JvmHprofParsingTest.kt

TLDR

This file, JvmHprofParsingTest.kt, contains a test class called JvmHprofParsingTest which tests the parsing of Hprof files in the Shark library. It includes methods that perform various tests on the Hprof files, such as reading strings, checking the translation of JVM object and primitive arrays class names, and retaining instances to prevent garbage collection. Additionally, there is a helper method called dumpHeapRetaining used by the tests.

Methods

dumpHeapRetaining

This method takes an object to be retained and dumps the heap to an Hprof file. It ensures that the object is not garbage collected before the heap is dumped.

Classes

JvmHprofParsingTest

This class contains test methods for parsing Hprof files in the Shark library. These methods include tests for reading strings, translating JVM object and primitive array class names, and retaining instances.

package shark

import java.io.File
import kotlin.reflect.KClass
import org.assertj.core.api.Assertions.assertThat
import org.junit.Rule
import org.junit.Test
import org.junit.rules.TemporaryFolder
import shark.HprofHeapGraph.Companion.openHeapGraph
import shark.HprofRecord.HeapDumpRecord.ObjectRecord.PrimitiveArrayDumpRecord.IntArrayDump
import shark.PrimitiveType.INT

class JvmHprofParsingTest {

  @get:Rule
  var testFolder = TemporaryFolder()

  @Test fun dumpHeapAndReadString() {
    val hprofFolder = testFolder.newFolder()
    val hprofFile = File(hprofFolder, "jvm_heap.hprof")

    JvmTestHeapDumper.dumpHeap(hprofFile.absolutePath)

    hprofFile.openHeapGraph().use { graph ->
      val testInstances = graph.instances
        .filter { it.instanceClassName == JvmHprofParsingTest::class.name }
        .toList()

      assertThat(testInstances).hasSize(1)
      val test = testInstances[0]
      val folderPath = test[JvmHprofParsingTest::class.name, "testFolder"]!!
        .valueAsInstance!![TemporaryFolder::class.name, "folder"]!!
        .valueAsInstance!![File::class.name, "path"]!!
        .value.readAsJavaString()!!

      assertThat(folderPath).isEqualTo(testFolder.root.path)
    }
  }

  @Test fun `JVM object array class name is translated to brackets`() {
    val objectArray = arrayOf<JvmHprofParsingTest>()
    val hprofFile = dumpHeapRetaining(objectArray)

    val expectedArrayClassName = "${JvmHprofParsingTest::class.java.name}[]"

    hprofFile.openHeapGraph().use { graph ->
      val arrayClass = graph.findClassByName(expectedArrayClassName)
      assertThat(arrayClass).isNotNull
      assertThat(arrayClass!!.isObjectArrayClass).isTrue()
      assertThat(arrayClass.name).isEqualTo(expectedArrayClassName)

      val array = arrayClass.objectArrayInstances.single()
      assertThat(array.arrayClassName).isEqualTo(expectedArrayClassName)
    }
  }

  @Test fun `JVM multi dimension object array class name is translated to brackets`() {
    val objectArray = arrayOf(arrayOf(), arrayOf<JvmHprofParsingTest>())
    val hprofFile = dumpHeapRetaining(objectArray)

    val expectedArrayClassName = "${JvmHprofParsingTest::class.java.name}[][]"

    hprofFile.openHeapGraph().use { graph ->
      val arrayClass = graph.findClassByName(expectedArrayClassName)
      assertThat(arrayClass).isNotNull
      assertThat(arrayClass!!.isObjectArrayClass).isTrue()
      assertThat(arrayClass.name).isEqualTo(expectedArrayClassName)

      val array = arrayClass.objectArrayInstances.single()
      assertThat(array.arrayClassName).isEqualTo(expectedArrayClassName)
    }
  }

  @Test fun `JVM primitive wrapper array class name is translated to brackets`() {
    val hprofFile = dumpHeapRetaining(arrayOfNulls<Int?>(42))

    val expectedArrayClassName = "java.lang.Integer[]"

    hprofFile.openHeapGraph().use { graph ->
      val arrayClass = graph.findClassByName(expectedArrayClassName)
      assertThat(arrayClass).isNotNull
      assertThat(arrayClass!!.isObjectArrayClass).isTrue()
      assertThat(arrayClass.name).isEqualTo(expectedArrayClassName)

      val array = arrayClass.objectArrayInstances.single { it.readElements().count() == 42 }
      assertThat(array.arrayClassName).isEqualTo(expectedArrayClassName)
    }
  }

  @Test fun `JVM multi dimension wrapper primitive array class name is translated to brackets`() {
    val hprofFile = dumpHeapRetaining(arrayOf(arrayOf(), arrayOf<Int?>()))

    val expectedArrayClassName = "java.lang.Integer[][]"

    hprofFile.openHeapGraph().use { graph ->
      val arrayClass = graph.findClassByName(expectedArrayClassName)
      assertThat(arrayClass).isNotNull
      assertThat(arrayClass!!.isObjectArrayClass).isTrue()
      assertThat(arrayClass.name).isEqualTo(expectedArrayClassName)

      val array = arrayClass.objectArrayInstances.single { it.readElements().count() == 2 }
      assertThat(array.arrayClassName).isEqualTo(expectedArrayClassName)
    }
  }

  @Test fun `JVM primitive array class name is translated to brackets`() {
    val hprofFile = dumpHeapRetaining(IntArray(42).apply { this[0] = 0xDad })

    val expectedArrayClassName = "int[]"

    hprofFile.openHeapGraph().use { graph ->
      val arrayClass = graph.findClassByName(expectedArrayClassName)
      assertThat(arrayClass).isNotNull
      assertThat(arrayClass!!.isPrimitiveArrayClass).isTrue()
      assertThat(arrayClass.name).isEqualTo(expectedArrayClassName)

      val array = arrayClass.primitiveArrayInstances.single {
        it.primitiveType == INT && it.readRecord()
          .run { size == 42 && (this as IntArrayDump).array[0] == 0xDad }
      }
      assertThat(array.arrayClassName).isEqualTo(expectedArrayClassName)
    }
  }

  @Test fun `JVM multi dimension primitive array class name is translated to brackets`() {
    val hprofFile = dumpHeapRetaining(arrayOf(IntArray(42), IntArray(42)))

    val expectedArrayClassName = "int[][]"

    hprofFile.openHeapGraph().use { graph ->
      val arrayClass = graph.findClassByName(expectedArrayClassName)
      assertThat(arrayClass).isNotNull
      assertThat(arrayClass!!.isPrimitiveArrayClass).isFalse()
      assertThat(arrayClass.name).isEqualTo(expectedArrayClassName)

      val array = arrayClass.objectArrayInstances.single {
        it.readRecord().elementIds.size == 2
      }
      assertThat(array.arrayClassName).isEqualTo(expectedArrayClassName)
    }
  }

  private fun dumpHeapRetaining(retained: Any): File {
    val hprofFolder = testFolder.newFolder()
    val hprofFile = File(hprofFolder, "jvm_heap.hprof")
    JvmTestHeapDumper.dumpHeap(hprofFile.absolutePath)
    // Dumb check to prevent instance from being garbage collected.
    check(retained::class::class.isInstance(KClass::class))
    return hprofFile
  }
}

private val KClass<out Any>.name: String
  get() = this.java.name