Debounce or Throttle Implementation

MediumPython

Problem

Braze Web SDK integrations may receive rapid browser events, such as clicks on a Braze In-App Message. Implement a deterministic simulator for either trailing-edge debouncing or leading-edge throttling without using timer libraries.

Given a nondecreasing list of event calls, return the calls that would invoke the wrapped callback.

Formal Specification

Implement rate_limit_events(calls, wait, mode), where calls is a list of [timestamp, value] pairs, wait is a positive integer number of milliseconds, and mode is either "debounce" or "throttle". Return a list of [timestamp, value] pairs representing callback invocations.

For debounce, each call cancels the previous pending invocation. The final call in a burst runs at last_call_timestamp + wait. A new call at exactly the scheduled invocation time is processed after the pending callback runs.

For throttle, the first call runs immediately. Later calls run only when at least wait milliseconds have elapsed since the previous invocation. Suppressed calls are discarded.

Constraints

0 <= len(calls) <= 10^5
0 <= calls[i][0] <= 10^9
Calls are sorted by nondecreasing timestamp.
1 <= wait <= 10^9
Each event value is an integer or string.
mode is either "debounce" or "throttle".

Function Signature

def rate_limit_events(calls, wait, mode):

Given a nondecreasing list of event calls, return the calls that would invoke the wrapped callback.

Formal Specification

For throttle, the first call runs immediately. Later calls run only when at least wait milliseconds have elapsed since the previous invocation. Suppressed calls are discarded.