Asynchronous programming
val a: Future[Int] = Future {
//time-consuming process
result
}
a.map(x => x + 1)
callback listener
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Asynchronous programming
val a: Future[Int] = ???
def f(x: Int): Future[Int] = ???
val r = a.map(x => f(x))
Future[Future[Int]]
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Asynchronous programming
val a: Future[Int] = ???
def f(x: Int): Future[Int] = ???
val r = a.flatMap(x => f(x))
Future[Int]
Slide 5
Slide 5 text
Asynchronous programming
val a: Future[Int] = ???
def f(x: Int): Future[Int] = ???
val r = a.flatMap(x => f(x))
val p = Await.result(r, 3.seconds)
Int
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T
T
T
T
T
T
T
Future { ??? }
a.map(???)
???
Await(???)
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T
T
T
T
T
T
T
Future { ??? }
a.map(???)
F
???
Await(???)
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T
T
T T
T
T
T
Future { ??? }
a.map(???)
F
???
Await(???)
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T
T
T
T
T
T
T
Future { ??? }
a.map(???)
F
???
F
Await(???)
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T
T
T
T
T
T
T
Future { ??? }
a.map(???)
F
???
F
Await(???)
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T
T
T
T
T
T
Future { ??? }
a.map(???)
F
F
???
Await(???)
T
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T
T
T
T
T
T
Future { ??? }
a.map(???)
F
F
???
Await(???)
T
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T
T
T
T
T
T
Future { ??? }
a.map(???)
F
F
???
Await(???)
T
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T
T
T
T
T
T
Future { ??? }
a.map(???)
F
F
???
Await(???)
T
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T
T
T
T
T
T
Future { ??? }
a.map(???)
F
F
???
Await(???)
T
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T
T
T
T
T
T
Future { ??? }
a.map(???)
F
F
???
Await(???)
T
C
C
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T
R
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T
R
R
R
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T
R
R
R
C C
C C C
C C C
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T
R
C C
C C C
C C C
T
T
R
R
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T
R
C C
C C C
C C C
T
T
R
R
R
R
R
R
R
R
R
R
R
R
R
R
1000+
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Orz
T
T
R
C C
C C C
C C
T
T
R
R
R
R
R
R
R
R
R
R
R
R
R
R
1000+
T
T
T
T
T
T
T
T
T
switching thread takes time...
crashed,
nothing get
computed
after all...
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R
C C
C C C
C C
T
R
R
R
R
R
R
R
R
R
R
R
R
R
R
1000+
T
thread pool
C
T
T T
T
T
T
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R
C C
C C C
C C
T
R
R
R
R
R
R
R
R
R
R
R
R
R
R
T
C
T
T T
T
T
T
access DB
long computing
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R
C C
C C C
C C
T
R
R
R
R
R
R
R
R
R
R
R
R
R
R
T
C
T
T T
T
T
T
access DB
long computing
blocking
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R
C C
C C
C
C C
T
R
R
R
R
R
R
R
R
R
R
R
R
R
R
C
T
T T
T T T
T T
T
T T
T T T
T T
T
T T
T T T
T T
T
T T
T
T
F
F F
F F
F
1000+
async squeeze out
the performance
of your machine
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Life is beautiful
...before you have states.
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HP
MP
position weapon
exp
hunger
Running
Attacked
Attacking
Eating
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HP
MP
position weapon
exp
hunger
Running
Attacked
Attacking
Need lock(s) to prevent
strange things happen.
Eating
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HP
MP
position weapon
exp
hunger
Running
Attacked
Attacking
No matter you forward
the job to DB or what.
Eating
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HP
MP
position weapon
exp
hunger
Running
Attacked
Attacking
All the other threads
get blocked.
Eating
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Can we get rid of the locks?
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P W
Wrap the states in an Actor.
T
m
h
p
a
e
mailbox
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P W
Wrap the states in an Actor.
T
m
h
p
a
e
mailbox T
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P W
Wrap the states in an Actor.
T
m
h
p
a
e
mailbox T
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T
T
T T
T
T
T
T
T
T
T
T
T
T T
T
T
front m back
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T
T
T T
T
T
T
T
T
T
T
T
T
T T
T
T
front m
l
back
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T
T
T T
T
T
T
T
T
T
T
T
T
T
T
T
T
front m
l
back
Disk
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Life is beautiful
...before you have many machines.
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T
T
T T
T
T
T
T
T
T
T
T T
T
T
T
T
front m
l
back
Machine A
T
T T
T
T T
s
Machine B
Disk
Slide 41
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Tell & Ask
val a: ActorRef = ctx.actorOf(???)
a ! “Hello!”
(a ? “What’s your name?”)
.mapTo[String]
.map(name => ???)
Slide 42
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Receive messages
class MyActor extends Actor {
def receive = {
case “Hello!” => ???
case “What’s your name?” =>
sender ! “Pishen”
}
}