New feature proposal: New Policy: "Polling"

[avavakin]

Polling

TL;DR: create a Polling which will encapsulate the polling strategy of some java code (e.g. API calls)

Case example

A service polls /get-some-task to monitor background jobs
A static 1s interval is inefficient: it over-polls long tasks with many requests and under-polls short tasks (too long delay)
The goal is to reach the target state of optimal polling range (configurable, but let's say 1-3 polls)

API proposal

// Declaration
final Polling<T> polling = Polling.adaptiveBuilder()
    .targetPolls(1.5)
    .minDelay(Duration.ofMillis(500))
    .maxDelay(Duration.ofSeconds(10))
    .timout(Duration.ofMinutes(1))
    .basedOnLast(10) // memory of adaptive poller on which it's calculate the avg
    .build();

// Usage
final var pollResult = polling.poll(() -> someCustomJavaCode());

Behaviour proposal (first strategy implementation - Adaptive with memory)

Estimation: Maintain an Exponentially Weighted Moving Average (EWMA) of total task durations.
Calculation: T_avg = α * T_actual_duration + ( 1 - α ) * T_avg

Where α - is configurable volatility coefficient in range (0, 1), let say by default 0.2
If task completion takes longer than the average, the algorithm treats it as a slow-outlier and adjusts the moving average upward, increasing the delay for subsequent polls.

Potential

• Allow users to configure other strategies of defining delay, based on some input data
• Allow users to configure strategy of defining taken time of pollable task (for example parse last response from poll, extract start and finish timestamps and provide duration as result) - by default: just calculate duration between first poll and last poll