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add metastore, switching sequence to use it

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metastore is for storing metadata. This will be used later when moving
to distributed master mode.
This commit is contained in:
Chris Lu
2013-11-05 01:59:00 -08:00
parent b579451db9
commit 5cb6590eae
5 changed files with 164 additions and 19 deletions
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47
go/sequence/sequence.go
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@@ -1,9 +1,10 @@
package sequence
import (
"bytes"
"code.google.com/p/weed-fs/go/glog"
"code.google.com/p/weed-fs/go/metastore"
"encoding/gob"
"os"
"path"
"sync"
)
@@ -24,25 +25,28 @@ type SequencerImpl struct {
FileIdSequence uint64
fileIdCounter uint64
metaStore *metastore.MetaStore
}
func NewSequencer(dirname string, filename string) (m *SequencerImpl) {
m = &SequencerImpl{dir: dirname, fileName: filename}
m.metaStore = &metastore.MetaStore{metastore.NewMetaStoreFileBacking()}
seqFile, se := os.OpenFile(path.Join(m.dir, m.fileName+".seq"), os.O_RDONLY, 0644)
if se != nil {
if !m.metaStore.Has(m.dir, m.fileName+".seq") {
m.FileIdSequence = FileIdSaveInterval
glog.V(0).Infoln("Setting file id sequence", m.FileIdSequence)
} else {
decoder := gob.NewDecoder(seqFile)
defer seqFile.Close()
if se = decoder.Decode(&m.FileIdSequence); se != nil {
glog.V(0).Infof("error decoding FileIdSequence: %s", se)
m.FileIdSequence = FileIdSaveInterval
glog.V(0).Infoln("Setting file id sequence", m.FileIdSequence)
var err error
if m.FileIdSequence, err = m.metaStore.GetUint64(m.dir, m.fileName+".seq"); err != nil {
if data, err := m.metaStore.Get(m.dir, m.fileName+".seq"); err == nil {
m.FileIdSequence = decode(data)
glog.V(0).Infoln("Decoding old version of FileIdSequence", m.FileIdSequence)
} else {
glog.V(0).Infof("No existing FileIdSequence: %s", err)
}
} else {
glog.V(0).Infoln("Loading file id sequence", m.FileIdSequence, "=>", m.FileIdSequence+FileIdSaveInterval)
m.FileIdSequence += FileIdSaveInterval
glog.V(0).Infoln("Loading file id sequence", m.FileIdSequence)
}
//in case the server stops between intervals
}
@@ -66,13 +70,18 @@ func (m *SequencerImpl) NextFileId(count int) (uint64, int) {
}
func (m *SequencerImpl) saveSequence() {
glog.V(0).Infoln("Saving file id sequence", m.FileIdSequence, "to", path.Join(m.dir, m.fileName+".seq"))
seqFile, e := os.OpenFile(path.Join(m.dir, m.fileName+".seq"), os.O_CREATE|os.O_WRONLY, 0644)
if e != nil {
glog.Fatalf("Sequence File Save [ERROR] %s", e)
}
defer seqFile.Close()
encoder := gob.NewEncoder(seqFile)
if e = encoder.Encode(m.FileIdSequence); e != nil {
glog.Fatalf("Sequence File Save [ERROR] %s", e)
if e := m.metaStore.SetUint64(m.FileIdSequence, m.dir, m.fileName+".seq"); e != nil {
glog.Fatalf("Sequence id Save [ERROR] %s", e)
}
}
//decode are for backward compatible purpose
func decode(input []byte) uint64 {
var x uint64
b := bytes.NewReader(input)
decoder := gob.NewDecoder(b)
if e := decoder.Decode(&x); e == nil {
return x
}
return 0
}