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/**
* Copyright (C) 2009-2014 Typesafe Inc.
*/
package akka.dispatch
import java.util.{ Comparator, PriorityQueue, Queue, Deque }
import java.util.concurrent._
import akka.AkkaException
import akka.dispatch.sysmsg._
import akka.actor.{ ActorCell, ActorRef, Cell, ActorSystem, InternalActorRef, DeadLetter }
import akka.util.{ Unsafe, BoundedBlockingQueue }
import akka.util.Helpers.ConfigOps
import akka.event.Logging.Error
import scala.concurrent.duration.Duration
import scala.concurrent.duration.FiniteDuration
import scala.annotation.tailrec
import scala.util.control.NonFatal
import com.typesafe.config.Config
/**
* INTERNAL API
*/
private[akka] object Mailbox {
type Status = Int
/*
* The following assigned numbers CANNOT be changed without looking at the code which uses them!
*/
// Primary status
final val Open = 0 // _status is not initialized in AbstractMailbox, so default must be zero! Deliberately without type ascription to make it a compile-time constant
final val Closed = 1 // Deliberately without type ascription to make it a compile-time constant
// Secondary status: Scheduled bit may be added to Open/Suspended
final val Scheduled = 2 // Deliberately without type ascription to make it a compile-time constant
// Shifted by 2: the suspend count!
final val shouldScheduleMask = 3
final val shouldNotProcessMask = ~2
final val suspendMask = ~3
final val suspendUnit = 4
// mailbox debugging helper using println (see below)
// since this is a compile-time constant, scalac will elide code behind if (Mailbox.debug) (RK checked with 2.9.1)
final val debug = false // Deliberately without type ascription to make it a compile-time constant
}
/**
* Mailbox and InternalMailbox is separated in two classes because ActorCell is needed for implementation,
* but can't be exposed to user defined mailbox subclasses.
*
* INTERNAL API
*/
private[akka] abstract class Mailbox(val messageQueue: MessageQueue)
extends SystemMessageQueue with Runnable {
import Mailbox._
/*
* This is needed for actually executing the mailbox, i.e. invoking the
* ActorCell. There are situations (e.g. RepointableActorRef) where a Mailbox
* is constructed but we know that we will not execute it, in which case this
* will be null. It must be a var to support switching into an “active”
* mailbox, should the owning ActorRef turn local.
*
* ANOTHER THING, IMPORTANT:
*
* actorCell.start() publishes actorCell & self to the dispatcher, which
* means that messages may be processed theoretically before self’s constructor
* ends. The JMM guarantees visibility for final fields only after the end
* of the constructor, so safe publication requires that THIS WRITE BELOW
* stay as it is.
*/
@volatile
var actor: ActorCell = _
def setActor(cell: ActorCell): Unit = actor = cell
def dispatcher: MessageDispatcher = actor.dispatcher
/**
* Try to enqueue the message to this queue, or throw an exception.
*/
def enqueue(receiver: ActorRef, msg: Envelope): Unit = messageQueue.enqueue(receiver, msg)
/**
* Try to dequeue the next message from this queue, return null failing that.
*/
def dequeue(): Envelope = messageQueue.dequeue()
/**
* Indicates whether this queue is non-empty.
*/
def hasMessages: Boolean = messageQueue.hasMessages
/**
* Should return the current number of messages held in this queue; may
* always return 0 if no other value is available efficiently. Do not use
* this for testing for presence of messages, use `hasMessages` instead.
*/
def numberOfMessages: Int = messageQueue.numberOfMessages
@volatile
protected var _statusDoNotCallMeDirectly: Status = _ //0 by default
@volatile
protected var _systemQueueDoNotCallMeDirectly: SystemMessage = _ //null by default
@inline
final def currentStatus: Mailbox.Status = Unsafe.instance.getIntVolatile(this, AbstractMailbox.mailboxStatusOffset)
@inline
final def shouldProcessMessage: Boolean = (currentStatus & shouldNotProcessMask) == 0
@inline
final def suspendCount: Int = currentStatus / suspendUnit
@inline
final def isSuspended: Boolean = (currentStatus & suspendMask) != 0
@inline
final def isClosed: Boolean = currentStatus == Closed
@inline
final def isScheduled: Boolean = (currentStatus & Scheduled) != 0
@inline
protected final def updateStatus(oldStatus: Status, newStatus: Status): Boolean =
Unsafe.instance.compareAndSwapInt(this, AbstractMailbox.mailboxStatusOffset, oldStatus, newStatus)
@inline
protected final def setStatus(newStatus: Status): Unit =
Unsafe.instance.putIntVolatile(this, AbstractMailbox.mailboxStatusOffset, newStatus)
/**
* Reduce the suspend count by one. Caller does not need to worry about whether
* status was Scheduled or not.
*
* @return true if the suspend count reached zero
*/
@tailrec
final def resume(): Boolean = currentStatus match {
case Closed ⇒
setStatus(Closed); false
case s ⇒
val next = if (s < suspendUnit) s else s - suspendUnit
if (updateStatus(s, next)) next < suspendUnit
else resume()
}
/**
* Increment the suspend count by one. Caller does not need to worry about whether
* status was Scheduled or not.
*
* @return true if the previous suspend count was zero
*/
@tailrec
final def suspend(): Boolean = currentStatus match {
case Closed ⇒
setStatus(Closed); false
case s ⇒
if (updateStatus(s, s + suspendUnit)) s < suspendUnit
else suspend()
}
/**
* set new primary status Closed. Caller does not need to worry about whether
* status was Scheduled or not.
*/
@tailrec
final def becomeClosed(): Boolean = currentStatus match {
case Closed ⇒
setStatus(Closed); false
case s ⇒ updateStatus(s, Closed) || becomeClosed()
}
/**
* Set Scheduled status, keeping primary status as is.
*/
@tailrec
final def setAsScheduled(): Boolean = {
val s = currentStatus
/*
* Only try to add Scheduled bit if pure Open/Suspended, not Closed or with
* Scheduled bit already set.
*/
if ((s & shouldScheduleMask) != Open) false
else updateStatus(s, s | Scheduled) || setAsScheduled()
}
/**
* Reset Scheduled status, keeping primary status as is.
*/
@tailrec
final def setAsIdle(): Boolean = {
val s = currentStatus
updateStatus(s, s & ~Scheduled) || setAsIdle()
}
/*
* AtomicReferenceFieldUpdater for system queue.
*/
protected final def systemQueueGet: LatestFirstSystemMessageList =
// Note: contrary how it looks, there is no allocation here, as SystemMessageList is a value class and as such
// it just exists as a typed view during compile-time. The actual return type is still SystemMessage.
new LatestFirstSystemMessageList(Unsafe.instance.getObjectVolatile(this, AbstractMailbox.systemMessageOffset).asInstanceOf[SystemMessage])
protected final def systemQueuePut(_old: LatestFirstSystemMessageList, _new: LatestFirstSystemMessageList): Boolean =
// Note: calling .head is not actually existing on the bytecode level as the parameters _old and _new
// are SystemMessage instances hidden during compile time behind the SystemMessageList value class.
// Without calling .head the parameters would be boxed in SystemMessageList wrapper.
Unsafe.instance.compareAndSwapObject(this, AbstractMailbox.systemMessageOffset, _old.head, _new.head)
final def canBeScheduledForExecution(hasMessageHint: Boolean, hasSystemMessageHint: Boolean): Boolean = currentStatus match {
case Open | Scheduled ⇒ hasMessageHint || hasSystemMessageHint || hasSystemMessages || hasMessages
case Closed ⇒ false
case _ ⇒ hasSystemMessageHint || hasSystemMessages
}
override final def run(): Unit = {
try {
if (!isClosed) { //Volatile read, needed here
processAllSystemMessages() //First, deal with any system messages
processMailbox() //Then deal with messages
}
} finally {
setAsIdle() //Volatile write, needed here
dispatcher.registerForExecution(this, false, false)
}
}
/**
* Process the messages in the mailbox
*/
@tailrec private final def processMailbox(
left: Int = java.lang.Math.max(dispatcher.throughput, 1),
deadlineNs: Long = if (dispatcher.isThroughputDeadlineTimeDefined == true) System.nanoTime + dispatcher.throughputDeadlineTime.toNanos else 0L): Unit =
if (shouldProcessMessage) {
val next = dequeue()
if (next ne null) {
if (Mailbox.debug) println(actor.self + " processing message " + next)
actor invoke next
if (Thread.interrupted())
throw new InterruptedException("Interrupted while processing actor messages")
processAllSystemMessages()
if ((left > 1) && ((dispatcher.isThroughputDeadlineTimeDefined == false) || (System.nanoTime - deadlineNs) < 0))
processMailbox(left - 1, deadlineNs)
}
}
/**
* Will at least try to process all queued system messages: in case of
* failure simply drop and go on to the next, because there is nothing to
* restart here (failure is in ActorCell somewhere …). In case the mailbox
* becomes closed (because of processing a Terminate message), dump all
* already dequeued message to deadLetters.
*/
final def processAllSystemMessages() {
var interruption: Throwable = null
var messageList = systemDrain(SystemMessageList.LNil)
while ((messageList.nonEmpty) && !isClosed) {
val msg = messageList.head
messageList = messageList.tail
msg.unlink()
if (debug) println(actor.self + " processing system message " + msg + " with " + actor.childrenRefs)
// we know here that systemInvoke ensures that only "fatal" exceptions get rethrown
actor systemInvoke msg
if (Thread.interrupted())
interruption = new InterruptedException("Interrupted while processing system messages")
// don’t ever execute normal message when system message present!
if ((messageList.isEmpty) && !isClosed) messageList = systemDrain(SystemMessageList.LNil)
}
/*
* if we closed the mailbox, we must dump the remaining system messages
* to deadLetters (this is essential for DeathWatch)
*/
val dlm = actor.dispatcher.mailboxes.deadLetterMailbox
while (messageList.nonEmpty) {
val msg = messageList.head
messageList = messageList.tail
msg.unlink()
try dlm.systemEnqueue(actor.self, msg)
catch {
case e: InterruptedException ⇒ interruption = e
case NonFatal(e) ⇒ actor.system.eventStream.publish(
Error(e, actor.self.path.toString, this.getClass, "error while enqueuing " + msg + " to deadLetters: " + e.getMessage))
}
}
// if we got an interrupted exception while handling system messages, then rethrow it
if (interruption ne null) {
Thread.interrupted() // clear interrupted flag before throwing according to java convention
throw interruption
}
}
/**
* Overridable callback to clean up the mailbox,
* called when an actor is unregistered.
* By default it dequeues all system messages + messages and ships them to the owning actors' systems' DeadLetterMailbox
*/
protected[dispatch] def cleanUp(): Unit =
if (actor ne null) { // actor is null for the deadLetterMailbox
val dlm = actor.dispatcher.mailboxes.deadLetterMailbox
var messageList = systemDrain(new LatestFirstSystemMessageList(NoMessage))
while (messageList.nonEmpty) {
// message must be “virgin” before being able to systemEnqueue again
val msg = messageList.head
messageList = messageList.tail
msg.unlink()
dlm.systemEnqueue(actor.self, msg)
}
if (messageQueue ne null) // needed for CallingThreadDispatcher, which never calls Mailbox.run()
messageQueue.cleanUp(actor.self, actor.dispatcher.mailboxes.deadLetterMailbox.messageQueue)
}
}
/**
* A MessageQueue is one of the core components in forming an Akka Mailbox.
* The MessageQueue is where the normal messages that are sent to Actors will be enqueued (and subsequently dequeued)
* It needs to at least support N producers and 1 consumer thread-safely.
*/
trait MessageQueue {
/**
* Try to enqueue the message to this queue, or throw an exception.
*/
def enqueue(receiver: ActorRef, handle: Envelope): Unit // NOTE: receiver is used only in two places, but cannot be removed
/**
* Try to dequeue the next message from this queue, return null failing that.
*/
def dequeue(): Envelope
/**
* Should return the current number of messages held in this queue; may
* always return 0 if no other value is available efficiently. Do not use
* this for testing for presence of messages, use `hasMessages` instead.
*/
def numberOfMessages: Int
/**
* Indicates whether this queue is non-empty.
*/
def hasMessages: Boolean
/**
* Called when the mailbox this queue belongs to is disposed of. Normally it
* is expected to transfer all remaining messages into the dead letter queue
* which is passed in. The owner of this MessageQueue is passed in if
* available (e.g. for creating DeadLetters()), “/deadletters” otherwise.
*/
def cleanUp(owner: ActorRef, deadLetters: MessageQueue): Unit
}
class NodeMessageQueue extends AbstractNodeQueue[Envelope] with MessageQueue with UnboundedMessageQueueSemantics {
final def enqueue(receiver: ActorRef, handle: Envelope): Unit = add(handle)
final def dequeue(): Envelope = poll()
final def numberOfMessages: Int = count()
final def hasMessages: Boolean = !isEmpty()
@tailrec final def cleanUp(owner: ActorRef, deadLetters: MessageQueue): Unit = {
val envelope = dequeue()
if (envelope ne null) {
deadLetters.enqueue(owner, envelope)
cleanUp(owner, deadLetters)
}
}
}
/**
* INTERNAL API
*/
private[akka] trait SystemMessageQueue {
/**
* Enqueue a new system message, e.g. by prepending atomically as new head of a single-linked list.
*/
def systemEnqueue(receiver: ActorRef, message: SystemMessage): Unit
/**
* Dequeue all messages from system queue and return them as single-linked list.
*/
def systemDrain(newContents: LatestFirstSystemMessageList): EarliestFirstSystemMessageList
def hasSystemMessages: Boolean
}
/**
* INTERNAL API
*/
private[akka] trait DefaultSystemMessageQueue { self: Mailbox ⇒
@tailrec
final def systemEnqueue(receiver: ActorRef, message: SystemMessage): Unit = {
assert(message.unlinked)
if (Mailbox.debug) println(receiver + " having enqueued " + message)
val currentList = systemQueueGet
if (currentList.head == NoMessage) {
if (actor ne null) actor.dispatcher.mailboxes.deadLetterMailbox.systemEnqueue(receiver, message)
} else {
if (!systemQueuePut(currentList, message :: currentList)) {
message.unlink()
systemEnqueue(receiver, message)
}
}
}
@tailrec
final def systemDrain(newContents: LatestFirstSystemMessageList): EarliestFirstSystemMessageList = {
val currentList = systemQueueGet
if (currentList.head == NoMessage) new EarliestFirstSystemMessageList(null)
else if (systemQueuePut(currentList, newContents)) currentList.reverse
else systemDrain(newContents)
}
def hasSystemMessages: Boolean = systemQueueGet.head match {
case null | NoMessage ⇒ false
case _ ⇒ true
}
}
/**
* This is a marker trait for message queues which support multiple consumers,
* as is required by the BalancingDispatcher.
*/
trait MultipleConsumerSemantics
/**
* A QueueBasedMessageQueue is a MessageQueue backed by a java.util.Queue.
*/
trait QueueBasedMessageQueue extends MessageQueue with MultipleConsumerSemantics {
def queue: Queue[Envelope]
def numberOfMessages = queue.size
def hasMessages = !queue.isEmpty
def cleanUp(owner: ActorRef, deadLetters: MessageQueue): Unit = {
if (hasMessages) {
var envelope = dequeue
while (envelope ne null) {
deadLetters.enqueue(owner, envelope)
envelope = dequeue
}
}
}
}
/**
* UnboundedMessageQueueSemantics adds unbounded semantics to a QueueBasedMessageQueue,
* i.e. a non-blocking enqueue and dequeue.
*/
trait UnboundedMessageQueueSemantics
trait UnboundedQueueBasedMessageQueue extends QueueBasedMessageQueue with UnboundedMessageQueueSemantics {
def enqueue(receiver: ActorRef, handle: Envelope): Unit = queue add handle
def dequeue(): Envelope = queue.poll()
}
/**
* BoundedMessageQueueSemantics adds bounded semantics to a QueueBasedMessageQueue,
* i.e. blocking enqueue with timeout.
*/
trait BoundedMessageQueueSemantics {
def pushTimeOut: Duration
}
trait BoundedQueueBasedMessageQueue extends QueueBasedMessageQueue with BoundedMessageQueueSemantics {
override def queue: BlockingQueue[Envelope]
def enqueue(receiver: ActorRef, handle: Envelope): Unit =
if (pushTimeOut.length >= 0) {
if (!queue.offer(handle, pushTimeOut.length, pushTimeOut.unit))
receiver.asInstanceOf[InternalActorRef].provider.deadLetters.tell(
DeadLetter(handle.message, handle.sender, receiver), handle.sender)
} else queue put handle
def dequeue(): Envelope = queue.poll()
}
/**
* DequeBasedMessageQueue refines QueueBasedMessageQueue to be backed by a java.util.Deque.
*/
trait DequeBasedMessageQueueSemantics {
def enqueueFirst(receiver: ActorRef, handle: Envelope): Unit
}
trait UnboundedDequeBasedMessageQueueSemantics extends DequeBasedMessageQueueSemantics with UnboundedMessageQueueSemantics
trait BoundedDequeBasedMessageQueueSemantics extends DequeBasedMessageQueueSemantics with BoundedMessageQueueSemantics
trait DequeBasedMessageQueue extends QueueBasedMessageQueue with DequeBasedMessageQueueSemantics {
def queue: Deque[Envelope]
}
/**
* UnboundedDequeBasedMessageQueueSemantics adds unbounded semantics to a DequeBasedMessageQueue,
* i.e. a non-blocking enqueue and dequeue.
*/
trait UnboundedDequeBasedMessageQueue extends DequeBasedMessageQueue with UnboundedDequeBasedMessageQueueSemantics {
def enqueue(receiver: ActorRef, handle: Envelope): Unit = queue add handle
def enqueueFirst(receiver: ActorRef, handle: Envelope): Unit = queue addFirst handle
def dequeue(): Envelope = queue.poll()
}
/**
* BoundedMessageQueueSemantics adds bounded semantics to a DequeBasedMessageQueue,
* i.e. blocking enqueue with timeout.
*/
trait BoundedDequeBasedMessageQueue extends DequeBasedMessageQueue with BoundedDequeBasedMessageQueueSemantics {
def pushTimeOut: Duration
override def queue: BlockingDeque[Envelope]
def enqueue(receiver: ActorRef, handle: Envelope): Unit =
if (pushTimeOut.length >= 0) {
if (!queue.offer(handle, pushTimeOut.length, pushTimeOut.unit))
receiver.asInstanceOf[InternalActorRef].provider.deadLetters.tell(
DeadLetter(handle.message, handle.sender, receiver), handle.sender)
} else queue put handle
def enqueueFirst(receiver: ActorRef, handle: Envelope): Unit =
if (pushTimeOut.length >= 0) {
if (!queue.offerFirst(handle, pushTimeOut.length, pushTimeOut.unit))
receiver.asInstanceOf[InternalActorRef].provider.deadLetters.tell(
DeadLetter(handle.message, handle.sender, receiver), handle.sender)
} else queue putFirst handle
def dequeue(): Envelope = queue.poll()
}
/**
* MailboxType is a factory to create MessageQueues for an optionally
* provided ActorContext.
*
* Possibly Important Notice
*
* When implementing a custom mailbox type, be aware that there is special
* semantics attached to `system.actorOf()` in that sending to the returned
* ActorRef may—for a short period of time—enqueue the messages first in a
* dummy queue. Top-level actors are created in two steps, and only after the
* guardian actor has performed that second step will all previously sent
* messages be transferred from the dummy queue into the real mailbox.
*/
trait MailboxType {
def create(owner: Option[ActorRef], system: Option[ActorSystem]): MessageQueue
}
trait ProducesMessageQueue[T <: MessageQueue]
/**
* UnboundedMailbox is the default unbounded MailboxType used by Akka Actors.
*/
case class UnboundedMailbox() extends MailboxType with ProducesMessageQueue[UnboundedMailbox.MessageQueue] {
def this(settings: ActorSystem.Settings, config: Config) = this()
final override def create(owner: Option[ActorRef], system: Option[ActorSystem]): MessageQueue =
new UnboundedMailbox.MessageQueue
}
object UnboundedMailbox {
class MessageQueue extends ConcurrentLinkedQueue[Envelope] with UnboundedQueueBasedMessageQueue {
final def queue: Queue[Envelope] = this
}
}
/**
* SingleConsumerOnlyUnboundedMailbox is a high-performance, multiple producer—single consumer, unbounded MailboxType,
* with the drawback that you can't have multiple consumers,
* which rules out using it with BalancingPool (BalancingDispatcher) for instance.
*
* Currently this queue is slower for some benchmarks than the ConcurrentLinkedQueue from JDK 8 that is used by default,
* so be sure to measure the performance in your particular setting in order to determine which one to use.
*/
case class SingleConsumerOnlyUnboundedMailbox() extends MailboxType with ProducesMessageQueue[NodeMessageQueue] {
def this(settings: ActorSystem.Settings, config: Config) = this()
final override def create(owner: Option[ActorRef], system: Option[ActorSystem]): MessageQueue = new NodeMessageQueue
}
/**
* BoundedMailbox is the default bounded MailboxType used by Akka Actors.
*/
case class BoundedMailbox(val capacity: Int, val pushTimeOut: FiniteDuration)
extends MailboxType with ProducesMessageQueue[BoundedMailbox.MessageQueue] {
def this(settings: ActorSystem.Settings, config: Config) = this(config.getInt("mailbox-capacity"),
config.getNanosDuration("mailbox-push-timeout-time"))
if (capacity < 0) throw new IllegalArgumentException("The capacity for BoundedMailbox can not be negative")
if (pushTimeOut eq null) throw new IllegalArgumentException("The push time-out for BoundedMailbox can not be null")
final override def create(owner: Option[ActorRef], system: Option[ActorSystem]): MessageQueue =
new BoundedMailbox.MessageQueue(capacity, pushTimeOut)
}
object BoundedMailbox {
class MessageQueue(capacity: Int, final val pushTimeOut: FiniteDuration)
extends LinkedBlockingQueue[Envelope](capacity) with BoundedQueueBasedMessageQueue {
final def queue: BlockingQueue[Envelope] = this
}
}
/**
* UnboundedPriorityMailbox is an unbounded mailbox that allows for prioritization of its contents.
* Extend this class and provide the Comparator in the constructor.
*/
class UnboundedPriorityMailbox(val cmp: Comparator[Envelope], val initialCapacity: Int)
extends MailboxType with ProducesMessageQueue[UnboundedPriorityMailbox.MessageQueue] {
def this(cmp: Comparator[Envelope]) = this(cmp, 11)
final override def create(owner: Option[ActorRef], system: Option[ActorSystem]): MessageQueue =
new UnboundedPriorityMailbox.MessageQueue(initialCapacity, cmp)
}
object UnboundedPriorityMailbox {
class MessageQueue(initialCapacity: Int, cmp: Comparator[Envelope])
extends PriorityBlockingQueue[Envelope](initialCapacity, cmp) with UnboundedQueueBasedMessageQueue {
final def queue: Queue[Envelope] = this
}
}
/**
* BoundedPriorityMailbox is a bounded mailbox that allows for prioritization of its contents.
* Extend this class and provide the Comparator in the constructor.
*/
class BoundedPriorityMailbox( final val cmp: Comparator[Envelope], final val capacity: Int, final val pushTimeOut: Duration)
extends MailboxType with ProducesMessageQueue[BoundedPriorityMailbox.MessageQueue] {
if (capacity < 0) throw new IllegalArgumentException("The capacity for BoundedMailbox can not be negative")
if (pushTimeOut eq null) throw new IllegalArgumentException("The push time-out for BoundedMailbox can not be null")
final override def create(owner: Option[ActorRef], system: Option[ActorSystem]): MessageQueue =
new BoundedPriorityMailbox.MessageQueue(capacity, cmp, pushTimeOut)
}
object BoundedPriorityMailbox {
class MessageQueue(capacity: Int, cmp: Comparator[Envelope], val pushTimeOut: Duration)
extends BoundedBlockingQueue[Envelope](capacity, new PriorityQueue[Envelope](11, cmp))
with BoundedQueueBasedMessageQueue {
final def queue: BlockingQueue[Envelope] = this
}
}
/**
* UnboundedDequeBasedMailbox is an unbounded MailboxType, backed by a Deque.
*/
case class UnboundedDequeBasedMailbox() extends MailboxType with ProducesMessageQueue[UnboundedDequeBasedMailbox.MessageQueue] {
def this(settings: ActorSystem.Settings, config: Config) = this()
final override def create(owner: Option[ActorRef], system: Option[ActorSystem]): MessageQueue =
new UnboundedDequeBasedMailbox.MessageQueue
}
object UnboundedDequeBasedMailbox {
class MessageQueue extends LinkedBlockingDeque[Envelope] with UnboundedDequeBasedMessageQueue {
final val queue = this
}
}
/**
* BoundedDequeBasedMailbox is an bounded MailboxType, backed by a Deque.
*/
case class BoundedDequeBasedMailbox( final val capacity: Int, final val pushTimeOut: FiniteDuration)
extends MailboxType with ProducesMessageQueue[BoundedDequeBasedMailbox.MessageQueue] {
def this(settings: ActorSystem.Settings, config: Config) = this(config.getInt("mailbox-capacity"),
config.getNanosDuration("mailbox-push-timeout-time"))
if (capacity < 0) throw new IllegalArgumentException("The capacity for BoundedDequeBasedMailbox can not be negative")
if (pushTimeOut eq null) throw new IllegalArgumentException("The push time-out for BoundedDequeBasedMailbox can not be null")
final override def create(owner: Option[ActorRef], system: Option[ActorSystem]): MessageQueue =
new BoundedDequeBasedMailbox.MessageQueue(capacity, pushTimeOut)
}
object BoundedDequeBasedMailbox {
class MessageQueue(capacity: Int, val pushTimeOut: FiniteDuration)
extends LinkedBlockingDeque[Envelope](capacity) with BoundedDequeBasedMessageQueue {
final val queue = this
}
}
/**
* Trait to signal that an Actor requires a certain type of message queue semantics.
*
* The mailbox type will be looked up by mapping the type T via akka.actor.mailbox.requirements in the config,
* to a mailbox configuration. If no mailbox is assigned on Props or in deployment config then this one will be used.
*
* The queue type of the created mailbox will be checked against the type T and actor creation will fail if it doesn't
* fulfill the requirements.
*/
trait RequiresMessageQueue[T]
