Module session_window 

Session Window Operators

Implementation of session windows for stream processing.

Session windows are dynamic windows that group events by activity periods separated by gaps. Unlike tumbling and sliding windows which have fixed boundaries, session windows grow with activity and close after inactivity.

Key Characteristics

• Dynamic boundaries: Sessions start with the first event and extend with each new event within the gap period
• Per-key tracking: Each key maintains independent session state
• Gap-based closure: Sessions close when no events arrive within the gap
• Session merging: Late data can merge previously separate sessions

Example

Gap: 30 seconds

Events: [t=0] [t=10] [t=20]  ...gap...  [t=100] [t=110]
        |<---- Session 1 ---->|          |<- Session 2 ->|
        [0, 50)                          [100, 140)

Usage

use laminar_core::operator::session_window::SessionWindowOperator;
use laminar_core::operator::window::CountAggregator;
use std::time::Duration;

// Create a session window with 30-second gap
let operator = SessionWindowOperator::new(
    Duration::from_secs(30),    // gap timeout
    CountAggregator::new(),
    Duration::from_secs(60),    // allowed lateness
);

Structs

ArchivedSessionState

An archived SessionState

SessionMetrics

Session metrics for monitoring.

SessionState

Session state tracking start/end times and key.

SessionStateResolver

The resolver for an archived SessionState

SessionWindowOperator

Session window operator.