Rate Limiting in Wolfram Language

Here’s the translation of the Go rate limiting example to Wolfram Language, formatted in Markdown suitable for Hugo:

Rate limiting is an important mechanism for controlling resource utilization and maintaining quality of service. Wolfram Language provides various tools and functions that can be used to implement rate limiting.

First, we’ll look at basic rate limiting. Suppose we want to limit our handling of incoming requests.

(* Create a list of requests *)
requests = Range[5];

(* Create a function to simulate processing a request *)
processRequest[req_] := (
  Print["Processing request ", req, " at ", DateString[]];
  Pause[0.2];  (* Simulate work *)
)

(* Process requests with rate limiting *)
Do[
  processRequest[req];
  Pause[0.2];  (* Rate limit: wait 200ms between requests *)
, {req, requests}]

This basic implementation processes one request every 200 milliseconds.

Now, let’s implement a more sophisticated rate limiting scheme that allows for bursts of requests while preserving the overall rate limit.

(* Create a function to generate a stream of timestamps *)
CreateRateLimiter[interval_] := 
  ResourceFunction["AsyncStreamMap"][
    ResourceFunction["AsyncTimer"][interval],
    DateObject[#]&
  ]

(* Create a rate limiter that ticks every 200ms *)
limiter = CreateRateLimiter[0.2];

(* Function to process a request with rate limiting *)
processRequestWithLimiter[req_, limiter_] := Module[{timestamp},
  timestamp = limiter[];  (* Wait for the next available slot *)
  Print["Processing request ", req, " at ", DateString[timestamp]];
]

(* Process requests with bursty rate limiting *)
Module[{burstyRequests = Range[10]},
  (* Allow an initial burst of 3 requests *)
  Do[processRequestWithLimiter[req, limiter], {req, Take[burstyRequests, 3]}];
  
  (* Process the remaining requests with rate limiting *)
  Do[processRequestWithLimiter[req, limiter], {req, Drop[burstyRequests, 3]}];
]

In this implementation, we create a rate limiter using AsyncStreamMap and AsyncTimer. This allows us to generate a stream of timestamps at regular intervals. We then use this limiter to control the processing of requests.

The processRequestWithLimiter function waits for the next available timestamp from the limiter before processing each request. This ensures that we maintain our desired rate limit.

We simulate a burst capability by immediately processing the first three requests, and then applying rate limiting to the remaining requests.

Running this program will show the first three requests processed immediately, followed by the remaining requests being processed approximately every 200 milliseconds.

This approach demonstrates how we can implement rate limiting in Wolfram Language, allowing for controlled bursts of activity while maintaining an overall limit on the rate of operations.