lowest value that can be
     * returned is $maxAge.
     *
     * @param int|null $maxAge
     *
     * @return int|null Unix system time passed to the PSR-6 cache
     */
    private function calculateCacheItemExpiresAfter($maxAge)
    {
        if ($this->config['cache_lifetime'] === null && $maxAge === null) {
            return;
        }

        return $this->config['cache_lifetime'] + $maxAge;
    }

    /**
     * Calculate the timestamp when a response expires. After that timestamp, we need to send a
     * If-Modified-Since / If-None-Match request to validate the response.
     *
     * @param int|null $maxAge
     *
     * @return int|null Unix system time. A null value means that the response expires when the cache item expires
     */
    private function calculateResponseExpiresAt($maxAge)
    {
        if ($maxAge === null) {
            return;
        }

        return time() + $maxAge;
    }

    /**
     * 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)
    {
        $body = (string) $request->getBody();
        if (!empty($body)) {
            $body = ' '.$body;
        }

        return hash($this->config['hash_algo'], $request->getMethod().' '.$request->getUri().$body);
    }

    /**
     * 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' => 0,
            'respect_cache_headers' => true,
            'hash_algo' => 'sha1',
            'methods' => ['GET', 'HEAD'],
        ]);

        $resolver->setAllowedTypes('cache_lifetime', ['int', 'null']);
        $resolver->setAllowedTypes('default_ttl', ['int', 'null']);
        $resolver->setAllowedTypes('respect_cache_headers', 'bool');
        $resolver->setAllowedTypes('methods', 'array');
        $resolver->setAllowedValues('hash_algo', hash_algos());
        $resolver->setAllowedValues('methods', function ($value) {
            /* RFC7230 sections 3.1.1 and 3.2.6 except limited to uppercase characters. */
            $matches = preg_grep('/[^A-Z0-9!#$%&\'*\/+\-.^_`|~]/', $value);

            return empty($matches);
        });
    }

    /**
     * @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 = $cacheItem->get();
        // The isset() is to be removed in 2.0.
        if (!isset($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 = $cacheItem->get();
        // The isset() is to be removed in 2.0.
        if (!isset($data['etag'])) {
            return;
        }

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

        foreach ($data['etag'] as $etag) {
            if (!empty($etag)) {
                return $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 (seconds) If we do not respect cache headers or can't calculate a good ttl, use this
43		* value
44		* @var string $hash_algo The hashing algorithm to use when generating cache keys
45		* @var int $cache_lifetime (seconds) To support serving a previous stale response when the server answers 304
46		* we have to store the cache for a longer time than the server originally says it is valid for.
47		* We store a cache item for $cache_lifetime + max age of the response.
48		* @var array $methods list of request methods which can be cached.
49		* }
50		*/
51	12	public function __construct(CacheItemPoolInterface $pool, StreamFactory $streamFactory, array $config = [])
52		{
53	12	$this->pool = $pool;
54	12	$this->streamFactory = $streamFactory;
55
56	12	$optionsResolver = new OptionsResolver();
57	12	$this->configureOptions($optionsResolver);
58	12	$this->config = $optionsResolver->resolve($config);
59	11	}
60
61		/**
62		* {@inheritdoc}
63		*/
64	9	public function handleRequest(RequestInterface $request, callable $next, callable $first)
65		{
66	9	$method = strtoupper($request->getMethod());
67		// if the request not is cachable, move to $next
68	9	if (!in_array($method, $this->config['methods'])) {
69	1	return $next($request);
70		}
71
72		// If we can cache the request
73	8	$key = $this->createCacheKey($request);
74	8	$cacheItem = $this->pool->getItem($key);
75
76	8	if ($cacheItem->isHit()) {
77	3	$data = $cacheItem->get();
78		// The array_key_exists() is to be removed in 2.0.
79	3	if (array_key_exists('expiresAt', $data) && ($data['expiresAt'] === null \|\| time() < $data['expiresAt'])) {
80		// This item is still valid according to previous cache headers
81	1	return new FulfilledPromise($this->createResponseFromCacheItem($cacheItem));
82		}
83
84		// Add headers to ask the server if this cache is still valid
85	2	if ($modifiedSinceValue = $this->getModifiedSinceHeaderValue($cacheItem)) {
86	2	$request = $request->withHeader('If-Modified-Since', $modifiedSinceValue);
87	2	}
88
89	2	if ($etag = $this->getETag($cacheItem)) {
90	2	$request = $request->withHeader('If-None-Match', $etag);
91	2	}
92	2	}
93
94		return $next($request)->then(function (ResponseInterface $response) use ($cacheItem) {
95	7	if (304 === $response->getStatusCode()) {
96	2	if (!$cacheItem->isHit()) {
97		/*
98		* We do not have the item in cache. This plugin did not add If-Modified-Since
99		* or If-None-Match headers. Return the response from server.
100		*/
101	1	return $response;
102		}
103
104		// The cached response we have is still valid
105	1	$data = $cacheItem->get();
106	1	$maxAge = $this->getMaxAge($response);
107	1	$data['expiresAt'] = $this->calculateResponseExpiresAt($maxAge);
108	1	$cacheItem->set($data)->expiresAfter($this->calculateCacheItemExpiresAfter($maxAge));
109	1	$this->pool->save($cacheItem);
110
111	1	return $this->createResponseFromCacheItem($cacheItem);
112		}
113
114	5	if ($this->isCacheable($response)) {
115	4	$bodyStream = $response->getBody();
116	4	$body = $bodyStream->__toString();
117	4	if ($bodyStream->isSeekable()) {
118	4	$bodyStream->rewind();
119	4	} else {
120		$response = $response->withBody($this->streamFactory->createStream($body));
121		}
122
123	4	$maxAge = $this->getMaxAge($response);
124		$cacheItem
125	4	->expiresAfter($this->calculateCacheItemExpiresAfter($maxAge))
126	4	->set([
127	4	'response' => $response,
128	4	'body' => $body,
129	4	'expiresAt' => $this->calculateResponseExpiresAt($maxAge),
130	4	'createdAt' => time(),
131	4	'etag' => $response->getHeader('ETag'),
132	4	]);
133	4	$this->pool->save($cacheItem);
134	4	}
135
136	5	return $response;
137	7	});
138		}
139
140		/**
141		* Calculate the timestamp when this cache item should be dropped from the cache. The lowest value that can be
142		* returned is $maxAge.
143		*
144		* @param int\|null $maxAge
145		*
146		* @return int\|null Unix system time passed to the PSR-6 cache
147		*/
148	5	private function calculateCacheItemExpiresAfter($maxAge)
149		{
150	5	if ($this->config['cache_lifetime'] === null && $maxAge === null) {
151		return;
152		}
153
154	5	return $this->config['cache_lifetime'] + $maxAge;
155		}
156
157		/**
158		* Calculate the timestamp when a response expires. After that timestamp, we need to send a
159		* If-Modified-Since / If-None-Match request to validate the response.
160		*
161		* @param int\|null $maxAge
162		*
163		* @return int\|null Unix system time. A null value means that the response expires when the cache item expires
164		*/
165	5	private function calculateResponseExpiresAt($maxAge)
166		{
167	5	if ($maxAge === null) {
168		return;
169		}
170
171	5	return time() + $maxAge;
172		}
173
174		/**
175		* Verify that we can cache this response.
176		*
177		* @param ResponseInterface $response
178		*
179		* @return bool
180		*/
181	5	protected function isCacheable(ResponseInterface $response)
182		{
183	5	if (!in_array($response->getStatusCode(), [200, 203, 300, 301, 302, 404, 410])) {
184	1	return false;
185		}
186	4	if (!$this->config['respect_cache_headers']) {
187		return true;
188		}
189	4	if ($this->getCacheControlDirective($response, 'no-store') \|\| $this->getCacheControlDirective($response, 'private')) {
190		return false;
191		}
192
193	4	return true;
194		}
195
196		/**
197		* Get the value of a parameter in the cache control header.
198		*
199		* @param ResponseInterface $response
200		* @param string $name The field of Cache-Control to fetch
201		*
202		* @return bool\|string The value of the directive, true if directive without value, false if directive not present
203		*/
204	5	private function getCacheControlDirective(ResponseInterface $response, $name)
205		{
206	5	$headers = $response->getHeader('Cache-Control');
207	5	foreach ($headers as $header) {
208	1	if (preg_match(sprintf('\|%s=?([0-9]+)?\|i', $name), $header, $matches)) {
209		// return the value for $name if it exists
210	1	if (isset($matches[1])) {
211	1	return $matches[1];
212		}
213
214		return true;
215		}
216	5	}
217
218	5	return false;
219		}
220
221		/**
222		* @param RequestInterface $request
223		*
224		* @return string
225		*/
226	8	private function createCacheKey(RequestInterface $request)
227		{
228	8	$body = (string) $request->getBody();
229	8	if (!empty($body)) {
230	1	$body = ' '.$body;
231	1	}
232
233	8	return hash($this->config['hash_algo'], $request->getMethod().' '.$request->getUri().$body);
234		}
235
236		/**
237		* Get a ttl in seconds. It could return null if we do not respect cache headers and got no defaultTtl.
238		*
239		* @param ResponseInterface $response
240		*
241		* @return int\|null
242		*/
243	5	private function getMaxAge(ResponseInterface $response)
244		{
245	5	if (!$this->config['respect_cache_headers']) {
246		return $this->config['default_ttl'];
247		}
248
249		// check for max age in the Cache-Control header
250	5	$maxAge = $this->getCacheControlDirective($response, 'max-age');
251	5	if (!is_bool($maxAge)) {
252	1	$ageHeaders = $response->getHeader('Age');
253	1	foreach ($ageHeaders as $age) {
254	1	return $maxAge - ((int) $age);
255		}
256
257		return (int) $maxAge;
258		}
259
260		// check for ttl in the Expires header
261	4	$headers = $response->getHeader('Expires');
262	4	foreach ($headers as $header) {
263		return (new \DateTime($header))->getTimestamp() - (new \DateTime())->getTimestamp();
264	4	}
265
266	4	return $this->config['default_ttl'];
267		}
268
269		/**
270		* Configure an options resolver.
271		*
272		* @param OptionsResolver $resolver
273		*/
274	12	private function configureOptions(OptionsResolver $resolver)
275		{
276	12	$resolver->setDefaults([
277	12	'cache_lifetime' => 86400 * 30, // 30 days
278	12	'default_ttl' => 0,
279	12	'respect_cache_headers' => true,
280	12	'hash_algo' => 'sha1',
281	12	'methods' => ['GET', 'HEAD'],
282	12	]);
283
284	12	$resolver->setAllowedTypes('cache_lifetime', ['int', 'null']);
285	12	$resolver->setAllowedTypes('default_ttl', ['int', 'null']);
286	12	$resolver->setAllowedTypes('respect_cache_headers', 'bool');
287	12	$resolver->setAllowedTypes('methods', 'array');
288	12	$resolver->setAllowedValues('hash_algo', hash_algos());
289	12	$resolver->setAllowedValues('methods', function ($value) {
290		/* RFC7230 sections 3.1.1 and 3.2.6 except limited to uppercase characters. */
291	12	$matches = preg_grep('/[^A-Z0-9!#$%&\'*\/+\-.^_`\|~]/', $value);
292
293	12	return empty($matches);
294	12	});
295	12	}
296
297		/**
298		* @param CacheItemInterface $cacheItem
299		*
300		* @return ResponseInterface
301		*/
302	2	private function createResponseFromCacheItem(CacheItemInterface $cacheItem)
303		{
304	2	$data = $cacheItem->get();
305
306		/** @var ResponseInterface $response */
307	2	$response = $data['response'];
308	2	$response = $response->withBody($this->streamFactory->createStream($data['body']));
309
310	2	return $response;
311		}
312
313		/**
314		* Get the value of the "If-Modified-Since" header.
315		*
316		* @param CacheItemInterface $cacheItem
317		*
318		* @return string\|null
319		*/
320	2	private function getModifiedSinceHeaderValue(CacheItemInterface $cacheItem)
321		{
322	2	$data = $cacheItem->get();
323		// The isset() is to be removed in 2.0.
324	2	if (!isset($data['createdAt'])) {
325		return;
326		}
327
328	2	$modified = new \DateTime('@'.$data['createdAt']);
329	2	$modified->setTimezone(new \DateTimeZone('GMT'));
330
331	2	return sprintf('%s GMT', $modified->format('l, d-M-y H:i:s'));
332		}
333
334		/**
335		* Get the ETag from the cached response.
336		*
337		* @param CacheItemInterface $cacheItem
338		*
339		* @return string\|null
340		*/
341	2	private function getETag(CacheItemInterface $cacheItem)
342		{
343	2	$data = $cacheItem->get();
344		// The isset() is to be removed in 2.0.
345	2	if (!isset($data['etag'])) {
346		return;
347		}
348
349	2	if (!is_array($data['etag'])) {
350		return $data['etag'];
351		}
352
353	2	foreach ($data['etag'] as $etag) {
354	2	if (!empty($etag)) {
355	2	return $etag;
356		}
357		}
358		}
359		}
360

php-http / cache-plugin

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