57 lines
2.0 KiB
C#
57 lines
2.0 KiB
C#
using System;
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using System.IO;
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using System.Threading;
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using System.Threading.Tasks;
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using MessagePack;
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using ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Shared.Contracts;
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namespace ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Shared;
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/// <summary>
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/// Writes length-prefixed, kind-tagged MessagePack frames to a stream. Thread-safe via
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/// <see cref="SemaphoreSlim"/> — multiple producers (e.g. heartbeat + data-plane sharing a
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/// stream) get serialized writes.
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/// </summary>
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public sealed class FrameWriter : IDisposable
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{
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private readonly Stream _stream;
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private readonly SemaphoreSlim _gate = new(1, 1);
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private readonly bool _leaveOpen;
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public FrameWriter(Stream stream, bool leaveOpen = false)
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{
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_stream = stream ?? throw new ArgumentNullException(nameof(stream));
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_leaveOpen = leaveOpen;
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}
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public async Task WriteAsync<T>(FocasMessageKind kind, T message, CancellationToken ct)
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{
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var body = MessagePackSerializer.Serialize(message, cancellationToken: ct);
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if (body.Length > Framing.MaxFrameBodyBytes)
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throw new InvalidOperationException(
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$"IPC frame body {body.Length} exceeds {Framing.MaxFrameBodyBytes} byte cap.");
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var lengthPrefix = new byte[Framing.LengthPrefixSize];
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lengthPrefix[0] = (byte)((body.Length >> 24) & 0xFF);
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lengthPrefix[1] = (byte)((body.Length >> 16) & 0xFF);
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lengthPrefix[2] = (byte)((body.Length >> 8) & 0xFF);
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lengthPrefix[3] = (byte)( body.Length & 0xFF);
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await _gate.WaitAsync(ct).ConfigureAwait(false);
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try
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{
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await _stream.WriteAsync(lengthPrefix, 0, lengthPrefix.Length, ct).ConfigureAwait(false);
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_stream.WriteByte((byte)kind);
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await _stream.WriteAsync(body, 0, body.Length, ct).ConfigureAwait(false);
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await _stream.FlushAsync(ct).ConfigureAwait(false);
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}
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finally { _gate.Release(); }
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}
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public void Dispose()
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{
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_gate.Dispose();
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if (!_leaveOpen) _stream.Dispose();
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}
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}
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