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feat: add byte-oriented parser view contract

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This commit is contained in:
Joseph Doherty
2026-03-13 09:54:25 -04:00
parent 98cbdbdeb8
commit ca7e12e753
2 changed files with 101 additions and 45 deletions
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101
src/NATS.Server/Protocol/NatsParser.cs
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@@ -38,22 +38,20 @@ public readonly struct ParsedCommand
public sealed class NatsParser public sealed class NatsParser
{ {
private static readonly byte[] CrLfBytes = "\r\n"u8.ToArray(); private static readonly byte[] CrLfBytes = "\r\n"u8.ToArray();
private readonly int _maxPayload;
private ILogger? _logger; private ILogger? _logger;
public ILogger? Logger { set => _logger = value; } public ILogger? Logger { set => _logger = value; }
// State for split-packet payload reading // State for split-packet payload reading
private bool _awaitingPayload; private bool _awaitingPayload;
private int _expectedPayloadSize; private int _expectedPayloadSize;
private string? _pendingSubject; private byte[]? _pendingSubject;
private string? _pendingReplyTo; private byte[]? _pendingReplyTo;
private int _pendingHeaderSize; private int _pendingHeaderSize;
private CommandType _pendingType; private CommandType _pendingType;
private string _pendingOperation = string.Empty; private string _pendingOperation = string.Empty;
public NatsParser(int maxPayload = NatsProtocol.MaxPayloadSize, ILogger? logger = null) public NatsParser(int maxPayload = NatsProtocol.MaxPayloadSize, ILogger? logger = null)
{ {
_maxPayload = maxPayload;
_logger = logger; _logger = logger;
} }
@@ -71,6 +69,17 @@ public sealed class NatsParser
{ {
command = default; command = default;
if (!TryParseView(ref buffer, out var view))
return false;
command = view.Materialize();
return true;
}
internal bool TryParseView(ref ReadOnlySequence<byte> buffer, out ParsedCommandView command)
{
command = default;
if (_awaitingPayload) if (_awaitingPayload)
return TryReadPayload(ref buffer, out command); return TryReadPayload(ref buffer, out command);
@@ -114,7 +123,7 @@ public sealed class NatsParser
case (byte)'p': case (byte)'p':
if (b1 == (byte)'i') // PING if (b1 == (byte)'i') // PING
{ {
command = ParsedCommand.Simple(CommandType.Ping, "PING"); command = ParsedCommandView.Simple(CommandType.Ping, "PING");
buffer = buffer.Slice(reader.Position); buffer = buffer.Slice(reader.Position);
TraceInOp("PING"); TraceInOp("PING");
return true; return true;
@@ -122,7 +131,7 @@ public sealed class NatsParser
if (b1 == (byte)'o') // PONG if (b1 == (byte)'o') // PONG
{ {
command = ParsedCommand.Simple(CommandType.Pong, "PONG"); command = ParsedCommandView.Simple(CommandType.Pong, "PONG");
buffer = buffer.Slice(reader.Position); buffer = buffer.Slice(reader.Position);
TraceInOp("PONG"); TraceInOp("PONG");
return true; return true;
@@ -188,13 +197,13 @@ public sealed class NatsParser
break; break;
case (byte)'+': // +OK case (byte)'+': // +OK
command = ParsedCommand.Simple(CommandType.Ok, "+OK"); command = ParsedCommandView.Simple(CommandType.Ok, "+OK");
buffer = buffer.Slice(reader.Position); buffer = buffer.Slice(reader.Position);
TraceInOp("+OK"); TraceInOp("+OK");
return true; return true;
case (byte)'-': // -ERR case (byte)'-': // -ERR
command = ParsedCommand.Simple(CommandType.Err, "-ERR"); command = ParsedCommandView.Simple(CommandType.Err, "-ERR");
buffer = buffer.Slice(reader.Position); buffer = buffer.Slice(reader.Position);
TraceInOp("-ERR"); TraceInOp("-ERR");
return true; return true;
@@ -227,7 +236,7 @@ public sealed class NatsParser
Span<byte> line, Span<byte> line,
ref ReadOnlySequence<byte> buffer, ref ReadOnlySequence<byte> buffer,
SequencePosition afterLine, SequencePosition afterLine,
out ParsedCommand command) out ParsedCommandView command)
{ {
command = default; command = default;
@@ -236,19 +245,19 @@ public sealed class NatsParser
var argsSpan = line[4..]; var argsSpan = line[4..];
int argCount = SplitArgs(argsSpan, ranges); int argCount = SplitArgs(argsSpan, ranges);
string subject; byte[] subject;
string? reply = null; byte[]? reply = null;
int size; int size;
if (argCount == 2) if (argCount == 2)
{ {
subject = Encoding.ASCII.GetString(argsSpan[ranges[0]]); subject = argsSpan[ranges[0]].ToArray();
size = ParseSize(argsSpan[ranges[1]]); size = ParseSize(argsSpan[ranges[1]]);
} }
else if (argCount == 3) else if (argCount == 3)
{ {
subject = Encoding.ASCII.GetString(argsSpan[ranges[0]]); subject = argsSpan[ranges[0]].ToArray();
reply = Encoding.ASCII.GetString(argsSpan[ranges[1]]); reply = argsSpan[ranges[1]].ToArray();
size = ParseSize(argsSpan[ranges[2]]); size = ParseSize(argsSpan[ranges[2]]);
} }
else else
@@ -277,7 +286,7 @@ public sealed class NatsParser
Span<byte> line, Span<byte> line,
ref ReadOnlySequence<byte> buffer, ref ReadOnlySequence<byte> buffer,
SequencePosition afterLine, SequencePosition afterLine,
out ParsedCommand command) out ParsedCommandView command)
{ {
command = default; command = default;
@@ -286,20 +295,20 @@ public sealed class NatsParser
var argsSpan = line[5..]; var argsSpan = line[5..];
int argCount = SplitArgs(argsSpan, ranges); int argCount = SplitArgs(argsSpan, ranges);
string subject; byte[] subject;
string? reply = null; byte[]? reply = null;
int hdrSize, totalSize; int hdrSize, totalSize;
if (argCount == 3) if (argCount == 3)
{ {
subject = Encoding.ASCII.GetString(argsSpan[ranges[0]]); subject = argsSpan[ranges[0]].ToArray();
hdrSize = ParseSize(argsSpan[ranges[1]]); hdrSize = ParseSize(argsSpan[ranges[1]]);
totalSize = ParseSize(argsSpan[ranges[2]]); totalSize = ParseSize(argsSpan[ranges[2]]);
} }
else if (argCount == 4) else if (argCount == 4)
{ {
subject = Encoding.ASCII.GetString(argsSpan[ranges[0]]); subject = argsSpan[ranges[0]].ToArray();
reply = Encoding.ASCII.GetString(argsSpan[ranges[1]]); reply = argsSpan[ranges[1]].ToArray();
hdrSize = ParseSize(argsSpan[ranges[2]]); hdrSize = ParseSize(argsSpan[ranges[2]]);
totalSize = ParseSize(argsSpan[ranges[3]]); totalSize = ParseSize(argsSpan[ranges[3]]);
} }
@@ -324,7 +333,7 @@ public sealed class NatsParser
return TryReadPayload(ref buffer, out command); return TryReadPayload(ref buffer, out command);
} }
private bool TryReadPayload(ref ReadOnlySequence<byte> buffer, out ParsedCommand command) private bool TryReadPayload(ref ReadOnlySequence<byte> buffer, out ParsedCommandView command)
{ {
command = default; command = default;
@@ -333,10 +342,7 @@ public sealed class NatsParser
if (buffer.Length < needed) if (buffer.Length < needed)
return false; return false;
// Extract payload
var payloadSlice = buffer.Slice(0, _expectedPayloadSize); var payloadSlice = buffer.Slice(0, _expectedPayloadSize);
var payload = new byte[_expectedPayloadSize];
payloadSlice.CopyTo(payload);
// Verify \r\n after payload // Verify \r\n after payload
var trailer = buffer.Slice(_expectedPayloadSize, 2); var trailer = buffer.Slice(_expectedPayloadSize, 2);
@@ -345,23 +351,25 @@ public sealed class NatsParser
if (trailerBytes[0] != (byte)'\r' || trailerBytes[1] != (byte)'\n') if (trailerBytes[0] != (byte)'\r' || trailerBytes[1] != (byte)'\n')
throw new ProtocolViolationException("Expected \\r\\n after payload"); throw new ProtocolViolationException("Expected \\r\\n after payload");
command = new ParsedCommand command = new ParsedCommandView
{ {
Type = _pendingType, Type = _pendingType,
Operation = _pendingOperation, Operation = _pendingOperation,
Subject = _pendingSubject, Subject = _pendingSubject,
ReplyTo = _pendingReplyTo, ReplyTo = _pendingReplyTo,
Payload = payload, Payload = payloadSlice,
HeaderSize = _pendingHeaderSize, HeaderSize = _pendingHeaderSize,
MaxMessages = -1, MaxMessages = -1,
}; };
buffer = buffer.Slice(buffer.GetPosition(needed)); buffer = buffer.Slice(buffer.GetPosition(needed));
_awaitingPayload = false; _awaitingPayload = false;
_pendingSubject = null;
_pendingReplyTo = null;
return true; return true;
} }
private static ParsedCommand ParseSub(Span<byte> line) private static ParsedCommandView ParseSub(Span<byte> line)
{ {
// SUB subject [queue] sid -- skip "SUB " // SUB subject [queue] sid -- skip "SUB "
if (line.Length < 5) if (line.Length < 5)
@@ -372,28 +380,28 @@ public sealed class NatsParser
return argCount switch return argCount switch
{ {
2 => new ParsedCommand 2 => new ParsedCommandView
{ {
Type = CommandType.Sub, Type = CommandType.Sub,
Operation = "SUB", Operation = "SUB",
Subject = Encoding.ASCII.GetString(argsSpan[ranges[0]]), Subject = CopyBytes(argsSpan[ranges[0]]),
Sid = Encoding.ASCII.GetString(argsSpan[ranges[1]]), Sid = CopyBytes(argsSpan[ranges[1]]),
MaxMessages = -1, MaxMessages = -1,
}, },
3 => new ParsedCommand 3 => new ParsedCommandView
{ {
Type = CommandType.Sub, Type = CommandType.Sub,
Operation = "SUB", Operation = "SUB",
Subject = Encoding.ASCII.GetString(argsSpan[ranges[0]]), Subject = CopyBytes(argsSpan[ranges[0]]),
Queue = Encoding.ASCII.GetString(argsSpan[ranges[1]]), Queue = CopyBytes(argsSpan[ranges[1]]),
Sid = Encoding.ASCII.GetString(argsSpan[ranges[2]]), Sid = CopyBytes(argsSpan[ranges[2]]),
MaxMessages = -1, MaxMessages = -1,
}, },
_ => throw new ProtocolViolationException("Invalid SUB arguments"), _ => throw new ProtocolViolationException("Invalid SUB arguments"),
}; };
} }
private static ParsedCommand ParseUnsub(Span<byte> line) private static ParsedCommandView ParseUnsub(Span<byte> line)
{ {
// UNSUB sid [max_msgs] -- skip "UNSUB " // UNSUB sid [max_msgs] -- skip "UNSUB "
if (line.Length < 7) if (line.Length < 7)
@@ -404,25 +412,25 @@ public sealed class NatsParser
return argCount switch return argCount switch
{ {
1 => new ParsedCommand 1 => new ParsedCommandView
{ {
Type = CommandType.Unsub, Type = CommandType.Unsub,
Operation = "UNSUB", Operation = "UNSUB",
Sid = Encoding.ASCII.GetString(argsSpan[ranges[0]]), Sid = CopyBytes(argsSpan[ranges[0]]),
MaxMessages = -1, MaxMessages = -1,
}, },
2 => new ParsedCommand 2 => new ParsedCommandView
{ {
Type = CommandType.Unsub, Type = CommandType.Unsub,
Operation = "UNSUB", Operation = "UNSUB",
Sid = Encoding.ASCII.GetString(argsSpan[ranges[0]]), Sid = CopyBytes(argsSpan[ranges[0]]),
MaxMessages = ParseSize(argsSpan[ranges[1]]), MaxMessages = ParseSize(argsSpan[ranges[1]]),
}, },
_ => throw new ProtocolViolationException("Invalid UNSUB arguments"), _ => throw new ProtocolViolationException("Invalid UNSUB arguments"),
}; };
} }
private static ParsedCommand ParseConnect(Span<byte> line) private static ParsedCommandView ParseConnect(Span<byte> line)
{ {
// CONNECT {json} -- find first space after command // CONNECT {json} -- find first space after command
int spaceIdx = line.IndexOf((byte)' '); int spaceIdx = line.IndexOf((byte)' ');
@@ -430,16 +438,16 @@ public sealed class NatsParser
throw new ProtocolViolationException("Invalid CONNECT"); throw new ProtocolViolationException("Invalid CONNECT");
var json = line[(spaceIdx + 1)..]; var json = line[(spaceIdx + 1)..];
return new ParsedCommand return new ParsedCommandView
{ {
Type = CommandType.Connect, Type = CommandType.Connect,
Operation = "CONNECT", Operation = "CONNECT",
Payload = json.ToArray(), Payload = new ReadOnlySequence<byte>(json.ToArray()),
MaxMessages = -1, MaxMessages = -1,
}; };
} }
private static ParsedCommand ParseInfo(Span<byte> line) private static ParsedCommandView ParseInfo(Span<byte> line)
{ {
// INFO {json} -- find first space after command // INFO {json} -- find first space after command
int spaceIdx = line.IndexOf((byte)' '); int spaceIdx = line.IndexOf((byte)' ');
@@ -447,15 +455,18 @@ public sealed class NatsParser
throw new ProtocolViolationException("Invalid INFO"); throw new ProtocolViolationException("Invalid INFO");
var json = line[(spaceIdx + 1)..]; var json = line[(spaceIdx + 1)..];
return new ParsedCommand return new ParsedCommandView
{ {
Type = CommandType.Info, Type = CommandType.Info,
Operation = "INFO", Operation = "INFO",
Payload = json.ToArray(), Payload = new ReadOnlySequence<byte>(json.ToArray()),
MaxMessages = -1, MaxMessages = -1,
}; };
} }
private static ReadOnlyMemory<byte> CopyBytes(ReadOnlySpan<byte> value) =>
value.IsEmpty ? ReadOnlyMemory<byte>.Empty : value.ToArray();
/// <summary> /// <summary>
/// Parse a decimal integer from ASCII bytes. Returns -1 on error. /// Parse a decimal integer from ASCII bytes. Returns -1 on error.
/// </summary> /// </summary>

45
src/NATS.Server/Protocol/ParsedCommandView.cs Normal file
View File

@@ -0,0 +1,45 @@
using System.Buffers;
using System.Text;
namespace NATS.Server.Protocol;
public readonly struct ParsedCommandView
{
public CommandType Type { get; init; }
public string? Operation { get; init; }
public ReadOnlyMemory<byte> Subject { get; init; }
public ReadOnlyMemory<byte> ReplyTo { get; init; }
public ReadOnlyMemory<byte> Queue { get; init; }
public ReadOnlyMemory<byte> Sid { get; init; }
public int MaxMessages { get; init; }
public int HeaderSize { get; init; }
public ReadOnlySequence<byte> Payload { get; init; }
public static ParsedCommandView Simple(CommandType type, string operation) =>
new() { Type = type, Operation = operation, MaxMessages = -1 };
public ParsedCommand Materialize() =>
new()
{
Type = Type,
Operation = Operation,
Subject = DecodeAsciiOrNull(Subject),
ReplyTo = DecodeAsciiOrNull(ReplyTo),
Queue = DecodeAsciiOrNull(Queue),
Sid = DecodeAsciiOrNull(Sid),
MaxMessages = MaxMessages,
HeaderSize = HeaderSize,
Payload = MaterializePayload(),
};
private ReadOnlyMemory<byte> MaterializePayload()
{
if (Payload.IsEmpty)
return ReadOnlyMemory<byte>.Empty;
return Payload.IsSingleSegment ? Payload.First : Payload.ToArray();
}
private static string? DecodeAsciiOrNull(ReadOnlyMemory<byte> value) =>
value.IsEmpty ? null : Encoding.ASCII.GetString(value.Span);
}