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php实现令牌桶

2026-02-15 06:20:14PHP

令牌桶算法简介

令牌桶算法是一种常用于流量控制和速率限制的算法。它维护一个固定容量的桶，按照固定速率向桶中添加令牌。请求需要获取令牌才能执行，若桶中没有足够令牌，请求会被限制。

PHP实现令牌桶

基于Redis的实现

使用Redis可以方便地实现分布式令牌桶，确保多服务器环境下的一致性。

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/秒
    }

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

            local lastTime = redis.call("hget", key, "time")
            local currentTokens = redis.call("hget", key, "tokens")

            if not lastTime then
                lastTime = now
                currentTokens = capacity
            else
                local elapsed = now - lastTime
                local newTokens = elapsed * rate
                currentTokens = math.min(capacity, currentTokens + newTokens)
                lastTime = now
            end

            if currentTokens >= tokens then
                currentTokens = currentTokens - tokens
                redis.call("hset", key, "time", lastTime)
                redis.call("hset", key, "tokens", currentTokens)
                return 1
            else
                return 0
            end
        ';

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

// 使用示例
$redis = new Redis();
$redis->connect('127.0.0.1', 6379);
$bucket = new TokenBucket($redis, 'api_rate_limit', 10, 1); // 容量10，每秒1个令牌

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

纯PHP实现

如果不依赖Redis，可以使用纯PHP实现单机版令牌桶。

class LocalTokenBucket {
    private $capacity;
    private $tokens;
    private $rate;
    private $lastTime;

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

    public function consume($tokens = 1) {
        $now = microtime(true);
        $elapsed = $now - $this->lastTime;
        $this->tokens = min($this->capacity, $this->tokens + $elapsed * $this->rate);
        $this->lastTime = $now;

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

// 使用示例
$bucket = new LocalTokenBucket(10, 1); // 容量10，每秒1个令牌
if ($bucket->consume()) {
    echo "请求通过";
} else {
    echo "请求被限制";
}