Jay Taylor's notes

1	// Copyright 2012-2018 The NATS Authors
2	// Licensed under the Apache License, Version 2.0 (the "License");
3	// you may not use this file except in compliance with the License.
4	// You may obtain a copy of the License at
5	//
6	// http://www.apache.org/licenses/LICENSE-2.0
7	//
8	// Unless required by applicable law or agreed to in writing, software
9	// distributed under the License is distributed on an "AS IS" BASIS,
10	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11	// See the License for the specific language governing permissions and
12	// limitations under the License.
13
14	package server
15
16	import (
17	" os "
18	" time "
19
20	" golang.org/x/sys/windows/svc "
21	" golang.org/x/sys/windows/svc/debug "
22	)
23
24	const (
25	serviceName = " gnatsd "
26	reopenLogCode = 128
27	reopenLogCmd = svc. Cmd (reopenLogCode)
28	acceptReopenLog = svc. Accepted (reopenLogCode)
29	)
30
31	// winServiceWrapper implements the svc.Handler interface for implementing
32	// gnatsd as a Windows service.
33	type winServiceWrapper struct {
34	server *Server
35	}
36
37	var dockerized = false
38
39	func init () {
40	if v , exists := os. LookupEnv ( " NATS_DOCKERIZED " ); exists && v == " 1 " {
41	dockerized = true
42	}
43	}
44
45	// Execute will be called by the package code at the start of
46	// the service, and the service will exit once Execute completes.
47	// Inside Execute you must read service change requests from r and
48	// act accordingly. You must keep service control manager up to date
49	// about state of your service by writing into s as required.
50	// args contains service name followed by argument strings passed
51	// to the service.
52	// You can provide service exit code in exitCode return parameter,
53	// with 0 being "no error". You can also indicate if exit code,
54	// if any, is service specific or not by using svcSpecificEC
55	// parameter.
56	func ( w * winServiceWrapper ) Execute (args []string, changes <-chan svc.ChangeRequest,
57	status chan<- svc.Status) (bool, uint32) {
58
59	status <- svc. Status {State: svc. StartPending }
60	go w. server . Start ()
61
62	// Wait for accept loop(s) to be started
63	if !w. server . ReadyForConnections ( 10 * time. Second ) {
64	// Failed to start.
65	return false , 1
66	}
67
68	status <- svc. Status {
69	State: svc. Running ,
70	Accepts: svc. AcceptStop \| svc. AcceptShutdown \| svc. AcceptParamChange \| acceptReopenLog,
71	}
72
73	loop:
74	for change := range changes {
75	switch change. Cmd {
76	case svc. Interrogate :
77	status <- change. CurrentStatus
78	case svc. Stop , svc. Shutdown :
79	w. server . Shutdown ()
80	break loop
81	case reopenLogCmd:
82	// File log re-open for rotating file logs.
83	w. server . ReOpenLogFile ()
84	case svc. ParamChange :
85	if err := w. server . Reload (); err != nil {
86	w. server . Errorf ( " Failed to reload server configuration: %s " , err)
87	}
88	default :
89	w. server . Debugf ( " Unexpected control request: %v " , change. Cmd )
90	}
91	}
92
93	status <- svc. Status {State: svc. StopPending }
94	return false , 0
95	}
96
97	// Run starts the NATS server as a Windows service.
98	func Run ( server * Server ) error {
99	if dockerized {
100	server. Start ()
101	return nil
102	}
103	run := svc. Run
104	isInteractive , err := svc. IsAnInteractiveSession ()
105	if err != nil {
106	return err
107	}
108	if isInteractive {
109	run = debug. Run
110	}
111	return run (serviceName, &winServiceWrapper{server})
112	}
113
114	// isWindowsService indicates if NATS is running as a Windows service.
115	func isWindowsService () bool {
116	if dockerized {
117	return false
118	}
119	isInteractive , _ := svc. IsAnInteractiveSession ()
120	return !isInteractive
121	}

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