// TODO: change etcdserver to raft interface when we have it.
// add test for healthHandler when we have the interface ready.
func healthHandler(server *etcdserver.EtcdServer) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
if !allowMethod(w, r.Method, "GET") {
return
}
if uint64(server.Leader()) == raft.None {
http.Error(w, `{"health": "false"}`, http.StatusServiceUnavailable)
return
}
// wait for raft's progress
index := server.Index()
for i := 0; i < 3; i++ {
time.Sleep(250 * time.Millisecond)
if server.Index() > index {
w.WriteHeader(http.StatusOK)
w.Write([]byte(`{"health": "true"}`))
return
}
}
http.Error(w, `{"health": "false"}`, http.StatusServiceUnavailable)
return
}
}
func newStreamInterceptor(s *etcdserver.EtcdServer) grpc.StreamServerInterceptor {
smap := monitorLeader(s)
return func(srv interface{}, ss grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
if !api.IsCapabilityEnabled(api.V3rpcCapability) {
return rpctypes.ErrGRPCNotCapable
}
md, ok := metadata.FromContext(ss.Context())
if ok {
if ks := md[rpctypes.MetadataRequireLeaderKey]; len(ks) > 0 && ks[0] == rpctypes.MetadataHasLeader {
if s.Leader() == types.ID(raft.None) {
return rpctypes.ErrGRPCNoLeader
}
cctx, cancel := context.WithCancel(ss.Context())
ss = serverStreamWithCtx{ctx: cctx, cancel: &cancel, ServerStream: ss}
smap.mu.Lock()
smap.streams[ss] = struct{}{}
smap.mu.Unlock()
defer func() {
smap.mu.Lock()
delete(smap.streams, ss)
smap.mu.Unlock()
cancel()
}()
}
}
return metricsStreamInterceptor(srv, ss, info, handler)
}
}
func newUnaryInterceptor(s *etcdserver.EtcdServer) grpc.UnaryServerInterceptor {
return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (resp interface{}, err error) {
if !api.IsCapabilityEnabled(api.V3rpcCapability) {
return nil, rpctypes.ErrGRPCNotCapable
}
md, ok := metadata.FromContext(ctx)
if ok {
if ks := md[rpctypes.MetadataRequireLeaderKey]; len(ks) > 0 && ks[0] == rpctypes.MetadataHasLeader {
if s.Leader() == types.ID(raft.None) {
return nil, rpctypes.ErrGRPCNoLeader
}
}
}
return metricsUnaryInterceptor(ctx, req, info, handler)
}
}
func monitorLeader(s *etcdserver.EtcdServer) *streamsMap {
smap := &streamsMap{
streams: make(map[grpc.ServerStream]struct{}),
}
go func() {
election := time.Duration(s.Cfg.TickMs) * time.Duration(s.Cfg.ElectionTicks) * time.Millisecond
noLeaderCnt := 0
for {
select {
case <-s.StopNotify():
return
case <-time.After(election):
if s.Leader() == types.ID(raft.None) {
noLeaderCnt++
} else {
noLeaderCnt = 0
}
// We are more conservative on canceling existing streams. Reconnecting streams
// cost much more than just rejecting new requests. So we wait until the member
// cannot find a leader for maxNoLeaderCnt election timeouts to cancel existing streams.
if noLeaderCnt >= maxNoLeaderCnt {
smap.mu.Lock()
for ss := range smap.streams {
if ssWithCtx, ok := ss.(serverStreamWithCtx); ok {
(*ssWithCtx.cancel)()
<-ss.Context().Done()
}
}
smap.streams = make(map[grpc.ServerStream]struct{})
smap.mu.Unlock()
}
}
}
}()
return smap
}