Ilya Gorbunov
103 lines
3.2 KiB
Kotlin
103 lines
3.2 KiB
Kotlin
@file:kotlin.jvm.JvmVersion
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package test.utils
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import kotlin.*
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import kotlin.test.*
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import java.io.*
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import java.util.concurrent.ConcurrentHashMap
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import java.util.concurrent.atomic.AtomicInteger
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import kotlin.concurrent.thread
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import org.junit.Test
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class LazyJVMTest {
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@Test fun synchronizedLazy() {
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val counter = AtomicInteger(0)
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val lazy = lazy {
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val value = counter.incrementAndGet()
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Thread.sleep(100)
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value
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}
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val accessThreads = listOf(lazy, lazy).map { thread { it.value } }
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accessThreads.forEach { it.join() }
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assertEquals(1, counter.get())
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}
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@Test fun externallySynchronizedLazy() {
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val counter = AtomicInteger(0)
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var initialized: Boolean = false
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val runs = ConcurrentHashMap<Int, Boolean>()
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val lock = Any()
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val initializer = {
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val value = counter.incrementAndGet()
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runs += (value to initialized)
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Thread.sleep(100)
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initialized = true
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value
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}
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val lazy1 = lazy(lock, initializer)
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val lazy2 = lazy(lock, initializer)
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val accessThreads = listOf(lazy1, lazy2).map { thread { it.value } }
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accessThreads.forEach { it.join() }
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assertEquals(2, counter.get())
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for ((counter, initialized) in runs) {
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assertEquals(initialized, counter == 2, "Expected uninitialized on first, initialized on second call: initialized=$initialized, counter=$counter")
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}
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}
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@Test fun publishOnceLazy() {
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val counter = AtomicInteger(0)
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var initialized: Boolean = false
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val runs = ConcurrentHashMap<Int, Boolean>()
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val initializer = {
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val value = counter.incrementAndGet()
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runs += (value to initialized)
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Thread.sleep((3 - value) * 100L)
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initialized = true
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value
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}
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val lazy = lazy(LazyThreadSafetyMode.PUBLICATION, initializer)
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val accessThreads = listOf(lazy, lazy).map { thread { it.value } }
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accessThreads.forEach { it.join() }
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assertEquals(2, counter.get())
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assertEquals(2, lazy.value)
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for ((counter, initialized) in runs) {
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assertFalse(initialized, "Expected uninitialized on first and second run")
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}
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}
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@Test fun lazyInitializationForcedOnSerialization() {
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for(mode in listOf(LazyThreadSafetyMode.SYNCHRONIZED, LazyThreadSafetyMode.PUBLICATION, LazyThreadSafetyMode.NONE)) {
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val lazy = lazy(mode) { "initialized" }
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assertFalse(lazy.isInitialized())
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val lazy2 = serializeAndDeserialize(lazy)
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assertTrue(lazy.isInitialized())
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assertTrue(lazy2.isInitialized())
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assertEquals(lazy.value, lazy2.value)
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}
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}
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private fun <T> serializeAndDeserialize(value: T): T {
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val outputStream = ByteArrayOutputStream()
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val objectOutputStream = ObjectOutputStream(outputStream)
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objectOutputStream.writeObject(value)
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objectOutputStream.close()
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outputStream.close()
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val inputStream = ByteArrayInputStream(outputStream.toByteArray())
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val inputObjectStream = ObjectInputStream(inputStream)
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return inputObjectStream.readObject() as T
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}
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} |