Files
dolt/datas/datastore.go
2015-10-21 19:29:11 -04:00

65 lines
2.1 KiB
Go

package datas
import (
"github.com/attic-labs/noms/chunks"
"github.com/attic-labs/noms/ref"
)
// DataStore provides versioned storage for noms values. Each DataStore instance represents one moment in history. Heads() returns the Commit from each active fork at that moment. The Commit() method returns a new DataStore, representing a new moment in history.
type DataStore interface {
chunks.ChunkStore
// MaybeHead returns the current Head Commit of this Datastore, which contains the current root of the DataStore's value tree, if available. If not, it returns a new Commit and 'false'.
MaybeHead(datasetID string) (Commit, bool)
// Head returns the current head Commit, which contains the current root of the DataStore's value tree.
Head(datasetID string) Commit
// Datasets returns the root of the datastore which is a MapOfStringToRefOfCommit where string is a datasetID.
Datasets() MapOfStringToRefOfCommit
// Commit updates the commit that a datastore points at. The new Commit is constructed using v and the current Head. If the update cannot be performed, e.g., because of a conflict, Commit returns 'false'. The newest snapshot of the datastore is always returned.
Commit(datasetID string, commit Commit) (DataStore, bool)
CopyReachableChunksP(r, exclude ref.Ref, sink chunks.ChunkSink, concurrency int)
}
func NewDataStore(cs chunks.ChunkStore) DataStore {
return newLocalDataStore(cs)
}
type Flags struct {
ldb chunks.LevelDBStoreFlags
memory chunks.MemoryStoreFlags
hflags chunks.HttpStoreFlags
}
func NewFlags() Flags {
return NewFlagsWithPrefix("")
}
func NewFlagsWithPrefix(prefix string) Flags {
return Flags{
chunks.LevelDBFlags(prefix),
chunks.MemoryFlags(prefix),
chunks.HttpFlags(prefix),
}
}
func (f Flags) CreateDataStore() (DataStore, bool) {
var cs chunks.ChunkStore
if cs = f.ldb.CreateStore(); cs != nil {
} else if cs = f.memory.CreateStore(); cs != nil {
}
if cs != nil {
return newLocalDataStore(cs), true
}
if cs = f.hflags.CreateStore(); cs != nil {
return newRemoteDataStore(cs), true
}
return &LocalDataStore{}, false
}