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package storage
import (
"encoding/json"
"errors"
"fmt"
"os"
"path/filepath"
"github.com/mcqueenorama/weed-fs/go/util"
"github.com/tgulacsi/go-cdb"
)
// CDB-backed read-only needle map
type cdbMap struct {
c1, c2 *cdb.Cdb
fn1, fn2 string
mapMetric
}
const maxCdbRecCount = 100000000
var errReadOnly = errors.New("cannot modify a read-only map")
// opens the cdb file(s) (base.cdb OR base.1.cdb AND base.2.cdb)
// in case of two files, the metric (at key 'M') must be in base.2.cdb
func OpenCdbMap(fileName string) (m *cdbMap, err error) {
m = new(cdbMap)
if m.c1, err = cdb.Open(fileName); err == nil {
m.fn1 = fileName
err = getMetric(m.c1, &m.mapMetric)
return
}
if os.IsNotExist(err) {
bn, ext := baseFilename(fileName)
m.fn1 = bn + ".1" + ext
if m.c1, err = cdb.Open(m.fn1); err != nil {
return nil, err
}
m.fn2 = bn + ".2" + ext
if m.c2, err = cdb.Open(m.fn2); err != nil {
return nil, err
}
err = getMetric(m.c2, &m.mapMetric)
return
}
return nil, err
}
func (m *cdbMap) Put(key uint64, offset uint32, size uint32) (int, error) {
return -1, errReadOnly
}
func (m *cdbMap) Delete(key uint64) error {
return errReadOnly
}
func (m *cdbMap) Close() {
if m.c2 != nil {
m.c2.Close()
m.c2 = nil
}
if m.c1 != nil {
m.c1.Close()
m.c1 = nil
}
}
func (m *cdbMap) Destroy() error {
return errors.New("Can not delete readonly volumes")
}
func (m cdbMap) ContentSize() uint64 {
return m.FileByteCounter
}
func (m cdbMap) DeletedSize() uint64 {
return m.DeletionByteCounter
}
func (m cdbMap) FileCount() int {
return m.FileCounter
}
func (m *cdbMap) DeletedCount() int {
return m.DeletionCounter
}
func (m *cdbMap) MaxFileKey() uint64 {
return m.MaximumFileKey
}
func getMetric(c *cdb.Cdb, m *mapMetric) error {
data, err := c.Data([]byte{'M'})
if err != nil {
return err
}
return json.Unmarshal(data, m)
}
func (m cdbMap) Get(key uint64) (element *NeedleValue, ok bool) {
var (
data []byte
k []byte = make([]byte, 8)
err error
)
util.Uint64toBytes(k, key)
if data, err = m.c1.Data(k); err != nil || data == nil {
if m.c2 == nil {
return nil, false
}
if data, err = m.c2.Data(k); err != nil || data == nil {
return nil, false
}
}
return &NeedleValue{Key: Key(key), Offset: util.BytesToUint32(data[:4]),
Size: util.BytesToUint32(data[4:])}, true
}
func (m cdbMap) Visit(visit func(NeedleValue) error) (err error) {
fh, err := os.Open(m.fn1)
if err != nil {
return fmt.Errorf("cannot open %s: %s", m.fn1, err)
}
defer fh.Close()
walk := func(elt cdb.Element) error {
if len(elt.Key) != 8 {
return nil
}
return visit(NeedleValue{Key: Key(util.BytesToUint64(elt.Key)),
Offset: util.BytesToUint32(elt.Data[:4]),
Size: util.BytesToUint32(elt.Data[4:8])})
}
if err = cdb.DumpMap(fh, walk); err != nil {
return err
}
if m.c2 == nil {
return nil
}
fh.Close()
if fh, err = os.Open(m.fn2); err != nil {
return fmt.Errorf("cannot open %s: %s", m.fn2, err)
}
return cdb.DumpMap(fh, walk)
}
// converts an .idx index to a cdb
func ConvertIndexToCdb(cdbName string, index *os.File) error {
idx, err := LoadNeedleMap(index)
if err != nil {
return fmt.Errorf("error loading needle map %s: %s", index.Name(), err)
}
defer idx.Close()
return DumpNeedleMapToCdb(cdbName, idx)
}
// dumps a NeedleMap into a cdb
func DumpNeedleMapToCdb(cdbName string, nm *NeedleMap) error {
tempnam := cdbName + "t"
fnames := make([]string, 1, 2)
adder, closer, err := openTempCdb(tempnam)
if err != nil {
return fmt.Errorf("error creating factory: %s", err)
}
fnames[0] = tempnam
elt := cdb.Element{Key: make([]byte, 8), Data: make([]byte, 8)}
fcount := uint64(0)
walk := func(key uint64, offset, size uint32) error {
if fcount >= maxCdbRecCount {
if err = closer(); err != nil {
return err
}
tempnam = cdbName + "t2"
if adder, closer, err = openTempCdb(tempnam); err != nil {
return fmt.Errorf("error creating second factory: %s", err)
}
fnames = append(fnames, tempnam)
fcount = 0
}
util.Uint64toBytes(elt.Key, key)
util.Uint32toBytes(elt.Data[:4], offset)
util.Uint32toBytes(elt.Data[4:], size)
fcount++
return adder(elt)
}
// and write out the cdb from there
err = nm.Visit(func(nv NeedleValue) error {
return walk(uint64(nv.Key), nv.Offset, nv.Size)
})
if err != nil {
closer()
return fmt.Errorf("error walking index %v: %s", nm, err)
}
// store fileBytes
data, e := json.Marshal(nm.mapMetric)
if e != nil {
return fmt.Errorf("error marshaling metric %v: %s", nm.mapMetric, e)
}
if err = adder(cdb.Element{Key: []byte{'M'}, Data: data}); err != nil {
return err
}
if err = closer(); err != nil {
return err
}
os.Remove(cdbName)
if len(fnames) == 1 {
return os.Rename(fnames[0], cdbName)
}
bn, ext := baseFilename(cdbName)
if err = os.Rename(fnames[0], bn+".1"+ext); err != nil {
return err
}
return os.Rename(fnames[1], bn+".2"+ext)
}
func openTempCdb(fileName string) (cdb.AdderFunc, cdb.CloserFunc, error) {
fh, err := os.Create(fileName)
if err != nil {
return nil, nil, fmt.Errorf("cannot create cdb file %s: %s", fileName, err.Error())
}
adder, closer, err := cdb.MakeFactory(fh)
if err != nil {
fh.Close()
return nil, nil, fmt.Errorf("error creating factory: %s", err.Error())
}
return adder, func() error {
if e := closer(); e != nil {
fh.Close()
return e
}
fh.Close()
return nil
}, nil
}
// returns filename without extension, and the extension
func baseFilename(fileName string) (string, string) {
ext := filepath.Ext(fileName)
return fileName[:len(fileName)-len(ext)], ext
}
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