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package scala.actors
package scheduler
import java.util.{Collection, ArrayList}
import scala.concurrent.forkjoin._
/** The <code>ForkJoinScheduler</code> is backed by a lightweight
* fork-join task execution framework.
*
* @author Philipp Haller
*/
@deprecated("Use the akka.actor package instead. For migration from the scala.actors package refer to the Actors Migration Guide.", "2.11.0")
class ForkJoinScheduler(val initCoreSize: Int, val maxSize: Int, daemon: Boolean, fair: Boolean)
extends Runnable with IScheduler with TerminationMonitor {
private var pool = makeNewPool() // guarded by this
private var terminating = false // guarded by this
private var snapshoting = false // guarded by this
// this has to be a java.util.Collection, since this is what
// the ForkJoinPool returns.
private var drainedTasks: Collection[ForkJoinTask[_]] = null
protected val CHECK_FREQ = 10
// this random number generator is only used in fair mode
private lazy val random = new java.util.Random // guarded by random
def this(d: Boolean, f: Boolean) {
this(ThreadPoolConfig.corePoolSize, ThreadPoolConfig.maxPoolSize, d, f)
}
def this(d: Boolean) {
this(d, true) // default is fair
}
def this() {
this(false) // default is non-daemon
}
private def makeNewPool(): DrainableForkJoinPool = {
val p = new DrainableForkJoinPool(initCoreSize, maxSize)
Debug.info(this+": parallelism "+p.getParallelism())
p
}
/** Starts this scheduler.
*/
def start() {
try {
val t = new Thread(this)
t.setDaemon(daemon)
t.setName("ForkJoinScheduler")
t.start()
} catch {
case e: Exception =>
Debug.info(this+": could not create scheduler thread: "+e)
}
}
override def run() {
try {
while (true) {
this.synchronized {
try {
wait(CHECK_FREQ.toLong)
} catch {
case _: InterruptedException =>
}
if (terminating)
throw new QuitControl
if (allActorsTerminated) {
Debug.info(this+": all actors terminated")
terminating = true
throw new QuitControl
}
if (!snapshoting) {
gc()
} else if (pool.isQuiescent()) {
val list = new ArrayList[ForkJoinTask[_]]
val num = pool.drainTasksTo(list)
Debug.info(this+": drained "+num+" tasks")
drainedTasks = list
terminating = true
throw new QuitControl
}
}
}
} catch {
case _: QuitControl =>
Debug.info(this+": initiating shutdown...")
while (!pool.isQuiescent()) {
try {
Thread.sleep(10)
} catch {
case ignore: InterruptedException =>
}
}
pool.shutdown()
// allow thread to exit
}
}
// TODO: when do we pass a task that is not a RecursiveAction?
def execute(task: Runnable) {
pool.execute(task)
}
override def executeFromActor(task: Runnable) {
// in fair mode: 2% chance of submitting to global task queue
if (fair && random.synchronized { random.nextInt(50) == 1 })
pool.execute(task)
else
task.asInstanceOf[RecursiveAction].fork()
}
/** Submits a closure for execution.
*
* @param fun the closure to be executed
*/
def execute(fun: => Unit): Unit =
execute(new Runnable {
def run() { fun }
})
/** Shuts down the scheduler.
*/
def shutdown(): Unit = synchronized {
terminating = true
}
def isActive = synchronized {
!terminating && (pool ne null) && !pool.isShutdown()
}
override def managedBlock(blocker: scala.concurrent.ManagedBlocker) {
ForkJoinPool.managedBlock(new ForkJoinPool.ManagedBlocker {
def block = blocker.block()
def isReleasable() = blocker.isReleasable
})
}
/** Suspends the scheduler. All threads that were in use by the
* scheduler and its internal thread pool are terminated.
*/
def snapshot() = synchronized {
snapshoting = true
}
/** Resumes the execution of the scheduler if it was previously
* suspended using <code>ForkJoinScheduler.snapshot</code>.
*/
def restart() {
synchronized {
if (!snapshoting)
sys.error("snapshot has not been invoked")
else if (isActive)
sys.error("scheduler is still active")
else
snapshoting = false
pool = makeNewPool()
}
val iter = drainedTasks.iterator()
while (iter.hasNext()) {
pool.execute(iter.next())
}
start()
}
}
|
