1 files changed, 78 insertions, 0 deletions
diff --git a/compiler/src/dotty/tools/dotc/util/Stats.scala b/compiler/src/dotty/tools/dotc/util/Stats.scala
new file mode 100644
index 000000000..b7e0996f5
--- /dev/null
+++ b/compiler/src/dotty/tools/dotc/util/Stats.scala
@@ -0,0 +1,78 @@
+package dotty.tools
+package dotc
+package util
+
+import core.Contexts._
+import collection.mutable
+
+@sharable object Stats {
+
+  final val enabled = false
+
+  /** The period in ms in which stack snapshots are displayed */
+  final val HeartBeatPeriod = 250
+
+  var monitored = false
+
+  @volatile private var stack: List[String] = Nil
+
+  val hits = new mutable.HashMap[String, Int] {
+    override def default(key: String): Int = 0
+  }
+
+  @inline
+  def record(fn: String, n: Int = 1) =
+    if (enabled) doRecord(fn, n)
+
+  private def doRecord(fn: String, n: Int) =
+    if (monitored) {
+      val name = if (fn.startsWith("member-")) "member" else fn
+      hits(name) += n
+    }
+
+  @inline
+  def track[T](fn: String)(op: => T) =
+    if (enabled) doTrack(fn)(op) else op
+
+  def doTrack[T](fn: String)(op: => T) =
+    if (monitored) {
+      stack = fn :: stack
+      record(fn)
+      try op
+      finally stack = stack.tail
+    } else op
+
+  class HeartBeat extends Thread() {
+    @volatile private[Stats] var continue = true
+
+    private def printStack(stack: List[String]): Unit = stack match {
+      case str :: rest =>
+        printStack(rest)
+        print(s"-> $str ")
+      case Nil =>
+        println()
+        print("|")
+    }
+
+    override final def run(): Unit = {
+      Thread.sleep(HeartBeatPeriod)
+      printStack(stack)
+      if (continue) run()
+    }
+  }
+
+  def monitorHeartBeat[T](op: => T)(implicit ctx: Context) = {
+    if (ctx.settings.Yheartbeat.value) {
+      var hb = new HeartBeat()
+      hb.start()
+      monitored = true
+      try op
+      finally {
+        hb.continue = false
+        println()
+        println(hits.toList.sortBy(_._2).map{ case (x, y) => s"$x -> $y" } mkString "\n")
+        println(s"sizes: ${ctx.base.uniquesSizes}")
+      }
+    } else op
+  }
+}