Better stats for unique tables

Now shows also total umber of accesses and hash collisions for each
unique types set.

Author: odersky

compiler/src/dotty/tools/dotc/core/Contexts.scala

@@ -618,7 +618,8 @@ object Contexts {
         "uniqueNamedTypes" -> uniqueNamedTypes)
 
     /** A map that associates label and size of all uniques sets */
-    def uniquesSizes: Map[String, Int] = uniqueSets.mapValues(_.size)
+    def uniquesSizes: Map[String, (Int, Int, Int)] =
+      uniqueSets.mapValues(s => (s.size, s.accesses, s.misses))
 
     /** Number of findMember calls on stack */
     private[core] var findMemberCount: Int = 0

compiler/src/dotty/tools/dotc/util/HashSet.scala

@@ -9,6 +9,10 @@ class HashSet[T >: Null <: AnyRef](powerOfTwoInitialCapacity: Int, loadFactor: F
 
   protected def isEqual(x: T, y: T): Boolean = x.equals(y)
 
+  // Counters for Stats
+  var accesses = 0
+  var misses = 0
+
   clear()
 
   /** The number of elements in the set */
@@ -37,10 +41,12 @@ class HashSet[T >: Null <: AnyRef](powerOfTwoInitialCapacity: Int, loadFactor: F
    *  If not, enter `x` in set and return `x`.
    */
   def findEntryOrUpdate(x: T): T = {
+    if (Stats.enabled) accesses += 1
     var h = index(hash(x))
     var entry = entryAt(h)
     while (entry ne null) {
       if (isEqual(x, entry)) return entry
+      if (Stats.enabled) misses += 1
       h = index(h + 1)
       entry = entryAt(h)
     }
@@ -57,9 +63,11 @@ class HashSet[T >: Null <: AnyRef](powerOfTwoInitialCapacity: Int, loadFactor: F
 
   /** The entry in the set such that `isEqual(x, entry)`, or else `null`. */
   def findEntry(x: T): T = {
+    if (Stats.enabled) accesses += 1
     var h = index(hash(x))
     var entry = entryAt(h)
     while ((entry ne null) && !isEqual(x, entry)) {
+      if (Stats.enabled) misses += 1
       h = index(h + 1)
       entry = entryAt(h)
     }
@@ -70,10 +78,12 @@ class HashSet[T >: Null <: AnyRef](powerOfTwoInitialCapacity: Int, loadFactor: F
 
   /** Add entry `x` to set */
   def addEntry(x: T): Unit = {
+    if (Stats.enabled) accesses += 1
     var h = index(hash(x))
     var entry = entryAt(h)
     while (entry ne null) {
       if (isEqual(x, entry)) return
+      if (Stats.enabled) misses += 1
       h = index(h + 1)
       entry = entryAt(h)
     }
@@ -109,10 +119,12 @@ class HashSet[T >: Null <: AnyRef](powerOfTwoInitialCapacity: Int, loadFactor: F
    *  follow a `findEntryByhash` or `nextEntryByHash` operation.
    */
   protected def nextEntryByHash(hashCode: Int): T = {
+    if (Stats.enabled) accesses += 1
     var entry = table(rover)
     while (entry ne null) {
       rover = index(rover + 1)
       if (hash(entry.asInstanceOf[T]) == hashCode) return entry.asInstanceOf[T]
+      if (Stats.enabled) misses += 1
       entry = table(rover)
     }
     null

compiler/src/dotty/tools/dotc/util/Stats.scala

@@ -83,7 +83,7 @@ import collection.mutable
         hb.continue = false
         println()
         println(hits.toList.sortBy(_._2).map{ case (x, y) => s"$x -> $y" } mkString "\n")
-        println(s"sizes: ${ctx.base.uniquesSizes}")
+        println(s"uniqieInfo (size, accesses, collisions): ${ctx.base.uniquesSizes}")
       }
     } else op
   }

tests/pos/i3965.scala

@@ -0,0 +1,19 @@
+trait Iterable[+A] extends  IterableOps[A, Iterable, Iterable[A]]
+trait IterableOps[+A, +CCop[_], +C]
+
+trait SortedSet[A] extends Iterable[A] with SortedSetOps[A, SortedSet, SortedSet[A]]
+
+trait SortedSetOps[A, +CCss[X] <: SortedSet[X], +C <: SortedSetOps[A, CCss, C]]
+
+class TreeSet[A]
+  extends SortedSet[A]
+    with SortedSetOps[A, TreeSet, TreeSet[A]]
+
+class Test {
+  def optionSequence1[CCos[X] <: IterableOps[X, CCos, _], A](xs: CCos[Option[A]]): Option[CCos[A]] = ???
+  def optionSequence1[CC[X] <: SortedSet[X] with SortedSetOps[X, CC, CC[X]], A : Ordering](xs: CC[Option[A]]): Option[CC[A]] = ???
+
+  def test(xs2: TreeSet[Option[String]]) = {
+    optionSequence1(xs2)
+  }
+}