From b79f34d4cc6fc288b8ca7360a5af14df121a8394 Mon Sep 17 00:00:00 2001
From: "Rune B. Broberg" <mihtjel@gmail.com>
Date: Sun, 16 Jul 2023 17:51:47 +0200
Subject: [PATCH] Fix for modifying an enumerated collection while traversing
 it.

---
 src/Docfx.Build.Engine/XRefMaps/XRefCollection.cs    | 9 +++++----
 src/Docfx.Build.Engine/XRefMaps/XRefMapDownloader.cs | 2 ++
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/Docfx.Build.Engine/XRefMaps/XRefCollection.cs b/src/Docfx.Build.Engine/XRefMaps/XRefCollection.cs
index fbe6e506f79..82cb5f8c549 100644
--- a/src/Docfx.Build.Engine/XRefMaps/XRefCollection.cs
+++ b/src/Docfx.Build.Engine/XRefMaps/XRefCollection.cs
@@ -45,13 +45,14 @@ public async Task<IXRefContainerReader> CreateAsync()
         {
             AddToDownloadList(_uris);
             var dict = new Dictionary<string, IXRefContainer>();
-            foreach (var item in _processing)
+            while (_processing.Any())
             {
-                var task = item.Key;
-                var uri = item.Value;
+                Task<IXRefContainer> task = await Task.WhenAny(_processing.Keys);
+                Uri uri = _processing[task];
+                _processing.Remove(task);
                 try
                 {
-                    var container = await task;
+                    IXRefContainer container = await task;
                     if (!container.IsEmbeddedRedirections)
                     {
                         AddToDownloadList(
diff --git a/src/Docfx.Build.Engine/XRefMaps/XRefMapDownloader.cs b/src/Docfx.Build.Engine/XRefMaps/XRefMapDownloader.cs
index c6c1524620e..24391f3edac 100644
--- a/src/Docfx.Build.Engine/XRefMaps/XRefMapDownloader.cs
+++ b/src/Docfx.Build.Engine/XRefMaps/XRefMapDownloader.cs
@@ -109,6 +109,7 @@ protected static IXRefContainer DownloadFromLocal(Uri uri)
 
     private static IXRefContainer ReadLocalFile(string filePath)
     {
+        Logger.LogVerbose($"Reading from file: {filePath}");
         if (".zip".Equals(Path.GetExtension(filePath), StringComparison.OrdinalIgnoreCase))
         {
             return XRefArchive.Open(filePath, XRefArchiveMode.Read);
@@ -120,6 +121,7 @@ private static IXRefContainer ReadLocalFile(string filePath)
 
     protected static async Task<XRefMap> DownloadFromWebAsync(Uri uri)
     {
+        Logger.LogVerbose($"Reading from web: {uri.OriginalString}");
         var baseUrl = uri.GetLeftPart(UriPartial.Path);
         baseUrl = baseUrl.Substring(0, baseUrl.LastIndexOf('/') + 1);