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/*
* MIT License
*
* Copyright (c) 2017 atlarge-research
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
package nl.atlarge.opendc.scheduler
import nl.atlarge.opendc.kernel.Context
import nl.atlarge.opendc.topology.Entity
import nl.atlarge.opendc.topology.machine.Machine
import nl.atlarge.opendc.workload.Task
import java.util.*
/**
* A [Scheduler] that distributes work according to the shortest job first policy.
*
* @author Fabian Mastenbroek (f.s.mastenbroek@student.tudelft.nl)
*/
class SrtfScheduler : Scheduler {
/**
* The set of machines the scheduler knows of.
*/
val machines: MutableSet<Machine> = HashSet()
/**
* The set of [Task]s that need to be scheduled.
*/
val tasks: MutableSet<Task> = HashSet()
/**
* (Re)schedule the tasks submitted to the scheduler over the specified set of machines.
*/
override suspend fun <E : Entity<*>> Context<E>.schedule() {
if (tasks.isEmpty()) {
return
}
val iterator = tasks.sortedBy { it.remaining }.iterator()
machines
.filter { it.state.status == Machine.Status.IDLE }
.forEach {
while (iterator.hasNext()) {
val task = iterator.next()
// TODO What to do with tasks that are not ready yet to be processed
if (!task.isReady()) {
submit(task)
continue
} else if (task.finished) {
tasks.remove(task)
continue
}
it.send(task)
break
}
}
}
/**
* Submit a [Task] to this scheduler.
*
* @param task The task to submit to the scheduler.
*/
override fun submit(task: Task) {
tasks.add(task)
}
/**
* Register a [Machine] to this scheduler.
*
* @param machine The machine to register.
*/
override fun register(machine: Machine) {
machines.add(machine)
}
/**
* Deregister a [Machine] from this scheduler.
*
* @param machine The machine to deregister.
*/
override fun deregister(machine: Machine) {
machines.remove(machine)
}
}
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