PIP-396: Align WindowFunction's WindowContext with BaseContext

Background knowledge

Pulsar Functions and Connectors provide a BaseContext object, enabling users to access the current execution environment, including logs, metrics, states, secrets, and other context-specific features. The WindowFunction, designed to process multiple messages at once, offers a WindowContext object with similar functionality. However, WindowContext lacks certain features available in BaseContext.

Motivation

Currently, the WindowContext interface does not include some critical methods provided by BaseContext, such as getSecret and deleteState. This limitation makes Window Functions feel less capable compared to standard Functions.

Goals

In Scope

• Enhance WindowContext by adding missing features from BaseContext.

Out of Scope

High-Level Design

The solution involves aligning WindowContext with BaseContext by extending the WindowContext interface and implementing missing methods in WindowContextImpl.

Detailed Design

Design & Implementation Details

Refer to implementation PR: https://github.com/apache/pulsar/pull/23628

The implementation strategy is straightforward:

• Update the WindowContext interface to extend the BaseContext interface.
• Remove duplicate method definitions in WindowContext already covered by BaseContext.
• Implement the following missing methods in the WindowContextImpl class:

@Override
public String getSecret(String secretName) {
    return this.context.getSecret(secretName);
}

@Override
public CompletableFuture<Void> incrCounterAsync(String key, long amount) {
    return this.context.incrCounterAsync(key, amount);
}

@Override
public CompletableFuture<Long> getCounterAsync(String key) {
    return this.context.getCounterAsync(key);
}

@Override
public CompletableFuture<Void> putStateAsync(String key, ByteBuffer value) {
    return this.context.putStateAsync(key, value);
}

@Override
public CompletableFuture<ByteBuffer> getStateAsync(String key) {
    return this.context.getStateAsync(key);
}

@Override
public void deleteState(String key) {
    this.context.deleteState(key);
}

@Override
public CompletableFuture<Void> deleteStateAsync(String key) {
    return this.context.deleteStateAsync(key);
}

@Override
public void fatal(Throwable t) {
    this.context.fatal(t);
}

Public-facing Changes

With this update, developers working on Window Functions can leverage the following new methods from WindowContext:

• getSecret
• incrCounterAsync
• getCounterAsync
• putStateAsync
• getStateAsync
• deleteState
• deleteStateAsync
• fatal

Configuration

Backward & Forward Compatibility

This update is fully backward-compatible. No existing methods in WindowContext are modified or removed, ensuring seamless integration with current implementations.