mirror of
https://github.com/seaweedfs/seaweedfs.git
synced 2024-01-19 02:48:24 +00:00
Tamás Gulácsi contributed cdb map for read only extremely low memory
implementation.
This commit is contained in:
Chris Lu
parent
fb635146a1
commit
715d327df0
230
go/storage/cdb_map.go
Normal file
230
go/storage/cdb_map.go
Normal file
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@ -0,0 +1,230 @@
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package storage
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import (
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"code.google.com/p/weed-fs/go/util"
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"encoding/json"
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"errors"
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"fmt"
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"github.com/tgulacsi/go-cdb"
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"os"
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"path/filepath"
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)
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// CDB-backed read-only needle map
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type cdbMap struct {
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c1, c2 *cdb.Cdb
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fn1, fn2 string
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mapMetric
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}
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const maxCdbRecCount = 100000000
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var errReadOnly = errors.New("cannot modify a read-only map")
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// opens the cdb file(s) (base.cdb OR base.1.cdb AND base.2.cdb)
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// in case of two files, the metric (at key 'M') must be in base.2.cdb
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func OpenCdbMap(fileName string) (m *cdbMap, err error) {
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m = new(cdbMap)
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if m.c1, err = cdb.Open(fileName); err == nil {
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m.fn1 = fileName
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err = getMetric(m.c1, &m.mapMetric)
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return
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}
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if os.IsNotExist(err) {
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bn, ext := nakeFilename(fileName)
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m.fn1 = bn + ".1" + ext
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if m.c1, err = cdb.Open(m.fn1); err != nil {
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return nil, err
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}
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m.fn2 = bn + ".2" + ext
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if m.c2, err = cdb.Open(m.fn2); err != nil {
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return nil, err
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}
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err = getMetric(m.c2, &m.mapMetric)
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return
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}
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return nil, err
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}
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func (m *cdbMap) Put(key uint64, offset uint32, size uint32) (int, error) {
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return -1, errReadOnly
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}
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func (m *cdbMap) Delete(key uint64) error {
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return errReadOnly
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}
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func (m *cdbMap) Close() {
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if m.c2 != nil {
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m.c2.Close()
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m.c2 = nil
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}
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if m.c1 != nil {
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m.c1.Close()
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m.c1 = nil
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}
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}
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func (m cdbMap) ContentSize() uint64 {
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return m.FileByteCounter
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}
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func (m cdbMap) DeletedSize() uint64 {
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return m.DeletionByteCounter
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}
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func (m cdbMap) FileCount() int {
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return m.FileCounter
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}
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func (m *cdbMap) DeletedCount() int {
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return m.DeletionCounter
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}
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func getMetric(c *cdb.Cdb, m *mapMetric) error {
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data, err := c.Data([]byte{'M'})
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if err != nil {
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return err
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}
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return json.Unmarshal(data, m)
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}
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func (m cdbMap) Get(key uint64) (element *NeedleValue, ok bool) {
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var (
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data []byte
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k []byte = make([]byte, 8)
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err error
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)
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util.Uint64toBytes(k, key)
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if data, err = m.c1.Data(k); err != nil || data == nil {
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if m.c2 == nil {
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return nil, false
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}
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if data, err = m.c2.Data(k); err != nil || data == nil {
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return nil, false
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}
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}
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return &NeedleValue{Key: Key(key), Offset: util.BytesToUint32(data[:4]),
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Size: util.BytesToUint32(data[4:])}, true
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}
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func (m cdbMap) Visit(visit func(NeedleValue) error) (err error) {
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fh, err := os.Open(m.fn1)
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if err != nil {
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return fmt.Errorf("cannot open %s: %s", m.fn1, err)
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}
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defer fh.Close()
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walk := func(elt cdb.Element) error {
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if len(elt.Key) != 8 {
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return nil
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}
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return visit(NeedleValue{Key: Key(util.BytesToUint64(elt.Key)),
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Offset: util.BytesToUint32(elt.Data[:4]),
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Size: util.BytesToUint32(elt.Data[4:8])})
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}
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if err = cdb.DumpMap(fh, walk); err != nil {
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return err
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}
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if m.c2 == nil {
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return nil
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}
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fh.Close()
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if fh, err = os.Open(m.fn2); err != nil {
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return fmt.Errorf("cannot open %s: %s", m.fn2, err)
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}
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return cdb.DumpMap(fh, walk)
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}
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// converts an .idx index to a cdb
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func ConvertIndexToCdb(cdbName string, index *os.File) error {
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idx, err := LoadNeedleMap(index)
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if err != nil {
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return fmt.Errorf("error loading needle map %s: %s", index, err)
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}
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defer idx.Close()
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return DumpNeedleMapToCdb(cdbName, idx)
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}
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// dumps a NeedleMap into a cdb
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func DumpNeedleMapToCdb(cdbName string, nm *NeedleMap) error {
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tempnam := cdbName + "t"
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fnames := make([]string, 1, 2)
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adder, closer, err := openTempCdb(tempnam)
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if err != nil {
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return fmt.Errorf("error creating factory: %s", err)
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}
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fnames[0] = tempnam
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elt := cdb.Element{Key: make([]byte, 8), Data: make([]byte, 8)}
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fcount := uint64(0)
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walk := func(key uint64, offset, size uint32) error {
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if fcount >= maxCdbRecCount {
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if err = closer(); err != nil {
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return err
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}
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tempnam = cdbName + "t2"
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if adder, closer, err = openTempCdb(tempnam); err != nil {
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return fmt.Errorf("error creating second factory: %s", err)
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}
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fnames = append(fnames, tempnam)
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fcount = 0
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}
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util.Uint64toBytes(elt.Key, key)
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util.Uint32toBytes(elt.Data[:4], offset)
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util.Uint32toBytes(elt.Data[4:], size)
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fcount++
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return adder(elt)
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}
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// and write out the cdb from there
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err = nm.Visit(func(nv NeedleValue) error {
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return walk(uint64(nv.Key), nv.Offset, nv.Size)
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})
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if err != nil {
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closer()
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return fmt.Errorf("error walking index %s: %s", nm, err)
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}
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// store fileBytes
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data, e := json.Marshal(nm.mapMetric)
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if e != nil {
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return fmt.Errorf("error marshaling metric %s: %s", nm.mapMetric, e)
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}
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if err = adder(cdb.Element{Key: []byte{'M'}, Data: data}); err != nil {
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return err
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}
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if err = closer(); err != nil {
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return err
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}
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os.Remove(cdbName)
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if len(fnames) == 1 {
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return os.Rename(fnames[0], cdbName)
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}
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bn, ext := nakeFilename(cdbName)
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if err = os.Rename(fnames[0], bn+".1"+ext); err != nil {
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return err
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}
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return os.Rename(fnames[1], bn+".2"+ext)
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}
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func openTempCdb(fileName string) (cdb.AdderFunc, cdb.CloserFunc, error) {
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fh, err := os.Create(fileName)
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if err != nil {
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return nil, nil, fmt.Errorf("cannot create cdb file %s: %s", fileName, err)
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}
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adder, closer, err := cdb.MakeFactory(fh)
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if err != nil {
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fh.Close()
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return nil, nil, fmt.Errorf("error creating factory: %s", err)
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}
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return adder, func() error {
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if e := closer(); e != nil {
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fh.Close()
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return e
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}
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fh.Close()
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return nil
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}, nil
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}
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// returns filename without extension, and the extension
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func nakeFilename(fileName string) (string, string) {
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ext := filepath.Ext(fileName)
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return fileName[:len(fileName)-len(ext)], ext
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}
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168
go/storage/cdb_map_test.go
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168
go/storage/cdb_map_test.go
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@ -0,0 +1,168 @@
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package storage
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import (
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"log"
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"math/rand"
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"os"
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"runtime"
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"testing"
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)
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var testIndexFilename string = "../../test/sample.idx"
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func TestCdbMap0Convert(t *testing.T) {
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indexFile, err := os.Open(testIndexFilename)
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if err != nil {
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t.Fatalf("cannot open %s: %s", testIndexFilename, err)
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}
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defer indexFile.Close()
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cdbFn := testIndexFilename + ".cdb"
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t.Logf("converting %s to %s", cdbFn, cdbFn)
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if err = ConvertIndexToCdb(cdbFn, indexFile); err != nil {
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t.Fatalf("error while converting: %s", err)
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}
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}
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func TestCdbMap1Mem(t *testing.T) {
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var nm NeedleMapper
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i := 0
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visit := func(nv NeedleValue) error {
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i++
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return nil
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}
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a := getMemStats()
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t.Logf("opening %s.cdb", testIndexFilename)
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nm, err := OpenCdbMap(testIndexFilename + ".cdb")
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if err != nil {
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t.Fatalf("error opening cdb: %s", err)
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}
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b := getMemStats()
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log.Printf("opening cdb consumed %d bytes", b-a)
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defer nm.Close()
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a = getMemStats()
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if err = nm.Visit(visit); err != nil {
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t.Fatalf("error visiting %s: %s", nm, err)
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}
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b = getMemStats()
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log.Printf("visit cdb %d consumed %d bytes", i, b-a)
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nm.Close()
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indexFile, err := os.Open(testIndexFilename)
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if err != nil {
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t.Fatalf("error opening idx: %s", err)
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}
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a = getMemStats()
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nm, err = LoadNeedleMap(indexFile)
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if err != nil {
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t.Fatalf("error loading idx: %s", err)
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}
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defer nm.Close()
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b = getMemStats()
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log.Printf("opening idx consumed %d bytes", b-a)
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i = 0
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a = getMemStats()
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if err = nm.Visit(visit); err != nil {
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t.Fatalf("error visiting %s: %s", nm, err)
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}
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b = getMemStats()
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log.Printf("visit idx %d consumed %d bytes", i, b-a)
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}
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func BenchmarkCdbMap9List(t *testing.B) {
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t.StopTimer()
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indexFile, err := os.Open(testIndexFilename)
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if err != nil {
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t.Fatalf("cannot open %s: %s", testIndexFilename, err)
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}
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defer indexFile.Close()
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a := getMemStats()
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t.Logf("opening %s", indexFile)
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idx, err := LoadNeedleMap(indexFile)
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if err != nil {
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t.Fatalf("cannot load %s: %s", indexFile, err)
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}
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defer idx.Close()
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b := getMemStats()
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log.Printf("LoadNeedleMap consumed %d bytes", b-a)
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cdbFn := testIndexFilename + ".cdb"
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a = getMemStats()
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t.Logf("opening %s", cdbFn)
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m, err := OpenCdbMap(cdbFn)
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if err != nil {
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t.Fatalf("error opening %s: %s", cdbFn, err)
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}
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defer m.Close()
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b = getMemStats()
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log.Printf("OpenCdbMap consumed %d bytes", b-a)
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i := 0
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log.Printf("checking whether the cdb contains every key")
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t.StartTimer()
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err = idx.Visit(func(nv NeedleValue) error {
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if i > t.N || rand.Intn(10) < 9 {
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return nil
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}
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i++
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if i%1000 == 0 {
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log.Printf("%d. %s", i, nv)
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}
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if nv2, ok := m.Get(uint64(nv.Key)); !ok || nv2 == nil {
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t.Errorf("%s in index, not in cdb", nv.Key)
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} else if nv2.Key != nv.Key {
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t.Errorf("requested key %d from cdb, got %d", nv.Key, nv2.Key)
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} else if nv2.Offset != nv.Offset {
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t.Errorf("offset is %d in index, %d in cdb", nv.Offset, nv2.Offset)
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} else if nv2.Size != nv.Size {
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t.Errorf("size is %d in index, %d in cdb", nv.Size, nv2.Size)
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}
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t.SetBytes(int64(nv.Size))
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return nil
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})
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t.StopTimer()
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if err != nil {
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t.Errorf("error visiting index: %s", err)
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}
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i = 0
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log.Printf("checking wheter the cdb contains no stray keys")
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t.StartTimer()
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err = m.Visit(func(nv NeedleValue) error {
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if i > t.N || rand.Intn(10) < 9 {
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return nil
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}
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if nv2, ok := m.Get(uint64(nv.Key)); !ok || nv2 == nil {
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t.Errorf("%s in cdb, not in index", nv.Key)
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} else if nv2.Key != nv.Key {
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t.Errorf("requested key %d from index, got %d", nv.Key, nv2.Key)
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} else if nv2.Offset != nv.Offset {
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t.Errorf("offset is %d in cdb, %d in index", nv.Offset, nv2.Offset)
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} else if nv2.Size != nv.Size {
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t.Errorf("size is %d in cdb, %d in index", nv.Size, nv2.Size)
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}
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i++
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if i%1000 == 0 {
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log.Printf("%d. %s", i, nv)
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}
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t.SetBytes(int64(nv.Size))
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return nil
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})
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t.StopTimer()
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if err != nil {
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t.Errorf("error visiting index: %s", err)
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}
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}
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var mem = new(runtime.MemStats)
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// returns MemStats.Alloc after a GC
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func getMemStats() int64 {
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runtime.GC()
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runtime.ReadMemStats(mem)
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return int64(mem.Alloc)
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}
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