Function EncodeNodeMetadata

kv/memberlist/node_meta.go:30–53

EncodeNodeMetadata encodes node metadata into a compact binary format. The encoding is versioned to allow future extensions while maintaining backward compatibility. We use a custom compact encoding rather than protobuf because memberlist has strict size limits for node metadata (typically 512 byte

(role NodeRole, zone string)

//
// The maximum metadata size is 19 bytes (1 + 1 + 1 + 16).
func EncodeNodeMetadata(role NodeRole, zone string) ([]byte, error) {
	// Validate zone name length.
	zoneLen := len(zone)
	if zoneLen > MaxZoneNameLength {
		return nil, fmt.Errorf("zone name too long: %d bytes (max %d)", zoneLen, MaxZoneNameLength)
	}

	// Allocate buffer: version(1) + role(1) + zone_len(1) + zone(variable).
	buf := make([]byte, 3+zoneLen)

	// Encode version.
	buf[0] = 1

	// Encode role.
	buf[1] = uint8(role)

	// Encode zone length.
	buf[2] = uint8(zoneLen)

	// Encode zone string.
	copy(buf[3:], zone)

	return buf, nil
}

// Role returns the node role with zero allocations.
// Returns NodeRoleMember if the metadata is invalid.