func (s *Space) ScanIndex(name, value string, scanner Scanner) {
if reader := s.findIndex(name, value); reader != nil {
for {
// If the next byte is 0, then that's an empty event offset,
// marking the end of the index. Nothing more to see here.
if next := reader.Peek(1); len(next) == 0 || next[0] == 0 {
return
}
// Each entry in the index is a 64 bit integer for the
// event's block offset in the file, and a 16 bit integer
// for the event's offset within the block (as each block
// is 4096 bytes long)
block := binary.ReadInt64(reader)
offset := binary.ReadInt16(reader)
// Move to the event's block
s.blocks.Seek(s.offset+block, 0)
// Read all data prior to the current event's offset.
binary.ReadBytes(s.blocks, offset)
event := pullEvent(s.blocks)
if event == nil || !scanner(event) {
return
}
}
}
}
func decodeEvent(b []byte) (*Event, error) {
buf := bytes.NewBuffer(b)
size := binary.ReadUvarint(buf)
data := binary.ReadBytes(buf, size)
numOffsets := int(binary.ReadUvarint(buf))
offsets := make(map[string]int64)
for i := 0; i < numOffsets; i++ {
length := binary.ReadUvarint(buf)
name := string(binary.ReadBytes(buf, length))
offset := binary.ReadUvarint(buf)
offsets[name] = offset
}
return NewEvent(data, offsets), nil
}
func pullEvent(r *blocks.Reader) (e *Event) {
size := binary.ReadUvarint(r)
timestamp := int(binary.ReadInt32(r))
data := binary.ReadBytes(r, size)
if len(data) > 0 {
e = &Event{Data: data, Timestamp: timestamp}
}
return
}
func readonly(path string) (Stream, error) {
file, err := os.Open(path)
if err != nil {
return nil, err
}
header := binary.ReadBytes(file, int64(len(MAGIC_HEADER)))
if string(header) != string(MAGIC_HEADER) {
return nil, CORRUPTED_HEADER
}
return newClosedStream(file)
}