Merge pull request #5673 from retronym/topic/hashmap-contains

Optimizations in immutable.Map.{get, contains}

1 files changed, 56 insertions, 0 deletions

diff --git a/test/benchmarks/src/main/scala/scala/collection/immutable/HashMapBenchmark.scala b/test/benchmarks/src/main/scala/scala/collection/immutable/HashMapBenchmark.scala
new file mode 100644
index 0000000000..134cd6879b
--- /dev/null
+++ b/test/benchmarks/src/main/scala/scala/collection/immutable/HashMapBenchmark.scala
@@ -0,0 +1,56 @@
+package scala.collection.immutable
+
+import org.openjdk.jmh.annotations._
+import org.openjdk.jmh.infra._
+import org.openjdk.jmh.runner.IterationType
+import benchmark._
+import java.util.concurrent.TimeUnit
+
+@BenchmarkMode(Array(Mode.AverageTime))
+@Fork(2)
+@Threads(1)
+@Warmup(iterations = 10)
+@Measurement(iterations = 10)
+@OutputTimeUnit(TimeUnit.NANOSECONDS)
+@State(Scope.Benchmark)
+class HashMapBenchmark {
+  @Param(Array("10", "100", "1000"))
+  var size: Int = _
+
+  var existingKeys: Array[Any] = _
+  var missingKeys: Array[Any] = _
+
+  @Setup(Level.Trial) def initKeys(): Unit = {
+    existingKeys = (0 to size).map(i => (i % 4) match {
+      case 0 => i.toString
+      case 1 => i.toChar
+      case 2 => i.toDouble
+      case 3 => i.toInt
+    }).toArray
+    missingKeys = (size to 2 * size).toArray
+  }
+
+  var map: collection.immutable.HashMap[Any, Any] = null
+
+  @Setup(Level.Trial) def initialize = {
+    map = collection.immutable.HashMap(existingKeys.map(x => (x, x)) : _*)
+  }
+
+  @Benchmark def contains(bh: Blackhole): Unit = {
+    var i = 0;
+    while (i < size) {
+      bh.consume(map.contains(existingKeys(i)))
+      bh.consume(map.contains(missingKeys(i)))
+      i += 1
+    }
+  }
+
+  @Benchmark def get(bh: Blackhole): Unit = {
+    var i = 0;
+    while (i < size) {
+      bh.consume(map.get(existingKeys(i)))
+      bh.consume(map.get(missingKeys(i)))
+      i += 1
+    }
+  }
+}