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[英]Play Framework 2.3.1 Promise exception handling within inner class
[英]Play Framework: handling timeout over controller promise
我所有应用程序的控制器(Play Framework 2.2.4,Java)都返回F.Promise:现在有一个控制器,我可以切换到另一个akka上下文,因为它的计算时间会更长。 上下文切换相当简单,因为您可以使用api:
return F.Promise.promise(...,executionContext)
并在application.conf中配置自定义executionContext。 现在问题出在计算时间超过指定的时间量时(让它超过20秒):我无法实现Promise超时。考虑到我不想调用get(20,TimeUnit.SECONDS )的promise方法,因为我确定play会做到这一点。我在akka执行服务中搜索了一些配置属性,发现了这个
thread-pool-executor {
# Keep alive time for threads
keep-alive-time = 60s
# Min number of threads to cap factor-based core number to
core-pool-size-min = 8
# The core pool size factor is used to determine thread pool core size
# using the following formula: ceil(available processors * factor).
# Resulting size is then bounded by the core-pool-size-min and
# core-pool-size-max values.
core-pool-size-factor = 3.0
# Max number of threads to cap factor-based number to
core-pool-size-max = 64
# Minimum number of threads to cap factor-based max number to
# (if using a bounded task queue)
max-pool-size-min = 8
# Max no of threads (if using a bounded task queue) is determined by
# calculating: ceil(available processors * factor)
max-pool-size-factor = 3.0
# Max number of threads to cap factor-based max number to
# (if using a bounded task queue)
max-pool-size-max = 64
# Specifies the bounded capacity of the task queue (< 1 == unbounded)
task-queue-size = -1
# Specifies which type of task queue will be used, can be "array" or
# "linked" (default)
task-queue-type = "linked"
# Allow core threads to time out
allow-core-timeout = on
}
但是keep-alive-time和allow-core-timeout属性都不能使长时间的计算承诺超时。
我试图将返回类型更改为:
F.Promise<Result> original = F.Promise.promise(...,customExecutionService);
return F.promise.timeout(original,10,TimeUnit.SECONDS);
但这只是将执行推迟了10秒钟。(超时方法文档非常混乱)
我尝试过的其他片段是:
F.Promise<Result> original = F.Promise.promise(...,customExecutionService);
return F.promise.timeout(original,10,TimeUnit.SECONDS).get(10,TimeUnit.SECONDS);
但是这次超时是外部包装器的承诺。
因此,我现在得出的结论是,我必须编写自己的自定义executeService,以设置超时侦听器并自行抛出TimeoutException,但是我确信要实现这一目标,可以采取一些更简单的方法。
我找到了一种解决方案,方法是使用以下代码包装原始响应(不会超时的响应):
Future<T> error = after(Duration.create(delay,unit),Akka.system().scheduler(),main,
Futures.failed(new TimeoutException("Future timed out")));
return Promise.wrap(Futures.firstCompletedOf(
Lists.newArrayList(original.wrapped(),error), main));
```
其中主要是主要的执行上下文, 之后从阿卡模式拍摄。 基本上,如果原始的承诺花费的时间超过了错误所传递的持续时间 ,则将来会通过抛出Timeout Exception来启动。
我将其放在过滤器中,以便每个带有该过滤器注释的控制器都具有相同的行为。
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