when many challenges, show correspondence challenges last

modules/challenge/src/main/ChallengeApi.scala

@@ -11,6 +11,7 @@ import lila.game.{ Game, Pov }
 import lila.hub.actorApi.socket.SendTo
 import lila.i18n.I18nLangPicker
 import lila.memo.CacheApi._
+import lila.memo.ExpireSetMemo
 import lila.user.{ User, UserRepo }
 
 final class ChallengeApi(
@@ -56,7 +57,10 @@ final class ChallengeApi(
 
   def createdByChallengerId = repo.createdByChallengerId() _
 
-  def createdByDestId = repo.createdByDestId() _
+  def createdByDestId(userId: User.ID) = countInFor get userId flatMap { nb =>
+    if (nb > 5) repo.createdByPopularDestId()(userId)
+    else repo.createdByDestId()(userId)
+  }
 
   def cancel(c: Challenge) =
     repo.cancel(c) >>- {
@@ -158,7 +162,7 @@ final class ChallengeApi(
 
   private object notifyUser {
     private val throttler = new lila.hub.EarlyMultiThrottler(logger)
-    def apply(userId: User.ID): Unit = throttler(userId, 2.seconds) {
+    def apply(userId: User.ID): Unit = throttler(userId, 3.seconds) {
       for {
         all  <- allFor(userId)
         lang <- userRepo langOf userId map I18nLangPicker.byStrOrDefault

modules/challenge/src/main/ChallengeRepo.scala

@@ -5,6 +5,7 @@ import scala.annotation.nowarn
 
 import lila.common.config.Max
 import lila.db.dsl._
+import lila.user.User
 
 final private class ChallengeRepo(colls: ChallengeColls, maxPerUser: Max)(implicit
     ec: scala.concurrent.ExecutionContext
@@ -34,19 +35,22 @@ final private class ChallengeRepo(colls: ChallengeColls, maxPerUser: Max)(implic
 
   def update(c: Challenge): Funit = coll.update.one($id(c.id), c).void
 
-  def createdByChallengerId(max: Int = 50)(userId: String): Fu[List[Challenge]] =
-    coll
-      .find(selectCreated ++ $doc("challenger.id" -> userId))
-      .sort($sort asc "createdAt")
-      .cursor[Challenge]()
-      .list(max)
+  private def createdList(selector: Bdoc, max: Int): Fu[List[Challenge]] =
+    coll.find(selectCreated ++ selector).sort($sort asc "createdAt").cursor[Challenge]().list(max)
 
-  def createdByDestId(max: Int = 50)(userId: String): Fu[List[Challenge]] =
-    coll
-      .find(selectCreated ++ $doc("destUser.id" -> userId))
-      .sort($doc($sort asc "createdAt"))
-      .cursor[Challenge]()
-      .list(max)
+  def createdByChallengerId(max: Int = 50)(userId: User.ID): Fu[List[Challenge]] =
+    createdList($doc("challenger.id" -> userId), max)
+
+  def createdByDestId(max: Int = 50)(userId: User.ID): Fu[List[Challenge]] =
+    createdList($doc("destUser.id" -> userId), max)
+
+  def createdByPopularDestId(max: Int = 50)(userId: User.ID): Fu[List[Challenge]] = for {
+    realTime <- createdList($doc("destUser.id" -> userId, "timeControl.l" $exists true), max)
+    corres <- (realTime.sizeIs < max) ?? createdList(
+      $doc($doc("destUser.id" -> userId), "timeControl.l" $exists false),
+      max - realTime.size
+    )
+  } yield realTime ::: corres
 
   def setChallenger(c: Challenge, color: Option[chess.Color]) =
     coll.update