cc.otavia.core.system.FIFOHouseQueue.scala Maven / Gradle / Ivy
/*
* Copyright 2022 Yan Kun
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package cc.otavia.core.system
import cc.otavia.core.util.{Nextable, SpinLock}
import java.util.concurrent.atomic.AtomicInteger
import scala.language.unsafeNulls
// MPSC
class FIFOHouseQueue(manager: HouseManager) extends HouseQueue(manager) {
private val readLock = new SpinLock()
private val writeLock = new SpinLock()
private val size = new AtomicInteger(0)
@volatile private var head: ActorHouse = _
@volatile private var tail: ActorHouse = _
override def available: Boolean = size.get() > 0
override def readies: Int = size.get()
override def isEmpty: Boolean = size.get() == 0
override def nonEmpty: Boolean = size.get() > 0
override def enqueue(house: ActorHouse): Unit = {
writeLock.lock()
if (size.get() == 0) {
readLock.lock()
head = house
tail = house
size.incrementAndGet()
writeLock.unlock()
readLock.unlock()
} else {
tail.next = house
tail = house
size.incrementAndGet()
writeLock.unlock()
}
}
final override def dequeue(): ActorHouse | Null = {
if (size.get() == 0) null
else dequeue0()
}
final private def dequeue0(): ActorHouse | Null = {
if (size.get() == 0) {
null
} else if (size.get() == 1) {
writeLock.lock()
readLock.lock()
if (size.get() == 1) {
val house = head
head = null
tail = null
size.decrementAndGet()
house.schedule()
writeLock.unlock()
readLock.unlock()
house
} else { // size.get() > 1
writeLock.unlock()
dequeue00()
}
} else {
readLock.lock()
dequeue00()
}
}
final private inline def dequeue00(): ActorHouse = {
val house = head
head = house.next.asInstanceOf[ActorHouse]
size.decrementAndGet()
house.schedule()
readLock.unlock()
house.deChain()
house
}
}