khenaidoo | ffe076b | 2019-01-15 16:08:08 -0500 | [diff] [blame^] | 1 | /* |
| 2 | * |
| 3 | * Copyright 2017 gRPC authors. |
| 4 | * |
| 5 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 6 | * you may not use this file except in compliance with the License. |
| 7 | * You may obtain a copy of the License at |
| 8 | * |
| 9 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | * |
| 11 | * Unless required by applicable law or agreed to in writing, software |
| 12 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 14 | * See the License for the specific language governing permissions and |
| 15 | * limitations under the License. |
| 16 | * |
| 17 | */ |
| 18 | |
| 19 | //go:generate ./regenerate.sh |
| 20 | |
| 21 | // Package health provides a service that exposes server's health and it must be |
| 22 | // imported to enable support for client-side health checks. |
| 23 | package health |
| 24 | |
| 25 | import ( |
| 26 | "context" |
| 27 | "sync" |
| 28 | |
| 29 | "google.golang.org/grpc/codes" |
| 30 | healthgrpc "google.golang.org/grpc/health/grpc_health_v1" |
| 31 | healthpb "google.golang.org/grpc/health/grpc_health_v1" |
| 32 | "google.golang.org/grpc/status" |
| 33 | ) |
| 34 | |
| 35 | // Server implements `service Health`. |
| 36 | type Server struct { |
| 37 | mu sync.Mutex |
| 38 | // statusMap stores the serving status of the services this Server monitors. |
| 39 | statusMap map[string]healthpb.HealthCheckResponse_ServingStatus |
| 40 | updates map[string]map[healthgrpc.Health_WatchServer]chan healthpb.HealthCheckResponse_ServingStatus |
| 41 | } |
| 42 | |
| 43 | // NewServer returns a new Server. |
| 44 | func NewServer() *Server { |
| 45 | return &Server{ |
| 46 | statusMap: map[string]healthpb.HealthCheckResponse_ServingStatus{"": healthpb.HealthCheckResponse_SERVING}, |
| 47 | updates: make(map[string]map[healthgrpc.Health_WatchServer]chan healthpb.HealthCheckResponse_ServingStatus), |
| 48 | } |
| 49 | } |
| 50 | |
| 51 | // Check implements `service Health`. |
| 52 | func (s *Server) Check(ctx context.Context, in *healthpb.HealthCheckRequest) (*healthpb.HealthCheckResponse, error) { |
| 53 | s.mu.Lock() |
| 54 | defer s.mu.Unlock() |
| 55 | if servingStatus, ok := s.statusMap[in.Service]; ok { |
| 56 | return &healthpb.HealthCheckResponse{ |
| 57 | Status: servingStatus, |
| 58 | }, nil |
| 59 | } |
| 60 | return nil, status.Error(codes.NotFound, "unknown service") |
| 61 | } |
| 62 | |
| 63 | // Watch implements `service Health`. |
| 64 | func (s *Server) Watch(in *healthpb.HealthCheckRequest, stream healthgrpc.Health_WatchServer) error { |
| 65 | service := in.Service |
| 66 | // update channel is used for getting service status updates. |
| 67 | update := make(chan healthpb.HealthCheckResponse_ServingStatus, 1) |
| 68 | s.mu.Lock() |
| 69 | // Puts the initial status to the channel. |
| 70 | if servingStatus, ok := s.statusMap[service]; ok { |
| 71 | update <- servingStatus |
| 72 | } else { |
| 73 | update <- healthpb.HealthCheckResponse_SERVICE_UNKNOWN |
| 74 | } |
| 75 | |
| 76 | // Registers the update channel to the correct place in the updates map. |
| 77 | if _, ok := s.updates[service]; !ok { |
| 78 | s.updates[service] = make(map[healthgrpc.Health_WatchServer]chan healthpb.HealthCheckResponse_ServingStatus) |
| 79 | } |
| 80 | s.updates[service][stream] = update |
| 81 | defer func() { |
| 82 | s.mu.Lock() |
| 83 | delete(s.updates[service], stream) |
| 84 | s.mu.Unlock() |
| 85 | }() |
| 86 | s.mu.Unlock() |
| 87 | |
| 88 | var lastSentStatus healthpb.HealthCheckResponse_ServingStatus = -1 |
| 89 | for { |
| 90 | select { |
| 91 | // Status updated. Sends the up-to-date status to the client. |
| 92 | case servingStatus := <-update: |
| 93 | if lastSentStatus == servingStatus { |
| 94 | continue |
| 95 | } |
| 96 | lastSentStatus = servingStatus |
| 97 | err := stream.Send(&healthpb.HealthCheckResponse{Status: servingStatus}) |
| 98 | if err != nil { |
| 99 | return status.Error(codes.Canceled, "Stream has ended.") |
| 100 | } |
| 101 | // Context done. Removes the update channel from the updates map. |
| 102 | case <-stream.Context().Done(): |
| 103 | return status.Error(codes.Canceled, "Stream has ended.") |
| 104 | } |
| 105 | } |
| 106 | } |
| 107 | |
| 108 | // SetServingStatus is called when need to reset the serving status of a service |
| 109 | // or insert a new service entry into the statusMap. |
| 110 | func (s *Server) SetServingStatus(service string, servingStatus healthpb.HealthCheckResponse_ServingStatus) { |
| 111 | s.mu.Lock() |
| 112 | defer s.mu.Unlock() |
| 113 | |
| 114 | s.statusMap[service] = servingStatus |
| 115 | for _, update := range s.updates[service] { |
| 116 | // Clears previous updates, that are not sent to the client, from the channel. |
| 117 | // This can happen if the client is not reading and the server gets flow control limited. |
| 118 | select { |
| 119 | case <-update: |
| 120 | default: |
| 121 | } |
| 122 | // Puts the most recent update to the channel. |
| 123 | update <- servingStatus |
| 124 | } |
| 125 | } |