Files
lmxopcua/src/ZB.MOM.WW.OtOpcUa.Core/Stability/MemoryRecycle.cs
Joseph Doherty 1d9008e354 Phase 6.1 Stream B.3/B.4/B.5 — MemoryRecycle + ScheduledRecycleScheduler + demand-aware WedgeDetector
Closes out Stream B per docs/v2/implementation/phase-6-1-resilience-and-observability.md.

Core.Abstractions:
- IDriverSupervisor — process-level supervisor contract a Tier C driver's
  out-of-process topology provides (Galaxy Proxy/Supervisor implements this in
  a follow-up Driver.Galaxy wiring PR). Concerns: DriverInstanceId + RecycleAsync.
  Tier A/B drivers don't implement this; Stream B code asserts tier == C before
  ever calling it.

Core.Stability:
- MemoryRecycle — companion to MemoryTracking. On HardBreach, invokes the
  supervisor IFF tier == C AND a supervisor is wired. Tier A/B HardBreach logs
  a promotion-to-Tier-C recommendation and returns false. Soft/None/Warming
  never triggers a recycle at any tier.
- ScheduledRecycleScheduler — Tier C opt-in periodic recycler per decision #67.
  Ctor throws for Tier A/B (structural guard — scheduled recycle on an
  in-process driver would kill every OPC UA session and every co-hosted
  driver). TickAsync(now) advances the schedule by one interval per fire;
  RequestRecycleNowAsync drives an ad-hoc recycle without shifting the cron.
- WedgeDetector — demand-aware per decision #147. Classify(state, demand, now)
  returns:
    * NotApplicable when driver state != Healthy
    * Idle when Healthy + no pending work (bulkhead=0 && monitored=0 && historic=0)
    * Healthy when Healthy + pending work + progress within threshold
    * Faulted when Healthy + pending work + no progress within threshold
  Threshold clamps to min 60 s. DemandSignal.HasPendingWork ORs the three counters.
  The three false-wedge cases the plan calls out all stay Healthy: idle
  subscription-only, slow historian backfill making progress, write-only burst
  with drained bulkhead.

Tests (22 new, all pass):
- MemoryRecycleTests (7): Tier C hard-breach requests recycle; Tier A/B
  hard-breach never requests; Tier C without supervisor no-ops; soft-breach
  at every tier never requests; None/Warming never request.
- ScheduledRecycleSchedulerTests (6): ctor throws for A/B; zero/negative
  interval throws; tick before due no-ops; tick at/after due fires once and
  advances; RequestRecycleNow fires immediately without shifting schedule;
  multiple fires across ticks advance one interval each.
- WedgeDetectorTests (9): threshold clamp to 60 s; unhealthy driver always
  NotApplicable; idle subscription stays Idle; pending+fresh progress stays
  Healthy; pending+stale progress is Faulted; MonitoredItems active but no
  publish is Faulted; MonitoredItems active with fresh publish stays Healthy;
  historian backfill with fresh progress stays Healthy; write-only burst with
  empty bulkhead is Idle; HasPendingWork theory for any non-zero counter.

Full solution dotnet test: 989 passing (baseline 906, +83 for Phase 6.1 so far).
Pre-existing Client.CLI Subscribe flake unchanged.

Stream B complete. Next up: Stream C (health endpoints + structured logging).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-04-19 08:03:18 -04:00

66 lines
3.1 KiB
C#

using Microsoft.Extensions.Logging;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
namespace ZB.MOM.WW.OtOpcUa.Core.Stability;
/// <summary>
/// Tier C only process-recycle companion to <see cref="MemoryTracking"/>. On a
/// <see cref="MemoryTrackingAction.HardBreach"/> signal, invokes the supplied
/// <see cref="IDriverSupervisor"/> to restart the out-of-process Host.
/// </summary>
/// <remarks>
/// Per <c>docs/v2/plan.md</c> decisions #74 and #145. Tier A/B hard-breach on an in-process
/// driver would kill every OPC UA session and every co-hosted driver, so for Tier A/B this
/// class logs a <b>promotion-to-Tier-C recommendation</b> and does NOT invoke any supervisor.
/// A future tier-migration workflow acts on the recommendation.
/// </remarks>
public sealed class MemoryRecycle
{
private readonly DriverTier _tier;
private readonly IDriverSupervisor? _supervisor;
private readonly ILogger<MemoryRecycle> _logger;
public MemoryRecycle(DriverTier tier, IDriverSupervisor? supervisor, ILogger<MemoryRecycle> logger)
{
_tier = tier;
_supervisor = supervisor;
_logger = logger;
}
/// <summary>
/// Handle a <see cref="MemoryTracking"/> classification for the driver. For Tier C with a
/// wired supervisor, <c>HardBreach</c> triggers <see cref="IDriverSupervisor.RecycleAsync"/>.
/// All other combinations are no-ops with respect to process state (soft breaches + Tier A/B
/// hard breaches just log).
/// </summary>
/// <returns>True when a recycle was requested; false otherwise.</returns>
public async Task<bool> HandleAsync(MemoryTrackingAction action, long footprintBytes, CancellationToken cancellationToken)
{
switch (action)
{
case MemoryTrackingAction.SoftBreach:
_logger.LogWarning(
"Memory soft-breach on driver {DriverId}: footprint={Footprint:N0} bytes, tier={Tier}. Surfaced to Admin; no action.",
_supervisor?.DriverInstanceId ?? "(unknown)", footprintBytes, _tier);
return false;
case MemoryTrackingAction.HardBreach when _tier == DriverTier.C && _supervisor is not null:
_logger.LogError(
"Memory hard-breach on Tier C driver {DriverId}: footprint={Footprint:N0} bytes. Requesting supervisor recycle.",
_supervisor.DriverInstanceId, footprintBytes);
await _supervisor.RecycleAsync($"Memory hard-breach: {footprintBytes} bytes", cancellationToken).ConfigureAwait(false);
return true;
case MemoryTrackingAction.HardBreach:
_logger.LogError(
"Memory hard-breach on Tier {Tier} in-process driver {DriverId}: footprint={Footprint:N0} bytes. " +
"Recommending promotion to Tier C; NOT auto-killing (decisions #74, #145).",
_tier, _supervisor?.DriverInstanceId ?? "(unknown)", footprintBytes);
return false;
default:
return false;
}
}
}