ballsy study optimisation: set shapes without updating the whole chapter

Featuring backtrack recursion \o/
Falls back to logged full update in case of failure (?!)

TODO: same thing for comments, adding/deleting nodes.

modules/study/src/main/BSONHandlers.scala

@@ -78,6 +78,12 @@ object BSONHandlers {
 
   private implicit val FenBSONHandler = stringAnyValHandler[FEN](_.value, FEN.apply)
 
+  implicit val ShapesBSONHandler: BSONHandler[BSONArray, Shapes] =
+    isoHandler[Shapes, List[Shape], BSONArray](
+      (s: Shapes) => s.value.distinct,
+      Shapes(_)
+    )
+
   import lila.tree.Node.{ Comment, Comments }
   private implicit val CommentIdBSONHandler = stringAnyValHandler[Comment.Id](_.value, Comment.Id.apply)
   private implicit val CommentTextBSONHandler = stringAnyValHandler[Comment.Text](_.value, Comment.Text.apply)
@@ -105,9 +111,6 @@ object BSONHandlers {
   private def readComments(r: Reader) =
     Comments(r.getsD[Comment]("co").filter(_.text.value.nonEmpty))
 
-  private def readShapes(r: Reader) =
-    Shapes(r.getsD[Shape]("h"))
-
   private implicit def CrazyDataBSONHandler: BSON[Crazyhouse.Data] = new BSON[Crazyhouse.Data] {
     private def writePocket(p: Crazyhouse.Pocket) = p.roles.map(_.forsyth).mkString
     private def readPocket(p: String) = Crazyhouse.Pocket(p.flatMap(chess.Role.forsyth)(scala.collection.breakOut))
@@ -139,7 +142,7 @@ object BSONHandlers {
       move = WithSan(r.get[Uci]("u"), r.str("s")),
       fen = r.get[FEN]("f"),
       check = r boolD "c",
-      shapes = readShapes(r),
+      shapes = r.getO[Shapes]("h") | Shapes.empty,
       comments = readComments(r),
       glyphs = r.getO[Glyphs]("g") | Glyphs.empty,
       crazyData = r.getO[Crazyhouse.Data]("z"),
@@ -167,7 +170,7 @@ object BSONHandlers {
       ply = r int "p",
       fen = r.get[FEN]("f"),
       check = r boolD "c",
-      shapes = readShapes(r),
+      shapes = r.getO[Shapes]("h") | Shapes.empty,
       comments = readComments(r),
       glyphs = r.getO[Glyphs]("g") | Glyphs.empty,
       clock = r.getO[Centis]("l"),

modules/study/src/main/ChapterRepo.scala

@@ -59,6 +59,27 @@ final class ChapterRepo(coll: Coll) {
   def setTagsFor(chapter: Chapter) =
     coll.updateField($id(chapter.id), "tags", chapter.tags).void
 
+  def setShapes(chapter: Chapter, path: Path, shapes: lila.tree.Node.Shapes): Option[Funit] =
+    pathToField(chapter, path) map { field =>
+      val shapesField = s"$field.h"
+      if (shapes.value.isEmpty) coll.unsetField($id(chapter.id), shapesField).void
+      else coll.updateField($id(chapter.id), shapesField, shapes).void
+    }
+
+  // root.n[0].n[0].n[1].n[0].n[2]
+  private def pathToField(chapter: Chapter, path: Path): Option[String] =
+    pathToIndexes(chapter.root.children, path) map { indexes =>
+      s"root.n.${indexes.mkString(".n.")}"
+    }
+
+  // List(0, 0, 1, 0, 2)
+  private def pathToIndexes(children: Node.Children, path: Path): Option[List[Int]] =
+    path.split.fold(List.empty[Int].some) {
+      case (head, tail) => children.getNodeAndIndex(head) flatMap {
+        case (node, index) => pathToIndexes(node.children, tail).map(rest => index :: rest)
+      }
+    }
+
   private[study] def idNamesByStudyIds(studyIds: Seq[Study.Id]): Fu[Map[Study.Id, Vector[Chapter.IdName]]] =
     coll.find(
       $doc("studyId" $in studyIds),

modules/study/src/main/Node.scala

@@ -130,6 +130,11 @@ object Node {
 
     def get(id: UciCharPair): Option[Node] = nodes.find(_.id == id)
 
+    def getNodeAndIndex(id: UciCharPair): Option[(Node, Int)] =
+      nodes.zipWithIndex.collectFirst {
+        case pair if pair._1.id == id => pair
+      }
+
     def has(id: UciCharPair): Boolean = nodes.exists(_.id == id)
 
     def updateWith(id: UciCharPair, op: Node => Option[Node]): Option[Children] =

modules/study/src/main/StudyApi.scala

@@ -251,7 +251,10 @@ final class StudyApi(
           chapter.setShapes(shapes, position.path) match {
             case Some(newChapter) =>
               studyRepo.updateNow(study)
-              chapterRepo.update(newChapter) >>-
+              chapterRepo.setShapes(newChapter, position.path, shapes) | {
+                logger.warn(s"Failed to setShapes $studyId $position")
+                chapterRepo update newChapter
+              } >>-
                 sendTo(study, Socket.SetShapes(position, shapes, uid))
             case None => fufail(s"Invalid setShapes $position $shapes") >>- reloadUid(study, uid)
           }

modules/tree/src/main/tree.scala

@@ -109,6 +109,9 @@ object Node {
     def list = value
     def ++(shapes: Shapes) = Shapes(value ::: shapes.value)
   }
+  object Shapes {
+    val empty = Shapes(Nil)
+  }
 
   case class Comment(id: Comment.Id, text: Comment.Text, by: Comment.Author) {
     def removeMeta = text.removeMeta map { t =>