Merge pull request #672 from aml-org/W-15207889/performance-fixes

W-15207889. Some performance improvements.

.nvmrc

@@ -0,0 +1 @@
+v16.17.1

.sdkmanrc

@@ -0,0 +1,5 @@
+# Enable auto-env through the sdkman_auto_env config
+# Add key=value pairs of SDKs to use below
+java=17.0.10-tem
+scala=2.12.15
+sbt=1.7.3

shared/src/main/scala/amf/core/internal/remote/Cache.scala

@@ -19,15 +19,40 @@ class Cache {
     dependencyGraph.update(to, fromNodes.+(from))
   }
 
-  protected def findCycles(node: String, acc: Set[String] = Set()): Boolean = {
-    if (acc.contains(node)) {
-      true
-    } else {
-      val sources = dependencyGraph.getOrElse(node, Set())
-      sources.exists { source =>
-        findCycles(source, acc + node)
+  protected def findCycles(initialNode: String): Boolean = {
+    // Mutable collections are used to improve performance
+    val allVisited   = mutable.Set[String]()
+    val visitedStack = mutable.Stack[String]()
+
+    def innerFindCycles(currentNode: String): Boolean = {
+      if (visitedStack.contains(currentNode)) {
+        // There is a cycle
+        return true
+      }
+
+      if (allVisited.contains(currentNode)) {
+        // This node has already been visited
+        return false
+      }
+
+      allVisited.add(currentNode)
+      visitedStack.push(currentNode)
+
+      val newNodes = dependencyGraph.getOrElse(currentNode, Set())
+      for (newNode <- newNodes) {
+        if (findCycles(newNode)) {
+          // Cycle found
+          visitedStack.pop()
+          return true
+        }
       }
+
+      // So far no cycles
+      visitedStack.pop()
+      false
     }
+
+    innerFindCycles(initialNode)
   }
 
   protected def beforeLast(elms: List[String]): Option[String] = {

shared/src/main/scala/amf/core/internal/transform/stages/UrlShortenerStage.scala

@@ -1,13 +1,12 @@
 package amf.core.internal.transform.stages
 import amf.core.client.scala.AMFGraphConfiguration
 import amf.core.client.scala.errorhandling.AMFErrorHandler
-import amf.core.internal.metamodel.Type.{ArrayLike, Iri}
-import amf.core.internal.metamodel.domain.LinkableElementModel
 import amf.core.client.scala.model.document.BaseUnit
 import amf.core.client.scala.model.domain._
 import amf.core.client.scala.transform.TransformationStep
-import amf.core.internal.parser.domain.FieldEntry
 import amf.core.client.scala.vocabulary.Namespace
+import amf.core.internal.metamodel.Type.{ArrayLike, Iri}
+import amf.core.internal.metamodel.domain.LinkableElementModel
 import amf.core.internal.parser.domain.{Annotations, FieldEntry, Value}
 
 import scala.collection.mutable
@@ -19,17 +18,23 @@ class UrlShortenerStage() extends TransformationStep {
       errorHandler: AMFErrorHandler,
       configuration: AMFGraphConfiguration
   ): BaseUnit = {
-    val ids: Set[String] = Set(model.id) ++ obtainNestedReferenceIds(model)
+    val ids: mutable.Set[String] = mutable.Set()
+    collectNestedReferenceIdsInSet(model, ids)
+    ids.add(model.id)
+
     shorten(model, ids)
     model.withId(base)
   }
 
-  private def obtainNestedReferenceIds[T <: BaseUnit](model: T): Seq[String] = {
-    val ids = model.references.map(_.id)
-    ids ++ model.references.flatMap(obtainNestedReferenceIds)
+  private def collectNestedReferenceIdsInSet[T <: BaseUnit](model: T, set: mutable.Set[String]): Unit = {
+    if (!set.contains(model.id)) {
+      set += model.id
+
+      model.references.foreach(collectNestedReferenceIdsInSet(_, set))
+    }
   }
 
-  def shorten(element: AmfElement, ids: Set[String]): Unit = {
+  def shorten(element: AmfElement, ids: Traversable[String]): Unit = {
     element match {
       case o: AmfObject =>
         val shorthenId = shortener.shorten(o.id)
@@ -64,7 +69,7 @@ class UrlShortenerStage() extends TransformationStep {
     shorten(element.annotations)
   }
 
-  private def shortenIriValue(element: AmfElement, ids: Set[String]): AmfElement = {
+  private def shortenIriValue(element: AmfElement, ids: Traversable[String]): AmfElement = {
     val stringValue = element.toString
     if (ids.exists(i => stringValue.startsWith(i)))
       AmfScalar(shortener.shorten(stringValue), element.annotations)