Refactor meta.copy() and page.init().

cursor.go

@@ -39,7 +39,6 @@ func (c *Cursor) Get(key []byte) []byte {
 func (c *Cursor) Goto(key []byte) bool {
 	// TODO(benbjohnson): Optimize for specific use cases.
 
-	// TODO: Check if len(key) > 0.
 	// TODO: Start from root page and traverse to correct page.
 
 	return false

db.go

@@ -91,11 +91,11 @@ func (db *DB) Open(path string, mode os.FileMode) error {
 		// Read the first meta page to determine the page size.
 		var buf [minPageSize]byte
 		if _, err := db.file.ReadAt(buf[:], 0); err == nil {
-			if m, err := db.pageInBuffer(buf[:], 0).meta(); err != nil {
-				return &Error{"meta bootstrap error", err}
-			} else if m != nil {
-				db.pageSize = int(m.pageSize)
+			m := db.pageInBuffer(buf[:], 0).meta()
+			if err := m.validate(); err != nil {
+				return &Error{"meta error", err}
 			}
+			db.pageSize = int(m.pageSize)
 		}
 	}
 
@@ -126,10 +126,14 @@ func (db *DB) mmap() error {
 	}
 
 	// Save references to the meta pages.
-	if db.meta0, err = db.page(0).meta(); err != nil {
+	db.meta0 = db.page(0).meta()
+	db.meta1 = db.page(1).meta()
+
+	// Validate the meta pages.
+	if err := db.meta0.validate(); err != nil {
 		return &Error{"meta0 error", err}
 	}
-	if db.meta1, err = db.page(1).meta(); err != nil {
+	if err := db.meta1.validate(); err != nil {
 		return &Error{"meta1 error", err}
 	}
 
@@ -146,7 +150,12 @@ func (db *DB) init() error {
 	for i := 0; i < 2; i++ {
 		p := db.pageInBuffer(buf[:], pgid(i))
 		p.id = pgid(i)
-		p.init(db.pageSize)
+		p.flags = p_meta
+
+		m := p.meta()
+		m.magic = magic
+		m.version = Version
+		m.pageSize = uint32(db.pageSize)
 	}
 
 	// Write the buffer to our data file.

db_test.go

@@ -121,13 +121,18 @@ func TestDBMmapError(t *testing.T) {
 // Ensure that corrupt meta0 page errors get returned.
 func TestDBCorruptMeta0(t *testing.T) {
 	withMockDB(func(db *DB, mockos *mockos, mocksyscall *mocksyscall, path string) {
+		var m meta
+		m.magic = magic
+		m.version = Version
+		m.pageSize = 0x8000
+
 		// Create a file with bad magic.
 		b := make([]byte, 0x10000)
 		p0, p1 := (*page)(unsafe.Pointer(&b[0x0000])), (*page)(unsafe.Pointer(&b[0x8000]))
-		p0.init(0x8000)
-		p1.init(0x8000)
-		m, _ := p0.meta()
-		m.magic = 0
+		p0.meta().magic = 0
+		p0.meta().version = Version
+		p1.meta().magic = magic
+		p1.meta().version = Version
 
 		// Mock file access.
 		file, metafile := &mockfile{}, &mockfile{}
@@ -141,7 +146,8 @@ func TestDBCorruptMeta0(t *testing.T) {
 
 		// Open the database.
 		err := db.Open(path, 0666)
-		assert.Equal(t, err, &Error{"meta bootstrap error", InvalidMetaPageError})
+		warn(err)
+		assert.Equal(t, err, &Error{"meta error", InvalidError})
 	})
 }
 

meta.go

@@ -3,7 +3,6 @@ package bolt
 var (
 	InvalidError         = &Error{"Invalid database", nil}
 	VersionMismatchError = &Error{"version mismatch", nil}
-	InvalidMetaPageError = &Error{"invalid meta page", nil}
 )
 
 const magic uint32 = 0xC0DEC0DE
@@ -12,10 +11,10 @@ const version uint32 = 1
 type meta struct {
 	magic    uint32
 	version  uint32
-	sys      bucket
 	pageSize uint32
 	pgid     pgid
 	txnid    txnid
+	sys      bucket
 }
 
 // validate checks the marker bytes and version of the meta page to ensure it matches this binary.
@@ -27,3 +26,11 @@ func (m *meta) validate() error {
 	}
 	return nil
 }
+
+// copy copies one meta object to another.
+func (m *meta) copy(dest *meta) {
+	dest.pageSize = m.pageSize
+	dest.pgid = m.pgid
+	dest.txnid = m.txnid
+	dest.sys = m.sys
+}

page.go

@@ -27,32 +27,16 @@ type page struct {
 }
 
 // meta returns a pointer to the metadata section of the page.
-func (p *page) meta() (*meta, error) {
-	// Exit if page is not a meta page.
-	if (p.flags & p_meta) == 0 {
-		return nil, InvalidMetaPageError
-	}
-
-	// Cast the meta section and validate before returning.
-	m := (*meta)(unsafe.Pointer(&p.ptr))
-	if err := m.validate(); err != nil {
-		return nil, err
-	}
-	return m, nil
-}
-
-// init initializes a page as a new meta page.
-func (p *page) init(pageSize int) {
-	p.flags = p_meta
-	m := (*meta)(unsafe.Pointer(&p.ptr))
-	m.magic = magic
-	m.version = version
-	m.pageSize = uint32(pageSize)
-	m.pgid = 1
-	m.sys.root = 0
+func (p *page) meta() *meta {
+	return (*meta)(unsafe.Pointer(&p.ptr))
 }
 
 // lnode retrieves the leaf node by index
 func (p *page) lnode(index int) *lnode {
 	return &((*[maxNodesPerPage]lnode)(unsafe.Pointer(&p.ptr)))[index]
 }
+
+// bnode retrieves the branch node by index
+func (p *page) bnode(index int) *bnode {
+	return &((*[maxNodesPerPage]bnode)(unsafe.Pointer(&p.ptr)))[index]
+}