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php实现令牌桶

2026-01-30 08:32:25PHP

令牌桶算法简介

令牌桶算法是一种常用的流量控制算法，通过固定速率生成令牌，请求需要获取令牌才能被处理。当令牌耗尽时，请求会被限制或拒绝。

php实现令牌桶

PHP实现令牌桶

使用Redis存储令牌状态

Redis适合存储和操作令牌桶的状态，利用其原子性操作保证并发安全。

class TokenBucket {
    private $redis;
    private $key;
    private $capacity;
    private $rate;

    public function __construct($redis, $key, $capacity, $rate) {
        $this->redis = $redis;
        $this->key = $key;
        $this->capacity = $capacity;
        $this->rate = $rate; // 令牌生成速率（个/秒）
    }

    public function tryAcquire($tokens = 1) {
        $now = microtime(true);
        $script = <<<LUA
local key = KEYS[1]
local now = tonumber(ARGV[1])
local rate = tonumber(ARGV[2])
local capacity = tonumber(ARGV[3])
local tokensRequested = tonumber(ARGV[4])

local lastTime = tonumber(redis.call("hget", key, "lastTime")) or now
local tokensAvailable = tonumber(redis.call("hget", key, "tokens")) or capacity

local elapsed = now - lastTime
local newTokens = elapsed * rate
if newTokens > 0 then
    tokensAvailable = math.min(capacity, tokensAvailable + newTokens)
    lastTime = now
end

if tokensAvailable >= tokensRequested then
    tokensAvailable = tokensAvailable - tokensRequested
    redis.call("hmset", key, "lastTime", lastTime, "tokens", tokensAvailable)
    return 1
else
    return 0
end
LUA;

        return $this->redis->eval($script, [$this->key, $now, $this->rate, $this->capacity, $tokens], 1);
    }
}

使用示例

$redis = new Redis();
$redis->connect('127.0.0.1', 6379);

$bucket = new TokenBucket($redis, 'api_rate_limit', 100, 10); // 容量100，每秒生成10个令牌

if ($bucket->tryAcquire()) {
    echo "请求通过";
} else {
    echo "请求被限流";
}

纯PHP实现（无Redis）

适合单机环境，使用文件或共享内存存储状态。

class FileTokenBucket {
    private $file;
    private $capacity;
    private $rate;

    public function __construct($file, $capacity, $rate) {
        $this->file = $file;
        $this->capacity = $capacity;
        $this->rate = $rate;
    }

    public function tryAcquire($tokens = 1) {
        $fp = fopen($this->file, 'c+');
        if (!flock($fp, LOCK_EX)) {
            fclose($fp);
            return false;
        }

        $data = @json_decode(fread($fp, filesize($this->file) ?: 1024), true) ?: [
            'tokens' => $this->capacity,
            'lastTime' => microtime(true)
        ];

        $now = microtime(true);
        $elapsed = $now - $data['lastTime'];
        $newTokens = $elapsed * $this->rate;
        $data['tokens'] = min($this->capacity, $data['tokens'] + $newTokens);
        $data['lastTime'] = $now;

        if ($data['tokens'] >= $tokens) {
            $data['tokens'] -= $tokens;
            ftruncate($fp, 0);
            fseek($fp, 0);
            fwrite($fp, json_encode($data));
            flock($fp, LOCK_UN);
            fclose($fp);
            return true;
        }

        flock($fp, LOCK_UN);
        fclose($fp);
        return false;
    }
}