// SetSnapshot causes reads to provided as they were when the passed in
// Snapshot was created by DB.NewSnapshot. This is useful for getting
// consistent reads during a bulk operation.
//
// See the LevelDB documentation for details.
func (ro *ReadOptions) SetSnapshot(snap *Snapshot) {
var s *C.rocksdb_snapshot_t
if snap != nil {
s = snap.snap
}
C.rocksdb_readoptions_set_snapshot(ro.Opt, s)
}
func (db *DB) NewReadOptions(createSnapshot bool) *ReadOptions {
var opt = new(ReadOptions)
opt.rOpt = C.rocksdb_readoptions_create()
if createSnapshot {
opt.snap = C.rocksdb_create_snapshot(db.db)
C.rocksdb_readoptions_set_snapshot(opt.rOpt, opt.snap)
opt.db = db.db
}
return opt
}
// GetSnapshot returns the value for the given key from the given
// snapshotID, nil otherwise.
func (r *RocksDB) GetSnapshot(key Key, snapshotID string) ([]byte, error) {
snapshotHandle, ok := r.snapshots[snapshotID]
if !ok {
return nil, util.Errorf("snapshotID %s does not exist", snapshotID)
}
opts := C.rocksdb_readoptions_create()
C.rocksdb_readoptions_set_snapshot(opts, snapshotHandle)
defer C.rocksdb_readoptions_destroy(opts)
return r.getInternal(key, opts)
}
// ScanSnapshot returns up to max key/value objects starting from
// start (inclusive) and ending at end (non-inclusive) from the
// given snapshotID.
// Specify max=0 for unbounded scans.
func (r *RocksDB) ScanSnapshot(start, end Key, max int64, snapshotID string) ([]proto.RawKeyValue, error) {
snapshotHandle, ok := r.snapshots[snapshotID]
if !ok {
return nil, util.Errorf("snapshotID %s does not exist", snapshotID)
}
opts := C.rocksdb_readoptions_create()
C.rocksdb_readoptions_set_fill_cache(opts, 0)
C.rocksdb_readoptions_set_snapshot(opts, snapshotHandle)
defer C.rocksdb_readoptions_destroy(opts)
return r.scanInternal(start, end, max, opts)
}
// If snapshot is set, read as of the supplied snapshot
// which must belong to the DB that is being read and which must
// not have been released.
// Default: nil
func (self *ReadOptions) SetSnapshot(snap *Snapshot) {
C.rocksdb_readoptions_set_snapshot(self.c, snap.c)
}