kotlinx-coroutines-core/jvm/test/internal/SegmentListTest.kt

package kotlinx.coroutines.internal

import kotlinx.atomicfu.*
import org.junit.Test
import kotlin.test.*

class SegmentListTest {
    @Test
    fun testRemoveTail() {
        val initialSegment = TestSegment(0, null, 2)
        val head = AtomicRefHolder(initialSegment)
        val tail = AtomicRefHolder(initialSegment)
        val s1 = tail.ref.findSegmentAndMoveForward(1, tail.ref.value, ::createTestSegment).segment
        assertFalse(s1.removed)
        tail.ref.value.onSlotCleaned()
        assertFalse(s1.removed)
        head.ref.findSegmentAndMoveForward(2, head.ref.value, ::createTestSegment)
        assertFalse(s1.removed)
        tail.ref.findSegmentAndMoveForward(2, head.ref.value, ::createTestSegment)
        assertTrue(s1.removed)
    }

    @Test
    fun testClose() {
        val initialSegment = TestSegment(0, null, 2)
        val head = AtomicRefHolder(initialSegment)
        val tail = AtomicRefHolder(initialSegment)
        tail.ref.findSegmentAndMoveForward(1, tail.ref.value, ::createTestSegment)
        assertEquals(tail.ref.value, tail.ref.value.close())
        assertTrue(head.ref.findSegmentAndMoveForward(2, head.ref.value, ::createTestSegment).isClosed)
    }
}

private class AtomicRefHolder<T>(initialValue: T) {
    val ref = atomic(initialValue)
}

private class TestSegment(id: Long, prev: TestSegment?, pointers: Int) : Segment<TestSegment>(id, prev, pointers) {
    override val maxSlots: Int get() = 1
}
private fun createTestSegment(id: Long, prev: TestSegment?) = TestSegment(id, prev, 0)