import java.util.concurrent.locks.ReentrantLock

import kotlin.concurrent.withLock


/**
 * A queue that gives priority to the most recently pushed element.
 */
internal
class ConcurrentGroupingQueue<T>(

    /**
     * Predicate to check whether the given most recently pushed element (the receiver)
     * supersedes the given less recent element (the argument).
     *

    fun `groups similar requests ordered by most recent`() {

        val requestsInGroup1 = (0..1).map { Request(1, it) }
        val requestsInGroup2 = (0..1).map { Request(2, it) }

        val subject = ConcurrentGroupingQueue<Request> { group == it.group }
        for ((r1, r2) in requestsInGroup1 zip requestsInGroup2) {
            // interleave the requests
            subject.push(r1)
            subject.push(r2)
        }

    }

    protected
    open fun fetch(request: KotlinBuildScriptModelRequest): KotlinBuildScriptModel =
        fetchKotlinBuildScriptModelFor(request)

    private
    val q = ConcurrentGroupingQueue<AsyncModelRequest> {
        first.scriptFile == it.first.scriptFile && first.projectDir == it.first.projectDir
    }

    private
    val processor = ResurrectingThread("Kotlin DSL Resolver") {