コード例 #1
0
ファイル: rocksdb.go プロジェクト: kuguobing/cockroach
// Scan returns up to max key/value objects starting from
// start (inclusive) and ending at end (non-inclusive).
// If max is zero then the number of key/values returned is unbounded.
func (r *RocksDB) Scan(start, end Key, max int64) ([]RawKeyValue, error) {
	var keyVals []RawKeyValue
	if bytes.Compare(start, end) >= 0 {
		return keyVals, nil
	}
	// In order to prevent content displacement, caching is disabled
	// when performing scans. Any options set within the shared read
	// options field that should be carried over needs to be set here
	// as well.
	opts := C.rocksdb_readoptions_create()
	C.rocksdb_readoptions_set_fill_cache(opts, 0)
	defer C.rocksdb_readoptions_destroy(opts)
	it := C.rocksdb_create_iterator(r.rdb, opts)
	defer C.rocksdb_iter_destroy(it)

	byteCount := len(start)
	if byteCount == 0 {
		// start=Key("") needs special treatment since we need
		// to access start[0] in an explicit seek.
		C.rocksdb_iter_seek_to_first(it)
	} else {
		C.rocksdb_iter_seek(it, bytesPointer(start), C.size_t(byteCount))
	}
	for i := int64(1); C.rocksdb_iter_valid(it) == 1; C.rocksdb_iter_next(it) {
		if max > 0 && i > max {
			break
		}
		var l C.size_t
		// The data returned by rocksdb_iter_{key,value} is not meant to be
		// freed by the client. It is a direct reference to the data managed
		// by the iterator, so it is copied instead of freed.
		data := C.rocksdb_iter_key(it, &l)
		k := C.GoBytes(unsafe.Pointer(data), C.int(l))
		if bytes.Compare(k, end) >= 0 {
			break
		}
		data = C.rocksdb_iter_value(it, &l)
		v := C.GoBytes(unsafe.Pointer(data), C.int(l))
		keyVals = append(keyVals, RawKeyValue{
			Key:   k,
			Value: v,
		})
		i++
	}
	// Check for any errors during iteration.
	var cErr *C.char
	C.rocksdb_iter_get_error(it, &cErr)
	if cErr != nil {
		return nil, charToErr(cErr)
	}
	return keyVals, nil
}
コード例 #2
0
ファイル: iterator.go プロジェクト: CowLeo/qdb
// SeekToFirst moves the iterator to the first key in the database, as defined
// by the Comparator in the ReadOptions used to create this Iterator.
//
// This method is safe to call when Valid returns false.
func (it *Iterator) SeekToFirst() {
	C.rocksdb_iter_seek_to_first(it.Iter)
}
コード例 #3
0
ファイル: iterator.go プロジェクト: daaku/gorocksdb
// SeekToFirst moves the iterator to the first key in the database.
func (i *Iterator) SeekToFirst() {
	C.rocksdb_iter_seek_to_first(i.c)
}
コード例 #4
0
ファイル: iterator.go プロジェクト: butine/research
// SeekToFirst moves the iterator to the first key in the database.
func (self *Iterator) SeekToFirst() {
	C.rocksdb_iter_seek_to_first(self.c)
}
コード例 #5
0
ファイル: db.go プロジェクト: tradia/gotable
func (iter *Iterator) SeekToFirst() {
	C.rocksdb_iter_seek_to_first(iter.it)
}