reifydb-core 0.4.12

Core database interfaces and data structures for ReifyDB
Documentation 
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// SPDX-License-Identifier: Apache-2.0
// Copyright (c) 2025 ReifyDB

//! Flow lag tracking interface for virtual table support.

use crate::interface::catalog::{flow::FlowId, shape::ShapeId};

/// A row in the system.flow_lags virtual table.
#[derive(Debug, Clone)]
pub struct FlowLagRow {
	/// The flow ID.
	pub flow_id: FlowId,
	/// The shape this flow subscribes to.
	pub shape_id: ShapeId,
	/// The lag: how many versions behind the flow is for this source.
	pub lag: u64,
}

/// Trait for providing flow lag data to virtual tables.
///
/// This trait is defined in the core crate to allow the engine crate
/// to use it without depending on the sub-flow crate.
///
/// Implemented by `FlowLagsProvider` in the sub-flow crate.
/// Used by the `FlowLags` virtual table in the engine crate.
pub trait FlowLagsProvider: Send + Sync {
	/// Get all flow lag rows.
	///
	/// Returns one row per (flow, source) pair, showing how far behind
	/// each flow is for each of its subscribed sources.
	fn all_lags(&self) -> Vec<FlowLagRow>;
}