actor | 易学教程

How to model if-expressions with actor systems?

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问题 I'm try to emulate a simple functional language using actors. Actor systems nowadays are used basically for speeding up all kind of stuff by avoiding OS locks and stalled threads or to make microservices less painful, but initially it was supposed to be an alternative model of computation in general [1][2] and therefore should be capable to cover any programming language construct and certainly an if , right? While I'm aware that this is occasionally met with irritation, I saw one timid

Compilation error using scala classes in java maven project

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问题 I have a java maven project , i installed scala plugin for eclipse and added scala nature to my project . Now , i have written some custom scala Actors and some other utility classes .I am using these scala classes in my java code . while writing the code , it doesn't throw any errors .But , when i do maven clean /build , it throws compilation error's like below 11/8/11 10:45:23 AM : [ERROR] ............\Simple.java:[86,10] cannot find symbol symbol : variable ExecutorObject location: class

Can Verilog/Systemverilog/VHDL be considered actor oriented programming languages?

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问题 These languages provide modules which are inherently concurrent and can handle asynchronous messages pretty neat (through ports). Keeping aside the fact that they cannot spawn module instances at runtime, do they qualify as actor based programming languages? Thanks EDIT: What I'm really looking for is how well the language semantics can be used to "model" actors, rather than how a simulator would handle the code (of course, they are all event-driven underneath; and further down, we end up

Neo4j 查询语法入门

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一：Node语法在cypher里面通过用一对小括号()表示一个节点，它在cypher里面查询形式如下： 1，() 代表匹配任意一个节点 2, (node1) 代表匹配任意一个节点，并给它起了一个别名 3, (:Lable) 代表查询一个类型的数据 4, (person:Lable) 代表查询一个类型的数据，并给它起了一个别名 5, (person:Lable {name:"小王"}) 查询某个类型下，节点属性满足某个值的数据 6, (person:Lable {name:"小王",age:23})　节点的属性可以同时存在多个，是一个AND的关系二：关系语法关系用一对-组成，关系分有方向的进和出，如果是无方向就是进和出都查询 1,--> 指向一个节点 2,-[role]-> 给关系加个别名 3,-[:acted_in]-> 访问某一类关系 4,-[role:acted_in]-> 访问某一类关系，并加了别名 5,-[role:acted_in {roles:["neo","hadoop"]}]-> 访问某一类关系下的某个属性的关系的数据三：模式语法模式语法是节点和关系查询语法的结合，通过模式语法我们可以进行我们想要的任意复杂的查询 (p1: Person:Actor {name:"tom"})-[role:acted_in {roles:["neo","actor"]}]-

Scala program exiting before the execution and completion of all Scala Actor messages being sent. How to stop this?

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问题 I am sending my Scala Actor its messages from a for loop. The scala actor is receiving the messages and getting to the job of processing them. The actors are processing cpu and disk intensive tasks such as unzipping and storing files. I deduced that the Actor part is working fine by putting in a delay Thread.sleep(200) in my message passing code in the for loop. for ( val e <- entries ) { MyActor ! new MyJob(e) Thread.sleep(100) } Now, my problem is that the program exits with a code 0 as

How can I get Fibonacci(n) in an efficient way with Scala Actor?

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问题 The algorithm is just like this. def fib(x: Int): BigInt = { x match { case 1 => BigInt(1) case 2 => BigInt(1) case x => fib(x-1) + fib(x-2) } } I try to make the algorithm parallel with Actor in Scala. But my code is extremely slow compare with the one without Actor! Is there a good way to make it work? 回答1: For not large size of n , the serial code will always be faster (Much much faster in cases of tail recursion). This is because calling a new function will be faster than starting a new

how to execute (exec) external system commands in Scala actor?

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问题 to run an external command, I should import sys.process._ val result="ls a" ! then when use actor, I need to also use "!" to send message. So ! is defined both in actor and in process, but I need to use them both in the same code block, how to do that? 回答1: I don't see the issue of Process and ActorRef both defining a method with the same name. An analog example would be class A { def ! = println("A") } class B { def ! = println("B") } val a = new A val b = new B a.! // "A" b.! // "B" There's

How to handle bursts with Actors?

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问题 Suppose I have an actor, which handles X requests per second. It is ok in average but sometimes there are bursts and clients send Y > X requests per second. Suppose also that all requests have timeouts so they cannot wait in queue forever. Assuming we program in Scala and Akka what are the best practices/design patterns to make the actor handle those bursts? Are there any code examples, which handle bursts? 回答1: As long as your machine can handle the increased load (i.e. has enough CPUs),

Use case diagram: of several actors of a use case, only some have access to an extending use case

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问题 How can I represent a diagram in which several actors have access to the same function, or "use case" but some of them have additional functions or "extends" (if im right) inside it, if i just extend on the main "use case" that would mean its accessible by everyone right? 回答1: When a use case extends the main use case, extension points at the main use case, can have conditions. As a condition you could specify a specific actor. If the actors can be generalized, I have seen this solution too.

How can I use a TypedActor in a Java application?

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问题 I try to implement a TypedActor in Java following the examples on Typed Actors (Java). But I'm struggling. I have added akka-actor-1.1-M1.jar , akka-typed-actor-1.1-M1.jar , scala-library.jar but it wasn't enough. I got errors in Eclipse so I also added aspectwerkz-2.0.jar and aspectwerkz-core-2.0.jar to my Build Path. I try to use a TypedActor with custom constructor. But now I get an error at compilation: Exception in thread "main" java.lang.NoSuchMethodError: org.codehaus.aspectwerkz.proxy