move inode operations(read/write) into package internal/common

Signed-off-by: Benjamin Wang <wachao@vmware.com>

internal/common/inode.go

@@ -1,5 +1,7 @@
 package common
 
+import "unsafe"
+
 // Inode represents an internal node inside of a node.
 // It can be used to point to elements in a page or point
 // to an element which hasn't been added to a page yet.
@@ -43,3 +45,61 @@ func (in *Inode) Value() []byte {
 func (in *Inode) SetValue(value []byte) {
 	in.value = value
 }
+
+func ReadInodeFromPage(p *Page) Inodes {
+	inodes := make(Inodes, int(p.Count()))
+	isLeaf := p.IsLeafPage()
+	for i := 0; i < int(p.Count()); i++ {
+		inode := &inodes[i]
+		if isLeaf {
+			elem := p.LeafPageElement(uint16(i))
+			inode.SetFlags(elem.Flags())
+			inode.SetKey(elem.Key())
+			inode.SetValue(elem.Value())
+		} else {
+			elem := p.BranchPageElement(uint16(i))
+			inode.SetPgid(elem.Pgid())
+			inode.SetKey(elem.Key())
+		}
+		Assert(len(inode.Key()) > 0, "read: zero-length inode key")
+	}
+
+	return inodes
+}
+
+func WriteInodeToPage(inodes Inodes, p *Page) uint32 {
+	// Loop over each item and write it to the page.
+	// off tracks the offset into p of the start of the next data.
+	off := unsafe.Sizeof(*p) + p.PageElementSize()*uintptr(len(inodes))
+	isLeaf := p.IsLeafPage()
+	for i, item := range inodes {
+		Assert(len(item.Key()) > 0, "write: zero-length inode key")
+
+		// Create a slice to write into of needed size and advance
+		// byte pointer for next iteration.
+		sz := len(item.Key()) + len(item.Value())
+		b := UnsafeByteSlice(unsafe.Pointer(p), off, 0, sz)
+		off += uintptr(sz)
+
+		// Write the page element.
+		if isLeaf {
+			elem := p.LeafPageElement(uint16(i))
+			elem.SetPos(uint32(uintptr(unsafe.Pointer(&b[0])) - uintptr(unsafe.Pointer(elem))))
+			elem.SetFlags(item.Flags())
+			elem.SetKsize(uint32(len(item.Key())))
+			elem.SetVsize(uint32(len(item.Value())))
+		} else {
+			elem := p.BranchPageElement(uint16(i))
+			elem.SetPos(uint32(uintptr(unsafe.Pointer(&b[0])) - uintptr(unsafe.Pointer(elem))))
+			elem.SetKsize(uint32(len(item.Key())))
+			elem.SetPgid(item.Pgid())
+			Assert(elem.Pgid() != p.Id(), "write: circular dependency occurred")
+		}
+
+		// Write data for the element to the end of the page.
+		l := copy(b, item.Key())
+		copy(b[l:], item.Value())
+	}
+
+	return uint32(off)
+}

internal/common/page.go

@@ -162,6 +162,13 @@ func (p *Page) hexdump(n int) {
 	fmt.Fprintf(os.Stderr, "%x\n", buf)
 }
 
+func (p *Page) PageElementSize() uintptr {
+	if p.IsLeafPage() {
+		return LeafPageElementSize
+	}
+	return BranchPageElementSize
+}
+
 func (p *Page) Id() Pgid {
 	return p.id
 }

node.go

@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"fmt"
 	"sort"
-	"unsafe"
 
 	"go.etcd.io/bbolt/internal/common"
 )
@@ -163,22 +162,7 @@ func (n *node) del(key []byte) {
 func (n *node) read(p *common.Page) {
 	n.pgid = p.Id()
 	n.isLeaf = p.IsLeafPage()
-	n.inodes = make(common.Inodes, int(p.Count()))
-
-	for i := 0; i < int(p.Count()); i++ {
-		inode := &n.inodes[i]
-		if n.isLeaf {
-			elem := p.LeafPageElement(uint16(i))
-			inode.SetFlags(elem.Flags())
-			inode.SetKey(elem.Key())
-			inode.SetValue(elem.Value())
-		} else {
-			elem := p.BranchPageElement(uint16(i))
-			inode.SetPgid(elem.Pgid())
-			inode.SetKey(elem.Key())
-		}
-		common.Assert(len(inode.Key()) > 0, "read: zero-length inode key")
-	}
+	n.inodes = common.ReadInodeFromPage(p)
 
 	// Save first key, so we can find the node in the parent when we spill.
 	if len(n.inodes) > 0 {
@@ -212,37 +196,7 @@ func (n *node) write(p *common.Page) {
 		return
 	}
 
-	// Loop over each item and write it to the page.
-	// off tracks the offset into p of the start of the next data.
-	off := unsafe.Sizeof(*p) + n.pageElementSize()*uintptr(len(n.inodes))
-	for i, item := range n.inodes {
-		common.Assert(len(item.Key()) > 0, "write: zero-length inode key")
-
-		// Create a slice to write into of needed size and advance
-		// byte pointer for next iteration.
-		sz := len(item.Key()) + len(item.Value())
-		b := common.UnsafeByteSlice(unsafe.Pointer(p), off, 0, sz)
-		off += uintptr(sz)
-
-		// Write the page element.
-		if n.isLeaf {
-			elem := p.LeafPageElement(uint16(i))
-			elem.SetPos(uint32(uintptr(unsafe.Pointer(&b[0])) - uintptr(unsafe.Pointer(elem))))
-			elem.SetFlags(item.Flags())
-			elem.SetKsize(uint32(len(item.Key())))
-			elem.SetVsize(uint32(len(item.Value())))
-		} else {
-			elem := p.BranchPageElement(uint16(i))
-			elem.SetPos(uint32(uintptr(unsafe.Pointer(&b[0])) - uintptr(unsafe.Pointer(elem))))
-			elem.SetKsize(uint32(len(item.Key())))
-			elem.SetPgid(item.Pgid())
-			common.Assert(elem.Pgid() != p.Id(), "write: circular dependency occurred")
-		}
-
-		// Write data for the element to the end of the page.
-		l := copy(b, item.Key())
-		copy(b[l:], item.Value())
-	}
+	common.WriteInodeToPage(n.inodes, p)
 
 	// DEBUG ONLY: n.dump()
 }