Drop or rename TODOs (issues will be created) and use logging for unexpected frame

rsocket-core/src/commonMain/kotlin/io/rsocket/kotlin/connection/ConnectionInbound.kt

@@ -54,7 +54,7 @@ internal class ConnectionInbound(
     }
 
     private fun receiveError(cause: Throwable) {
-        throw cause // TODO?
+        throw cause
     }
 
     fun createOperation(type: FrameType, requestJob: Job): ResponderOperation = when (type) {

rsocket-core/src/commonMain/kotlin/io/rsocket/kotlin/connection/ConnectionInitializer.kt

@@ -20,13 +20,16 @@ import io.rsocket.kotlin.*
 import io.rsocket.kotlin.core.*
 import io.rsocket.kotlin.frame.*
 import io.rsocket.kotlin.internal.io.*
+import io.rsocket.kotlin.logging.*
 import io.rsocket.kotlin.transport.*
 import kotlinx.coroutines.*
 
+@RSocketLoggingApi
 @RSocketTransportApi
 internal abstract class ConnectionInitializer(
     private val isClient: Boolean,
     private val frameCodec: FrameCodec,
+    private val frameLogger: Logger,
     private val connectionAcceptor: ConnectionAcceptor,
     private val interceptors: Interceptors,
 ) {
@@ -42,11 +45,11 @@ internal abstract class ConnectionInitializer(
                 else     -> connection.acceptStream() ?: error("Initial stream should be received")
             }
             initialStream.setSendPriority(0)
-            MultiplexedConnection(isClient, frameCodec, connection, initialStream, requestsScope)
+            MultiplexedConnection(isClient, frameCodec, frameLogger, connection, initialStream, requestsScope)
         }
 
         is RSocketSequentialConnection  -> {
-            SequentialConnection(isClient, frameCodec, connection, requestsScope)
+            SequentialConnection(isClient, frameCodec, frameLogger, connection, requestsScope)
         }
     }
 

rsocket-core/src/commonMain/kotlin/io/rsocket/kotlin/connection/MultiplexedConnection.kt

@@ -16,18 +16,22 @@
 
 package io.rsocket.kotlin.connection
 
+import io.rsocket.kotlin.*
 import io.rsocket.kotlin.frame.*
 import io.rsocket.kotlin.internal.*
+import io.rsocket.kotlin.logging.*
 import io.rsocket.kotlin.operation.*
 import io.rsocket.kotlin.payload.*
 import io.rsocket.kotlin.transport.*
 import kotlinx.coroutines.*
 import kotlinx.io.*
 
+@RSocketLoggingApi
 @RSocketTransportApi
 internal class MultiplexedConnection(
     isClient: Boolean,
     frameCodec: FrameCodec,
+    private val frameLogger: Logger,
     private val connection: RSocketMultiplexedConnection,
     private val initialStream: RSocketMultiplexedConnection.Stream,
     private val requestsScope: CoroutineScope,
@@ -146,7 +150,7 @@ internal class MultiplexedConnection(
                         // request is cancelled during fragmentation
                         is CancelFrame  -> error("Request was cancelled by remote party")
                         is RequestFrame -> {
-                            // TODO: extract assembly logic?
+                            // TODO[fragmentation]: extract assembly logic?
                             when {
                                 // for RC, it could contain the complete flag
                                 // complete+follows=complete, "complete" overrides "follows" flag
@@ -194,7 +198,7 @@ internal class MultiplexedConnection(
     ): Unit = coroutineScope {
         val outbound = Outbound(streamId, stream)
         val receiveJob = launch {
-            val handler = OperationFrameHandler(operation)
+            val handler = OperationFrameHandler(operation, frameLogger)
             try {
                 while (true) {
                     val frame = frameCodec.decodeFrame(

rsocket-core/src/commonMain/kotlin/io/rsocket/kotlin/connection/SequentialConnection.kt

@@ -16,17 +16,21 @@
 
 package io.rsocket.kotlin.connection
 
+import io.rsocket.kotlin.*
 import io.rsocket.kotlin.frame.*
+import io.rsocket.kotlin.logging.*
 import io.rsocket.kotlin.operation.*
 import io.rsocket.kotlin.payload.*
 import io.rsocket.kotlin.transport.*
 import kotlinx.coroutines.*
 import kotlinx.io.*
 
+@RSocketLoggingApi
 @RSocketTransportApi
 internal class SequentialConnection(
     isClient: Boolean,
     frameCodec: FrameCodec,
+    private val frameLogger: Logger,
     private val connection: RSocketSequentialConnection,
     private val requestsScope: CoroutineScope,
 ) : ConnectionOutbound(frameCodec) {
@@ -60,7 +64,7 @@ internal class SequentialConnection(
     ): Job = requestsScope.launch(start = CoroutineStart.ATOMIC) {
         operation.handleExecutionFailure(requestPayload) {
             ensureActive() // because of atomic start
-            val streamId = storage.createStream(OperationFrameHandler(operation))
+            val streamId = storage.createStream(OperationFrameHandler(operation, frameLogger))
             try {
                 operation.execute(Outbound(streamId), requestPayload)
             } finally {
@@ -116,7 +120,8 @@ internal class SequentialConnection(
                     when {
                         frame.follows -> ResponderInboundWrapper(connectionInbound, operationData)
                         else          -> acceptRequest(connectionInbound, operationData)
-                    }
+                    },
+                    frameLogger
                 )
                 if (storage.acceptStream(streamId, handler)) {
                     // for fragmentation
@@ -159,7 +164,7 @@ internal class SequentialConnection(
                     )
                 )
                 // close old handler
-                storage.replaceStream(operationData.streamId, OperationFrameHandler(operation))?.close()
+                storage.replaceStream(operationData.streamId, OperationFrameHandler(operation, frameLogger))?.close()
             } else {
                 // should not happen really
                 storage.removeStream(operationData.streamId)?.close()

rsocket-core/src/commonMain/kotlin/io/rsocket/kotlin/core/RSocketConnector.kt

@@ -66,6 +66,7 @@ public class RSocketConnector internal constructor(
     private inner class SetupConnection() : ConnectionInitializer(
         isClient = true,
         frameCodec = FrameCodec(maxFragmentSize),
+        frameLogger = frameLogger,
         connectionAcceptor = acceptor,
         interceptors = interceptors
     ) {

rsocket-core/src/commonMain/kotlin/io/rsocket/kotlin/core/RSocketServer.kt

@@ -66,6 +66,7 @@ public class RSocketServer internal constructor(
     private inner class AcceptConnection(acceptor: ConnectionAcceptor) : ConnectionInitializer(
         isClient = false,
         frameCodec = FrameCodec(maxFragmentSize),
+        frameLogger = frameLogger,
         connectionAcceptor = acceptor,
         interceptors = interceptors
     ) {

rsocket-core/src/commonMain/kotlin/io/rsocket/kotlin/frame/Frame.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2024 the original author or authors.
+ * Copyright 2015-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -41,7 +41,8 @@ internal sealed class Frame : AutoCloseable {
     }
 
     internal fun dump(length: Long): String = buildString {
-        append("\n").append(type).append(" frame -> Stream Id: ").append(streamId).append(" Length: ").append(length)
+        append("\n").append(type).append(" frame -> Stream Id: ").append(streamId)
+        if (length != -1L) append(" Length: ").append(length)
         append("\nFlags: 0b").append(flags.toBinaryString()).append(" (").apply { appendFlags() }.append(")")
         appendSelf()
     }

rsocket-core/src/commonMain/kotlin/io/rsocket/kotlin/frame/FrameCodec.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2024 the original author or authors.
+ * Copyright 2015-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -32,5 +32,5 @@ internal class FrameCodec(
 
     fun encodeFrame(frame: Frame): Buffer = frame.toBuffer()
 
-    // TODO: move fragmentation logic here or into separate class?
+    // TODO[fragmentation]: move fragmentation logic here or into separate class?
 }

rsocket-core/src/commonMain/kotlin/io/rsocket/kotlin/frame/RequestFrame.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2024 the original author or authors.
+ * Copyright 2015-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -78,7 +78,7 @@ internal fun Source.readRequest(
     return RequestFrame(type, streamId, fragmentFollows, complete, next, initialRequest, payload)
 }
 
-//TODO rename or remove on fragmentation implementation
+//TODO[fragmentation] rename or remove on fragmentation implementation
 internal fun RequestFireAndForgetFrame(streamId: Int, payload: Payload): RequestFrame =
     RequestFrame(FrameType.RequestFnF, streamId, false, false, false, 0, payload)
 

rsocket-core/src/commonMain/kotlin/io/rsocket/kotlin/frame/SetupFrame.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2024 the original author or authors.
+ * Copyright 2015-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,7 +25,7 @@ private const val HonorLeaseFlag = 64
 private const val ResumeEnabledFlag = 128
 
 internal class SetupFrame(
-    val version: Version, //TODO check
+    val version: Version,
     val honorLease: Boolean,
     val keepAlive: KeepAlive,
     val resumeToken: Buffer?,
@@ -104,7 +104,7 @@ private fun Source.readStringMimeType(): String {
 }
 
 private fun Sink.writeStringMimeType(mimeType: String) {
-    val bytes = mimeType.encodeToByteArray() //TODO check
+    val bytes = mimeType.encodeToByteArray()
     writeByte(bytes.size.toByte())
     write(bytes)
 }

rsocket-core/src/commonMain/kotlin/io/rsocket/kotlin/internal/IntMap.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2024 the original author or authors.
+ * Copyright 2015-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,11 +24,6 @@ private fun safeFindNextPositivePowerOfTwo(value: Int): Int = when {
     else                -> 1 shl 32 - (value - 1).countLeadingZeroBits()
 }
 
-// TODO: may be move to `internal-io` (and rename to just `rsocket-internal`)
-//  and use in prioritization queue to support more granular prioritization for streams
-//
-// TODO decide, is it needed, or can be replaced by simple map, or concurrent map on JVM?
-//  do benchmarks
 /**
  * IntMap implementation based on Netty IntObjectHashMap.
  */

rsocket-core/src/commonMain/kotlin/io/rsocket/kotlin/internal/PayloadAssembler.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2024 the original author or authors.
+ * Copyright 2015-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,9 +20,8 @@ import io.rsocket.kotlin.frame.io.*
 import io.rsocket.kotlin.payload.*
 import kotlinx.io.*
 
-// TODO: make metadata should be fully transmitted before data
+// TODO[fragmentation]: make metadata should be fully transmitted before data
 internal class PayloadAssembler : AutoCloseable {
-    // TODO: better name
     val hasPayload: Boolean
         get() = data != null
 

rsocket-core/src/commonMain/kotlin/io/rsocket/kotlin/internal/PayloadChannel.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2024 the original author or authors.
+ * Copyright 2015-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,7 +24,6 @@ import kotlinx.coroutines.channels.*
 import kotlinx.coroutines.flow.*
 
 internal class PayloadChannel {
-    // TODO: capacity should be configurable
     private val payloads = channelForCloseable<Payload>(Channel.UNLIMITED)
     private val requestNs = Channel<Int>(Channel.UNLIMITED)
 
@@ -39,7 +38,6 @@ internal class PayloadChannel {
 
     @ExperimentalStreamsApi
     suspend fun consumeInto(collector: FlowCollector<Payload>, strategy: RequestStrategy.Element): Throwable? {
-        // TODO: requestNs should be cancelled on success path?
         payloads.consume {
             while (true) {
                 payloads

rsocket-core/src/commonMain/kotlin/io/rsocket/kotlin/operation/OperationInbound.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2024 the original author or authors.
+ * Copyright 2015-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,8 +16,10 @@
 
 package io.rsocket.kotlin.operation
 
+import io.rsocket.kotlin.*
 import io.rsocket.kotlin.frame.*
 import io.rsocket.kotlin.internal.*
+import io.rsocket.kotlin.logging.*
 import io.rsocket.kotlin.payload.*
 
 internal interface OperationInbound {
@@ -33,8 +35,11 @@ internal interface OperationInbound {
     fun receiveDone() {}
 }
 
-// TODO: merge into OperationInbound?
-internal class OperationFrameHandler(private val inbound: OperationInbound) {
+@RSocketLoggingApi
+internal class OperationFrameHandler(
+    private val inbound: OperationInbound,
+    private val frameLogger: Logger,
+) {
     private val assembler = PayloadAssembler()
 
     fun close() {
@@ -47,8 +52,7 @@ internal class OperationFrameHandler(private val inbound: OperationInbound) {
 
     fun handleFrame(frame: Frame) {
         if (!inbound.shouldReceiveFrame(frame.type)) {
-            // TODO: replace with logging
-            println("unexpected frame: $frame")
+            frameLogger.debug { "Received unexpected frame: ${frame.dump(-1)}" }
             return frame.close()
         }
 
@@ -57,14 +61,13 @@ internal class OperationFrameHandler(private val inbound: OperationInbound) {
             is ErrorFrame    -> inbound.receiveErrorFrame(frame.throwable)
             is RequestNFrame -> inbound.receiveRequestNFrame(frame.requestN)
             is RequestFrame  -> {
-                // TODO: split frames
                 if (frame.initialRequest != 0) inbound.receiveRequestNFrame(frame.initialRequest)
 
                 val payload = when {
                     // complete+follows=complete
                     frame.complete -> when {
                         frame.next -> assembler.assemblePayload(frame.payload)
-                        // TODO - what if we previously received fragment?
+                        // TODO[fragmentation] - what if we previously received fragment?
                         else       -> {
                             check(!assembler.hasPayload) { "wrong combination of frames" }
                             null
@@ -85,11 +88,9 @@ internal class OperationFrameHandler(private val inbound: OperationInbound) {
                 }
 
                 inbound.receivePayloadFrame(payload, frame.complete)
-//
-//
-//                // TODO: recheck notes
-//                // TODO: if there are no fragments saved and there are no following - we can ignore going through buffer
-//                // TODO: really, fragment could be NULL when `complete` is true, but `next` is false
+
+//                // TODO[fragmentation]: if there are no fragments saved and there are no following - we can ignore going through buffer
+//                // TODO[fragmentation]: really, fragment could be NULL when `complete` is true, but `next` is false
 //                if (frame.next || frame.type.isRequestType) appendFragment(frame.payload)
 //                if (frame.complete) inbound.receivePayloadFrame(assemblePayload(), complete = true)
 //                else if (!frame.follows) inbound.receivePayloadFrame(assemblePayload(), complete = false)

rsocket-core/src/commonMain/kotlin/io/rsocket/kotlin/operation/OperationOutbound.kt

@@ -31,7 +31,7 @@ internal abstract class OperationOutbound(
     protected val streamId: Int,
     private val frameCodec: FrameCodec,
 ) {
-    // TODO: decide on it
+    // TODO[fragmentation]: decide on it
     // private var firstRequestFrameSent: Boolean = false
 
     protected abstract suspend fun sendFrame(frame: Buffer)
@@ -71,8 +71,7 @@ internal abstract class OperationOutbound(
         return sendRequestPayload(type, payload, complete, initialRequest)
     }
 
-    // TODO rework/simplify later
-    // TODO release on fail ?
+    // TODO[fragmentation] rework/simplify later, release on fail ?
     private suspend fun sendRequestPayload(type: FrameType, payload: Payload, complete: Boolean, initialRequest: Int) {
         if (!payload.isFragmentable(type.hasInitialRequest)) {
             return sendFrame(RequestFrame(type, streamId, false, complete, true, initialRequest, payload))

rsocket-core/src/commonMain/kotlin/io/rsocket/kotlin/operation/RequesterRequestChannelOperation.kt

@@ -77,7 +77,6 @@ internal class RequesterRequestChannelOperation(
         responsePayloads.isActive -> frameType == FrameType.Payload || frameType == FrameType.Error
         else                      -> false
     } || when {
-        // TODO: handle cancel, when `senderJob` is not started
         senderJob == null || senderJob?.isActive == true -> frameType == FrameType.RequestN || frameType == FrameType.Cancel
         else                                             -> false
     }

rsocket-core/src/commonMain/kotlin/io/rsocket/kotlin/operation/RequesterRequestResponseOperation.kt

@@ -35,7 +35,6 @@ internal class RequesterRequestResponseOperation(
             )
             responseDeferred.join()
         } catch (cause: Throwable) {
-            // TODO: we don't need to send cancel if we have sent no frames
             nonCancellable { outbound.sendCancel() }
             throw cause
         }

rsocket-core/src/commonMain/kotlin/io/rsocket/kotlin/operation/ResponderRequestChannelOperation.kt

@@ -72,7 +72,7 @@ internal class ResponderRequestChannelOperation(
         frameType === FrameType.Cancel || when {
             requestPayloads.isActive -> frameType === FrameType.Payload || frameType === FrameType.Error
             else                     -> false
-        } || frameType === FrameType.RequestN // TODO
+        } || frameType === FrameType.RequestN
 
     override fun receiveRequestNFrame(requestN: Int) {
         limiter.updateRequests(requestN)