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php实现令牌桶

2026-03-13 05:20:14PHP

php实现令牌桶

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，请求需获取令牌才能执行，未获取令牌的请求会被限制或排队。适用于API限流、接口防刷等场景。

PHP实现令牌桶

基本实现思路

维护一个容器存储令牌（可用Redis或内存变量）
设定令牌生成速率和桶容量
每次请求时检查可用令牌数量
有足够令牌则扣除并允许请求，否则拒绝

基于Redis的实现

<?php
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("hmset", key, "time", lastTime, "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_limit', 10, 1); // 容量10，速率1个/秒

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

纯PHP实现（无Redis）

<?php
class MemoryTokenBucket {
    private $tokens;
    private $capacity;
    private $rate;
    private $lastTime;

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

    public function consume($tokens = 1) {
        $now = microtime(true);
        $elapsed = $now - $this->lastTime;
        $this->lastTime = $now;

        $this->tokens = min(
            $this->capacity,
            $this->tokens + $elapsed * $this->rate
        );

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

        return false;
    }
}

// 使用示例
$bucket = new MemoryTokenBucket(10, 1); // 容量10，速率1个/秒
if ($bucket->consume()) {
    echo "请求通过";
} else {
    echo "请求被限流";
}
?>