forked from gocraft/work
-
Notifications
You must be signed in to change notification settings - Fork 0
/
observer.go
244 lines (204 loc) · 5.75 KB
/
observer.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
package work
import (
"encoding/json"
"fmt"
"time"
"github.com/gomodule/redigo/redis"
)
// An observer observes a single worker. Each worker has its own observer.
type observer struct {
namespace string
workerID string
pool *redis.Pool
// nil: worker isn't doing anything that we know of
// not nil: the last started observation that we received on the channel.
// if we get an checkin, we'll just update the existing observation
currentStartedObservation *observation
// version of the data that we wrote to redis.
// each observation we get, we'll update version. When we flush it to redis, we'll update lastWrittenVersion.
// This will keep us from writing to redis unless necessary
version, lastWrittenVersion int64
observationsChan chan *observation
stopChan chan struct{}
doneStoppingChan chan struct{}
drainChan chan struct{}
doneDrainingChan chan struct{}
}
type observationKind int
const (
observationKindStarted observationKind = iota
observationKindDone
observationKindCheckin
)
type observation struct {
kind observationKind
// These fields always need to be set
jobName string
jobID string
// These need to be set when starting a job
startedAt int64
argsJSON []byte // job's arguments after json.Marshal
argsJSONErr error // json.Marshal's error
// If we're done w/ the job, err will indicate the success/failure of it
err error // nil: success. not nil: the error we got when running the job
// If this is a checkin, set these.
checkin string
checkinAt int64
}
const observerBufferSize = 1024
func newObserver(namespace string, pool *redis.Pool, workerID string) *observer {
return &observer{
namespace: namespace,
workerID: workerID,
pool: pool,
observationsChan: make(chan *observation, observerBufferSize),
stopChan: make(chan struct{}),
doneStoppingChan: make(chan struct{}),
drainChan: make(chan struct{}),
doneDrainingChan: make(chan struct{}),
}
}
func (o *observer) start() {
go o.loop()
}
func (o *observer) stop() {
o.stopChan <- struct{}{}
<-o.doneStoppingChan
}
func (o *observer) drain() {
o.drainChan <- struct{}{}
<-o.doneDrainingChan
}
func (o *observer) observeStarted(jobName, jobID string, arguments map[string]interface{}) {
var argsJSON []byte
var err error
if len(arguments) == 0 {
argsJSON = []byte("")
} else {
argsJSON, err = json.Marshal(arguments)
}
o.observationsChan <- &observation{
kind: observationKindStarted,
jobName: jobName,
jobID: jobID,
startedAt: nowEpochSeconds(),
argsJSON: argsJSON,
argsJSONErr: err,
}
}
func (o *observer) observeDone(jobName, jobID string, err error) {
o.observationsChan <- &observation{
kind: observationKindDone,
jobName: jobName,
jobID: jobID,
err: err,
}
}
func (o *observer) observeCheckin(jobName, jobID, checkin string) {
o.observationsChan <- &observation{
kind: observationKindCheckin,
jobName: jobName,
jobID: jobID,
checkin: checkin,
checkinAt: nowEpochSeconds(),
}
}
func (o *observer) loop() {
// Every tick we'll update redis if necessary
// We don't update it on every job because the only purpose of this data is for humans to inspect the system,
// and a fast worker could move onto new jobs every few ms.
ticker := time.Tick(1000 * time.Millisecond)
for {
select {
case <-o.stopChan:
o.doneStoppingChan <- struct{}{}
return
case <-o.drainChan:
DRAIN_LOOP:
for {
select {
case obv := <-o.observationsChan:
o.process(obv)
default:
if err := o.writeStatus(o.currentStartedObservation); err != nil {
logError("observer.write", err)
}
o.doneDrainingChan <- struct{}{}
break DRAIN_LOOP
}
}
case <-ticker:
if o.lastWrittenVersion != o.version {
if err := o.writeStatus(o.currentStartedObservation); err != nil {
logError("observer.write", err)
}
o.lastWrittenVersion = o.version
}
case obv := <-o.observationsChan:
o.process(obv)
}
}
}
func (o *observer) process(obv *observation) {
if obv.kind == observationKindStarted {
o.currentStartedObservation = obv
} else if obv.kind == observationKindDone {
o.currentStartedObservation = nil
} else if obv.kind == observationKindCheckin {
if (o.currentStartedObservation != nil) && (obv.jobID == o.currentStartedObservation.jobID) {
o.currentStartedObservation.checkin = obv.checkin
o.currentStartedObservation.checkinAt = obv.checkinAt
} else {
logError("observer.checkin_mismatch", fmt.Errorf("got checkin but mismatch on job ID or no job"))
}
}
o.version++
// If this is the version observation we got, just go ahead and write it.
if o.version == 1 {
if err := o.writeStatus(o.currentStartedObservation); err != nil {
logError("observer.first_write", err)
}
o.lastWrittenVersion = o.version
}
}
func (o *observer) writeStatus(obv *observation) error {
conn := o.pool.Get()
defer conn.Close()
key := redisKeyWorkerObservation(o.namespace, o.workerID)
if obv == nil {
if _, err := conn.Do("DEL", key); err != nil {
return err
}
} else {
// hash:
// job_name -> obv.Name
// job_id -> obv.jobID
// started_at -> obv.startedAt
// args -> obv.argsJSON
// checkin -> obv.checkin
// checkin_at -> obv.checkinAt
if obv.argsJSONErr != nil {
return obv.argsJSONErr
}
args := make([]interface{}, 0, 13)
args = append(args,
key,
"job_name", obv.jobName,
"job_id", obv.jobID,
"started_at", obv.startedAt,
"args", obv.argsJSON,
)
if (obv.checkin != "") && (obv.checkinAt > 0) {
args = append(args,
"checkin", obv.checkin,
"checkin_at", obv.checkinAt,
)
}
conn.Send("HMSET", args...)
conn.Send("EXPIRE", key, 60*60*24)
if err := conn.Flush(); err != nil {
return err
}
}
return nil
}