feat: impl reader ydb topics

src/Ydb.Sdk/src/Services/Topic/Exceptions.cs

@@ -17,7 +17,20 @@ public WriterException(string message, Exception inner) : base(message, inner)
 
 public class ReaderException : Exception
 {
-    protected ReaderException(string message) : base(message)
+    public ReaderException(string message) : base(message)
     {
+        Status = new Status(StatusCode.Unspecified);
     }
+
+    public ReaderException(string message, Status status) : base(message + ": " + status)
+    {
+        Status = status;
+    }
+
+    public ReaderException(string message, Driver.TransportException e) : base(message, e)
+    {
+        Status = e.Status;
+    }
+
+    public Status Status { get; }
 }

src/Ydb.Sdk/src/Services/Topic/IReader.cs

@@ -2,9 +2,9 @@
 
 namespace Ydb.Sdk.Services.Topic;
 
-public interface IReader<TValue>
+public interface IReader<TValue> : IDisposable
 {
-    public Task<TValue> ReadAsync();
+    public ValueTask<Message<TValue>> ReadAsync(CancellationToken cancellationToken = default);
 
-    public Task<Message<TValue>> ReadMessageAsync();
+    public ValueTask<BatchMessage<TValue>> ReadBatchAsync(CancellationToken cancellationToken = default);
 }

src/Ydb.Sdk/src/Services/Topic/Reader/InternalMessage.cs

@@ -0,0 +1,89 @@
+using System.Collections.Immutable;
+using Google.Protobuf;
+using Google.Protobuf.Collections;
+using Google.Protobuf.WellKnownTypes;
+using Ydb.Topic;
+
+namespace Ydb.Sdk.Services.Topic.Reader;
+
+internal class InternalMessage
+{
+    public InternalMessage(
+        ByteString data,
+        string topic,
+        long partitionId,
+        string producerId,
+        OffsetsRange offsetsRange,
+        Timestamp createdAt,
+        RepeatedField<MetadataItem> metadataItems,
+        long dataSize)
+    {
+        Data = data;
+        Topic = topic;
+        PartitionId = partitionId;
+        ProducerId = producerId;
+        OffsetsRange = offsetsRange;
+        CreatedAt = createdAt;
+        MetadataItems = metadataItems;
+        DataSize = dataSize;
+    }
+
+    private ByteString Data { get; }
+
+    private string Topic { get; }
+
+    private long PartitionId { get; }
+
+    private string ProducerId { get; }
+
+    private OffsetsRange OffsetsRange { get; }
+
+    private Timestamp CreatedAt { get; }
+
+    private RepeatedField<MetadataItem> MetadataItems { get; }
+
+    private long DataSize { get; }
+
+    internal Message<TValue> ToPublicMessage<TValue>(IDeserializer<TValue> deserializer, ReaderSession readerSession)
+    {
+        return new Message<TValue>(
+            data: deserializer.Deserialize(Data.ToByteArray()),
+            topic: Topic,
+            partitionId: PartitionId,
+            producerId: ProducerId,
+            createdAt: CreatedAt.ToDateTime(),
+            metadata: MetadataItems.Select(item => new Metadata(item.Key, item.Value.ToByteArray())).ToImmutableArray(),
+            offsetsRange: OffsetsRange,
+            readerSession: readerSession
+        );
+    }
+}
+
+internal class InternalBatchMessage
+{
+    public InternalBatchMessage(
+        OffsetsRange batchOffsetsRange,
+        Queue<InternalMessage> internalMessages,
+        ReaderSession readerSession, 
+        long approximatelyBatchSize)
+    {
+        BatchOffsetsRange = batchOffsetsRange;
+        InternalMessages = internalMessages;
+        ReaderSession = readerSession;
+        ApproximatelyBatchSize = approximatelyBatchSize;
+    }
+
+    internal OffsetsRange BatchOffsetsRange { get; }
+
+    internal Queue<InternalMessage> InternalMessages { get; }
+
+    internal ReaderSession ReaderSession { get; }
+
+    internal long ApproximatelyBatchSize { get; }
+}
+
+internal record CommitSending(
+    OffsetsRange OffsetsRange,
+    long PartitionSessionId,
+    TaskCompletionSource TcsCommit
+);

src/Ydb.Sdk/src/Services/Topic/Reader/Message.cs

@@ -1,5 +1,92 @@
+using System.Collections.Immutable;
+using Ydb.Topic;
+
 namespace Ydb.Sdk.Services.Topic.Reader;
 
 public class Message<TValue>
 {
+    private readonly OffsetsRange _offsetsRange;
+    private readonly ReaderSession _readerSession;
+
+    internal Message(
+        TValue data,
+        string topic,
+        long partitionId,
+        string producerId,
+        DateTime createdAt,
+        ImmutableArray<Metadata> metadata,
+        OffsetsRange offsetsRange,
+        ReaderSession readerSession)
+    {
+        Data = data;
+        Topic = topic;
+        PartitionId = partitionId;
+        ProducerId = producerId;
+        CreatedAt = createdAt;
+        Metadata = metadata;
+
+        _offsetsRange = offsetsRange;
+        _readerSession = readerSession;
+    }
+
+    public TValue Data { get; }
+
+    /// <summary>
+    /// The topic associated with the message.
+    /// </summary>
+    public string Topic { get; }
+
+    public long PartitionId { get; }
+
+    public string ProducerId { get; }
+
+    public DateTime CreatedAt { get; }
+
+    public ImmutableArray<Metadata> Metadata { get; }
+
+    internal long Start => _offsetsRange.Start;
+    internal long End => _offsetsRange.End;
+
+    public Task CommitAsync()
+    {
+        return _readerSession.CommitOffsetRange(_offsetsRange, PartitionId);
+    }
+}
+
+public class BatchMessage<TValue>
+{
+    private readonly ReaderSession _readerSession;
+
+    public ImmutableArray<Message<TValue>> Batch { get; }
+
+    internal BatchMessage(ImmutableArray<Message<TValue>> batch, ReaderSession readerSession)
+    {
+        Batch = batch;
+        _readerSession = readerSession;
+    }
+
+    public Task CommitBatchAsync()
+    {
+        if (Batch.Length == 0)
+        {
+            return Task.CompletedTask;
+        }
+
+        var offsetsRange = new OffsetsRange { Start = Batch.First().Start, End = Batch.Last().End };
+
+        return _readerSession.CommitOffsetRange(offsetsRange, Batch.First().PartitionId);
+    }
+}
+
+public class TopicPartitionOffset
+{
+    public TopicPartitionOffset(long offset, long partitionId)
+    {
+        Offset = offset;
+        PartitionId = partitionId;
+    }
+
+    public long Offset { get; }
+
+    public long PartitionId { get; }
 }