Parallelize graph verifications

[nk-ag]

Summary

Parallelize graph verification to reduce end-to-end validation time in verify_graph.

Target

Run the following in parallel since they are independent:

• verify_nodes_names(graph_template.nodes)
• verify_nodes_namespace(graph_template.nodes, graph_template.namespace)
• verify_node_exists(graph_template.nodes, database_nodes)
• verify_node_identifiers(graph_template.nodes)
• verify_secrets(graph_template, database_nodes)

Run verify_topology(graph_template.nodes) after the above complete.

Plan

• Refactor each verifier to return list[str] of errors instead of mutating a shared errors list.
• Aggregate results with asyncio.gather, then call topology verification only if no blocking errors.
• Keep DB calls async. If needed, bound concurrency with a semaphore for lookups.

Sketch

import asyncio

async def verify_graph(graph_template, database_nodes):
    tasks = [
        verify_nodes_names(graph_template.nodes),
        verify_nodes_namespace(graph_template.nodes, graph_template.namespace),
        verify_node_exists(graph_template.nodes, database_nodes),
        verify_node_identifiers(graph_template.nodes),
        verify_secrets(graph_template, database_nodes),
    ]
    results = await asyncio.gather(*tasks, return_exceptions=True)

    errors = []
    for r in results:
        if isinstance(r, Exception):
            errors.append(f"Verifier failed: {r}")
        else:
            errors.extend(r)

    dependency_graph = None
    if not errors:
        dependency_graph = await verify_topology(graph_template.nodes)

    return dependency_graph, errors

Tests

• Unit tests: each verifier returns errors deterministically, no shared state.
• Integration: simulate slow I/O in one verifier and confirm total time is close to the max of individual times, not the sum.
• Failure path: any verifier raises or returns errors, topology is skipped.

Acceptance criteria

• Verifiers run concurrently and overall verification time decreases.
• No shared mutable errors across tasks.
• Topology runs only after basic checks pass.
• CI green with new tests and type hints updated.

[NiveditJain]

ongoing PR to fix this #290