131 lines
2.8 KiB
PHP
131 lines
2.8 KiB
PHP
<?php
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namespace Illuminate\Redis\Limiters;
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use Illuminate\Contracts\Redis\LimiterTimeoutException;
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class ConcurrencyLimiter
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{
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/**
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* The Redis factory implementation.
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*
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* @var \Illuminate\Redis\Connections\Connection
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*/
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protected $redis;
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/**
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* The name of the limiter.
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*
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* @var string
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*/
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protected $name;
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/**
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* The allowed number of concurrent tasks.
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*
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* @var int
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*/
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protected $maxLocks;
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/**
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* The number of seconds a slot should be maintained.
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*
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* @var int
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*/
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protected $releaseAfter;
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/**
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* Create a new concurrency limiter instance.
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*
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* @param \Illuminate\Redis\Connections\Connection $redis
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* @param string $name
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* @param int $maxLocks
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* @param int $releaseAfter
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* @return void
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*/
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public function __construct($redis, $name, $maxLocks, $releaseAfter)
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{
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$this->name = $name;
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$this->redis = $redis;
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$this->maxLocks = $maxLocks;
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$this->releaseAfter = $releaseAfter;
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}
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/**
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* Attempt to acquire the lock for the given number of seconds.
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*
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* @param int $timeout
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* @param callable|null $callback
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* @return bool
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* @throws \Illuminate\Contracts\Redis\LimiterTimeoutException
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*/
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public function block($timeout, $callback = null)
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{
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$starting = time();
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while (! $slot = $this->acquire()) {
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if (time() - $timeout >= $starting) {
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throw new LimiterTimeoutException;
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}
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usleep(250 * 1000);
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}
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if (is_callable($callback)) {
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return tap($callback(), function () use ($slot) {
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$this->release($slot);
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});
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}
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return true;
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}
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/**
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* Attempt to acquire the lock.
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*
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* @return mixed
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*/
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protected function acquire()
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{
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$slots = array_map(function ($i) {
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return $this->name.$i;
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}, range(1, $this->maxLocks));
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return $this->redis->eval($this->luaScript(), count($slots),
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...array_merge($slots, [$this->name, $this->releaseAfter])
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);
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}
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/**
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* Get the Lua script for acquiring a lock.
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*
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* KEYS - The keys that represent available slots
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* ARGV[1] - The limiter name
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* ARGV[2] - The number of seconds the slot should be reserved
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*
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* @return string
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*/
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protected function luaScript()
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{
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return <<<'LUA'
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for index, value in pairs(redis.call('mget', unpack(KEYS))) do
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if not value then
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redis.call('set', ARGV[1]..index, "1", "EX", ARGV[2])
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return ARGV[1]..index
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end
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end
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LUA;
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}
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/**
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* Release the lock.
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*
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* @param string $key
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* @return void
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*/
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protected function release($key)
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{
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$this->redis->del($key);
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}
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}
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