README

• 参考: https://github.com/jhurliman/node-rate-limiter

为Web和node.js提供通用速率限制器。适用于API客户端、网络爬虫或其他需要节流的任务。暴露了两个类，RateLimiter和TokenBucket。TokenBucket提供了一种低级接口来进行速率限制，具有可配置的突发速率和滴答速率。RateLimiter位于TokenBucket之上，并添加了对每个间隔期间可以移除的最大令牌数的限制，以符合常见的API限制，如“每小时最多150个请求”。

安装

composer require wpjscc/reactphp-limiter

使用方法

一个简单的示例，每小时允许150个请求

use Wpjscc\React\Limiter\RateLimiter;
use function React\Async\async;
use function React\Async\await;

// Allow 150 requests per hour (the Twitter search limit). Also understands
// 'second', 'minute', 'day', or a number of milliseconds
$limiter = new RateLimiter(150, "hour");

async (function sendRequest() {
  // This call will throw if we request more than the maximum number of requests
  // that were set in the constructor
  // remainingRequests tells us how many additional requests could be sent
  // right this moment
    $remainingRequests = await($limiter->removeTokens(1));
    callMyRequestSendingFunction(...);
})();

另一个示例，每250毫秒允许发送一条消息

use Wpjscc\React\Limiter\RateLimiter;
use function React\Async\async;
use function React\Async\await;

$limiter = new RateLimiter(1, 250);

async(function sendMessage() {
    $remainingMessages = await($limiter->removeTokens(1));
    callMyMessageSendingFunction(...);
})();

默认行为是在解析承诺之前等待当前生效的速率限制的时间长度，但如果您传入"fireImmediately": true，承诺将立即解析，并将remainingRequests设置为-1

use Wpjscc\React\Limiter\RateLimiter;
use function React\Async\async;
use function React\Async\await;

$limiter = new RateLimiter(
    150,
    "hour",
    true
);

async(function requestHandler(request, response) {
  // Immediately send 429 header to client when rate limiting is in effect
  $remainingRequests = await($limiter->removeTokens(1));
  if ($remainingRequests < 0) {
    $response.writeHead(429, {'Content-Type': 'text/plain;charset=UTF-8'});
    $response.end('429 Too Many Requests - your IP is being rate limited');
  } else {
    callMyMessageSendingFunction(...);
  }
})();

RateLimiter和TokenBucket都提供了一个同步方法tryRemoveTokens()。这将立即返回一个布尔值，指示令牌移除是否成功。

use Wpjscc\React\Limiter\RateLimiter;
use function React\Async\async;
use function React\Async\await;

$limiter = new RateLimiter(10,"second");

if ($limiter->tryRemoveTokens(5))
  echo('Tokens removed');
else
  echo('No tokens removed');

要获取removeTokens承诺之外的剩余令牌数，只需使用getTokensRemaining方法。

use Wpjscc\React\Limiter\RateLimiter;
use function React\Async\async;
use function React\Async\await;

$limiter = new RateLimiter(1, 250);

// Prints 1 since we did not remove a token and our number of tokens per
// interval is 1
echo($limiter->getTokensRemaining());

直接使用令牌桶在字节级别进行节流

use Wpjscc\React\Limiter\TokenBucket;
use function React\Async\async;
use function React\Async\await;

define("BURST_RATE", 1024 * 1024 * 150); // 150KB/sec burst rate
define("FILL_RATE", 1024 * 1024 * 50); // 50KB/sec sustained rate

// We could also pass a parent token bucket in to create a hierarchical token
// bucket
// bucketSize, tokensPerInterval, interval
const bucket = new TokenBucket(
  BURST_RATE,
  FILL_RATE,
  "second"
);

async(function handleData($myData) use ($bucket) {
  await($bucket->removeTokens(strlen($myData));
  sendMyData($myData);
})();

附加说明

令牌桶和速率限制器都应该与消息队列或防止多次同时调用removeTokens()的方式一起使用。否则，如果较新的消息不断耗尽令牌桶，则较早的消息可能会被长时间挂起。这可能导致消息顺序错误或在高负载下出现“丢失”消息的情况。

许可

MIT许可