Reduce memory use by reducing array allocations

src/Umbraco.Core/Composing/TypeFinder.cs

@@ -195,7 +195,7 @@ private static IEnumerable<Assembly> GetFilteredAssemblies(
             if (excludeFromResults == null)
                 excludeFromResults = new HashSet<Assembly>();
             if (exclusionFilter == null)
-                exclusionFilter = new string[] { };
+                exclusionFilter = Array.Empty<string>();
 
             return GetAllAssemblies()
                 .Where(x => excludeFromResults.Contains(x) == false

src/Umbraco.Core/Constants-StringArrays.cs

@@ -0,0 +1,21 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Umbraco.Core
+{
+    public static partial class Constants
+    {
+
+        public static class StringArrays
+        {
+
+            /// <summary>
+            /// String array containing "value"
+            /// </summary>
+            public static readonly string[] ValueLower = Constants.StringArrays.ValueLower;
+        }
+    }
+}

src/Umbraco.Core/Logging/Serilog/SerilogLogger.cs

@@ -184,8 +184,7 @@ private static void DumpThreadAborts(global::Serilog.ILogger logger, LogEventLev
                     messageTemplate += "\r\nFailed to create a minidump";
 
                     //Log a new entry (as opposed to appending to same log entry)
-                    logger.Write(level, ex, "Failed to create a minidump ({ExType}: {ExMessage})",
-                        new object[]{ ex.GetType().FullName, ex.Message });
+                    logger.Write(level, ex, "Failed to create a minidump ({ExType}: {ExMessage})", ex.GetType().FullName, ex.Message);
                 }
             }
         }

src/Umbraco.Core/Models/CultureImpact.cs

@@ -64,6 +64,12 @@ private CultureImpact(string culture, bool isDefault = false)
         /// </summary>
         public static CultureImpact Invariant { get; } = new CultureImpact(null);
 
+
+        /// <summary>
+        /// Gets the impact of the invariant culture as an array.
+        /// </summary>
+        public static CultureImpact[] InvariantArray { get; } = new[] { new CultureImpact(null) };
+
         /// <summary>
         /// Creates an impact instance representing the impact of a specific culture.
         /// </summary>

src/Umbraco.Core/Models/Membership/User.cs

@@ -24,8 +24,8 @@ public User()
             _language = Current.Configs.Global().DefaultUILanguage; // TODO: inject
             _isApproved = true;
             _isLockedOut = false;
-            _startContentIds = new int[] { };
-            _startMediaIds = new int[] { };
+            _startContentIds = Array.Empty<int>();
+            _startMediaIds = Array.Empty<int>();
             //cannot be null
             _rawPasswordValue = "";
         }
@@ -52,8 +52,8 @@ public User(string name, string email, string username, string rawPasswordValue)
             _userGroups = new HashSet<IReadOnlyUserGroup>();
             _isApproved = true;
             _isLockedOut = false;
-            _startContentIds = new int[] { };
-            _startMediaIds = new int[] { };
+            _startContentIds = Array.Empty<int>();
+            _startMediaIds = Array.Empty<int>();
         }
 
         /// <summary>

src/Umbraco.Core/Persistence/Repositories/Implement/TemplateRepository.cs

@@ -570,6 +570,9 @@ private void AddChildren(ITemplate[] all, List<ITemplate> descendants, string ma
             }
         }
 
+        private static readonly string[] _validTemplateDirs = new[] { SystemDirectories.MvcViews };
+        private static readonly IEnumerable<string> _validTemplateFileExtensions = new[] { "cshtml", "vbhtml" };
+
         /// <summary>
         /// Validates a <see cref="ITemplate"/>
         /// </summary>
@@ -582,17 +585,9 @@ public bool ValidateTemplate(ITemplate template)
             // are we using Path for something else?!
             var path = template.VirtualPath;
 
-            // get valid paths
-            var validDirs = new[] { SystemDirectories.MvcViews };
-
-            // get valid extensions
-            var validExts = new List<string>();
-            validExts.Add("cshtml");
-            validExts.Add("vbhtml");
-
             // validate path and extension
-            var validFile = IOHelper.VerifyEditPath(path, validDirs);
-            var validExtension = IOHelper.VerifyFileExtension(path, validExts);
+            var validFile = IOHelper.VerifyEditPath(path, _validTemplateDirs);
+            var validExtension = IOHelper.VerifyFileExtension(path, _validTemplateFileExtensions);
             return validFile && validExtension;
         }
 

src/Umbraco.Core/PropertyEditors/Validators/DecimalValidator.cs

@@ -19,7 +19,7 @@ public IEnumerable<ValidationResult> Validate(object value, string valueType, ob
 
             var result = value.TryConvertTo<decimal>();
             if (result.Success == false)
-                yield return new ValidationResult("The value " + value + " is not a valid decimal", new[] { "value" });
+                yield return new ValidationResult("The value " + value + " is not a valid decimal", Constants.StringArrays.ValueLower);
         }
     }
 }

src/Umbraco.Core/PropertyEditors/Validators/EmailValidator.cs

@@ -21,7 +21,7 @@ public IEnumerable<ValidationResult> Validate(object value, string valueType, ob
             if (asString != string.Empty && emailVal.IsValid(asString) == false)
             {
                 // TODO: localize these!
-                yield return new ValidationResult("Email is invalid", new[] { "value" });
+                yield return new ValidationResult("Email is invalid", Constants.StringArrays.ValueLower);
             }
         }
     }

src/Umbraco.Core/PropertyEditors/Validators/IntegerValidator.cs

@@ -19,7 +19,7 @@ public IEnumerable<ValidationResult> Validate(object value, string valueType, ob
                 var result = value.TryConvertTo<int>();
                 if (result.Success == false)
                 {
-                    yield return new ValidationResult("The value " + value + " is not a valid integer", new[] { "value" });
+                    yield return new ValidationResult("The value " + value + " is not a valid integer", Constants.StringArrays.ValueLower);
                 }
             }
         }

src/Umbraco.Core/PropertyEditors/Validators/RegexValidator.cs

@@ -72,7 +72,7 @@ public IEnumerable<ValidationResult> ValidateFormat(object value, string valueTy
             if (string.IsNullOrWhiteSpace(format)) throw new ArgumentException("Value can't be empty or consist only of white-space characters.", nameof(format));
             if (value == null || !new Regex(format).IsMatch(value.ToString()))
             {
-                yield return new ValidationResult(_textService.Localize("validation", "invalidPattern"), new[] { "value" });
+                yield return new ValidationResult(_textService.Localize("validation", "invalidPattern"), Constants.StringArrays.ValueLower);
             }
         }
     }

src/Umbraco.Core/PropertyEditors/Validators/RequiredValidator.cs

@@ -35,23 +35,23 @@ public IEnumerable<ValidationResult> ValidateRequired(object value, string value
         {
             if (value == null)
             {
-                yield return new ValidationResult(_textService.Localize("validation", "invalidNull"), new[] { "value" });
+                yield return new ValidationResult(_textService.Localize("validation", "invalidNull"), Constants.StringArrays.ValueLower);
                 yield break;
             }
 
             if (valueType.InvariantEquals(ValueTypes.Json))
             {
                 if (value.ToString().DetectIsEmptyJson())
                 {
-                    yield return new ValidationResult(_textService.Localize("validation", "invalidEmpty"), new[] { "value" });
+                    yield return new ValidationResult(_textService.Localize("validation", "invalidEmpty"), Constants.StringArrays.ValueLower);
                 }
 
                 yield break;
             }
 
             if (value.ToString().IsNullOrWhiteSpace())
             {
-                yield return new ValidationResult(_textService.Localize("validation", "invalidEmpty"), new[] { "value" });
+                yield return new ValidationResult(_textService.Localize("validation", "invalidEmpty"), Constants.StringArrays.ValueLower);
             }
         }
     }

src/Umbraco.Core/Services/ContentTypeServiceExtensions.cs

@@ -131,7 +131,7 @@ internal static ContentTypeAvailableCompositionsResults GetAvailableCompositeCon
 
         private static IContentTypeComposition[] GetAncestors(IContentTypeComposition ctype, IContentTypeComposition[] allContentTypes)
         {
-            if (ctype == null) return new IContentTypeComposition[] {};
+            if (ctype == null) return Array.Empty<IContentTypeComposition>();
             var ancestors = new List<IContentTypeComposition>();
             var parentId = ctype.ParentId;
             while (parentId > 0)

src/Umbraco.Core/Services/Implement/ContentService.cs

@@ -2647,7 +2647,7 @@ private PublishResult StrategyCanPublish(IScope scope, IContent content, bool ch
             var variesByCulture = content.ContentType.VariesByCulture();
 
             var impactsToPublish = culturesPublishing == null
-                ? new[] { CultureImpact.Invariant } //if it's null it's invariant
+                ? CultureImpact.InvariantArray  //if it's null it's invariant
                 : culturesPublishing.Select(x => CultureImpact.Explicit(x, allLangs.Any(lang => lang.IsoCode.InvariantEquals(x) && lang.IsMandatory))).ToArray();
 
             // publish the culture(s)

src/Umbraco.Core/Services/UserServiceExtensions.cs

@@ -57,7 +57,7 @@ public static EntityPermissionSet GetPermissionsForPath(this IUserService servic
         /// <param name="entityIds"></param>
         public static void RemoveUserGroupPermissions(this IUserService userService, int groupId, params int[] entityIds)
         {
-            userService.ReplaceUserGroupPermissions(groupId, new char[] {}, entityIds);
+            userService.ReplaceUserGroupPermissions(groupId, Array.Empty<char>(), entityIds);
         }
 
         /// <summary>

src/Umbraco.Core/Umbraco.Core.csproj

@@ -130,6 +130,7 @@
     <Compile Include="AssemblyExtensions.cs" />
     <Compile Include="Constants-CharArrays.cs" />
     <Compile Include="Constants-SqlTemplates.cs" />
+    <Compile Include="Constants-StringArrays.cs" />
     <Compile Include="Migrations\Upgrade\V_8_0_0\Models\ContentTypeDto80.cs" />
     <Compile Include="Migrations\Upgrade\V_8_0_0\Models\PropertyDataDto80.cs" />
     <Compile Include="Migrations\Upgrade\V_8_0_0\Models\PropertyTypeDto80.cs" />

src/Umbraco.Core/UriExtensions.cs

@@ -136,6 +136,7 @@ internal static bool IsDefaultBackOfficeRequest(this Uri url, IGlobalSettings gl
             return false;
         }
 
+        private static string[] toInclude = new[] { ".aspx", ".ashx", ".asmx", ".axd", ".svc" };
         /// <summary>
         /// This is a performance tweak to check if this not an ASP.Net server file
         /// .Net will pass these requests through to the module when in integrated mode.
@@ -149,7 +150,6 @@ internal static bool IsClientSideRequest(this Uri url)
             {
                 var ext = Path.GetExtension(url.LocalPath);
                 if (ext.IsNullOrWhiteSpace()) return false;
-                var toInclude = new[] {".aspx", ".ashx", ".asmx", ".axd", ".svc"};
                 return toInclude.Any(ext.InvariantEquals) == false;
             }
             catch (ArgumentException)

src/Umbraco.Core/Xml/XPath/MacroNavigator.cs

@@ -175,7 +175,7 @@ private class MacroRoot
         {
             public MacroRoot(IEnumerable<MacroParameter> parameters)
             {
-                Parameters = parameters == null ? new MacroParameter[] {} : parameters.ToArray();
+                Parameters = parameters == null ? Array.Empty<MacroParameter>() : parameters.ToArray();
             }
 
             public MacroParameter[] Parameters { get; private set; }

src/Umbraco.Web/Editors/BackOfficeServerVariables.cs

@@ -62,7 +62,7 @@ internal Dictionary<string, object> BareMinimumServerVariables()
                 {"umbracoUrls", new[] {"authenticationApiBaseUrl", "serverVarsJs", "externalLoginsUrl", "currentUserApiBaseUrl", "iconApiBaseUrl"}},
                 {"umbracoSettings", new[] {"allowPasswordReset", "imageFileTypes", "maxFileSize", "loginBackgroundImage", "canSendRequiredEmail", "usernameIsEmail"}},
                 {"application", new[] {"applicationPath", "cacheBuster"}},
-                {"isDebuggingEnabled", new string[] { }},
+                {"isDebuggingEnabled", Array.Empty<string>()},
                 {"features", new [] {"disabledFeatures"}}
             };
             //now do the filtering...

src/Umbraco.Web/Mvc/RenderViewEngine.cs

@@ -66,14 +66,14 @@ public override ViewEngineResult FindView(ControllerContext controllerContext, s
         {
             return ShouldFindView(controllerContext, false)
                 ? base.FindView(controllerContext, viewName, masterName, useCache)
-                : new ViewEngineResult(new string[] { });
+                : new ViewEngineResult(Array.Empty<string>());
         }
 
         public override ViewEngineResult FindPartialView(ControllerContext controllerContext, string partialViewName, bool useCache)
         {
             return ShouldFindView(controllerContext, true)
                 ? base.FindPartialView(controllerContext, partialViewName, useCache)
-                : new ViewEngineResult(new string[] { });
+                : new ViewEngineResult(Array.Empty<string>());
         }
 
         /// <summary>

src/Umbraco.Web/PropertyEditors/DateTimeConfigurationEditor.cs

@@ -9,13 +9,14 @@ namespace Umbraco.Web.PropertyEditors
     /// </summary>
     public class DateTimeConfigurationEditor : ConfigurationEditor<DateTimeConfiguration>
     {
+        private static readonly string[] _timeChars = new string[] { "H", "m", "s" };
         public override IDictionary<string, object> ToValueEditor(object configuration)
         {
             var d = base.ToValueEditor(configuration);
 
             var format = d["format"].ToString();
 
-            d["pickTime"] = format.ContainsAny(new string[] { "H", "m", "s" });
+            d["pickTime"] = format.ContainsAny(_timeChars);
 
             return d;
         }