Joseph Doherty
1ea1da8236
Since #516 a DriverConfig change is stop + respawn, so DriverSpawnPlan.ToApplyDelta was always empty and the in-place path had no producer. #663 and #664 were both latent bugs in it. This deletes it: - host: ApplyChildDelta, _pendingDelta, HandleApplyResult and HandleDeltaApplied - plan: DriverSpawnPlan.ToApplyDelta - actor: the ApplyDelta, ApplyResult and DeltaApplied messages, the Connected reinit handler and the mid-connect AdoptConfigDuringInit - tests: the actor tests that drove the seam IDriver.ReinitializeAsync and each driver's implementation and unit tests stay. Comments and docs that cited AdoptConfigDuringInit as the reason a driver must release prior state at init now cite the IDriver contract and overlapping retries, which still apply. Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe
70 lines
4.6 KiB
C#
70 lines
4.6 KiB
C#
namespace ZB.MOM.WW.OtOpcUa.Core.Abstractions;
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/// <summary>
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/// Required capability for every driver instance. Owns lifecycle, metadata, health.
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/// Other capabilities (<see cref="ITagDiscovery"/>, <see cref="IReadable"/>,
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/// <see cref="IWritable"/>, <see cref="ISubscribable"/>, <see cref="IAlarmSource"/>,
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/// <see cref="IRediscoverable"/>,
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/// <see cref="IHostConnectivityProbe"/>) are composable — a driver implements only what its
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/// backend actually supports.
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/// </summary>
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public interface IDriver
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{
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/// <summary>Stable logical ID of this driver instance, sourced from the central config DB.</summary>
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string DriverInstanceId { get; }
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/// <summary>Driver type name (e.g. "Galaxy", "Modbus", "AbCip"). Matches <c>DriverInstance.DriverType</c>.</summary>
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string DriverType { get; }
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/// <summary>Initialize the driver from its <c>DriverConfig</c> JSON; open connections; prepare for first use.</summary>
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/// <param name="driverConfigJson">The driver configuration as JSON.</param>
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/// <param name="cancellationToken">Cancellation token for the operation.</param>
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/// <returns>A task that represents the asynchronous operation.</returns>
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Task InitializeAsync(string driverConfigJson, CancellationToken cancellationToken);
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/// <summary>
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/// Apply a config change in place without tearing down the driver process.
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/// <para>The runtime does not call this today: since #516 a DriverConfig change is a stop + respawn,
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/// and #665 deleted <c>DriverInstanceActor</c>'s in-place <c>ApplyDelta</c> path. Kept as the in-place
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/// contract each driver implements and tests.</para>
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/// </summary>
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/// <remarks>
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/// Per <c>docs/v2/driver-stability.md</c> §"In-process only (Tier A/B)" — Reinitialize is the
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/// only Core-initiated recovery path for in-process drivers; if it fails, the driver instance
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/// is marked Faulted and its nodes go Bad quality, but the server process keeps running.
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/// </remarks>
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/// <param name="driverConfigJson">The driver configuration as JSON.</param>
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/// <param name="cancellationToken">Cancellation token for the operation.</param>
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/// <returns>A task that represents the asynchronous operation.</returns>
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Task ReinitializeAsync(string driverConfigJson, CancellationToken cancellationToken);
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/// <summary>Stop the driver, close connections, release resources. Called on shutdown or driver removal.</summary>
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/// <remarks>
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/// <para><b>Land the terminal health value AFTER the teardown, never only before it</b> (Gitea #517).
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/// Teardown drains in-flight poll / probe loops, and those loops write health as they unwind — so a
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/// driver that wrote <see cref="DriverState.Unknown"/> first and then tore down could have a late
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/// loop overwrite it with <see cref="DriverState.Healthy"/> and leave THAT as the resting state,
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/// with every connection already closed. This is why the fleet writes last, and it is the reason
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/// #517's original suggestion — "write the transitional value before disposing" — is only safe as an
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/// ADDITIONAL write, bracketing the teardown, rather than as a move.</para>
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/// <para>Bracketing matters wherever a <see cref="GetHealth"/> can land mid-teardown. It cannot on
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/// this path today: <c>DriverInstanceActor</c> calls this from <c>PostStop</c>, on the actor thread,
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/// after the mailbox has drained, so its health poll is serialised against it. It CAN on the
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/// initialize path, which the same actor runs on a fire-and-forget <c>Task.Run</c> while the health
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/// tick keeps firing — so a driver whose <see cref="InitializeAsync"/> disposes anything on its
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/// failure path must write the failed state before disposing as well as after.</para>
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/// </remarks>
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/// <param name="cancellationToken">Cancellation token for the operation.</param>
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/// <returns>A task that represents the asynchronous operation.</returns>
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Task ShutdownAsync(CancellationToken cancellationToken);
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/// <summary>Current health snapshot, polled by Core for the status dashboard and ServiceLevel.
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/// <para>Must reflect the driver's ACTUAL state rather than a constant — a hard-coded
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/// <see cref="DriverState.Healthy"/> reports a healthy driver after shutdown and before initialize
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/// alike, which is what Gitea #517 found in <c>CalculationDriver</c>. A driver with no transport still
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/// has a running / not-running distinction worth reporting.</para></summary>
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/// <returns>The driver's current health snapshot.</returns>
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DriverHealth GetHealth();
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}
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