Transaction::replace() - Code Metrics - matthiasmullie/scrapbook - Measure and Improve Code Quality continuously with Scrutinizer

Transaction::replace() A
last analyzed 2022-11-07 14:18 UTC

↳ Parent: Transaction

Complexity

Conditions	3
Paths	3

Size

Total Lines	18
Code Lines	7

Duplication

Lines	0
Ratio	0 %

Importance

Changes	1
Bugs	0	Features	0

Metric	Value
cc	3
eloc	7
nc	3
nop	3
dl	0
loc	18
rs	10
c	1
b	0
f	0

<?php

namespace MatthiasMullie\Scrapbook\Buffered\Utils;

use MatthiasMullie\Scrapbook\Adapters\Collections\MemoryStore as BufferCollection;
.
|-- OtherDir
|   |-- Bar.php
|   `-- Foo.php
`-- SomeDir
    `-- Foo.php
use MatthiasMullie\Scrapbook\KeyValueStore;

/**
 * This is a helper class for BufferedStore & TransactionalStore, which buffer
 * real cache requests in memory.
 *
 * This class accepts 2 caches: a KeyValueStore object (the real cache) and a
 * Buffer instance (to read data from as long as it hasn't been committed)
 *
 * Every write action will first store the data in the Buffer instance, and
 * then pas update along to $defer.
 * Once commit() is called, $defer will execute all these updates against the
 * real cache. All deferred writes that fail to apply will cause that cache key
 * to be deleted, to ensure cache consistency.
 * Until commit() is called, all data is read from the temporary Buffer instance.
 *
 * @author Matthias Mullie <[email protected]>
 * @copyright Copyright (c) 2014, Matthias Mullie. All rights reserved
 * @license LICENSE MIT
 */
class Transaction implements KeyValueStore
{
    /**
     * @var KeyValueStore
     */
    protected $cache;

    /**
     * @var Buffer
     */
    protected $local;

    /**
     * We'll return stub CAS tokens in order to reliably replay the CAS actions
     * to the real cache. This will hold a map of stub token => value, used to
     * verify when we do the actual CAS.
     *
     * @see cas()
     *
     * @var mixed[]
     */
    protected $tokens = array();

    /**
     * Deferred updates to be committed to real cache.
     *
     * @var Defer
     */
    protected $defer;

    /**
     * Suspend reads from real cache. This is used when a flush is issued but it
     * has not yet been committed. In that case, we don't want to fall back to
     * real cache values, because they're about to be flushed.
     *
     * @var bool
     */
    protected $suspend = false;

    /**
     * @var Transaction[]
     */
    protected $collections = array();

    /**
     * @param Buffer|BufferCollection $local
     */
    public function __construct(/* Buffer|BufferCollection */ $local, KeyValueStore $cache)
    {
        // can't do double typehint, so let's manually check the type
        if (!$local instanceof Buffer && !$local instanceof BufferCollection) {

            $error = 'Invalid class for $local: '.get_class($local);
            if (class_exists('\TypeError')) {
                throw new \TypeError($error);
            }
            trigger_error($error, E_USER_ERROR);
        }

        $this->cache = $cache;

        // (uncommitted) writes must never be evicted (even if that means
        // crashing because we run out of memory)
        $this->local = $local;
class Id
{
    public $id;

    public function __construct($id)
    {
        $this->id = $id;
    }

}

class Account
{
    /** @var  Id $id */
    public $id;
}

$account_id = false;

if (starsAreRight()) {
    $account_id = new Id(42);
}

$account = new Account();
if ($account instanceof Id)
{
    $account->id = $account_id;
}

        $this->defer = new Defer($this->cache);
    }

    /**
     * {@inheritdoc}
     */
    public function get($key, &$token = null)
    {
        $value = $this->local->get($key, $token);

        // short-circuit reading from real cache if we have an uncommitted flush
        if ($this->suspend && null === $token) {
            // flush hasn't been committed yet, don't read from real cache!
            return false;
        }

        if (false === $value) {
            if ($this->local->expired($key)) {
                /*
                 * Item used to exist in local cache, but is now expired. This
                 * is used when values are to be deleted: we don't want to reach
                 * out to real storage because that would respond with the not-
                 * yet-deleted value.
                 */

                return false;
            }

            // unknown in local cache = fetch from source cache
            $value = $this->cache->get($key, $token);
        }

        // no value = quit early, don't generate a useless token
        if (false === $value) {
            return false;
        }

        /*
         * $token will be unreliable to the deferred updates so generate
         * a custom one and keep the associated value around.
         * Read more details in PHPDoc for function cas().
         * uniqid is ok here. Doesn't really have to be unique across
         * servers, just has to be unique every time it's called in this
         * one particular request - which it is.
         */
        $token = uniqid();
        $this->tokens[$token] = serialize($value);

        return $value;
    }

    /**
     * {@inheritdoc}
     */
    public function getMulti(array $keys, array &$tokens = null)
    {
        // retrieve all that we can from local cache
        $values = $this->local->getMulti($keys);
        $tokens = array();

        // short-circuit reading from real cache if we have an uncommitted flush
        if (!$this->suspend) {
            // figure out which missing key we need to get from real cache
            $keys = array_diff($keys, array_keys($values));
            foreach ($keys as $i => $key) {
                // don't reach out to real cache for keys that are about to be gone
                if ($this->local->expired($key)) {
                    unset($keys[$i]);
                }
            }

            // fetch missing values from real cache
            if ($keys) {

                $missing = $this->cache->getMulti($keys);
                $values += $missing;
            }
        }

        // any tokens we get will be unreliable, so generate some replacements
        // (more elaborate explanation in get())
        foreach ($values as $key => $value) {
            $token = uniqid();
            $tokens[$key] = $token;
            $this->tokens[$token] = serialize($value);
        }

        return $values;
    }

    /**
     * {@inheritdoc}
     */
    public function set($key, $value, $expire = 0)
    {
        // store the value in memory, so that when we ask for it again later in
        // this same request, we get the value we just set
        $success = $this->local->set($key, $value, $expire);
        if (false === $success) {

            return false;
        }

        $this->defer->set($key, $value, $expire);

        return true;
    }

    /**
     * {@inheritdoc}
     */
    public function setMulti(array $items, $expire = 0)
    {
        // store the values in memory, so that when we ask for it again later in
        // this same request, we get the value we just set
        $success = $this->local->setMulti($items, $expire);

        // only attempt to store those that we've set successfully to local
        $successful = array_intersect_key($items, $success);
        if (!empty($successful)) {
            $this->defer->setMulti($successful, $expire);
        }

        return $success;
    }

    /**
     * {@inheritdoc}
     */
    public function delete($key)
    {
        // check the current value to see if it currently exists, so we can
        // properly return true/false as would be expected from KeyValueStore
        $value = $this->get($key);
        if (false === $value) {
            return false;
        }

        /*
         * To make sure that subsequent get() calls for this key don't return
         * a value (it's supposed to be deleted), we'll make it expired in our
         * temporary bag (as opposed to deleting it from out bag, in which case
         * we'd fall back to fetching it from real store, where the transaction
         * might not yet be committed)
         */
        $this->local->set($key, $value, -1);

        $this->defer->delete($key);

        return true;
    }

    /**
     * {@inheritdoc}
     */
    public function deleteMulti(array $keys)
    {
        // check the current values to see if they currently exists, so we can
        // properly return true/false as would be expected from KeyValueStore
        $items = $this->getMulti($keys);
        $success = array();
        foreach ($keys as $key) {
            $success[$key] = array_key_exists($key, $items);
        }

        // only attempt to store those that we've deleted successfully to local
        $values = array_intersect_key($success, array_flip($keys));
        if (empty($values)) {
            return array();
        }

        // mark all as expired in local cache (see comment in delete())
        $this->local->setMulti($values, -1);

        $this->defer->deleteMulti(array_keys($values));

        return $success;
    }

    /**
     * {@inheritdoc}
     */
    public function add($key, $value, $expire = 0)
    {
        // before adding, make sure the value doesn't yet exist (in real cache,
        // nor in memory)
        if (false !== $this->get($key)) {
            return false;
        }

        // store the value in memory, so that when we ask for it again later
        // in this same request, we get the value we just set
        $success = $this->local->set($key, $value, $expire);
        if (false === $success) {

            return false;
        }

        $this->defer->add($key, $value, $expire);

        return true;
    }

    /**
     * {@inheritdoc}
     */
    public function replace($key, $value, $expire = 0)
    {
        // before replacing, make sure the value actually exists (in real cache,
        // or already created in memory)
        if (false === $this->get($key)) {
            return false;
        }

        // store the value in memory, so that when we ask for it again later
        // in this same request, we get the value we just set
        $success = $this->local->set($key, $value, $expire);
        if (false === $success) {

            return false;
        }

        $this->defer->replace($key, $value, $expire);

        return true;
    }

    /**
     * Since our CAS is deferred, the CAS token we got from our original
     * get() will likely not be valid by the time we want to store it to
     * the real cache. Imagine this scenario:
     * * a value is fetched from (real) cache
     * * an new value key is CAS'ed (into temp cache - real CAS is deferred)
     * * this key's value is fetched again (this time from temp cache)
     * * and a new value is CAS'ed again (into temp cache...).
     *
     * In this scenario, when we finally want to replay the write actions
     * onto the real cache, the first 3 actions would likely work fine.
     * The last (second CAS) however would not, since it never got a real
     * updated $token from the real cache.
     *
     * To work around this problem, all get() calls will return a unique
     * CAS token and store the value-at-that-time associated with that
     * token. All we have to do when we want to write the data to real cache
     * is, right before was CAS for real, get the value & (real) cas token
     * from storage & compare that value to the one we had stored. If that
     * checks out, we can safely resume the CAS with the real token we just
     * received.
     *
     * {@inheritdoc}
     */
    public function cas($token, $key, $value, $expire = 0)
    {
        $originalValue = isset($this->tokens[$token]) ? $this->tokens[$token] : null;

        // value is no longer the same as what we used for token
        if (serialize($this->get($key)) !== $originalValue) {
            return false;
        }

        // "CAS" value to local cache/memory
        $success = $this->local->set($key, $value, $expire);
        if (false === $success) {

            return false;
        }

        // only schedule the CAS to be performed on real cache if it was OK on
        // local cache
        $this->defer->cas($originalValue, $key, $value, $expire);

        return true;
    }

    /**
     * {@inheritdoc}
     */
    public function increment($key, $offset = 1, $initial = 0, $expire = 0)
    {
        if ($offset <= 0 || $initial < 0) {
            return false;
        }

        // get existing value (from real cache or memory) so we know what to
        // increment in memory (where we may not have anything yet, so we should
        // adjust our initial value to what's already in real cache)
        $value = $this->get($key);
        if (false === $value) {
            $value = $initial - $offset;
        }

        if (!is_numeric($value) || !is_numeric($offset)) {
            return false;
        }

        // store the value in memory, so that when we ask for it again later
        // in this same request, we get the value we just set
        $value = max(0, $value + $offset);
        $success = $this->local->set($key, $value, $expire);
        if (false === $success) {

            return false;
        }

        $this->defer->increment($key, $offset, $initial, $expire);

        return $value;
    }

    /**
     * {@inheritdoc}
     */
    public function decrement($key, $offset = 1, $initial = 0, $expire = 0)
    {
        if ($offset <= 0 || $initial < 0) {
            return false;
        }

        // get existing value (from real cache or memory) so we know what to
        // increment in memory (where we may not have anything yet, so we should
        // adjust our initial value to what's already in real cache)
        $value = $this->get($key);
        if (false === $value) {
            $value = $initial + $offset;
        }

        if (!is_numeric($value) || !is_numeric($offset)) {
            return false;
        }

        // store the value in memory, so that when we ask for it again later
        // in this same request, we get the value we just set
        $value = max(0, $value - $offset);
        $success = $this->local->set($key, $value, $expire);
        if (false === $success) {

            return false;
        }

        $this->defer->decrement($key, $offset, $initial, $expire);

        return $value;
    }

    /**
     * {@inheritdoc}
     */
    public function touch($key, $expire)
    {
        // grab existing value (from real cache or memory) and re-save (to
        // memory) with updated expiration time
        $value = $this->get($key);
        if (false === $value) {
            return false;
        }

        $success = $this->local->set($key, $value, $expire);
        if (false === $success) {

            return false;
        }

        $this->defer->touch($key, $expire);

        return true;
    }

    /**
     * {@inheritdoc}
     */
    public function flush()
    {
        foreach ($this->collections as $collection) {
            $collection->flush();
        }

        $success = $this->local->flush();
        if (false === $success) {

            return false;
        }

        // clear all buffered writes, flush wipes them out anyway
        $this->clear();

        // make sure that reads, from now on until commit, don't read from cache
        $this->suspend = true;

        $this->defer->flush();

        return true;
    }

    /**
     * {@inheritdoc}
     */
    public function getCollection($name)
    {
        if (!isset($this->collections[$name])) {
            $this->collections[$name] = new static(
                $this->local->getCollection($name),
                $this->cache->getCollection($name)
            );
        }

        return $this->collections[$name];
    }

    /**
     * Commits all deferred updates to real cache.
     * that had already been written to will be deleted.
     *
     * @return bool
     */
    public function commit()
    {
        $this->clear();

        return $this->defer->commit();
    }

    /**
     * Roll back all scheduled changes.
     *
     * @return bool
     */
    public function rollback()
    {
        $this->clear();
        $this->defer->clear();

        return true;
    }

    /**
     * Clears all transaction-related data stored in memory.
     */
    protected function clear()
    {
        $this->tokens = array();
        $this->suspend = false;
    }
}


1			<?php
2
3			namespace MatthiasMullie\Scrapbook\Buffered\Utils;
4
5			use MatthiasMullie\Scrapbook\Adapters\Collections\MemoryStore as BufferCollection;
			0 ignored issues – show Bug introduced 2022-11-07 14:11 UTC by Report Bug Copy Issue Report This use statement conflicts with another class in this namespace, `MatthiasMullie\Scrapbook...\Utils\BufferCollection`. Consider defining an alias. Let?s assume that you have a directory layout like this: . \|-- OtherDir \| \|-- Bar.php \| `-- Foo.php `-- SomeDir `-- Foo.php and let?s assume the following content of `Bar.php`: // Bar.php namespace OtherDir; use SomeDir\Foo; // This now conflicts the class OtherDir\Foo If both files `OtherDir/Foo.php` and `SomeDir/Foo.php` are loaded in the same runtime, you will see a PHP error such as the following: PHP Fatal error: Cannot use SomeDir\Foo as Foo because the name is already in use in OtherDir/Foo.php However, as `OtherDir/Foo.php` does not necessarily have to be loaded and the error is only triggered if it is loaded before `OtherDir/Bar.php`, this problem might go unnoticed for a while. In order to prevent this error from surfacing, you must import the namespace with a different alias: // Bar.php namespace OtherDir; use SomeDir\Foo as SomeDirFoo; // There is no conflict anymore. Loading history...
6			use MatthiasMullie\Scrapbook\KeyValueStore;
7
8			/**
9			* This is a helper class for BufferedStore & TransactionalStore, which buffer
10			* real cache requests in memory.
11			*
12			* This class accepts 2 caches: a KeyValueStore object (the real cache) and a
13			* Buffer instance (to read data from as long as it hasn't been committed)
14			*
15			* Every write action will first store the data in the Buffer instance, and
16			* then pas update along to $defer.
17			* Once commit() is called, $defer will execute all these updates against the
18			* real cache. All deferred writes that fail to apply will cause that cache key
19			* to be deleted, to ensure cache consistency.
20			* Until commit() is called, all data is read from the temporary Buffer instance.
21			*
22			* @author Matthias Mullie <[email protected]>
23			* @copyright Copyright (c) 2014, Matthias Mullie. All rights reserved
24			* @license LICENSE MIT
25			*/
26			class Transaction implements KeyValueStore
27			{
28			/**
29			* @var KeyValueStore
30			*/
31			protected $cache;
32
33			/**
34			* @var Buffer
35			*/
36			protected $local;
37
38			/**
39			* We'll return stub CAS tokens in order to reliably replay the CAS actions
40			* to the real cache. This will hold a map of stub token => value, used to
41			* verify when we do the actual CAS.
42			*
43			* @see cas()
44			*
45			* @var mixed[]
46			*/
47			protected $tokens = array();
48
49			/**
50			* Deferred updates to be committed to real cache.
51			*
52			* @var Defer
53			*/
54			protected $defer;
55
56			/**
57			* Suspend reads from real cache. This is used when a flush is issued but it
58			* has not yet been committed. In that case, we don't want to fall back to
59			* real cache values, because they're about to be flushed.
60			*
61			* @var bool
62			*/
63			protected $suspend = false;
64
65			/**
66			* @var Transaction[]
67			*/
68			protected $collections = array();
69
70			/**
71			* @param Buffer\|BufferCollection $local
72			*/
73			public function __construct(/* Buffer\|BufferCollection */ $local, KeyValueStore $cache)
74			{
75			// can't do double typehint, so let's manually check the type
76			if (!$local instanceof Buffer && !$local instanceof BufferCollection) {
			0 ignored issues – show introduced 2022-11-07 14:11 UTC by Report Bug Copy Issue Report `$local` is always a sub-type of `MatthiasMullie\Scrapbook...Collections\MemoryStore`. Loading history...
77			$error = 'Invalid class for $local: '.get_class($local);
78			if (class_exists('\TypeError')) {
79			throw new \TypeError($error);
80			}
81			trigger_error($error, E_USER_ERROR);
82			}
83
84			$this->cache = $cache;
85
86			// (uncommitted) writes must never be evicted (even if that means
87			// crashing because we run out of memory)
88			$this->local = $local;
			0 ignored issues – show Documentation Bug introduced 2022-11-07 14:11 UTC by Report Bug Copy Issue Report It seems like `$local` can also be of type `MatthiasMullie\Scrapbook...Collections\MemoryStore`. However, the property `$local` is declared as type `MatthiasMullie\Scrapbook\Buffered\Utils\Buffer`. Maybe add an additional type check? Our type inference engine has found a suspicous assignment of a value to a property. This check raises an issue when a value that can be of a mixed type is assigned to a property that is type hinted more strictly. For example, imagine you have a variable `$accountId` that can either hold an Id object or false (if there is no account id yet). Your code now assigns that value to the `id` property of an instance of the `Account` class. This class holds a proper account, so the id value must no longer be false. Either this assignment is in error or a type check should be added for that assignment. class Id { public $id; public function __construct($id) { $this->id = $id; } } class Account { /** @var Id $id */ public $id; } $account_id = false; if (starsAreRight()) { $account_id = new Id(42); } $account = new Account(); if ($account instanceof Id) { $account->id = $account_id; } Loading history...
89
90			$this->defer = new Defer($this->cache);
91			}
92
93			/**
94			* {@inheritdoc}
95			*/
96			public function get($key, &$token = null)
97			{
98			$value = $this->local->get($key, $token);
99
100			// short-circuit reading from real cache if we have an uncommitted flush
101			if ($this->suspend && null === $token) {
102			// flush hasn't been committed yet, don't read from real cache!
103			return false;
104			}
105
106			if (false === $value) {
107			if ($this->local->expired($key)) {
108			/*
109			* Item used to exist in local cache, but is now expired. This
110			* is used when values are to be deleted: we don't want to reach
111			* out to real storage because that would respond with the not-
112			* yet-deleted value.
113			*/
114
115			return false;
116			}
117
118			// unknown in local cache = fetch from source cache
119			$value = $this->cache->get($key, $token);
120			}
121
122			// no value = quit early, don't generate a useless token
123			if (false === $value) {
124			return false;
125			}
126
127			/*
128			* $token will be unreliable to the deferred updates so generate
129			* a custom one and keep the associated value around.
130			* Read more details in PHPDoc for function cas().
131			* uniqid is ok here. Doesn't really have to be unique across
132			* servers, just has to be unique every time it's called in this
133			* one particular request - which it is.
134			*/
135			$token = uniqid();
136			$this->tokens[$token] = serialize($value);
137
138			return $value;
139			}
140
141			/**
142			* {@inheritdoc}
143			*/
144			public function getMulti(array $keys, array &$tokens = null)
145			{
146			// retrieve all that we can from local cache
147			$values = $this->local->getMulti($keys);
148			$tokens = array();
149
150			// short-circuit reading from real cache if we have an uncommitted flush
151			if (!$this->suspend) {
152			// figure out which missing key we need to get from real cache
153			$keys = array_diff($keys, array_keys($values));
154			foreach ($keys as $i => $key) {
155			// don't reach out to real cache for keys that are about to be gone
156			if ($this->local->expired($key)) {
157			unset($keys[$i]);
158			}
159			}
160
161			// fetch missing values from real cache
162			if ($keys) {
			0 ignored issues – show Bug Best Practice introduced 2022-11-07 14:11 UTC by Report Bug Copy Issue Report The expression `$keys` of type `array` is implicitly converted to a boolean; are you sure this is intended? If so, consider using `! empty($expr)` instead to make it clear that you intend to check for an array without elements. This check marks implicit conversions of arrays to boolean values in a comparison. While in PHP an empty array is considered to be equal (but not identical) to false, this is not always apparent. Consider making the comparison explicit by using `empty(..)` or `! empty(...)` instead. Loading history...
163			$missing = $this->cache->getMulti($keys);
164			$values += $missing;
165			}
166			}
167
168			// any tokens we get will be unreliable, so generate some replacements
169			// (more elaborate explanation in get())
170			foreach ($values as $key => $value) {
171			$token = uniqid();
172			$tokens[$key] = $token;
173			$this->tokens[$token] = serialize($value);
174			}
175
176			return $values;
177			}
178
179			/**
180			* {@inheritdoc}
181			*/
182			public function set($key, $value, $expire = 0)
183			{
184			// store the value in memory, so that when we ask for it again later in
185			// this same request, we get the value we just set
186			$success = $this->local->set($key, $value, $expire);
187			if (false === $success) {
			0 ignored issues – show introduced 2022-11-07 14:11 UTC by Report Bug Copy Issue Report The condition `false === $success` is always `false`. Loading history...
188			return false;
189			}
190
191			$this->defer->set($key, $value, $expire);
192
193			return true;
194			}
195
196			/**
197			* {@inheritdoc}
198			*/
199			public function setMulti(array $items, $expire = 0)
200			{
201			// store the values in memory, so that when we ask for it again later in
202			// this same request, we get the value we just set
203			$success = $this->local->setMulti($items, $expire);
204
205			// only attempt to store those that we've set successfully to local
206			$successful = array_intersect_key($items, $success);
207			if (!empty($successful)) {
208			$this->defer->setMulti($successful, $expire);
209			}
210
211			return $success;
212			}
213
214			/**
215			* {@inheritdoc}
216			*/
217			public function delete($key)
218			{
219			// check the current value to see if it currently exists, so we can
220			// properly return true/false as would be expected from KeyValueStore
221			$value = $this->get($key);
222			if (false === $value) {
223			return false;
224			}
225
226			/*
227			* To make sure that subsequent get() calls for this key don't return
228			* a value (it's supposed to be deleted), we'll make it expired in our
229			* temporary bag (as opposed to deleting it from out bag, in which case
230			* we'd fall back to fetching it from real store, where the transaction
231			* might not yet be committed)
232			*/
233			$this->local->set($key, $value, -1);
234
235			$this->defer->delete($key);
236
237			return true;
238			}
239
240			/**
241			* {@inheritdoc}
242			*/
243			public function deleteMulti(array $keys)
244			{
245			// check the current values to see if they currently exists, so we can
246			// properly return true/false as would be expected from KeyValueStore
247			$items = $this->getMulti($keys);
248			$success = array();
249			foreach ($keys as $key) {
250			$success[$key] = array_key_exists($key, $items);
251			}
252
253			// only attempt to store those that we've deleted successfully to local
254			$values = array_intersect_key($success, array_flip($keys));
255			if (empty($values)) {
256			return array();
257			}
258
259			// mark all as expired in local cache (see comment in delete())
260			$this->local->setMulti($values, -1);
261
262			$this->defer->deleteMulti(array_keys($values));
263
264			return $success;
265			}
266
267			/**
268			* {@inheritdoc}
269			*/
270			public function add($key, $value, $expire = 0)
271			{
272			// before adding, make sure the value doesn't yet exist (in real cache,
273			// nor in memory)
274			if (false !== $this->get($key)) {
275			return false;
276			}
277
278			// store the value in memory, so that when we ask for it again later
279			// in this same request, we get the value we just set
280			$success = $this->local->set($key, $value, $expire);
281			if (false === $success) {
			0 ignored issues – show introduced 2022-11-07 14:11 UTC by Report Bug Copy Issue Report The condition `false === $success` is always `false`. Loading history...
282			return false;
283			}
284
285			$this->defer->add($key, $value, $expire);
286
287			return true;
288			}
289
290			/**
291			* {@inheritdoc}
292			*/
293			public function replace($key, $value, $expire = 0)
294			{
295			// before replacing, make sure the value actually exists (in real cache,
296			// or already created in memory)
297			if (false === $this->get($key)) {
298			return false;
299			}
300
301			// store the value in memory, so that when we ask for it again later
302			// in this same request, we get the value we just set
303			$success = $this->local->set($key, $value, $expire);
304			if (false === $success) {
			0 ignored issues – show introduced 2022-11-07 14:11 UTC by Report Bug Copy Issue Report The condition `false === $success` is always `false`. Loading history...
305			return false;
306			}
307
308			$this->defer->replace($key, $value, $expire);
309
310			return true;
311			}
312
313			/**
314			* Since our CAS is deferred, the CAS token we got from our original
315			* get() will likely not be valid by the time we want to store it to
316			* the real cache. Imagine this scenario:
317			* * a value is fetched from (real) cache
318			* * an new value key is CAS'ed (into temp cache - real CAS is deferred)
319			* * this key's value is fetched again (this time from temp cache)
320			* * and a new value is CAS'ed again (into temp cache...).
321			*
322			* In this scenario, when we finally want to replay the write actions
323			* onto the real cache, the first 3 actions would likely work fine.
324			* The last (second CAS) however would not, since it never got a real
325			* updated $token from the real cache.
326			*
327			* To work around this problem, all get() calls will return a unique
328			* CAS token and store the value-at-that-time associated with that
329			* token. All we have to do when we want to write the data to real cache
330			* is, right before was CAS for real, get the value & (real) cas token
331			* from storage & compare that value to the one we had stored. If that
332			* checks out, we can safely resume the CAS with the real token we just
333			* received.
334			*
335			* {@inheritdoc}
336			*/
337			public function cas($token, $key, $value, $expire = 0)
338			{
339			$originalValue = isset($this->tokens[$token]) ? $this->tokens[$token] : null;
340
341			// value is no longer the same as what we used for token
342			if (serialize($this->get($key)) !== $originalValue) {
343			return false;
344			}
345
346			// "CAS" value to local cache/memory
347			$success = $this->local->set($key, $value, $expire);
348			if (false === $success) {
			0 ignored issues – show introduced 2022-11-07 14:11 UTC by Report Bug Copy Issue Report The condition `false === $success` is always `false`. Loading history...
349			return false;
350			}
351
352			// only schedule the CAS to be performed on real cache if it was OK on
353			// local cache
354			$this->defer->cas($originalValue, $key, $value, $expire);
355
356			return true;
357			}
358
359			/**
360			* {@inheritdoc}
361			*/
362			public function increment($key, $offset = 1, $initial = 0, $expire = 0)
363			{
364			if ($offset <= 0 \|\| $initial < 0) {
365			return false;
366			}
367
368			// get existing value (from real cache or memory) so we know what to
369			// increment in memory (where we may not have anything yet, so we should
370			// adjust our initial value to what's already in real cache)
371			$value = $this->get($key);
372			if (false === $value) {
373			$value = $initial - $offset;
374			}
375
376			if (!is_numeric($value) \|\| !is_numeric($offset)) {
377			return false;
378			}
379
380			// store the value in memory, so that when we ask for it again later
381			// in this same request, we get the value we just set
382			$value = max(0, $value + $offset);
383			$success = $this->local->set($key, $value, $expire);
384			if (false === $success) {
			0 ignored issues – show introduced 2022-11-07 14:11 UTC by Report Bug Copy Issue Report The condition `false === $success` is always `false`. Loading history...
385			return false;
386			}
387
388			$this->defer->increment($key, $offset, $initial, $expire);
389
390			return $value;
391			}
392
393			/**
394			* {@inheritdoc}
395			*/
396			public function decrement($key, $offset = 1, $initial = 0, $expire = 0)
397			{
398			if ($offset <= 0 \|\| $initial < 0) {
399			return false;
400			}
401
402			// get existing value (from real cache or memory) so we know what to
403			// increment in memory (where we may not have anything yet, so we should
404			// adjust our initial value to what's already in real cache)
405			$value = $this->get($key);
406			if (false === $value) {
407			$value = $initial + $offset;
408			}
409
410			if (!is_numeric($value) \|\| !is_numeric($offset)) {
411			return false;
412			}
413
414			// store the value in memory, so that when we ask for it again later
415			// in this same request, we get the value we just set
416			$value = max(0, $value - $offset);
417			$success = $this->local->set($key, $value, $expire);
418			if (false === $success) {
			0 ignored issues – show introduced 2022-11-07 14:11 UTC by Report Bug Copy Issue Report The condition `false === $success` is always `false`. Loading history...
419			return false;
420			}
421
422			$this->defer->decrement($key, $offset, $initial, $expire);
423
424			return $value;
425			}
426
427			/**
428			* {@inheritdoc}
429			*/
430			public function touch($key, $expire)
431			{
432			// grab existing value (from real cache or memory) and re-save (to
433			// memory) with updated expiration time
434			$value = $this->get($key);
435			if (false === $value) {
436			return false;
437			}
438
439			$success = $this->local->set($key, $value, $expire);
440			if (false === $success) {
			0 ignored issues – show introduced 2022-11-07 14:11 UTC by Report Bug Copy Issue Report The condition `false === $success` is always `false`. Loading history...
441			return false;
442			}
443
444			$this->defer->touch($key, $expire);
445
446			return true;
447			}
448
449			/**
450			* {@inheritdoc}
451			*/
452			public function flush()
453			{
454			foreach ($this->collections as $collection) {
455			$collection->flush();
456			}
457
458			$success = $this->local->flush();
459			if (false === $success) {
			0 ignored issues – show introduced 2022-11-07 14:11 UTC by Report Bug Copy Issue Report The condition `false === $success` is always `false`. Loading history...
460			return false;
461			}
462
463			// clear all buffered writes, flush wipes them out anyway
464			$this->clear();
465
466			// make sure that reads, from now on until commit, don't read from cache
467			$this->suspend = true;
468
469			$this->defer->flush();
470
471			return true;
472			}
473
474			/**
475			* {@inheritdoc}
476			*/
477			public function getCollection($name)
478			{
479			if (!isset($this->collections[$name])) {
480			$this->collections[$name] = new static(
481			$this->local->getCollection($name),
482			$this->cache->getCollection($name)
483			);
484			}
485
486			return $this->collections[$name];
487			}
488
489			/**
490			* Commits all deferred updates to real cache.
491			* that had already been written to will be deleted.
492			*
493			* @return bool
494			*/
495			public function commit()
496			{
497			$this->clear();
498
499			return $this->defer->commit();
500			}
501
502			/**
503			* Roll back all scheduled changes.
504			*
505			* @return bool
506			*/
507			public function rollback()
508			{
509			$this->clear();
510			$this->defer->clear();
511
512			return true;
513			}
514
515			/**
516			* Clears all transaction-related data stored in memory.
517			*/
518			protected function clear()
519			{
520			$this->tokens = array();
521			$this->suspend = false;
522			}
523			}
524

matthiasmullie / scrapbook

Transaction::replace() A last analyzed 2022-11-07 14:18 UTC

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Transaction::replace() A
last analyzed 2022-11-07 14:18 UTC