switch to []unsafe.Pointer

Author: Noam Preil

arrow/ipc/message.go

@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"io"
 	"sync/atomic"
+	"unsafe"
 
 	"github.com/apache/arrow-go/v18/arrow/internal/debug"
 	"github.com/apache/arrow-go/v18/arrow/internal/flatbuf"
@@ -86,7 +87,7 @@ func NewMessage(meta, body *memory.Buffer) *Message {
 		body: body,
 	}
 	m.Refcount.Buffers = []**memory.Buffer{&m.meta, &m.body}
-	m.Additional = func() { m.msg = nil }
+	m.Derived = []unsafe.Pointer{unsafe.Pointer(&m.msg)}
 	m.Retain()
 	return m
 }
@@ -102,7 +103,7 @@ func newMessageFromFB(meta *flatbuf.Message, body *memory.Buffer) *Message {
 		body: body,
 	}
 	m.Refcount.Buffers = []**memory.Buffer{&m.meta, &m.body}
-	m.Additional = func() { m.msg = nil }
+	m.Derived = []unsafe.Pointer{unsafe.Pointer(&m.msg)}
 	m.Retain()
 	return m
 }

arrow/memory/refcount.go

@@ -2,6 +2,7 @@ package memory
 
 import (
 	"sync/atomic"
+	"unsafe"
 
 	"github.com/apache/arrow-go/v18/arrow/internal/debug"
 )
@@ -10,7 +11,7 @@ type Refcount struct {
 	count        atomic.Int64
 	Dependencies []**Refcount
 	Buffers []**Buffer
-	Additional func()
+	Derived []unsafe.Pointer
 }
 
 func (r *Refcount) Retain() {
@@ -30,8 +31,8 @@ func (r *Refcount) Release() {
 		}
 		r.Buffers = nil
 		r.Dependencies = nil
-		if r.Additional != nil {
-			r.Additional()
+		for _, derived := range r.Derived {
+			*((*uintptr)(derived)) = 0
 		}
 	} else if new < 0 {
 		// This branch can be optimized out when !debug