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<?php
namespace React\Cache;
use React\Promise;
use React\Promise\PromiseInterface;
class ArrayCache implements CacheInterface
{
private $limit;
private $data = array();
private $expires = array();
private $supportsHighResolution;
/**
* The `ArrayCache` provides an in-memory implementation of the [`CacheInterface`](#cacheinterface).
*
* ```php
* $cache = new ArrayCache();
*
* $cache->set('foo', 'bar');
* ```
*
* Its constructor accepts an optional `?int $limit` parameter to limit the
* maximum number of entries to store in the LRU cache. If you add more
* entries to this instance, it will automatically take care of removing
* the one that was least recently used (LRU).
*
* For example, this snippet will overwrite the first value and only store
* the last two entries:
*
* ```php
* $cache = new ArrayCache(2);
*
* $cache->set('foo', '1');
* $cache->set('bar', '2');
* $cache->set('baz', '3');
* ```
*
* This cache implementation is known to rely on wall-clock time to schedule
* future cache expiration times when using any version before PHP 7.3,
* because a monotonic time source is only available as of PHP 7.3 (`hrtime()`).
* While this does not affect many common use cases, this is an important
* distinction for programs that rely on a high time precision or on systems
* that are subject to discontinuous time adjustments (time jumps).
* This means that if you store a cache item with a TTL of 30s on PHP < 7.3
* and then adjust your system time forward by 20s, the cache item may
* expire in 10s. See also [`set()`](#set) for more details.
*
* @param int|null $limit maximum number of entries to store in the LRU cache
*/
public function __construct($limit = null)
{
$this->limit = $limit;
// prefer high-resolution timer, available as of PHP 7.3+
$this->supportsHighResolution = \function_exists('hrtime');
}
public function get($key, $default = null)
{
// delete key if it is already expired => below will detect this as a cache miss
if (isset($this->expires[$key]) && $this->now() - $this->expires[$key] > 0) {
unset($this->data[$key], $this->expires[$key]);
}
if (!\array_key_exists($key, $this->data)) {
return Promise\resolve($default);
}
// remove and append to end of array to keep track of LRU info
$value = $this->data[$key];
unset($this->data[$key]);
$this->data[$key] = $value;
return Promise\resolve($value);
}
public function set($key, $value, $ttl = null)
{
// unset before setting to ensure this entry will be added to end of array (LRU info)
unset($this->data[$key]);
$this->data[$key] = $value;
// sort expiration times if TTL is given (first will expire first)
unset($this->expires[$key]);
if ($ttl !== null) {
$this->expires[$key] = $this->now() + $ttl;
\asort($this->expires);
}
// ensure size limit is not exceeded or remove first entry from array
if ($this->limit !== null && \count($this->data) > $this->limit) {
// first try to check if there's any expired entry
// expiration times are sorted, so we can simply look at the first one
\reset($this->expires);
$key = \key($this->expires);
// check to see if the first in the list of expiring keys is already expired
// if the first key is not expired, we have to overwrite by using LRU info
if ($key === null || $this->now() - $this->expires[$key] < 0) {
\reset($this->data);
$key = \key($this->data);
}
unset($this->data[$key], $this->expires[$key]);
}
return Promise\resolve(true);
}
public function delete($key)
{
unset($this->data[$key], $this->expires[$key]);
return Promise\resolve(true);
}
public function getMultiple(array $keys, $default = null)
{
$values = array();
foreach ($keys as $key) {
$values[$key] = $this->get($key, $default);
}
return Promise\all($values);
}
public function setMultiple(array $values, $ttl = null)
{
foreach ($values as $key => $value) {
$this->set($key, $value, $ttl);
}
return Promise\resolve(true);
}
public function deleteMultiple(array $keys)
{
foreach ($keys as $key) {
unset($this->data[$key], $this->expires[$key]);
}
return Promise\resolve(true);
}
public function clear()
{
$this->data = array();
$this->expires = array();
return Promise\resolve(true);
}
public function has($key)
{
// delete key if it is already expired
if (isset($this->expires[$key]) && $this->now() - $this->expires[$key] > 0) {
unset($this->data[$key], $this->expires[$key]);
}
if (!\array_key_exists($key, $this->data)) {
return Promise\resolve(false);
}
// remove and append to end of array to keep track of LRU info
$value = $this->data[$key];
unset($this->data[$key]);
$this->data[$key] = $value;
return Promise\resolve(true);
}
/**
* @return float
*/
private function now()
{
return $this->supportsHighResolution ? \hrtime(true) * 1e-9 : \microtime(true);
}
}
|
