[英]Using Actor Supervised , how to retry the same message for defined number of times with defined interval if failure occur
I am following code from akka.io fault tolerance http://doc.akka.io/docs/akka/current/java/fault-tolerance.html
.I have taken this code as reference.My requirement is as follow : Let's assume the actor crashes on a message and is restarted by his supervisor. 我正在遵循akka.io容错
http://doc.akka.io/docs/akka/current/java/fault-tolerance.html
代码。我已将此代码作为参考。我的要求如下:让我们假设演员在一条消息上崩溃并由他的主管重新启动。 Then he starts to process the next message in his mailbox. 然后他开始处理他邮箱中的下一条消息。 The message which caused the crash is 'dropped'.But I want to process the same action for a particular number of time(suppose 3 times) with a defined interval between them(suppose 1 second).How to do this using akka supervision.
导致崩溃的消息被“丢弃”。但我想在特定时间内(假设3次)处理相同的动作,并且它们之间有一个定义的间隔(假设为1秒)。如何使用akka监督来执行此操作。 Actually through actor I am trying to check whether a particular service api is working or not(ie giving some exception).So if there is any exception on a particular try,(suppose 404 not found),resend the message to the failed worker until maxNrOfRetries is reached as specified by supervisorStrategy.
实际上通过actor我试图检查特定服务api是否正常工作(即给出一些例外)。因此,如果在特定尝试中有任何异常,(假设404未找到),则将消息重新发送给失败的工作者,直到按照supervisorStrategy的规定达到maxNrOfRetries。 If the worker has failed "maxNrOfRetries" times then just logged like"max number of tries reached for this xx message".How will I do it in java.
如果工作人员失败了“maxNrOfRetries”次,那么只记录为“此xx消息的最大尝试次数”。如何在java中执行此操作。
my supervisor class : 我的主管班:
public class Supervisor extends UntypedActor {
private static SupervisorStrategy strategy =
new OneForOneStrategy(3, Duration.create("1 minute"),
new Function<Throwable, Directive>() {
@Override
public Directive apply(Throwable t) {
if (t instanceof Exception) {
return restart();
}else if (t instanceof IllegalArgumentException) {
return stop();
} else {
return escalate();
}
}
});
@Override
public SupervisorStrategy supervisorStrategy() {
return strategy;
}
public void onReceive(Object o) {
if (o instanceof Props) {
getSender().tell(getContext().actorOf((Props) o), getSelf());
} else {
unhandled(o);
}
}
}
Child Class : 儿童班:
public class Child extends UntypedActor {
public void onReceive(Object o) throws Exception {
if (o instanceof String) {
Object response = someFunction( (String) message);//this function returns either successfull messgae as string or exception
if(response instanceOf Exception) {
throw (Exception) response;
}
else
getSender().tell(response, getSelf())
}else {
unhandled(o);
}
}
}
Creating actor : 创建演员:
Props superprops = Props.create(Supervisor.class);
ActorRef supervisor = system.actorOf(superprops, "supervisor");
ActorRef child = (ActorRef) Await.result(ask(supervisor,
Props.create(Child.class), 5000), timeout);
child.tell("serVice_url", ActorRef.noSender());
For the service_url I want to repeat the process if failure occurs.But it's not happening. 对于service_url,如果发生故障,我想重复该过程。但它没有发生。 if write the next line in creatng actor as
child.tell("serVice_url_2", ActorRef.noSender());
如果将creatng actor中的下一行写为
child.tell("serVice_url_2", ActorRef.noSender());
then this line is exucted but I want to process the same action (for which failure occurs) for a particular number of time(suppose 3 times) with a defined interval between them. 然后这条线被引导但我想处理相同的动作(发生故障)特定的时间(假设3次),并且它们之间有一个定义的间隔。 Please guide me to achieve this.
请指导我实现这一目标。
I think I have developed a way.Though I will still have to do a test on production level.I am writing the answer below as it might be helpful to someone trying to achieve the same thing.If someone finds a better approach then he/she is welcomed. 我想我已经开发了一种方法。虽然我仍然需要在生产水平上进行测试。我正在写下面的答案,因为它可能对尝试实现同样的事情有所帮助。如果有人找到更好的方法,那么他/她很受欢迎。 Want to mention here that through this approach Supervisor process the same action (with the message for which failure occurs) for a particular number of times(suppose 3 times) within a time range.I was not been able to defined an interval between them.
这里要提一下,通过这种方法, Supervisor在一个时间范围内处理相同的动作(发生故障的消息)特定次数(假设3次)。我无法定义它们之间的间隔。 here is the code.
这是代码。 The Supervisor class.
主管班。
public class MyUntypedActor extends UntypedActor {
//here I have given Max no retrilas as 10.I will controll this number from logic as per my own requirements.But user given number of retrials can not exceed 10.
private static SupervisorStrategy strategy = new AllForOneStrategy(10, Duration.create(5, TimeUnit.MINUTES),
new Function<Throwable, SupervisorStrategy.Directive>() {
@Override
public SupervisorStrategy.Directive apply(Throwable t) {
if (t instanceof Exception) {
//System.out.println("exception" + "*****" + t.getMessage() + "***" + t.getLocalizedMessage());
return restart();
} else if (t instanceof NullPointerException) {
return restart();
} else if (t instanceof IllegalArgumentException) {
return stop();
} else {
return escalate();
}
}
});
@Override
public SupervisorStrategy supervisorStrategy() {
return strategy;
}
public void onReceive(Object o) {
if (o instanceof Props) {
getSender().tell(getContext().actorOf((Props) o), getSelf());
} else {
unhandled(o);
}
}
}
The child class where we will write our logic. 我们将编写逻辑的子类。
public class Child extends UntypedActor {
//Through preRestart it will push the message for which exception occured before the restart of the child
@Override
public void preRestart(final Throwable reason, final scala.Option<Object> message) throws Exception {
System.out.println("reStarting :::" + message.get());
SetRules.setRemainingTrials(SetRules.remainingTrials + 1);
getSelf().tell(message.get(), getSender());
};
public void onReceive(Object o) throws Exception {
if (o instanceof Exception) {
throw (Exception) o;
} else if (o instanceof Integer) {
} else if (o.equals("get")) {
getSender().tell("get", getSelf());
} else if (o instanceof String) {
try {
// here either we can write our logic directly or for a better
// approach can call a function where the logic will be excuted.
getSender().tell("{\"meggase\":\"Succesfull after " + SetRules.remainingTrials + " retrials\"}",
getSelf());
} catch (Exception ex) {
if (SetRules.remainingTrials == SetRules.noOfRetries) {
getSender().tell("{\"meggase\":\"Failed to connect after " + SetRules.noOfRetries + " retrials\"}",
getSelf());
} else {
Exception value1 = ex;
throw (Exception) value1;
}
}
} else {
unhandled(o);
}
}
}
The SetRules class which have the information about user provide noOfRetrials and also store the information about the number of retrials at each sate of retrying through remainingTrials 具有关于用户的信息的SetRules类提供noOfRetrials,并且还存储关于通过remainingTrials重试的每个重试次数的信息
public class SetRules {
public static int noOfRetries;
public static int remainingTrials;
public SetRules(int noOfRetries, int remainingTrials) {
super();
SetRules.noOfRetries = noOfRetries;
SetRules.remainingTrials = remainingTrials;
}
public int getRemainingTrials() {
return remainingTrials;
}
public static void setRemainingTrials(int remainingTrials) {
SetRules.remainingTrials = remainingTrials;
}
}
Now lets create the actor. 现在让我们创建一个actor。
Props superprops = Props.create(MyUntypedActor.class);
SetRules setRules=new SetRules(3,0);
ActorSystem system = ActorSystem.create("helloakka");
ActorRef supervisor = system.actorOf(superprops, "supervisor");
ActorRef child = (ActorRef) Await.result(ask(supervisor, Props.create(Child.class), 5000), Duration.create(5, "minutes"));
Future<Object> future = Patterns.ask(child, service_Url, new Timeout(Duration.create(5, "minutes")));
Object result = Await.result(future, Duration.create(5, "minutes"));
System.out.println(result);
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