clear scope.disposables collection when disposing container to preven…

…t ConcurrentBag memory leak

ConcurrentBag is using thread locals variables to store it's content. in some cases when the Bag contains elements
that have circular references (reference an instance of this Bag) the whole graph of objects stay in memory
if the Bag is not cleared before all references are released

src/Lamar.Testing/IoC/Acceptance/disposing_container.cs

@@ -230,6 +230,23 @@ public void should_dispose_lambda_instance_with_transient_scope_parent_is_scoped
             disposableDependent.WasDisposed.ShouldBeTrue();
             disposableDependent.ChildDisposable.WasDisposed.ShouldBeTrue();
         }
+
+        [Theory]
+        [InlineData(DisposalLock.Ignore)]
+        [InlineData(DisposalLock.Unlocked)]
+        public void should_clear_disposables_collection_when_disposed(DisposalLock disposalLock)
+        {
+            var container = new Container(x =>
+            {
+                x.For<Disposable>().Use<Disposable>();
+            });
+
+            var service = container.GetInstance<Disposable>();
+            container.DisposalLock = disposalLock;
+            container.Dispose();
+
+            container.Disposables.ShouldBeEmpty();
+        }
     }
 
     public class DisposableDependent : IDisposable

src/Lamar/IoC/Scope.cs

@@ -1,5 +1,4 @@
 using System;
-using System.CodeDom.Compiler;
 using System.Collections;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
@@ -10,7 +9,6 @@
 using Lamar.IoC.Diagnostics;
 using Lamar.IoC.Frames;
 using Lamar.IoC.Instances;
-using Lamar.Scanning;
 using LamarCodeGeneration;
 using LamarCodeGeneration.Model;
 using LamarCodeGeneration.Util;
@@ -45,8 +43,6 @@ public Scope(IServiceCollection services, PerfTimer timer = null)
                 Bootstrapping.MarkStart("Lamar Scope Creation");
             }
 
-
-
             Root = this;
 
             Bootstrapping.MarkStart("Build ServiceGraph");
@@ -63,16 +59,12 @@ public Scope(IServiceCollection services, PerfTimer timer = null)
             {
                 Bootstrapping.MarkFinished("Lamar Scope Creation");
             }
-
-
         }
 
         protected Scope(){}
 
         public Scope Root { get; protected set; }
 
-
-
         public Scope(ServiceGraph serviceGraph, Scope root)
         {
             ServiceGraph = serviceGraph;
@@ -103,18 +95,21 @@ protected void assertNotDisposed()
 
         internal readonly Dictionary<int, object> Services = new Dictionary<int, object>();
 
-
-
         public virtual void Dispose()
         {
-            if (DisposalLock == DisposalLock.Ignore) return;
-
             if (DisposalLock == DisposalLock.ThrowOnDispose) throw new InvalidOperationException("This Container has DisposalLock = DisposalLock.ThrowOnDispose and cannot be disposed until the lock is cleared");
 
             if (_hasDisposed) return;
             _hasDisposed = true;
 
-            foreach (var disposable in Disposables.Distinct())
+            var distinctDisposables = Disposables.Distinct().ToArray();
+            // clear disposables bag to prevent memory leak. current implementation of ConcurrentBag is using thread local storage and in some cases
+            // e.g. an object from Disposables collection is referencing this Scope instance the whole graph can stay in memory after it was disposed
+            while (Disposables.TryTake(out _)) { }
+
+            if (DisposalLock == DisposalLock.Ignore) return;
+
+            foreach (var disposable in distinctDisposables)
             {
                 disposable.SafeDispose();
             }
@@ -209,8 +204,7 @@ public object QuickBuild(Type objectType)
             var constructorInstance = new ConstructorInstance(objectType, objectType, ServiceLifetime.Transient);
             var ctor = constructorInstance.DetermineConstructor(ServiceGraph, out var message);
             var setters = constructorInstance.FindSetters(ServiceGraph);
-
-
+
             if (ctor == null) throw new InvalidOperationException(message);
 
             var dependencies = ctor.GetParameters().Select(x =>
@@ -270,7 +264,6 @@ public IEnumerable GetAllInstances(Type serviceType)
         }
 
 
-
         public string WhatDoIHave(Type serviceType = null, Assembly assembly = null, string @namespace = null,
             string typeName = null)
         {
@@ -285,7 +278,7 @@ public string WhatDoIHave(Type serviceType = null, Assembly assembly = null, str
                 TypeName = typeName
             });
         }
-        
+
         public string HowDoIBuild(Type serviceType = null, Assembly assembly = null, string @namespace = null,
             string typeName = null)
         {
@@ -342,13 +335,10 @@ public string WhatDidIScan()
             }
         }
 
-
         public IServiceVariableSource CreateServiceVariableSource()
         {
             return new ServiceVariableSource(ServiceGraph);
         }
-
-
 
         public string GenerateCodeWithInlineServices(GeneratedAssembly assembly)
         {
@@ -398,7 +388,7 @@ public void TryAddDisposable(object @object)
                 Disposables.Add(disposable);
             }
         }
-        
+
         public object AddDisposable(object @object)
         {
             Disposables.Add((IDisposable) @object);
@@ -409,7 +399,7 @@ public Func<string, T> FactoryByNameFor<T>()
         {
             return GetInstance<T>;
         }
-        
+
         public Func<T> FactoryFor<T>()
         {
             return GetInstance<T>;