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package scala.tools.nsc
package util
import scala.collection.mutable.Queue
class WorkScheduler {
type Action = () => Unit
private var todo = new Queue[Action]
private var throwables = new Queue[Throwable]
private var interruptReqs = new Queue[InterruptReq]
/** Called from server: block until one of todo list, throwables or interruptReqs is nonempty */
def waitForMoreWork() = synchronized {
while (todo.isEmpty && throwables.isEmpty && interruptReqs.isEmpty) { wait() }
}
/** called from Server: test whether one of todo list, throwables, or InterruptReqs is nonempty */
def moreWork(): Boolean = synchronized {
todo.nonEmpty || throwables.nonEmpty || interruptReqs.nonEmpty
}
/** Called from server: get first action in todo list, and pop it off */
def nextWorkItem(): Option[Action] = synchronized {
if (todo.isEmpty) None else Some(todo.dequeue())
}
/** Called from server: return optional exception posted by client
* Reset to no exception.
*/
def pollThrowable(): Option[Throwable] = synchronized {
if (throwables.isEmpty)
None
else {
val result = Some(throwables.dequeue())
if (!throwables.isEmpty)
postWorkItem { () => }
result
}
}
def pollInterrupt(): Option[InterruptReq] = synchronized {
if (interruptReqs.isEmpty) None else Some(interruptReqs.dequeue())
}
/** Called from client: have interrupt executed by server and return result */
def doQuickly[A](op: () => A): A = {
val ir = new InterruptReq {
type R = A
val todo = op
}
synchronized {
interruptReqs enqueue ir
}
ir.getResult()
}
/** Called from client: have action executed by server */
def postWorkItem(action: Action) = synchronized {
todo enqueue action
notify()
}
/** Called from client: cancel all queued actions */
def cancelQueued() = synchronized {
todo.clear()
}
/** Called from client:
* Require an exception to be thrown on next poll.
*/
def raise(exc: Throwable) = synchronized {
throwables enqueue exc
postWorkItem { () => }
}
}
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