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php实现令牌桶

2026-02-16 01:44:50PHP

令牌桶算法简介

令牌桶算法是一种常用的流量控制算法，用于限制请求速率。核心思想是系统以固定速率向桶中添加令牌，请求处理需要消耗令牌，桶空时拒绝请求。

PHP实现令牌桶类

class TokenBucket {
    private $capacity;      // 桶容量
    private $tokens;        // 当前令牌数
    private $lastTime;      // 上次更新时间
    private $rate;          // 令牌生成速率(个/秒)

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

    private function addTokens() {
        $now = time();
        $elapsed = $now - $this->lastTime;
        $newTokens = $elapsed * $this->rate;

        $this->tokens = min($this->capacity, $this->tokens + $newTokens);
        $this->lastTime = $now;
    }

    public function consume($tokens = 1) {
        $this->addTokens();

        if ($this->tokens >= $tokens) {
            $this->tokens -= $tokens;
            return true;
        }
        return false;
    }
}

使用示例

// 创建容量为10，速率1个/秒的令牌桶
$bucket = new TokenBucket(10, 1);

// 模拟请求处理
for ($i = 0; $i < 15; $i++) {
    if ($bucket->consume()) {
        echo "处理请求 $i\n";
    } else {
        echo "拒绝请求 $i (限流)\n";
    }
    sleep(1); // 模拟请求间隔
}

Redis实现分布式令牌桶

对于分布式系统，可使用Redis实现：

class RedisTokenBucket {
    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;
    }

    public function consume($tokens = 1) {
        $script = '
            local key = KEYS[1]
            local capacity = tonumber(ARGV[1])
            local rate = tonumber(ARGV[2])
            local tokens = tonumber(ARGV[3])
            local now = tonumber(ARGV[4])

            local last = redis.call("hget", key, "last")
            local current = redis.call("hget", key, "tokens") or capacity

            if last then
                local elapsed = now - last
                current = math.min(capacity, current + elapsed * rate)
            end

            if current >= tokens then
                current = current - tokens
                redis.call("hmset", key, "tokens", current, "last", now)
                return 1
            end
            return 0
        ';

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