Merge pull request #26 from sql-bi/marco-fixTSort

Fix stack overflow error
sql-bi · Sep 8, 2022 · 9082e18 · 9082e18
2 parents 8887a82 + f397f5d
commit 9082e18
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Showing 5 changed files with 45 additions and 15 deletions.
diff --git a/src/Dax.Template/Exceptions/CircularDependencyException.cs b/src/Dax.Template/Exceptions/CircularDependencyException.cs
@@ -0,0 +1,8 @@
+namespace Dax.Template.Exceptions
+{
+    public class CircularDependencyException : TemplateException
+    {
+        public CircularDependencyException(string? variableName, string? daxExpressionmessage)
+            : base($"Circulare dependency in variable definition {variableName??"[undefined]"} with DAX expression: {daxExpressionmessage??"[undefined]"}") { }
+    }
+}
diff --git a/src/Dax.Template/Extensions/TSort.cs b/src/Dax.Template/Extensions/TSort.cs
@@ -1,13 +1,15 @@
 using System;
 using System.Linq;
 using System.Collections.Generic;
+using Dax.Template.Syntax;
+using Dax.Template.Exceptions;
 
 namespace Dax.Template.Extensions
 {
 
     public static partial class Extensions
     {
-        
+
         public static IEnumerable<(T item, int level)> TSort<T>(this IEnumerable<T> source, Func<T, IEnumerable<T>?> dependencies, bool onlyAddLevel = true) where T : Syntax.IDependencies<Syntax.DaxBase>
         {
             var sorted = new List<(T item, int level)>();
@@ -18,25 +20,26 @@ public static partial class Extensions
                 return sorted;
             }
 
-            foreach (var item in source.Where(n=>(!onlyAddLevel) || n.AddLevel))
+            foreach (var item in source.Where(n => (!onlyAddLevel) || n.AddLevel))
             {
                 Visit(item, visited, sorted, dependencies);
             }
-            
+
             if (!sorted.Any())
             {
                 return sorted;
             }
 
             // Add the dependencies required in each level (usually row variables)
             var result = new List<(T item, int level)>();
-            int min = sorted.Min( element => element.level );
-            int max = sorted.Max( element => element.level );
-            for (int currentLoopLevel = min; currentLoopLevel <= max; currentLoopLevel++) {
+            int min = sorted.Min(element => element.level);
+            int max = sorted.Max(element => element.level);
+            for (int currentLoopLevel = min; currentLoopLevel <= max; currentLoopLevel++)
+            {
                 result.AddRange(sorted.Where(element => element.level == currentLoopLevel && element.item.AddLevel));
                 var referencedVariables =
                     from element in sorted
-                    where element.level == currentLoopLevel && element.item.AddLevel == false 
+                    where element.level == currentLoopLevel && element.item.AddLevel == false
                     select element;
                 var referencedDependencies =
                     (from element in sorted
@@ -50,12 +53,12 @@ select element.item as Syntax.IDependencies<Syntax.DaxBase>
                     result.InsertRange(
                         result.IndexOf(pos),
                         from element in sorted
-                        where element.level < currentLoopLevel 
-                            && element.item.AddLevel == false 
-                            && previousVariables.Any(item => object.ReferenceEquals(item.item,element.item))
-                            && !result.Any(existingItem => object.ReferenceEquals(existingItem.item,element.item) && existingItem.level == currentLoopLevel)
+                        where element.level < currentLoopLevel
+                            && element.item.AddLevel == false
+                            && previousVariables.Any(item => object.ReferenceEquals(item.item, element.item))
+                            && !result.Any(existingItem => object.ReferenceEquals(existingItem.item, element.item) && existingItem.level == currentLoopLevel)
                             && element.item is not Syntax.IGlobalScope
-                        select (element.item, currentLoopLevel )
+                        select (element.item, currentLoopLevel)
                     );
                     result.InsertRange(
                         result.IndexOf(pos),
@@ -84,6 +87,11 @@ from element in referencedVariables
             return result;
         }
 
+        /// <summary>
+        /// Maximum number of nested calls in VisitDependencies
+        /// </summary>
+        private const int MAX_NESTED_CALLS = 1000;
+
         private static void Visit<T>(T item, HashSet<T> visited, List<(T, int level)> sorted, Func<T, IEnumerable<T>?> dependencies) where T : Syntax.IDependencies<Syntax.DaxBase>
         {
             if (!visited.Contains(item))
@@ -105,18 +113,29 @@ private static void Visit<T>(T item, HashSet<T> visited, List<(T, int level)> so
             }
         }
 
-        private static int VisitDependencies<T>(T item, HashSet<T> visited, List<(T, int level)> sorted, Func<T, IEnumerable<T>?> dependencies, int level = 0) where T : Syntax.IDependencies<Syntax.DaxBase>
+        private static int VisitDependencies<T>(T item, HashSet<T> visited, List<(T, int level)> sorted, Func<T, IEnumerable<T>?> dependencies, int level = 0, int nestedCalls = 0) where T : Syntax.IDependencies<Syntax.DaxBase>
         {
             var allDependencies = dependencies(item);
             // var dependenciesListAddLevel = allDependencies?.Where(d => d.AddLevel == true);
 
+            if (nestedCalls > MAX_NESTED_CALLS)
+            {
+                string? varName = (item as IDaxName)?.DaxName.ToString();
+                throw new CircularDependencyException(varName, "{STACK OVERFLOW: check complex dependencies}");
+            }
+
+            if (allDependencies?.Contains(item) == true)
+            {
+                throw new CircularDependencyException((item as IDaxName)?.DaxName.ToString(), item.Expression);
+            }
+
             level += item.AddLevel ? 1 : 0;
             int maxLevel = level;
             if (allDependencies != null)
             {
                 foreach (var dep in allDependencies)
                 {
-                    var nestedLevel = VisitDependencies(dep, visited, sorted, dependencies, level);
+                    var nestedLevel = VisitDependencies(dep, visited, sorted, dependencies, level, ++nestedCalls);
                     if (nestedLevel > maxLevel)
                     {
                         maxLevel = nestedLevel;

diff --git a/src/Dax.Template/Syntax/DaxElement.cs b/src/Dax.Template/Syntax/DaxElement.cs
@@ -1,5 +1,7 @@
 namespace Dax.Template.Syntax
 {
+    using System.Xml.Linq;
+
     /// <summary>
     /// Internal use to create automatic DAX code in templates
     /// This could be partial code, it has no name because it is assigned internally 

diff --git a/src/Dax.Template/Syntax/IDependencies.cs b/src/Dax.Template/Syntax/IDependencies.cs
@@ -6,6 +6,7 @@ public interface IDependencies<T> where T : DaxBase
         public bool IgnoreAutoDependency { get; init; }
         public IDependencies<T>[]? Dependencies { get; set; }
         public string? Expression { get; set; } 
+
         public string GetDebugInfo();
     }
 }

diff --git a/src/Dax.Template/Syntax/Var.cs b/src/Dax.Template/Syntax/Var.cs
@@ -11,7 +11,7 @@ public abstract class Var : DaxBase, IDependencies<DaxBase>, IDaxName, IDaxComme
         public string[]? Comments { get; set; } 
         public string DaxName { get { return Name; } }
 
-        public IDependencies<DaxBase>[]? Dependencies { get; set; } 
+        public IDependencies<DaxBase>[]? Dependencies { get; set; }
         public string GetDebugInfo() { return $"VAR {Name}: {Expression}"; }
         public override string ToString()
         {