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 // Package connectivity defines connectivity semantics.
20 // For details, see https://github.com/grpc/grpc/blob/master/doc/connectivity-semantics-and-api.md.
21 package connectivity
22 23 import (
24 "google.golang.org/grpc/grpclog"
25 )
26 27 var logger = grpclog.Component("core")
28 29 // State indicates the state of connectivity.
30 // It can be the state of a ClientConn or SubConn.
31 type State int
32 33 func (s State) String() string {
34 switch s {
35 case Idle:
36 return "IDLE"
37 case Connecting:
38 return "CONNECTING"
39 case Ready:
40 return "READY"
41 case TransientFailure:
42 return "TRANSIENT_FAILURE"
43 case Shutdown:
44 return "SHUTDOWN"
45 default:
46 logger.Errorf("unknown connectivity state: %d", s)
47 return "INVALID_STATE"
48 }
49 }
50 51 const (
52 // Idle indicates the ClientConn is idle.
53 Idle State = iota
54 // Connecting indicates the ClientConn is connecting.
55 Connecting
56 // Ready indicates the ClientConn is ready for work.
57 Ready
58 // TransientFailure indicates the ClientConn has seen a failure but expects to recover.
59 TransientFailure
60 // Shutdown indicates the ClientConn has started shutting down.
61 Shutdown
62 )
63 64 // ServingMode indicates the current mode of operation of the server.
65 //
66 // Only xDS enabled gRPC servers currently report their serving mode.
67 type ServingMode int
68 69 const (
70 // ServingModeStarting indicates that the server is starting up.
71 ServingModeStarting ServingMode = iota
72 // ServingModeServing indicates that the server contains all required
73 // configuration and is serving RPCs.
74 ServingModeServing
75 // ServingModeNotServing indicates that the server is not accepting new
76 // connections. Existing connections will be closed gracefully, allowing
77 // in-progress RPCs to complete. A server enters this mode when it does not
78 // contain the required configuration to serve RPCs.
79 ServingModeNotServing
80 )
81 82 func (s ServingMode) String() string {
83 switch s {
84 case ServingModeStarting:
85 return "STARTING"
86 case ServingModeServing:
87 return "SERVING"
88 case ServingModeNotServing:
89 return "NOT_SERVING"
90 default:
91 logger.Errorf("unknown serving mode: %d", s)
92 return "INVALID_MODE"
93 }
94 }
95