src/dedo.go: Simplify initDB()

2 files changed, 129 insertions, 110 deletions

diff --git a/src/dedo.go b/src/dedo.go
index 416d575..a7bc629 100644
--- a/src/dedo.go
+++ b/src/dedo.go
@@ -1729,16 +1729,15 @@ func (db *DB) String() string {
 }
 
 func newDB(path string, file *os.File) *DB {
-	db := &DB{
+	return &DB{
 		MaxBatchSize:  DefaultMaxBatchSize,
 		MaxBatchDelay: DefaultMaxBatchDelay,
 		AllocSize:     DefaultAllocSize,
 		opened:        true,
 		path:          path,
 		file:          file,
-		ops:           dbops{file.WriteAt},
+		ops:           dbops{writeAt: file.WriteAt},
 	}
-	return db
 }
 
 func openFile(path string) (*os.File, error) {
@@ -1760,9 +1759,82 @@ func openFile(path string) (*os.File, error) {
 	return os.OpenFile(path, flagsRO, fileMode)
 }
 
+func readPageSize(db *DB) (int, error) {
+	// Read the first meta page to determine the page size.
+	const size4KiB = 0x1000
+	buf := [0x1000]byte{}
+	_, err := db.file.ReadAt(buf[:], 0)
+	if err != nil {
+		return 0, err
+	}
+
+	m := pageInBuffer(db, buf[:], 0).meta()
+	err = m.validate()
+	if err != nil {
+		return 0, err
+	}
+
+	return int(m.pageSize), nil
+}
+
+// init creates a new database file and initializes its meta pages.
+func initDB(db *DB, size int64) error {
+	if size != 0 {
+		pageSize, err := readPageSize(db)
+		if err != nil {
+			return err
+		}
+
+		db.pageSize = pageSize
+		return nil
+	}
+	// Set the page size to the OS page size.
+	db.pageSize = os.Getpagesize()
+
+	// Create two meta pages on a buffer.
+	buf := make([]byte, db.pageSize*4)
+	for i := 0; i < 2; i++ {
+		p := pageInBuffer(db, buf[:], pgid(i))
+		p.id = pgid(i)
+		p.flags = metaPageFlag
+
+		// Initialize the meta page.
+		m := p.meta()
+		m.magic = magic
+		m.version = version
+		m.pageSize = uint32(db.pageSize)
+		m.freelist = 2
+		m.root = bucket{root: 3}
+		m.pgid = 4
+		m.txid = txid(i)
+		m.checksum = m.sum64()
+	}
+
+	// Write an empty freelist at page 3.
+	p := pageInBuffer(db, buf[:], pgid(2))
+	p.id = pgid(2)
+	p.flags = freelistPageFlag
+	p.count = 0
+
+	// Write an empty leaf page at page 4.
+	p = pageInBuffer(db, buf[:], pgid(3))
+	p.id = pgid(3)
+	p.flags = leafPageFlag
+	p.count = 0
+
+	// Write the buffer to our data file.
+	if _, err := db.ops.writeAt(buf, 0); err != nil {
+		return err
+	}
+	if err := fdatasync(db); err != nil {
+		return err
+	}
+
+	return nil
+}
+
 // Open creates and opens a database at the given path.
 // If the file does not exist then it will be created automatically.
-// Passing in nil options will cause Bolt to open the database with the default options.
 func Open(path string) (*DB, error) {
 	file, err := openFile(path)
 	if err != nil {
@@ -1776,14 +1848,9 @@ func Open(path string) (*DB, error) {
 	}
 
 	db := newDB(path, file)
-	// Lock file so that other processes using Bolt in read-write mode cannot
-	// use the database  at the same time. This would cause corruption since
-	// the two processes would write meta pages and free pages separately.
-	// The database file is locked exclusively (only one process can grab the lock)
-	// if !options.ReadOnly.
-	// The database file is locked using the shared lock (more than one process may
-	// hold a lock at the same time) otherwise (options.ReadOnly is set).
-	if err := flock(db); err != nil {
+
+	err = flock(db)
+	if err != nil {
 		_ = db.close()
 		return nil, err
 	}
@@ -1801,7 +1868,8 @@ func Open(path string) (*DB, error) {
 	}
 
 	// Memory map the data file.
-	if err := db.mmap(0); err != nil {
+	err = db.mmap(0)
+	if err != nil {
 		_ = db.close()
 		return nil, err
 	}
@@ -1913,80 +1981,6 @@ func (db *DB) mmapSize(size int) (int, error) {
 	return int(sz), nil
 }
 
-func readPageSize(db *DB) (int, error) {
-	// Read the first meta page to determine the page size.
-	var buf [0x1000]byte
-	_, err := db.file.ReadAt(buf[:], 0)
-	if err != nil {
-		return 0, err
-	}
-
-	m := db.pageInBuffer(buf[:], 0).meta()
-	err = m.validate()
-	if err != nil {
-		// return 0, err
-		return os.Getpagesize(), nil
-	}
-
-	return int(m.pageSize), nil
-}
-
-// init creates a new database file and initializes its meta pages.
-func initDB(db *DB, size int64) error {
-	if size != 0 {
-		pageSize, err := readPageSize(db)
-		if err != nil {
-			return err
-		}
-
-		db.pageSize = pageSize
-		return nil
-	}
-	// Set the page size to the OS page size.
-	db.pageSize = os.Getpagesize()
-
-	// Create two meta pages on a buffer.
-	buf := make([]byte, db.pageSize*4)
-	for i := 0; i < 2; i++ {
-		p := db.pageInBuffer(buf[:], pgid(i))
-		p.id = pgid(i)
-		p.flags = metaPageFlag
-
-		// Initialize the meta page.
-		m := p.meta()
-		m.magic = magic
-		m.version = version
-		m.pageSize = uint32(db.pageSize)
-		m.freelist = 2
-		m.root = bucket{root: 3}
-		m.pgid = 4
-		m.txid = txid(i)
-		m.checksum = m.sum64()
-	}
-
-	// Write an empty freelist at page 3.
-	p := db.pageInBuffer(buf[:], pgid(2))
-	p.id = pgid(2)
-	p.flags = freelistPageFlag
-	p.count = 0
-
-	// Write an empty leaf page at page 4.
-	p = db.pageInBuffer(buf[:], pgid(3))
-	p.id = pgid(3)
-	p.flags = leafPageFlag
-	p.count = 0
-
-	// Write the buffer to our data file.
-	if _, err := db.ops.writeAt(buf, 0); err != nil {
-		return err
-	}
-	if err := fdatasync(db); err != nil {
-		return err
-	}
-
-	return nil
-}
-
 // Close releases all database resources.
 // All transactions must be closed before closing the database.
 func (db *DB) Close() error {
@@ -2356,7 +2350,7 @@ func (db *DB) page(id pgid) *page {
 }
 
 // pageInBuffer retrieves a page reference from a given byte array based on the current page size.
-func (db *DB) pageInBuffer(b []byte, id pgid) *page {
+func pageInBuffer(db *DB, b []byte, id pgid) *page {
 	return (*page)(unsafe.Pointer(&b[id*pgid(db.pageSize)]))
 }
 
@@ -4003,7 +3997,7 @@ func (tx *Tx) write() error {
 func (tx *Tx) writeMeta() error {
 	// Create a temporary buffer for the meta page.
 	buf := make([]byte, tx.db.pageSize)
-	p := tx.db.pageInBuffer(buf, 0)
+	p := pageInBuffer(tx.db, buf, 0)
 	tx.meta.write(p)
 
 	// Write the meta page to file.
diff --git a/tests/dedo.go b/tests/dedo.go
index 0def91d..1ab2b61 100644
--- a/tests/dedo.go
+++ b/tests/dedo.go
@@ -34,6 +34,25 @@ import (
 func test_newDB() {
 	g.TestStart("newDB()")
 
+	g.Testing("different path are given back", func() {
+		db1 := newDB("path1", nil)
+		db2 := newDB("path2", nil)
+
+		g.TAssertEqual(db1.path, "path1")
+		g.TAssertEqual(db2.path, "path2")
+	})
+
+	g.Testing("diferent *os.File pointers", func() {
+		f1 := new(os.File)
+		f2 := new(os.File)
+
+		db1 := newDB("path", f1)
+		db2 := newDB("path", f2)
+
+		g.TAssertEqual(db1.ops.writeAt == nil, false)
+		g.TAssertEqual(db2.ops.writeAt == nil, false)
+		g.TAssertEqual(db1 == db2, false)
+	})
 }
 
 func test_openFile() {
@@ -81,6 +100,29 @@ func test_openFile() {
 	})
 }
 
+func test_readPageSize() {
+	g.TestStart("readPageSize()")
+
+	g.Testing("empty page gives us EOF", func() {
+	})
+	g.Testing("page smaller than 4KiB also gives us EOF", func() { })
+	g.Testing("zeroed 4KiB page gives us ErrInvalid", func() {
+	})
+}
+
+func test_initDB() {
+	g.TestStart("initDB()")
+}
+
+func test_Open() {
+	g.TestStart("Open()")
+}
+
+// Ensure that opening a file that is not a Bolt database returns ErrInvalid.
+func TestOpen_ErrInvalid(t *testing.T) {
+	return
+}
+
 // Ensure that a bucket that gets a non-existent key returns nil.
 func TestBucket_Get_NonExistent(t *testing.T) {
 	db := MustOpenDB()
@@ -2884,27 +2926,6 @@ func TestOpen_ErrNotExists(t *testing.T) {
 	}
 }
 
-// Ensure that opening a file that is not a Bolt database returns ErrInvalid.
-func TestOpen_ErrInvalid(t *testing.T) {
-	path := tempfile()
-	defer os.Remove(path)
-
-	f, err := os.Create(path)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if _, err := fmt.Fprintln(f, "this is not a bolt database"); err != nil {
-		t.Fatal(err)
-	}
-	if err := f.Close(); err != nil {
-		t.Fatal(err)
-	}
-
-	if _, err := Open(path); err != ErrInvalid {
-		t.Fatalf("unexpected error: %s", err)
-	}
-}
-
 // Ensure that opening a file with two invalid versions returns ErrVersionMismatch.
 func TestOpen_ErrVersionMismatch(t *testing.T) {
 	if pageSize != os.Getpagesize() {
@@ -6264,7 +6285,11 @@ func walkBucket(parent *Bucket, k []byte, v []byte, w io.Writer) error {
 func MainTest() {
 	tempdir = getTempdir()
 
+	test_newDB()
 	test_openFile()
+	test_readPageSize()
+	test_initDB()
+	test_Open()
 
 	tests := []testing.InternalTest{
 		{ "TestBucket_Get_NonExistent", TestBucket_Get_NonExistent },