-
Notifications
You must be signed in to change notification settings - Fork 45
/
Lifecycle.java
417 lines (376 loc) · 12 KB
/
Lifecycle.java
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
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
/*
* Copyright 2011,2012 Metamarkets Group Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.metamx.common.lifecycle;
import com.google.common.base.Throwables;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.metamx.common.ISE;
import com.metamx.common.logger.Logger;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.atomic.AtomicBoolean;
/**
* A manager of object Lifecycles.
*
* This object has methods for registering objects that should be started and stopped. The Lifecycle allows for
* two stages: Stage.NORMAL and Stage.LAST.
*
* Things added at Stage.NORMAL will be started first (in the order that they are added to the Lifecycle instance) and
* then things added at Stage.LAST will be started.
*
* The close operation goes in reverse order, starting with the last thing added at Stage.LAST and working backwards.
*
* There are two sets of methods to add things to the Lifecycle. One set that will just add instances and enforce that
* start() has not been called yet. The other set will add instances and, if the lifecycle is already started, start
* them.
*/
public class Lifecycle
{
private static final Logger log = new Logger(Lifecycle.class);
private final Map<Stage, CopyOnWriteArrayList<Handler>> handlers;
private final AtomicBoolean started = new AtomicBoolean(false);
private final AtomicBoolean shutdownHookRegistered = new AtomicBoolean(false);
private volatile Stage currStage = null;
public static enum Stage
{
NORMAL,
LAST
}
public Lifecycle()
{
handlers = Maps.newHashMap();
for (Stage stage : Stage.values()) {
handlers.put(stage, new CopyOnWriteArrayList<Handler>());
}
}
/**
* Adds a "managed" instance (annotated with {@link LifecycleStart} and {@link LifecycleStop}) to the Lifecycle at
* Stage.NORMAL. If the lifecycle has already been started, it throws an {@link ISE}
*
* @param o The object to add to the lifecycle
*
* @throws ISE {@link Lifecycle#addHandler(Handler, Stage)}
*/
public <T> T addManagedInstance(T o)
{
addHandler(new AnnotationBasedHandler(o));
return o;
}
/**
* Adds a "managed" instance (annotated with {@link LifecycleStart} and {@link LifecycleStop}) to the Lifecycle.
* If the lifecycle has already been started, it throws an {@link ISE}
*
* @param o The object to add to the lifecycle
* @param stage The stage to add the lifecycle at
*
* @throws ISE {@link Lifecycle#addHandler(Handler, Stage)}
*/
public <T> T addManagedInstance(T o, Stage stage)
{
addHandler(new AnnotationBasedHandler(o), stage);
return o;
}
/**
* Adds an instance with a start() and/or close() method to the Lifecycle at Stage.NORMAL. If the lifecycle has
* already been started, it throws an {@link ISE}
*
* @param o The object to add to the lifecycle
*
* @throws ISE {@link Lifecycle#addHandler(Handler, Stage)}
*/
public <T> T addStartCloseInstance(T o)
{
addHandler(new StartCloseHandler(o));
return o;
}
/**
* Adds an instance with a start() and/or close() method to the Lifecycle. If the lifecycle has already been started,
* it throws an {@link ISE}
*
* @param o The object to add to the lifecycle
* @param stage The stage to add the lifecycle at
*
* @throws ISE {@link Lifecycle#addHandler(Handler, Stage)}
*/
public <T> T addStartCloseInstance(T o, Stage stage)
{
addHandler(new StartCloseHandler(o), stage);
return o;
}
/**
* Adds a handler to the Lifecycle at the Stage.NORMAL stage. If the lifecycle has already been started, it throws
* an {@link ISE}
*
* @param handler The hander to add to the lifecycle
*
* @throws ISE {@link Lifecycle#addHandler(Handler, Stage)}
*/
public void addHandler(Handler handler)
{
addHandler(handler, Stage.NORMAL);
}
/**
* Adds a handler to the Lifecycle. If the lifecycle has already been started, it throws an {@link ISE}
*
* @param handler The hander to add to the lifecycle
* @param stage The stage to add the lifecycle at
*
* @throws ISE indicates that the lifecycle has already been started and thus cannot be added to
*/
public void addHandler(Handler handler, Stage stage)
{
synchronized (handlers) {
if (started.get()) {
throw new ISE("Cannot add a handler after the Lifecycle has started, it doesn't work that way.");
}
handlers.get(stage).add(handler);
}
}
/**
* Adds a "managed" instance (annotated with {@link LifecycleStart} and {@link LifecycleStop}) to the Lifecycle at
* Stage.NORMAL and starts it if the lifecycle has already been started.
*
* @param o The object to add to the lifecycle
*
* @throws Exception {@link Lifecycle#addMaybeStartHandler(Handler, Stage)}
*/
public <T> T addMaybeStartManagedInstance(T o) throws Exception
{
addMaybeStartHandler(new AnnotationBasedHandler(o));
return o;
}
/**
* Adds a "managed" instance (annotated with {@link LifecycleStart} and {@link LifecycleStop}) to the Lifecycle
* and starts it if the lifecycle has already been started.
*
* @param o The object to add to the lifecycle
* @param stage The stage to add the lifecycle at
*
* @throws Exception {@link Lifecycle#addMaybeStartHandler(Handler, Stage)}
*/
public <T> T addMaybeStartManagedInstance(T o, Stage stage) throws Exception
{
addMaybeStartHandler(new AnnotationBasedHandler(o), stage);
return o;
}
/**
* Adds an instance with a start() and/or close() method to the Lifecycle at Stage.NORMAL and starts it if the
* lifecycle has already been started.
*
* @param o The object to add to the lifecycle
*
* @throws Exception {@link Lifecycle#addMaybeStartHandler(Handler, Stage)}
*/
public <T> T addMaybeStartStartCloseInstance(T o) throws Exception
{
addMaybeStartHandler(new StartCloseHandler(o));
return o;
}
/**
* Adds an instance with a start() and/or close() method to the Lifecycle and starts it if the lifecycle has
* already been started.
*
* @param o The object to add to the lifecycle
* @param stage The stage to add the lifecycle at
*
* @throws Exception {@link Lifecycle#addMaybeStartHandler(Handler, Stage)}
*/
public <T> T addMaybeStartStartCloseInstance(T o, Stage stage) throws Exception
{
addMaybeStartHandler(new StartCloseHandler(o), stage);
return o;
}
/**
* Adds a handler to the Lifecycle at the Stage.NORMAL stage and starts it if the lifecycle has already been started.
*
* @param handler The hander to add to the lifecycle
*
* @throws Exception {@link Lifecycle#addMaybeStartHandler(Handler, Stage)}
*/
public void addMaybeStartHandler(Handler handler) throws Exception
{
addMaybeStartHandler(handler, Stage.NORMAL);
}
/**
* Adds a handler to the Lifecycle and starts it if the lifecycle has already been started.
*
* @param handler The hander to add to the lifecycle
* @param stage The stage to add the lifecycle at
*
* @throws Exception an exception thrown from handler.start(). If an exception is thrown, the handler is *not* added
*/
public void addMaybeStartHandler(Handler handler, Stage stage) throws Exception
{
synchronized (handlers) {
if (started.get()) {
if (currStage == null || stage.compareTo(currStage) < 1) {
handler.start();
}
}
handlers.get(stage).add(handler);
}
}
public void start() throws Exception
{
synchronized (handlers) {
if (!started.compareAndSet(false, true)) {
throw new ISE("Already started");
}
for (Stage stage : stagesOrdered()) {
currStage = stage;
for (Handler handler : handlers.get(stage)) {
handler.start();
}
}
}
}
public void stop()
{
synchronized (handlers) {
if (!started.compareAndSet(true, false)) {
log.info("Already stopped and stop was called. Silently skipping");
return;
}
List<Exception> exceptions = Lists.newArrayList();
for (Stage stage : Lists.reverse(stagesOrdered())) {
final CopyOnWriteArrayList<Handler> stageHandlers = handlers.get(stage);
final ListIterator<Handler> iter = stageHandlers.listIterator(stageHandlers.size());
while (iter.hasPrevious()) {
final Handler handler = iter.previous();
try {
handler.stop();
}
catch (Exception e) {
log.warn(e, "exception thrown when stopping %s", handler);
exceptions.add(e);
}
}
}
if (!exceptions.isEmpty()) {
throw Throwables.propagate(exceptions.get(0));
}
}
}
public void ensureShutdownHook()
{
if (shutdownHookRegistered.compareAndSet(false, true)) {
Runtime.getRuntime().addShutdownHook(
new Thread(
new Runnable()
{
@Override
public void run()
{
log.info("Running shutdown hook");
stop();
}
}
)
);
}
}
public void join() throws InterruptedException
{
ensureShutdownHook();
Thread.currentThread().join();
}
private static List<Stage> stagesOrdered()
{
return Arrays.asList(Stage.NORMAL, Stage.LAST);
}
public static interface Handler
{
public void start() throws Exception;
public void stop();
}
private static class AnnotationBasedHandler implements Handler
{
private static final Logger log = new Logger(AnnotationBasedHandler.class);
private final Object o;
public AnnotationBasedHandler(Object o)
{
this.o = o;
}
@Override
public void start() throws Exception
{
for (Method method : o.getClass().getMethods()) {
if (method.getAnnotation(LifecycleStart.class) != null) {
log.info("Invoking start method[%s] on object[%s].", method, o);
method.invoke(o);
}
}
}
@Override
public void stop()
{
for (Method method : o.getClass().getMethods()) {
if (method.getAnnotation(LifecycleStop.class) != null) {
log.info("Invoking stop method[%s] on object[%s].", method, o);
try {
method.invoke(o);
}
catch (Exception e) {
log.error(e, "Exception when stopping method[%s] on object[%s]", method, o);
}
}
}
}
}
public boolean isStarted()
{
return started.get();
}
private static class StartCloseHandler implements Handler
{
private static final Logger log = new Logger(StartCloseHandler.class);
private final Object o;
private final Method startMethod;
private final Method stopMethod;
public StartCloseHandler(Object o)
{
this.o = o;
try {
startMethod = o.getClass().getMethod("start");
stopMethod = o.getClass().getMethod("close");
}
catch (NoSuchMethodException e) {
throw new RuntimeException(e);
}
}
@Override
public void start() throws Exception
{
log.info("Starting object[%s]", o);
startMethod.invoke(o);
}
@Override
public void stop()
{
log.info("Stopping object[%s]", o);
try {
stopMethod.invoke(o);
}
catch (Exception e) {
log.error(e, "Unable to invoke stopMethod() on %s", o.getClass());
}
}
}
}