Joseph Doherty
0868613890
The DL205/DL260 ECOM emits no TCP keepalives, so an idle backend socket can be silently dropped by a middlebox (switch, firewall, NAT) after 2-5 minutes. Enable OS SO_KEEPALIVE on backend and accepted upstream sockets, and drive a periodic synthetic FC03 heartbeat on each idle backend socket so a dead path is detected before a real client request hits it. Controlled by Connection.Keepalive (ON by default). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
139 lines
4.9 KiB
C#
139 lines
4.9 KiB
C#
using System.Text.Json.Serialization;
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namespace Mbproxy.Admin;
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// ── Wire DTOs for GET /status.json ───────────────────────────────────────────
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// Field names must match docs/Operations/StatusPage.md tables EXACTLY (camelCase via
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// JsonKnownNamingPolicy.CamelCase on the source-gen context).
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/// <summary>
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/// Top-level response envelope for <c>GET /status.json</c>.
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/// </summary>
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public sealed record StatusResponse(
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ServiceFields Service,
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ListenersAggregate Listeners,
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IReadOnlyList<PlcStatus> Plcs);
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/// <summary>Service-wide identity and reload counters.</summary>
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public sealed record ServiceFields(
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long UptimeSeconds,
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string Version,
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DateTimeOffset? ConfigLastReloadUtc,
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int ConfigReloadCount,
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int ConfigReloadRejectedCount);
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/// <summary>Aggregate listener state across all configured PLCs.</summary>
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public sealed record ListenersAggregate(int Bound, int Configured);
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/// <summary>Per-PLC status row.</summary>
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public sealed record PlcStatus(
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string Name,
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string Host,
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int ListenPort,
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PlcListenerStatus Listener,
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PlcClientsStatus Clients,
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PlcPdusStatus Pdus,
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PlcBackendStatus Backend,
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PlcBytesStatus Bytes);
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/// <summary>Listener state sub-object.</summary>
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public sealed record PlcListenerStatus(
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string State,
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string? LastBindError,
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int RecoveryAttempts);
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/// <summary>Connected-clients sub-object.</summary>
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public sealed record PlcClientsStatus(
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int Connected,
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IReadOnlyList<ClientSnapshot> RemoteEndpoints);
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/// <summary>Per-connection-pair snapshot for the status page.</summary>
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public sealed record ClientSnapshot(
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string Remote,
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DateTimeOffset ConnectedAtUtc,
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long PdusForwarded);
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/// <summary>PDU counters sub-object.</summary>
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public sealed record PlcPdusStatus(
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long Forwarded,
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FcCounts ByFc,
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long RewrittenSlots,
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long PartialBcdWarnings,
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/// <summary>
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/// Count of BCD-rewriter slot decisions where the wire value was not a valid BCD
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/// nibble pattern (e.g. <c>0xABCD</c> at a tag address). The slot passes through
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/// unrewritten and this counter increments.
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/// </summary>
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long InvalidBcdWarnings);
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/// <summary>Per-function-code request counts.</summary>
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public sealed record FcCounts(
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long Fc03,
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long Fc04,
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long Fc06,
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long Fc16,
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long Other);
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/// <summary>
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/// Backend connect, exception, and multiplexer telemetry, including the in-flight
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/// multiplexer fields (<c>InFlight</c>, <c>MaxInFlight</c>, <c>TxIdWraps</c>,
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/// <c>DisconnectCascades</c>, <c>QueueDepth</c>), the read-coalescing counters
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/// (<c>CoalescedHitCount</c>, <c>CoalescedMissCount</c>, <c>CoalescedResponseToDeadUpstream</c>),
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/// and the response-cache counters (<c>CacheHitCount</c>, <c>CacheMissCount</c>,
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/// <c>CacheInvalidations</c>, <c>CacheEntryCount</c>, <c>CacheBytes</c>).
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///
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/// <para>The dashboard-side derived ratios <c>coalescingRatio</c> and <c>cacheHitRatio</c>
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/// are intentionally NOT carried on the wire — consumers compute <c>Hit / (Hit + Miss)</c>
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/// from the raw counters.</para>
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/// </summary>
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public sealed record PlcBackendStatus(
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long ConnectsSuccess,
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long ConnectsFailed,
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ExceptionCounts ExceptionsByCode,
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double LastRoundTripMs,
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long InFlight,
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long MaxInFlight,
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long TxIdWraps,
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long DisconnectCascades,
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long QueueDepth,
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long CoalescedHitCount,
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long CoalescedMissCount,
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long CoalescedResponseToDeadUpstream,
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long CacheHitCount,
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long CacheMissCount,
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long CacheInvalidations,
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long CacheEntryCount,
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long CacheBytes,
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/// <summary>Backend keepalive heartbeat probes issued on idle backend sockets.</summary>
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long BackendHeartbeatsSent,
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/// <summary>Keepalive heartbeat probes that timed out (backend not answering).</summary>
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long BackendHeartbeatsFailed,
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/// <summary>Backend teardowns triggered by a failed keepalive heartbeat.</summary>
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long BackendIdleDisconnects);
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/// <summary>Modbus exception counts by code.</summary>
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public sealed record ExceptionCounts(
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long Code01,
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long Code02,
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long Code03,
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long Code04,
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/// <summary>
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/// Backend exceptions whose response code is not 01–04 (e.g. 0x06 Server Device
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/// Busy, 0x0B Gateway Target Failed To Respond, vendor-specific codes).
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/// </summary>
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long CodeOther);
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/// <summary>Byte-transfer counters.</summary>
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public sealed record PlcBytesStatus(
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long UpstreamIn,
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long UpstreamOut);
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// ── Source-generation context ─────────────────────────────────────────────────
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// TreatWarningsAsErrors is on, so the context must include every reachable type.
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[JsonSerializable(typeof(StatusResponse))]
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[JsonSourceGenerationOptions(
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WriteIndented = false,
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PropertyNamingPolicy = JsonKnownNamingPolicy.CamelCase)]
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internal partial class StatusJsonContext : JsonSerializerContext;
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