Initial commit

lib/wal/segment-header.go

@@ -0,0 +1,44 @@
+package wal
+
+import "encoding/binary"
+
+type segmentHeader struct {
+	CreatedAt       int64
+	ArchivedAt      int64
+	FirstSeqNum     int64
+	LastSeqNum      int64 // FirstSeqNum - 1  if empty.
+	LastTimestampMS int64 // 0 if empty.
+	InsertAt        int64
+}
+
+func (h segmentHeader) WriteTo(b []byte) {
+	vals := []int64{
+		h.CreatedAt,
+		h.ArchivedAt,
+		h.FirstSeqNum,
+		h.LastSeqNum,
+		h.LastTimestampMS,
+		h.InsertAt,
+	}
+
+	for _, val := range vals {
+		binary.LittleEndian.PutUint64(b[0:8], uint64(val))
+		b = b[8:]
+	}
+}
+
+func (h *segmentHeader) ReadFrom(b []byte) {
+	ptrs := []*int64{
+		&h.CreatedAt,
+		&h.ArchivedAt,
+		&h.FirstSeqNum,
+		&h.LastSeqNum,
+		&h.LastTimestampMS,
+		&h.InsertAt,
+	}
+
+	for _, ptr := range ptrs {
+		*ptr = int64(binary.LittleEndian.Uint64(b[0:8]))
+		b = b[8:]
+	}
+}