Headers parsing

NATS.Client.sln

@@ -49,6 +49,10 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Example.Core.PublishModel",
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "NATS.Client.Core.MemoryTests", "tests\NATS.Client.Core.MemoryTests\NATS.Client.Core.MemoryTests.csproj", "{B26DE6AC-A4D5-4427-8453-EE3514E4B513}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Example.Core.PublishHeaders", "sandbox\Example.Core.PublishHeaders\Example.Core.PublishHeaders.csproj", "{B0C82F24-BDEC-4420-A02A-F74E2423D755}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Example.Core.SubscribeHeaders", "sandbox\Example.Core.SubscribeHeaders\Example.Core.SubscribeHeaders.csproj", "{A96660DB-DAEB-4C57-8096-F236AC4FA927}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -115,6 +119,14 @@ Global
 		{B26DE6AC-A4D5-4427-8453-EE3514E4B513}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{B26DE6AC-A4D5-4427-8453-EE3514E4B513}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{B26DE6AC-A4D5-4427-8453-EE3514E4B513}.Release|Any CPU.Build.0 = Release|Any CPU
+		{B0C82F24-BDEC-4420-A02A-F74E2423D755}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{B0C82F24-BDEC-4420-A02A-F74E2423D755}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{B0C82F24-BDEC-4420-A02A-F74E2423D755}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{B0C82F24-BDEC-4420-A02A-F74E2423D755}.Release|Any CPU.Build.0 = Release|Any CPU
+		{A96660DB-DAEB-4C57-8096-F236AC4FA927}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{A96660DB-DAEB-4C57-8096-F236AC4FA927}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{A96660DB-DAEB-4C57-8096-F236AC4FA927}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{A96660DB-DAEB-4C57-8096-F236AC4FA927}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -136,6 +148,8 @@ Global
 		{C85BA135-3C21-4027-BE5A-849E1011DD0A} = {95A69671-16CA-4133-981C-CC381B7AAA30}
 		{29F96D05-D02F-4610-A8FB-3527BF83C4A5} = {95A69671-16CA-4133-981C-CC381B7AAA30}
 		{B26DE6AC-A4D5-4427-8453-EE3514E4B513} = {C526E8AB-739A-48D7-8FC4-048978C9B650}
+		{B0C82F24-BDEC-4420-A02A-F74E2423D755} = {95A69671-16CA-4133-981C-CC381B7AAA30}
+		{A96660DB-DAEB-4C57-8096-F236AC4FA927} = {95A69671-16CA-4133-981C-CC381B7AAA30}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {8CBB7278-D093-448E-B3DE-B5991209A1AA}

NATS.Client.sln.DotSettings

@@ -0,0 +1,6 @@
+<wpf:ResourceDictionary xml:space="preserve" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:s="clr-namespace:System;assembly=mscorlib" xmlns:ss="urn:shemas-jetbrains-com:settings-storage-xaml" xmlns:wpf="http://schemas.microsoft.com/winfx/2006/xaml/presentation">
+	<s:String x:Key="/Default/CodeStyle/Naming/CSharpNaming/Abbreviations/=ASCII/@EntryIndexedValue">ASCII</s:String>
+	<s:String x:Key="/Default/CodeStyle/Naming/CSharpNaming/Abbreviations/=CR/@EntryIndexedValue">CR</s:String>
+	<s:String x:Key="/Default/CodeStyle/Naming/CSharpNaming/Abbreviations/=LF/@EntryIndexedValue">LF</s:String>
+	<s:Boolean x:Key="/Default/UserDictionary/Words/=HMSG/@EntryIndexedValue">True</s:Boolean>
+	<s:Boolean x:Key="/Default/UserDictionary/Words/=HPUB/@EntryIndexedValue">True</s:Boolean></wpf:ResourceDictionary>

sandbox/Example.Core.PublishHeaders/Example.Core.PublishHeaders.csproj

@@ -0,0 +1,14 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <OutputType>Exe</OutputType>
+        <TargetFramework>net6.0</TargetFramework>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
+    </PropertyGroup>
+
+    <ItemGroup>
+      <ProjectReference Include="..\..\src\NATS.Client.Core\NATS.Client.Core.csproj" />
+    </ItemGroup>
+
+</Project>

sandbox/Example.Core.PublishHeaders/Program.cs

@@ -0,0 +1,31 @@
+// > nats sub bar.*
+using Microsoft.Extensions.Logging;
+using NATS.Client.Core;
+
+var subject = "bar.xyz";
+var options = NatsOptions.Default with { LoggerFactory = new MinimumConsoleLoggerFactory(LogLevel.Error) };
+
+Print("[CON] Connecting...\n");
+
+await using var connection = new NatsConnection(options);
+
+for (int i = 0; i < 10; i++)
+{
+    Print($"[PUB] Publishing to subject ({i}) '{subject}'...\n");
+    await connection.PublishAsync<Bar>(
+        subject,
+        new Bar { Id = i, Name = "Baz" },
+        new NatsPubOpts { Headers = new NatsHeaders { ["XFoo"] = $"bar{i}" } });
+}
+
+void Print(string message)
+{
+    Console.Write($"{DateTime.Now:HH:mm:ss} {message}");
+}
+
+public record Bar
+{
+    public int Id { get; set; }
+
+    public string? Name { get; set; }
+}

sandbox/Example.Core.SubscribeHeaders/Example.Core.SubscribeHeaders.csproj

@@ -0,0 +1,14 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <OutputType>Exe</OutputType>
+        <TargetFramework>net6.0</TargetFramework>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
+    </PropertyGroup>
+
+    <ItemGroup>
+      <ProjectReference Include="..\..\src\NATS.Client.Core\NATS.Client.Core.csproj" />
+    </ItemGroup>
+
+</Project>

sandbox/Example.Core.SubscribeHeaders/Program.cs

@@ -0,0 +1,41 @@
+// > nats pub bar.xyz --count=10 "my_message_{{ Count }}" -H X-Foo:Baz
+
+using System.Text;
+using Microsoft.Extensions.Logging;
+using NATS.Client.Core;
+
+var subject = "bar.*";
+var options = NatsOptions.Default with { LoggerFactory = new MinimumConsoleLoggerFactory(LogLevel.Error) };
+
+Print("[CON] Connecting...\n");
+
+await using var connection = new NatsConnection(options);
+
+Print($"[SUB] Subscribing to subject '{subject}'...\n");
+
+NatsSub sub = await connection.SubscribeAsync(subject);
+
+await foreach (var msg in sub.Msgs.ReadAllAsync())
+{
+    Print($"[RCV] {msg.Subject}: {Encoding.UTF8.GetString(msg.Data.Span)}\n");
+    if (msg.Headers != null)
+    {
+        foreach (var (key, values) in msg.Headers)
+        {
+            foreach (var value in values)
+                Print($"  {key}: {value}\n");
+        }
+    }
+}
+
+void Print(string message)
+{
+    Console.Write($"{DateTime.Now:HH:mm:ss} {message}");
+}
+
+public record Bar
+{
+    public int Id { get; set; }
+
+    public string? Name { get; set; }
+}

src/NATS.Client.Core/Commands/CommandConstants.cs

@@ -13,6 +13,9 @@ internal static class CommandConstants
     // string.Join(",", Encoding.ASCII.GetBytes("PUB "))
     public static ReadOnlySpan<byte> PubWithPadding => new byte[] { 80, 85, 66, 32 };
 
+    // string.Join(",", Encoding.ASCII.GetBytes("HPUB "))
+    public static ReadOnlySpan<byte> HPubWithPadding => new byte[] { 72, 80, 85, 66, 32 };
+
     // string.Join(",", Encoding.ASCII.GetBytes("SUB "))
     public static ReadOnlySpan<byte> SubWithPadding => new byte[] { 83, 85, 66, 32 };
 
@@ -24,4 +27,7 @@ internal static class CommandConstants
 
     // string.Join(",", Encoding.ASCII.GetBytes("PONG\r\n"))
     public static ReadOnlySpan<byte> PongNewLine => new byte[] { 80, 79, 78, 71, 13, 10 };
+
+    // string.Join(",", Encoding.ASCII.GetBytes("NATS/1.0\r\n"))
+    public static ReadOnlySpan<byte> NatsHeaders10NewLine => new byte[] { 78, 65, 84, 83, 47, 49, 46, 48, 13, 10 };
 }

src/NATS.Client.Core/Commands/ProtocolWriter.cs

@@ -1,5 +1,6 @@
 using System.Buffers;
 using System.Buffers.Text;
+using System.Text;
 using System.Text.Json;
 using System.Text.Json.Serialization;
 using NATS.Client.Core.Internal;
@@ -12,6 +13,9 @@ internal sealed class ProtocolWriter
     private const int NewLineLength = 2; // \r\n
 
     private readonly FixedArrayBufferWriter _writer; // where T : IBufferWriter<byte>
+    private readonly FixedArrayBufferWriter _bufferHeaders = new();
+    private readonly FixedArrayBufferWriter _bufferPayload = new();
+    private readonly HeaderWriter _headerWriter = new(Encoding.UTF8);
 
     public ProtocolWriter(FixedArrayBufferWriter writer)
     {
@@ -46,159 +50,63 @@ public void WritePong()
     }
 
     // https://docs.nats.io/reference/reference-protocols/nats-protocol#pub
-    // PUB <subject> [reply-to] <#bytes>\r\n[payload]
-    // To omit the payload, set the payload size to 0, but the second CRLF is still required.
-    public void WritePublish(string subject, string? replyTo, ReadOnlySequence<byte> payload)
+    // PUB <subject> [reply-to] <#bytes>\r\n[payload]\r\n
+    public void WritePublish(string subject, string? replyTo, NatsHeaders? headers, ReadOnlySequence<byte> payload)
     {
-        var offset = 0;
-        var maxLength = CommandConstants.PubWithPadding.Length
-            + subject.Length + 1 // with space padding
-            + (replyTo == null ? 0 : replyTo.Length + 1)
-            + MaxIntStringLength
-            + NewLineLength
-            + (int)payload.Length
-            + NewLineLength;
-
-        var writableSpan = _writer.GetSpan(maxLength);
-
-        CommandConstants.PubWithPadding.CopyTo(writableSpan);
-        offset += CommandConstants.PubWithPadding.Length;
+        // We use a separate buffer to write the headers so that we can calculate the
+        // size before we write to the output buffer '_writer'.
+        if (headers != null)
+        {
+            _bufferHeaders.Reset();
+            _headerWriter.Write(_bufferHeaders, headers);
+        }
 
-        subject.WriteASCIIBytes(writableSpan.Slice(offset));
-        offset += subject.Length;
-        writableSpan.Slice(offset)[0] = (byte)' ';
-        offset += 1;
+        // Start writing the message to buffer:
+        // PUP / HPUB
+        _writer.WriteSpan(headers == null ? CommandConstants.PubWithPadding : CommandConstants.HPubWithPadding);
+        _writer.WriteASCIIAndSpace(subject);
 
         if (replyTo != null)
         {
-            replyTo.WriteASCIIBytes(writableSpan.Slice(offset));
-            offset += replyTo.Length;
-            writableSpan.Slice(offset)[0] = (byte)' ';
-            offset += 1;
+            _writer.WriteASCIIAndSpace(replyTo);
         }
 
-        if (!Utf8Formatter.TryFormat(payload.Length, writableSpan.Slice(offset), out var written))
+        if (headers == null)
         {
-            throw new NatsException("Can not format integer.");
+            _writer.WriteNumber(payload.Length);
         }
-
-        offset += written;
-
-        CommandConstants.NewLine.CopyTo(writableSpan.Slice(offset));
-        offset += CommandConstants.NewLine.Length;
-
-        if (payload.Length != 0)
+        else
         {
-            payload.CopyTo(writableSpan.Slice(offset));
-            offset += (int)payload.Length;
+            var headersLength = _bufferHeaders.WrittenSpan.Length;
+            _writer.WriteNumber(CommandConstants.NatsHeaders10NewLine.Length + headersLength);
+            _writer.WriteSpace();
+            var total = CommandConstants.NatsHeaders10NewLine.Length + headersLength + payload.Length;
+            _writer.WriteNumber(total);
         }
 
-        CommandConstants.NewLine.CopyTo(writableSpan.Slice(offset));
-        offset += CommandConstants.NewLine.Length;
-
-        _writer.Advance(offset);
-    }
-
-    public void WritePublish<T>(string subject, string? replyTo, T? value, INatsSerializer serializer)
-    {
-        var offset = 0;
-        var maxLengthWithoutPayload = CommandConstants.PubWithPadding.Length
-            + subject.Length + 1
-            + (replyTo == null ? 0 : replyTo.Length + 1)
-            + MaxIntStringLength
-            + NewLineLength;
-
-        var writableSpan = _writer.GetSpan(maxLengthWithoutPayload);
-
-        CommandConstants.PubWithPadding.CopyTo(writableSpan);
-        offset += CommandConstants.PubWithPadding.Length;
-
-        subject.WriteASCIIBytes(writableSpan.Slice(offset));
-        offset += subject.Length;
-        writableSpan.Slice(offset)[0] = (byte)' ';
-        offset += 1;
+        // End of message first line
+        _writer.WriteNewLine();
 
-        if (replyTo != null)
+        if (headers != null)
         {
-            replyTo.WriteASCIIBytes(writableSpan.Slice(offset));
-            offset += replyTo.Length;
-            writableSpan.Slice(offset)[0] = (byte)' ';
-            offset += 1;
+            _writer.WriteSpan(CommandConstants.NatsHeaders10NewLine);
+            _writer.WriteSpan(_bufferHeaders.WrittenSpan);
         }
 
-        // Advance for written.
-        _writer.Advance(offset);
-
-        // preallocate range for write #bytes(write after serialized)
-        var preallocatedRange = _writer.PreAllocate(MaxIntStringLength);
-        offset += MaxIntStringLength;
-
-        CommandConstants.NewLine.CopyTo(writableSpan.Slice(offset));
-        _writer.Advance(CommandConstants.NewLine.Length);
-
-        var payloadLength = serializer.Serialize(_writer, value);
-        var payloadLengthSpan = _writer.GetSpanInPreAllocated(preallocatedRange);
-        payloadLengthSpan.Fill((byte)' ');
-        if (!Utf8Formatter.TryFormat(payloadLength, payloadLengthSpan, out var written))
+        if (payload.Length != 0)
         {
-            throw new NatsException("Can not format integer.");
+            _writer.WriteSequence(payload);
         }
 
-        WriteConstant(CommandConstants.NewLine);
+        _writer.WriteNewLine();
     }
 
-    public void WritePublish<T>(string subject, ReadOnlyMemory<byte> inboxPrefix, int id, T? value, INatsSerializer serializer)
+    public void WritePublish<T>(string subject, string? replyTo, NatsHeaders? headers, T? value, INatsSerializer serializer)
     {
-        Span<byte> idBytes = stackalloc byte[10];
-        if (Utf8Formatter.TryFormat(id, idBytes, out var written))
-        {
-            idBytes = idBytes.Slice(0, written);
-        }
-
-        var offset = 0;
-        var maxLengthWithoutPayload = CommandConstants.PubWithPadding.Length
-            + subject.Length + 1
-            + (inboxPrefix.Length + idBytes.Length + 1) // with space
-            + MaxIntStringLength
-            + NewLineLength;
-
-        var writableSpan = _writer.GetSpan(maxLengthWithoutPayload);
-
-        CommandConstants.PubWithPadding.CopyTo(writableSpan);
-        offset += CommandConstants.PubWithPadding.Length;
-
-        subject.WriteASCIIBytes(writableSpan.Slice(offset));
-        offset += subject.Length;
-        writableSpan.Slice(offset)[0] = (byte)' ';
-        offset += 1;
-
-        // build reply-to
-        inboxPrefix.Span.CopyTo(writableSpan.Slice(offset));
-        offset += inboxPrefix.Length;
-        idBytes.CopyTo(writableSpan.Slice(offset));
-        offset += idBytes.Length;
-        writableSpan.Slice(offset)[0] = (byte)' ';
-        offset += 1;
-
-        // Advance for written.
-        _writer.Advance(offset);
-
-        // preallocate range for write #bytes(write after serialized)
-        var preallocatedRange = _writer.PreAllocate(MaxIntStringLength);
-        offset += MaxIntStringLength;
-
-        CommandConstants.NewLine.CopyTo(writableSpan.Slice(offset));
-        _writer.Advance(CommandConstants.NewLine.Length);
-
-        var payloadLength = serializer.Serialize(_writer, value);
-        var payloadLengthSpan = _writer.GetSpanInPreAllocated(preallocatedRange);
-        payloadLengthSpan.Fill((byte)' ');
-        if (!Utf8Formatter.TryFormat(payloadLength, payloadLengthSpan, out written))
-        {
-            throw new NatsException("Can not format integer.");
-        }
-
-        WriteConstant(CommandConstants.NewLine);
+        _bufferPayload.Reset();
+        serializer.Serialize(_bufferPayload, value);
+        var payload = new ReadOnlySequence<byte>(_bufferPayload.WrittenMemory);
+        WritePublish(subject, replyTo, headers, payload);
     }
 
     // https://docs.nats.io/reference/reference-protocols/nats-protocol#sub