Replace array with slice in writer implementation

Author: stringintech

kernel/writer_helper.go

@@ -1,7 +1,6 @@
 package kernel
 
-// Writer implementation that minimizes memory copies where possible
-// by using direct memory operations, though buffer growth requires copying
+// Writer implementation that minimizes memory copies
 
 /*
 #include "kernel/bitcoinkernel.h"
@@ -20,9 +19,8 @@ import (
 // writerCallbackData holds the growing buffer that collects written bytes
 // Uses a capacity-based growth strategy to reduce reallocations
 type writerCallbackData struct {
-	buffer   []byte // Pre-allocated buffer
-	position int    // Current write position
-	err      error
+	buffer []byte // Pre-allocated buffer
+	err    error
 }
 
 //export go_writer_callback_bridge
@@ -32,40 +30,18 @@ func go_writer_callback_bridge(bytes unsafe.Pointer, size C.size_t, userdata uns
 	// Retrieve original Go callback data struct
 	data := handle.Value().(*writerCallbackData)
 
-	bytesSize := int(size)
-	requiredCapacity := data.position + bytesSize
-
-	// Grow buffer if needed (double capacity strategy)
-	if requiredCapacity > len(data.buffer) {
-		newCapacity := len(data.buffer) * 2
-		if newCapacity < requiredCapacity {
-			newCapacity = requiredCapacity
-		}
-		newBuffer := make([]byte, newCapacity)
-		copy(newBuffer[:data.position], data.buffer[:data.position])
-		data.buffer = newBuffer
-	}
-
-	if bytesSize > 0 {
-		// Get pointer to destination in Go buffer
-		dstPtr := unsafe.Pointer(&data.buffer[data.position])
-		// Use C's memmove to copy directly
-		C.memmove(dstPtr, bytes, size)
-		data.position += bytesSize
+	if size > 0 {
+		// Create a Go slice view of the C memory
+		cBytes := unsafe.Slice((*byte)(bytes), int(size))
+		data.buffer = append(data.buffer, cBytes...)
 	}
-
-	return 0 // success
+	return 0
 }
 
 // writeToBytes is a helper function that uses a callback pattern to collect bytes
 // It takes a function that calls the C API with the writer callback
 func writeToBytes(writerFunc func(C.btck_WriteBytes, unsafe.Pointer) C.int) ([]byte, error) {
-	// Pre-allocate buffer with reasonable initial capacity
-	initialCapacity := 1024 // Start with 1KB, will grow as needed
-	callbackData := &writerCallbackData{
-		buffer:   make([]byte, initialCapacity),
-		position: 0,
-	}
+	callbackData := &writerCallbackData{}
 
 	// Create cgo handle for the callback data
 	handle := cgo.NewHandle(callbackData)
@@ -82,5 +58,5 @@ func writeToBytes(writerFunc func(C.btck_WriteBytes, unsafe.Pointer) C.int) ([]b
 	}
 
 	// Return exactly the bytes that were written (slice the buffer to actual size)
-	return callbackData.buffer[:callbackData.position], nil
+	return callbackData.buffer, nil
 }