LimitedExec: A Rate Limited Executor for Go

Overview

LimitedExec is a Go package designed to manage the execution rate of certain functions based on unique keys. This ensures that the associated function for a particular key isn't executed more than once within a specified time duration.

A common use case might be in situations where there's a frequent, repetitive event (e.g., requests from a banned IP address) that could overwhelm logs or system resources. Using LimitedExec, one can throttle these events to ensure they're logged or processed at a manageable rate.

Features

• Rate Limiting: Provides an easy-to-use function to rate limit executions.
• Concurrent Safety: Uses Go's sync.Map and sync.Mutex to ensure concurrent safety.
• Periodic Cleanup: Periodically cleans up the map to ensure it doesn’t grow infinitely.

Usage

The main function, Exec, is used to attempt the execution of a function based on a key:

Exec(k interface{}, t time.Duration, fun func())

Parameters:

• k: Unique key for identifying the function (e.g., "banned "+ip).
• t: Time duration within which the function shouldn’t be executed again.
• fun: Function to be executed if allowed.

Example:

Consider you're tracking events of banned IPs:

12:12: came banned ip xx
12:13: came banned ip xx
...

Using LimitedExec, you can reduce the frequency:

limitedexec.Exec("banned "+ip, time.Minute, func() { log.Print("came banned ip xx") })

This will produce:

12:12: came banned ip xx
13:12: came banned ip xx
...

Testing

The package also contains tests to validate its functionality. It tests scenarios like multiple executions within the limited duration and checks if the map cleanup mechanism works as expected.