rate_limiter_en.md

Rate Limiter

Token bucket rate limiter for limiting request frequency.

Constructor

rate_limiter(double rate, int burst)

Parameter	Description
rate	Token generation rate (tokens per second)
burst	Maximum bucket capacity

The bucket is initialized as full at creation time.

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Synchronous Interface

bool allow()

Check if 1 token can be obtained immediately.

• Returns true if allowed, false if insufficient tokens.

bool allow_n_tokens(int n)

Check if n tokens can be obtained immediately.

• Returns true if allowed, false if insufficient tokens.
• Use case: non-blocking rate limiting (reject requests when insufficient).

void wait()

Block current thread until 1 token is obtained.

• Automatically waits the required time if tokens are insufficient.

void wait_n_tokens(int n)

Block current thread until n tokens are obtained.

• Automatically waits the required time if tokens are insufficient.

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Asynchronous Interface

awaitable wait_async()

Return a coroutine awaitable for asynchronously waiting for 1 token.

• Must be used with co_await in a coroutine.

awaitable wait_async_n(int n)

Return a coroutine awaitable for asynchronously waiting for n tokens.

• Must be used with co_await in a coroutine.

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Example

#include "cinatra/rate_limiter.hpp"
#include "async_simple/coro/Lazy.h"

using namespace cinatra;

// Synchronous usage
void sync_example() {
    rate_limiter limiter(10.0, 5);  // 10 tokens/sec, max 5

    // Non-blocking check
    if (limiter.allow()) {
        // Process request
    }

    // Blocking wait
    limiter.wait_n_tokens(3);  // Wait until 3 tokens are available
}

// Asynchronous usage
async_simple::coro::Lazy<void> async_example() {
    rate_limiter limiter(10.0, 5);

    co_await limiter.wait_async_n(3);  // Async wait for 3 tokens
}