Refactored serialization logic to use Span<byte> for buffer manipulation, improving performance, memory efficiency, and code readability. Updated method signatures to eliminate explicit writePosition management, replaced incremental write logic with consistent += operations, and streamlined encoding methods. Enhanced test coverage to validate edge cases and updated all test cases to align with the new implementation. Applied changes consistently across all serializers, ensuring backward compatibility and laying the groundwork for future optimizations. Improved error handling, debugging, and documentation for better maintainability and robustness.

Author: paulomorgado

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/Implementation/Serializer/ProtobufOtlpLogSerializer.cs

@@ -62,13 +62,13 @@ internal static int TryWriteResourceLogs(ref byte[] buffer, int writePosition, S
 
             try
             {
-                writePosition = ProtobufSerializer.WriteTag(buffer, writePosition, ProtobufOtlpLogFieldNumberConstants.LogsData_Resource_Logs, ProtobufWireType.LEN);
+                writePosition += ProtobufSerializer.WriteTag(buffer.AsSpan(writePosition), ProtobufOtlpLogFieldNumberConstants.LogsData_Resource_Logs, ProtobufWireType.LEN);
                 int logsDataLengthPosition = writePosition;
                 writePosition += ReserveSizeForLength;
 
                 writePosition = WriteResourceLogs(buffer, writePosition, sdkLimitOptions, experimentalOptions, resource, scopeLogs);
 
-                ProtobufSerializer.WriteReservedLength(buffer, logsDataLengthPosition, writePosition - (logsDataLengthPosition + ReserveSizeForLength));
+                ProtobufSerializer.WriteReservedLength(buffer.AsSpan(logsDataLengthPosition), writePosition - (logsDataLengthPosition + ReserveSizeForLength));
 
                 // Serialization succeeded, return the final write position
                 return writePosition;
@@ -129,12 +129,12 @@ internal static int WriteScopeLogs(byte[] buffer, int writePosition, SdkLimitOpt
         {
             foreach (KeyValuePair<string, List<LogRecord>> entry in scopeLogs)
             {
-                writePosition = ProtobufSerializer.WriteTag(buffer, writePosition, ProtobufOtlpLogFieldNumberConstants.ResourceLogs_Scope_Logs, ProtobufWireType.LEN);
+                writePosition += ProtobufSerializer.WriteTag(buffer.AsSpan(writePosition), ProtobufOtlpLogFieldNumberConstants.ResourceLogs_Scope_Logs, ProtobufWireType.LEN);
                 int resourceLogsScopeLogsLengthPosition = writePosition;
                 writePosition += ReserveSizeForLength;
 
                 writePosition = WriteScopeLog(buffer, writePosition, sdkLimitOptions, experimentalOptions, entry.Value[0].Logger.Name, entry.Value);
-                ProtobufSerializer.WriteReservedLength(buffer, resourceLogsScopeLogsLengthPosition, writePosition - (resourceLogsScopeLogsLengthPosition + ReserveSizeForLength));
+                ProtobufSerializer.WriteReservedLength(buffer.AsSpan(resourceLogsScopeLogsLengthPosition), writePosition - (resourceLogsScopeLogsLengthPosition + ReserveSizeForLength));
             }
         }
 
@@ -148,8 +148,8 @@ internal static int WriteScopeLog(byte[] buffer, int writePosition, SdkLimitOpti
         var serializedLengthSize = ProtobufSerializer.ComputeVarInt64Size((ulong)numberOfUtf8CharsInString);
 
         // numberOfUtf8CharsInString + tagSize + length field size.
-        writePosition = ProtobufSerializer.WriteTagAndLength(buffer, writePosition, numberOfUtf8CharsInString + 1 + serializedLengthSize, ProtobufOtlpLogFieldNumberConstants.ScopeLogs_Scope, ProtobufWireType.LEN);
-        writePosition = ProtobufSerializer.WriteStringWithTag(buffer, writePosition, ProtobufOtlpCommonFieldNumberConstants.InstrumentationScope_Name, numberOfUtf8CharsInString, value);
+        writePosition += ProtobufSerializer.WriteTagAndLength(buffer.AsSpan(writePosition), numberOfUtf8CharsInString + 1 + serializedLengthSize, ProtobufOtlpLogFieldNumberConstants.ScopeLogs_Scope, ProtobufWireType.LEN);
+        writePosition += ProtobufSerializer.WriteStringWithTag(buffer.AsSpan(writePosition), ProtobufOtlpCommonFieldNumberConstants.InstrumentationScope_Name, numberOfUtf8CharsInString, value);
 
         for (int i = 0; i < logRecords.Count; i++)
         {
@@ -175,23 +175,23 @@ internal static int WriteLogRecord(byte[] buffer, int writePosition, SdkLimitOpt
 
         ref var otlpTagWriterState = ref state.TagWriterState;
 
-        otlpTagWriterState.WritePosition = ProtobufSerializer.WriteTag(otlpTagWriterState.Buffer, otlpTagWriterState.WritePosition, ProtobufOtlpLogFieldNumberConstants.ScopeLogs_Log_Records, ProtobufWireType.LEN);
+        otlpTagWriterState.WritePosition += ProtobufSerializer.WriteTag(otlpTagWriterState.Buffer.AsSpan(otlpTagWriterState.WritePosition), ProtobufOtlpLogFieldNumberConstants.ScopeLogs_Log_Records, ProtobufWireType.LEN);
         int logRecordLengthPosition = otlpTagWriterState.WritePosition;
         otlpTagWriterState.WritePosition += ReserveSizeForLength;
 
         var timestamp = (ulong)logRecord.Timestamp.ToUnixTimeNanoseconds();
-        otlpTagWriterState.WritePosition = ProtobufSerializer.WriteFixed64WithTag(otlpTagWriterState.Buffer, otlpTagWriterState.WritePosition, ProtobufOtlpLogFieldNumberConstants.LogRecord_Time_Unix_Nano, timestamp);
-        otlpTagWriterState.WritePosition = ProtobufSerializer.WriteFixed64WithTag(otlpTagWriterState.Buffer, otlpTagWriterState.WritePosition, ProtobufOtlpLogFieldNumberConstants.LogRecord_Observed_Time_Unix_Nano, timestamp);
+        otlpTagWriterState.WritePosition += ProtobufSerializer.WriteFixed64WithTag(otlpTagWriterState.Buffer.AsSpan(otlpTagWriterState.WritePosition), ProtobufOtlpLogFieldNumberConstants.LogRecord_Time_Unix_Nano, timestamp);
+        otlpTagWriterState.WritePosition += ProtobufSerializer.WriteFixed64WithTag(otlpTagWriterState.Buffer.AsSpan(otlpTagWriterState.WritePosition), ProtobufOtlpLogFieldNumberConstants.LogRecord_Observed_Time_Unix_Nano, timestamp);
 
-        otlpTagWriterState.WritePosition = ProtobufSerializer.WriteEnumWithTag(otlpTagWriterState.Buffer, otlpTagWriterState.WritePosition, ProtobufOtlpLogFieldNumberConstants.LogRecord_Severity_Number, logRecord.Severity.HasValue ? (int)logRecord.Severity : 0);
+        otlpTagWriterState.WritePosition += ProtobufSerializer.WriteEnumWithTag(otlpTagWriterState.Buffer.AsSpan(otlpTagWriterState.WritePosition), ProtobufOtlpLogFieldNumberConstants.LogRecord_Severity_Number, logRecord.Severity.HasValue ? (int)logRecord.Severity : 0);
 
         if (!string.IsNullOrWhiteSpace(logRecord.SeverityText))
         {
-            otlpTagWriterState.WritePosition = ProtobufSerializer.WriteStringWithTag(otlpTagWriterState.Buffer, otlpTagWriterState.WritePosition, ProtobufOtlpLogFieldNumberConstants.LogRecord_Severity_Text, logRecord.SeverityText!);
+            otlpTagWriterState.WritePosition += ProtobufSerializer.WriteStringWithTag(otlpTagWriterState.Buffer.AsSpan(otlpTagWriterState.WritePosition), ProtobufOtlpLogFieldNumberConstants.LogRecord_Severity_Text, logRecord.SeverityText!);
         }
         else if (logRecord.Severity.HasValue)
         {
-            otlpTagWriterState.WritePosition = ProtobufSerializer.WriteStringWithTag(otlpTagWriterState.Buffer, otlpTagWriterState.WritePosition, ProtobufOtlpLogFieldNumberConstants.LogRecord_Severity_Text, logRecord.Severity.Value.ToShortName());
+            otlpTagWriterState.WritePosition += ProtobufSerializer.WriteStringWithTag(otlpTagWriterState.Buffer.AsSpan(otlpTagWriterState.WritePosition), ProtobufOtlpLogFieldNumberConstants.LogRecord_Severity_Text, logRecord.Severity.Value.ToShortName());
         }
 
         if (experimentalOptions.EmitLogEventAttributes)
@@ -248,30 +248,29 @@ internal static int WriteLogRecord(byte[] buffer, int writePosition, SdkLimitOpt
 
         if (logRecord.TraceId != default && logRecord.SpanId != default)
         {
-            otlpTagWriterState.WritePosition = ProtobufSerializer.WriteTagAndLength(otlpTagWriterState.Buffer, otlpTagWriterState.WritePosition, TraceIdSize, ProtobufOtlpLogFieldNumberConstants.LogRecord_Trace_Id, ProtobufWireType.LEN);
+            otlpTagWriterState.WritePosition += ProtobufSerializer.WriteTagAndLength(otlpTagWriterState.Buffer.AsSpan(otlpTagWriterState.WritePosition), TraceIdSize, ProtobufOtlpLogFieldNumberConstants.LogRecord_Trace_Id, ProtobufWireType.LEN);
             otlpTagWriterState.WritePosition = ProtobufOtlpTraceSerializer.WriteTraceId(otlpTagWriterState.Buffer, otlpTagWriterState.WritePosition, logRecord.TraceId);
 
-            otlpTagWriterState.WritePosition = ProtobufSerializer.WriteTagAndLength(otlpTagWriterState.Buffer, otlpTagWriterState.WritePosition, SpanIdSize, ProtobufOtlpLogFieldNumberConstants.LogRecord_Span_Id, ProtobufWireType.LEN);
+            otlpTagWriterState.WritePosition += ProtobufSerializer.WriteTagAndLength(otlpTagWriterState.Buffer.AsSpan(otlpTagWriterState.WritePosition), SpanIdSize, ProtobufOtlpLogFieldNumberConstants.LogRecord_Span_Id, ProtobufWireType.LEN);
             otlpTagWriterState.WritePosition = ProtobufOtlpTraceSerializer.WriteSpanId(otlpTagWriterState.Buffer, otlpTagWriterState.WritePosition, logRecord.SpanId);
 
-            otlpTagWriterState.WritePosition = ProtobufSerializer.WriteFixed32WithTag(otlpTagWriterState.Buffer, otlpTagWriterState.WritePosition, ProtobufOtlpLogFieldNumberConstants.LogRecord_Flags, (uint)logRecord.TraceFlags);
+            otlpTagWriterState.WritePosition += ProtobufSerializer.WriteFixed32WithTag(otlpTagWriterState.Buffer.AsSpan(otlpTagWriterState.WritePosition), ProtobufOtlpLogFieldNumberConstants.LogRecord_Flags, (uint)logRecord.TraceFlags);
         }
 
         if (logRecord.EventId.Name != null)
         {
-            otlpTagWriterState.WritePosition = ProtobufSerializer.WriteStringWithTag(otlpTagWriterState.Buffer, otlpTagWriterState.WritePosition, ProtobufOtlpLogFieldNumberConstants.LogRecord_Event_Name, logRecord.EventId.Name!);
+            otlpTagWriterState.WritePosition += ProtobufSerializer.WriteStringWithTag(otlpTagWriterState.Buffer.AsSpan(otlpTagWriterState.WritePosition), ProtobufOtlpLogFieldNumberConstants.LogRecord_Event_Name, logRecord.EventId.Name!);
         }
 
         logRecord.ForEachScope(ProcessScope, state);
 
         if (otlpTagWriterState.DroppedTagCount > 0)
         {
-            otlpTagWriterState.WritePosition = ProtobufSerializer.WriteTag(buffer, otlpTagWriterState.WritePosition, ProtobufOtlpLogFieldNumberConstants.LogRecord_Dropped_Attributes_Count, ProtobufWireType.VARINT);
-            otlpTagWriterState.WritePosition = ProtobufSerializer.WriteVarInt32(buffer, otlpTagWriterState.WritePosition, (uint)otlpTagWriterState.DroppedTagCount);
+            otlpTagWriterState.WritePosition += ProtobufSerializer.WriteTag(buffer.AsSpan(otlpTagWriterState.WritePosition), ProtobufOtlpLogFieldNumberConstants.LogRecord_Dropped_Attributes_Count, ProtobufWireType.VARINT);
+            otlpTagWriterState.WritePosition += ProtobufSerializer.WriteVarInt32(buffer.AsSpan(otlpTagWriterState.WritePosition), (uint)otlpTagWriterState.DroppedTagCount);
         }
 
-        ProtobufSerializer.WriteReservedLength(otlpTagWriterState.Buffer, logRecordLengthPosition, otlpTagWriterState.WritePosition - (logRecordLengthPosition + ReserveSizeForLength));
-
+        ProtobufSerializer.WriteReservedLength(otlpTagWriterState.Buffer.AsSpan(logRecordLengthPosition), otlpTagWriterState.WritePosition - (logRecordLengthPosition + ReserveSizeForLength));
         return otlpTagWriterState.WritePosition;
 
         static void ProcessScope(LogRecordScope scope, SerializationState state)
@@ -314,8 +313,9 @@ private static int WriteLogRecordBody(byte[] buffer, int writePosition, ReadOnly
         var serializedLengthSize = ProtobufSerializer.ComputeVarInt64Size((ulong)numberOfUtf8CharsInString);
 
         // length = numberOfUtf8CharsInString + tagSize + length field size.
-        writePosition = ProtobufSerializer.WriteTagAndLength(buffer, writePosition, numberOfUtf8CharsInString + 1 + serializedLengthSize, ProtobufOtlpLogFieldNumberConstants.LogRecord_Body, ProtobufWireType.LEN);
-        writePosition = ProtobufSerializer.WriteStringWithTag(buffer, writePosition, ProtobufOtlpCommonFieldNumberConstants.AnyValue_String_Value, numberOfUtf8CharsInString, value);
+
+        writePosition += ProtobufSerializer.WriteTagAndLength(buffer.AsSpan(writePosition), numberOfUtf8CharsInString + 1 + serializedLengthSize, ProtobufOtlpLogFieldNumberConstants.LogRecord_Body, ProtobufWireType.LEN);
+        writePosition += ProtobufSerializer.WriteStringWithTag(buffer.AsSpan(writePosition), ProtobufOtlpCommonFieldNumberConstants.AnyValue_String_Value, numberOfUtf8CharsInString, value);
         return writePosition;
     }
 
@@ -332,14 +332,14 @@ private static void AddLogAttribute(SerializationState state, string key, object
         }
         else
         {
-            state.TagWriterState.WritePosition = ProtobufSerializer.WriteTag(state.TagWriterState.Buffer, state.TagWriterState.WritePosition, ProtobufOtlpLogFieldNumberConstants.LogRecord_Attributes, ProtobufWireType.LEN);
+            state.TagWriterState.WritePosition += ProtobufSerializer.WriteTag(state.TagWriterState.Buffer.AsSpan(state.TagWriterState.WritePosition), ProtobufOtlpLogFieldNumberConstants.LogRecord_Attributes, ProtobufWireType.LEN);
             int logAttributesLengthPosition = state.TagWriterState.WritePosition;
             state.TagWriterState.WritePosition += ReserveSizeForLength;
 
             ProtobufOtlpTagWriter.Instance.TryWriteTag(ref state.TagWriterState, key, value, state.AttributeValueLengthLimit);
 
             var logAttributesLength = state.TagWriterState.WritePosition - (logAttributesLengthPosition + ReserveSizeForLength);
-            ProtobufSerializer.WriteReservedLength(state.TagWriterState.Buffer, logAttributesLengthPosition, logAttributesLength);
+            ProtobufSerializer.WriteReservedLength(state.TagWriterState.Buffer.AsSpan(logAttributesLengthPosition), logAttributesLength);
             state.TagWriterState.TagCount++;
         }
     }