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graph: make quadstore init functions idempotent

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This commit is contained in:
Barak Michener 2015-11-25 14:28:15 -05:00
parent 9658689995
commit e849da9402
7 changed files with 63 additions and 24 deletions
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20
graph/leveldb/quadstore.go
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@ -48,6 +48,8 @@ const (
DefaultCacheSize = 2
DefaultWriteBufferSize = 20
QuadStoreType = "leveldb"
horizonKey = "__horizon"
sizeKey = "__size"
)
var (
@ -87,6 +89,16 @@ func createNewLevelDB(path string, _ graph.Options) error {
qs.writeopts = &opt.WriteOptions{
Sync: true,
}
qs.readopts = &opt.ReadOptions{}
_, err = qs.db.Get([]byte(horizonKey), qs.readopts)
if err != nil && err != leveldb.ErrNotFound {
glog.Errorln("couldn't read from leveldb during init")
return err
}
if err != leveldb.ErrNotFound {
return graph.ErrDatabaseExists
}
// Write some metadata
qs.Close()
return nil
}
@ -343,7 +355,7 @@ func (qs *QuadStore) Close() {
buf := new(bytes.Buffer)
err := binary.Write(buf, binary.LittleEndian, qs.size)
if err == nil {
werr := qs.db.Put([]byte("__size"), buf.Bytes(), qs.writeopts)
werr := qs.db.Put([]byte(sizeKey), buf.Bytes(), qs.writeopts)
if werr != nil {
glog.Error("could not write size before closing!")
}
@ -353,7 +365,7 @@ func (qs *QuadStore) Close() {
buf.Reset()
err = binary.Write(buf, binary.LittleEndian, qs.horizon)
if err == nil {
werr := qs.db.Put([]byte("__horizon"), buf.Bytes(), qs.writeopts)
werr := qs.db.Put([]byte(horizonKey), buf.Bytes(), qs.writeopts)
if werr != nil {
glog.Error("could not write horizon before closing!")
}
@ -444,11 +456,11 @@ func (qs *QuadStore) getInt64ForKey(key string, empty int64) (int64, error) {
func (qs *QuadStore) getMetadata() error {
var err error
qs.size, err = qs.getInt64ForKey("__size", 0)
qs.size, err = qs.getInt64ForKey(sizeKey, 0)
if err != nil {
return err
}
qs.horizon, err = qs.getInt64ForKey("__horizon", 0)
qs.horizon, err = qs.getInt64ForKey(horizonKey, 0)
return err
}