Fix for throughput impact on AppService plan.

When compiling Expressions during startup time, preferInterpretation will be set to true to significanly improve cold start in consumption mode
however it will be set to false for premium and appservice plans to make sure throughput is not impacted
there is no throughput drop in consumption with this setting.

Author: safihamid

src/WebJobs.Script.WebHost/DependencyInjection/DryIoc/Container.cs

@@ -71,22 +71,22 @@ namespace DryIoc
     public sealed partial class Container : IContainer
     {
         /// <summary>Creates new container with default rules <see cref="DryIoc.Rules.Default"/>.</summary>
-        public Container() : this(Rules.Default, Ref.Of(Registry.Default), NewSingletonScope())
+        public Container(bool preferInterpretation = false) : this(Rules.Default, Ref.Of(Registry.Default), NewSingletonScope(), preferInterpretation: preferInterpretation)
         { }
 
         /// <summary>Creates new container, optionally providing <see cref="Rules"/> to modify default container behavior.</summary>
         /// <param name="rules">(optional) Rules to modify container default resolution behavior.
         /// If not specified, then <see cref="DryIoc.Rules.Default"/> will be used.</param>
         /// <param name="scopeContext">(optional) Scope context to use for scoped reuse.</param>
-        public Container(Rules rules = null, IScopeContext scopeContext = null)
-            : this(rules ?? Rules.Default, Ref.Of(Registry.Default), NewSingletonScope(), scopeContext)
+        public Container(Rules rules = null, IScopeContext scopeContext = null, bool preferInterpretation = false)
+            : this(rules ?? Rules.Default, Ref.Of(Registry.Default), NewSingletonScope(), scopeContext, preferInterpretation: preferInterpretation)
         { }
 
         /// <summary>Creates new container with configured rules.</summary>
         /// <param name="configure">Allows to modify <see cref="DryIoc.Rules.Default"/> rules.</param>
         /// <param name="scopeContext">(optional) Scope context to use for <see cref="Reuse.InCurrentScope"/>.</param>
-        public Container(Func<Rules, Rules> configure, IScopeContext scopeContext = null)
-            : this(configure.ThrowIfNull()(Rules.Default) ?? Rules.Default, scopeContext)
+        public Container(Func<Rules, Rules> configure, IScopeContext scopeContext = null, bool preferInterpretation = false)
+            : this(configure.ThrowIfNull()(Rules.Default) ?? Rules.Default, scopeContext, preferInterpretation: preferInterpretation)
         { }
 
         /// <summary>Helper to create singleton scope</summary>
@@ -1417,6 +1417,10 @@ private Factory GetWrapperFactoryOrDefault(Request request)
         private readonly IResolverContext _root;
         private readonly IResolverContext _parent;
 
+        private readonly bool _preferInterpretation;
+
+        internal bool PreferInterpretation => _preferInterpretation;
+
         internal sealed class InstanceFactory : Factory
         {
             public override Type ImplementationType { get; }
@@ -1927,7 +1931,8 @@ public Registry WithNoMoreRegistrationAllowed(bool ignoreInsteadOfThrow) =>
         private Container(Rules rules, Ref<Registry> registry, IScope singletonScope,
             IScopeContext scopeContext = null, IScope ownCurrentScope = null,
             int disposed = 0, StackTrace disposeStackTrace = null,
-            IResolverContext parent = null, IResolverContext root = null)
+            IResolverContext parent = null, IResolverContext root = null,
+            bool preferInterpretation = false)
         {
             Rules = rules;
 
@@ -1942,6 +1947,7 @@ private Container(Rules rules, Ref<Registry> registry, IScope singletonScope,
 
             _parent = parent;
             _root = root;
+            _preferInterpretation = preferInterpretation;
         }
 
         #endregion
@@ -2022,7 +2028,7 @@ public static FactoryDelegateExpr WrapInFactoryExpression(this Expr expression)
 
         /// <summary>First wraps the input service expression into lambda expression and
         /// then compiles lambda expression to actual <see cref="FactoryDelegate"/> used for service resolution.</summary>
-        public static FactoryDelegate CompileToFactoryDelegate(this Expr expression)
+        public static FactoryDelegate CompileToFactoryDelegate(this Expr expression, bool preferInterpretation = false)
         {
             expression = expression.NormalizeExpression();
 
@@ -2046,8 +2052,8 @@ public static FactoryDelegate CompileToFactoryDelegate(this Expr expression)
             return lambdaExpr.ToLambdaExpression().Compile();
 #else
             // Passing preferInterpretation: true as the default value of False uses JIT compile which has a huge impact on Functions cold start time
-            // This optimization is needed for Functions Host only and is not part of the DryIoc codebase which it was copied from.
-            return lambdaExpr.Compile(preferInterpretation: true);
+            // This optimization is needed for Functions Host only and is not part of the DryIoc codebase which it was copied from.            
+            return lambdaExpr.Compile(preferInterpretation: preferInterpretation);
 #endif
         }
 
@@ -6574,7 +6580,8 @@ reuse is SingletonReuse && request.Rules.EagerCachingSingletonForFasterAccess &&
                 !request.TracksTransientDisposable &&
                 !request.IsWrappedInFunc())
             {
-                var factoryDelegate = serviceExpr.CompileToFactoryDelegate();
+                var container = request.Container as Container;
+                var factoryDelegate = serviceExpr.CompileToFactoryDelegate(container != null ? container.PreferInterpretation : false);
                 var factory = factoryDelegate;
 
                 if (Setup.WeaklyReferenced)

src/WebJobs.Script.WebHost/DependencyInjection/JobHostServiceProvider.cs

@@ -60,7 +60,11 @@ private Container BuildContainer(IServiceCollection descriptors)
                     return new DelegateFactory(_ => _rootProvider.GetService(request.ServiceType));
                 });
 
-            var container = new Container(r => rules);
+            // preferInterpretation will be set to true to significanly improve cold start in consumption mode
+            // it will be set to false for premium and appservice plans to make sure throughput is not impacted
+            // there is no throughput drop in consumption with this setting.
+            var preferInterpretation = SystemEnvironment.Instance.IsDynamic() ? true : false;
+            var container = new Container(r => rules, preferInterpretation: preferInterpretation);
 
             container.Populate(descriptors);
             container.UseInstance<IServiceProvider>(this);

src/WebJobs.Script.WebHost/DependencyInjection/WebHostServiceProvider.cs

@@ -29,7 +29,11 @@ public WebHostServiceProvider(IServiceCollection descriptors)
                 throw new ArgumentNullException(nameof(descriptors));
             }
 
-            _container = new Container(_defaultContainerRules);
+            // preferInterpretation will be set to true to significanly improve cold start in consumption mode
+            // it will be set to false for premium and appservice plans to make sure throughput is not impacted
+            // there is no throughput drop in consumption with this setting.
+            var preferInterpretation = SystemEnvironment.Instance.IsDynamic() ? true : false;
+            _container = new Container(_defaultContainerRules, preferInterpretation: preferInterpretation);
             _container.Populate(descriptors);
             _container.UseInstance<IServiceProvider>(this);
             _container.UseInstance<IServiceScopeFactory>(this);