From 99facf88ad11f3c0e9940ee610b4cb93484302e7 Mon Sep 17 00:00:00 2001
From: MLopez <Mario.lopez@adssistemas.mx>
Date: Wed, 1 Feb 2023 19:41:29 -0700
Subject: [PATCH] ClsPaginas: Usar ThreadSafeRandom() en vez de Random()
 -RAZONAMIENTO:  Random() no es thread safe, esto puede ocasionar problemas
 cuando dos hilos intenten acceder a la  instancia de Random() y que termine
 generando puros ceros.

 En .NET Core 6.0 se introduce Random.Shared para compartir una instancia de Random() entre hilos distintos.
 https://learn.microsoft.com/en-us/dotnet/api/system.random.shared?view=net-7.0

 Para .NET 4.8, se implementa la clase ThreadSafeRandom() que cumple la misma funcionalidad.
 Basado en https://stackoverflow.com/a/57962385/3529902
---
 App_Code/ClsPaginas.vb       |  4 +---
 App_Code/ThreadSafeRandom.vb | 15 +++++++++++++++
 2 files changed, 16 insertions(+), 3 deletions(-)
 create mode 100644 App_Code/ThreadSafeRandom.vb

diff --git a/App_Code/ClsPaginas.vb b/App_Code/ClsPaginas.vb
index 71f9a5e21..7aa2895e1 100644
--- a/App_Code/ClsPaginas.vb
+++ b/App_Code/ClsPaginas.vb
@@ -12,7 +12,6 @@ Imports Microsoft.Reporting.WebForms
 Imports Newtonsoft.Json
 Imports Newtonsoft.Json.Linq
 
-
 'NOTA AD TEAM
 'COLOR PARA ROW TOTAL EN REPORT VIEWER: #67809F (AZULITO)
 
@@ -46,8 +45,7 @@ Public Class ClsPaginas
     End Property
 
 #Region "Propiedades"
-    Private Shared ReadOnly Property Rand As New Random()
-
+    Private Shared ReadOnly Property Rand As New ThreadSafeRandom()
     Private Property SubReportData As Modelos.MSubReportData
         Get
             Return If(IsNothing(ViewState("SubReportData")), Nothing, DirectCast(ViewState("SubReportData"), Modelos.MSubReportData))
diff --git a/App_Code/ThreadSafeRandom.vb b/App_Code/ThreadSafeRandom.vb
new file mode 100644
index 000000000..825913ccb
--- /dev/null
+++ b/App_Code/ThreadSafeRandom.vb
@@ -0,0 +1,15 @@
+Imports System.Threading
+
+NotInheritable Class ThreadSafeRandom
+    Private Shared ReadOnly GlobalRandom As New Random()
+    Private Shared ReadOnly LocalRandom As New ThreadLocal(Of Random)(Function()
+
+                                                                          SyncLock GlobalRandom
+                                                                              Return New Random(GlobalRandom.Next())
+                                                                          End SyncLock
+                                                                      End Function)
+
+    Function [Next](Optional min As Integer = 0, Optional max As Integer = Integer.MaxValue) As Integer
+        Return LocalRandom.Value.Next(min, max)
+    End Function
+End Class
\ No newline at end of file