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
|
/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2005-2010, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id$
package scala.actors
import scala.actors.scheduler.{DelegatingScheduler, DefaultThreadPoolScheduler,
ForkJoinScheduler, ThreadPoolConfig}
private[actors] object Reactor {
val scheduler = new DelegatingScheduler {
def makeNewScheduler: IScheduler = {
val sched = if (!ThreadPoolConfig.useForkJoin) {
// default is non-daemon
val s = new DefaultThreadPoolScheduler(false)
s.start()
s
} else {
// default is non-daemon, non-fair
val s = new ForkJoinScheduler(ThreadPoolConfig.corePoolSize, ThreadPoolConfig.maxPoolSize, false, false)
s.start()
s
}
Debug.info(this+": starting new "+sched+" ["+sched.getClass+"]")
sched
}
}
val waitingForNone = new PartialFunction[Any, Unit] {
def isDefinedAt(x: Any) = false
def apply(x: Any) {}
}
}
/**
* The Reactor trait provides lightweight actors.
*
* @author Philipp Haller
*/
trait Reactor extends OutputChannel[Any] {
/* The actor's mailbox. */
private[actors] val mailbox = new MQueue("Reactor")
// guarded by this
private[actors] val sendBuffer = new MQueue("SendBuffer")
/* Whenever this actor executes on some thread, `waitingFor` is
* guaranteed to be equal to `Reactor.waitingForNone`.
*
* In other words, whenever `waitingFor` is not equal to
* `Reactor.waitingForNone`, this actor is guaranteed not to execute
* on some thread.
*
* If the actor waits in a `react`, `waitingFor` holds the
* message handler that `react` was called with.
*
* guarded by this
*/
private[actors] var waitingFor: PartialFunction[Any, Any] =
Reactor.waitingForNone
/**
* The behavior of an actor is specified by implementing this
* abstract method.
*/
def act(): Unit
protected[actors] def exceptionHandler: PartialFunction[Exception, Unit] =
Map()
protected[actors] def scheduler: IScheduler =
Reactor.scheduler
protected[actors] def mailboxSize: Int =
mailbox.size
/**
* Sends <code>msg</code> to this actor (asynchronous) supplying
* explicit reply destination.
*
* @param msg the message to send
* @param replyTo the reply destination
*/
def send(msg: Any, replyTo: OutputChannel[Any]) {
val todo = synchronized {
if (waitingFor ne Reactor.waitingForNone) {
val savedWaitingFor = waitingFor
waitingFor = Reactor.waitingForNone
startSearch(msg, replyTo, savedWaitingFor)
} else {
sendBuffer.append(msg, replyTo)
() => { /* do nothing */ }
}
}
todo()
}
private[actors] def startSearch(msg: Any, replyTo: OutputChannel[Any], handler: PartialFunction[Any, Any]) =
() => scheduler execute (makeReaction(() => {
val startMbox = new MQueue("Start")
synchronized { startMbox.append(msg, replyTo) }
searchMailbox(startMbox, handler, true)
}))
private[actors] def makeReaction(fun: () => Unit): Runnable =
new ReactorTask(this, fun)
private[actors] def resumeReceiver(item: (Any, OutputChannel[Any]), handler: PartialFunction[Any, Any], onSameThread: Boolean) {
if (onSameThread)
handler(item._1)
else {
scheduleActor(handler, item._1)
/* Here, we throw a SuspendActorException to avoid
terminating this actor when the current ReactorTask
is finished.
The SuspendActorException skips the termination code
in ReactorTask.
*/
throw Actor.suspendException
}
}
def !(msg: Any) {
send(msg, null)
}
def forward(msg: Any) {
send(msg, null)
}
def receiver: Actor = this.asInstanceOf[Actor]
// guarded by this
private[actors] def drainSendBuffer(mbox: MQueue) {
sendBuffer.foreachDequeue(mbox)
}
private[actors] def searchMailbox(startMbox: MQueue,
handler: PartialFunction[Any, Any],
resumeOnSameThread: Boolean) {
var tmpMbox = startMbox
var done = false
while (!done) {
val qel = tmpMbox.extractFirst(handler)
if (tmpMbox ne mailbox)
tmpMbox.foreachAppend(mailbox)
if (null eq qel) {
synchronized {
// in mean time new stuff might have arrived
if (!sendBuffer.isEmpty) {
tmpMbox = new MQueue("Temp")
drainSendBuffer(tmpMbox)
// keep going
} else {
waitingFor = handler
/* Here, we throw a SuspendActorException to avoid
terminating this actor when the current ReactorTask
is finished.
The SuspendActorException skips the termination code
in ReactorTask.
*/
throw Actor.suspendException
}
}
} else {
resumeReceiver((qel.msg, qel.session), handler, resumeOnSameThread)
done = true
}
}
}
protected[actors] def react(f: PartialFunction[Any, Unit]): Nothing = {
assert(Actor.rawSelf(scheduler) == this, "react on channel belonging to other actor")
synchronized { drainSendBuffer(mailbox) }
searchMailbox(mailbox, f, false)
throw Actor.suspendException
}
/* This method is guaranteed to be executed from inside
* an actors act method.
*
* assume handler != null
*
* never throws SuspendActorException
*/
private[actors] def scheduleActor(handler: PartialFunction[Any, Any], msg: Any) = {
val fun = () => handler(msg)
val task = new ReactorTask(this, fun)
scheduler executeFromActor task
}
def start(): Reactor = {
scheduler.newActor(this)
val task = new ReactorTask(this, () => act())
scheduler execute task
this
}
/* This closure is used to implement control-flow operations
* built on top of `seq`. Note that the only invocation of
* `kill` is supposed to be inside `ReactorTask.run`.
*/
@volatile
private[actors] var kill: () => Unit =
() => { exit() }
private[actors] def seq[a, b](first: => a, next: => b): Unit = {
val s = Actor.rawSelf(scheduler)
val killNext = s.kill
s.kill = () => {
s.kill = killNext
// to avoid stack overflow:
// instead of directly executing `next`,
// schedule as continuation
scheduleActor({ case _ => next }, 1)
throw Actor.suspendException
}
first
throw new KillActorException
}
protected[this] def exit(): Nothing = {
terminated()
throw Actor.suspendException
}
private[actors] def terminated() {
scheduler.terminated(this)
}
}
|
