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package scala.collection.mutable
import org.junit.Assert._
import org.junit.Test
import org.junit.runner.RunWith
import org.junit.runners.JUnit4
import org.openjdk.jol.info.{GraphPathRecord, GraphVisitor, GraphWalker}
/** Tests for [[OpenHashMap]]. */
@RunWith(classOf[JUnit4])
class OpenHashMapTest {
/** Test that an [[OpenHashMap]] correctly maintains its internal `deleted` count. */
@Test
def maintainsDeletedCount {
val m = OpenHashMap.empty[Int, Int]
// Reflect to get the private `deleted` field's value, which should be zero.
/* TODO Doesn't work, due to SI-9306.
import scala.reflect.runtime.{universe => ru}
val mirror = ru.runtimeMirror(m.getClass.getClassLoader)
val mapType = ru.typeOf[OpenHashMap[Int, Int]]
val termSym = mapType.decls
.filterNot { s => s.isMethod }
.filter { s => s.fullName.endsWith("deleted") }
.head.asTerm
val fieldMirror = mirror.reflect(m).reflectField(termSym)
*/
// Use Java reflection instead for now.
val field =
try { // Name may or not be mangled, depending on what the compiler authors are doing.
m.getClass.getDeclaredField("scala$collection$mutable$OpenHashMap$$deleted")
} catch {
case _: NoSuchFieldException =>
m.getClass.getDeclaredField("deleted")
}
field.setAccessible(true)
m.put(0, 0)
m.remove(0)
assertEquals(1, field.getInt(m))
m.put(0, 0) // Add an entry with the same key
// TODO assertEquals(0, fieldMirror.get.asInstanceOf[Int])
assertEquals(0, field.getInt(m))
}
/** Test that an [[OpenHashMap]] frees references to a deleted key (SI-9522). */
@Test
def freesDeletedKey {
import scala.language.reflectiveCalls
class MyClass {
override def hashCode() = 42
}
val counter = new GraphVisitor() {
private[this] var instanceCount: Int = _
def countInstances(obj: AnyRef) = {
instanceCount = 0
val walker = new GraphWalker(obj)
walker.addVisitor(this)
walker.walk
instanceCount
}
override def visit(record: GraphPathRecord) {
if (record.klass() == classOf[MyClass]) instanceCount += 1
}
}
val m = OpenHashMap.empty[MyClass, Int]
val obj = new MyClass
assertEquals("Found a key instance in the map before adding one!?", 0, counter.countInstances(m))
m.put(obj, 0)
assertEquals("There should be only one key instance in the map.", 1, counter.countInstances(m))
m.put(obj, 1)
assertEquals("There should still be only one key instance in the map.", 1, counter.countInstances(m))
m.remove(obj)
assertEquals("There should be no key instance in the map.", 0, counter.countInstances(m))
val obj2 = new MyClass
assertEquals("The hash codes of the test objects need to match.", obj.##, obj2.##)
m.put(obj, 0)
m.put(obj2, 0)
assertEquals("There should be two key instances in the map.", 2, counter.countInstances(m))
m.remove(obj)
assertEquals("There should be one key instance in the map.", 1, counter.countInstances(m))
m.remove(obj2)
assertEquals("There should be no key instance in the map.", 0, counter.countInstances(m))
}
}
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