From e2b12060f38dc39972bf018fe3ea1f428a449422 Mon Sep 17 00:00:00 2001
From: Javier Calvarro Nelson <jacalvar@microsoft.com>
Date: Thu, 26 Sep 2024 13:05:36 +0200
Subject: [PATCH] [StaticWebAssets] Avoid reading manifest for hash

---
 .../Targets/Microsoft.NET.Sdk.StaticWebAssets.targets  |  5 ++++-
 .../Tasks/GenerateStaticWebAssetsManifest.cs           | 10 +++++++++-
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/StaticWebAssetsSdk/Targets/Microsoft.NET.Sdk.StaticWebAssets.targets b/src/StaticWebAssetsSdk/Targets/Microsoft.NET.Sdk.StaticWebAssets.targets
index 436cdac4cb77..717c203aa732 100644
--- a/src/StaticWebAssetsSdk/Targets/Microsoft.NET.Sdk.StaticWebAssets.targets
+++ b/src/StaticWebAssetsSdk/Targets/Microsoft.NET.Sdk.StaticWebAssets.targets
@@ -437,6 +437,7 @@ Copyright (c) .NET Foundation. All rights reserved.
       <!-- Manifest paths -->
       <_StaticWebAssetsManifestBase Condition="'$(_StaticWebAssetsManifestBase)' == ''">$(IntermediateOutputPath)</_StaticWebAssetsManifestBase>
       <StaticWebAssetBuildManifestPath>$(_StaticWebAssetsManifestBase)staticwebassets.build.json</StaticWebAssetBuildManifestPath>
+      <StaticWebAssetsBuildManifestCacheFilePath>$(StaticWebAssetBuildManifestPath).cache</StaticWebAssetsBuildManifestCacheFilePath>
       <StaticWebAssetPackManifestPath>$(_StaticWebAssetsManifestBase)staticwebassets.pack.json</StaticWebAssetPackManifestPath>
       <StaticWebAssetDevelopmentManifestPath>$(_StaticWebAssetsManifestBase)staticwebassets.development.json</StaticWebAssetDevelopmentManifestPath>
       <StaticWebAssetEndpointsBuildManifestPath>$(_StaticWebAssetsManifestBase)staticwebassets.build.endpoints.json</StaticWebAssetEndpointsBuildManifestPath>
@@ -620,7 +621,8 @@ Copyright (c) .NET Foundation. All rights reserved.
       DiscoveryPatterns="@(StaticWebAssetDiscoveryPattern)"
       Assets="@(StaticWebAsset)"
       Endpoints="@(StaticWebAssetEndpoint)"
-      ManifestPath="$(StaticWebAssetBuildManifestPath)">
+      ManifestPath="$(StaticWebAssetBuildManifestPath)"
+      ManifestCacheFilePath="$(StaticWebAssetsBuildManifestCacheFilePath)">
     </GenerateStaticWebAssetsManifest>
 
     <GenerateStaticWebAssetEndpointsManifest
@@ -649,6 +651,7 @@ Copyright (c) .NET Foundation. All rights reserved.
 
     <ItemGroup>
       <FileWrites Include="$(StaticWebAssetBuildManifestPath)" />
+      <FileWrites Include="$(StaticWebAssetsBuildManifestCacheFilePath)" />
       <FileWrites Include="$(StaticWebAssetDevelopmentManifestPath)" />
       <FileWrites Include="$(StaticWebAssetEndpointsBuildManifestPath)" />
     </ItemGroup>
diff --git a/src/StaticWebAssetsSdk/Tasks/GenerateStaticWebAssetsManifest.cs b/src/StaticWebAssetsSdk/Tasks/GenerateStaticWebAssetsManifest.cs
index c7117defc054..a4b9efd39e8f 100644
--- a/src/StaticWebAssetsSdk/Tasks/GenerateStaticWebAssetsManifest.cs
+++ b/src/StaticWebAssetsSdk/Tasks/GenerateStaticWebAssetsManifest.cs
@@ -36,6 +36,9 @@ public class GenerateStaticWebAssetsManifest : Task
         [Required]
         public string ManifestPath { get; set; }
 
+        [Required]
+        public string ManifestCacheFilePath { get; set; }
+
         public override bool Execute()
         {
             try
@@ -117,18 +120,23 @@ private IEnumerable<StaticWebAssetEndpoint> FilterPublishEndpointsIfNeeded(IEnum
         private void PersistManifest(StaticWebAssetsManifest manifest)
         {
             var data = JsonSerializer.SerializeToUtf8Bytes(manifest, StaticWebAssetsJsonSerializerContext.RelaxedEscaping.StaticWebAssetsManifest);
+            var cacheFileExists = File.Exists(ManifestCacheFilePath);
             var fileExists = File.Exists(ManifestPath);
-            var existingManifestHash = fileExists ? StaticWebAssetsManifest.FromJsonBytes(File.ReadAllBytes(ManifestPath)).Hash : "";
+            var existingManifestHash = cacheFileExists ?
+                File.ReadAllText(ManifestCacheFilePath) :
+                fileExists ? StaticWebAssetsManifest.FromJsonBytes(File.ReadAllBytes(ManifestPath)).Hash : "";
 
             if (!fileExists)
             {
                 Log.LogMessage(MessageImportance.Low, $"Creating manifest because manifest file '{ManifestPath}' does not exist.");
                 File.WriteAllBytes(ManifestPath, data);
+                File.WriteAllText(ManifestCacheFilePath, manifest.Hash);
             }
             else if (!string.Equals(manifest.Hash, existingManifestHash, StringComparison.Ordinal))
             {
                 Log.LogMessage(MessageImportance.Low, $"Updating manifest because manifest version '{manifest.Hash}' is different from existing manifest hash '{existingManifestHash}'.");
                 File.WriteAllBytes(ManifestPath, data);
+                File.WriteAllText(ManifestCacheFilePath, manifest.Hash);
             }
             else
             {