Exclude isolation-violating cache results from output results cache (#4386)

src/Build.UnitTests/BackEnd/CacheSerialization_Tests.cs

@@ -0,0 +1,79 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System.Collections.Generic;
+using System.IO;
+using Microsoft.Build.BackEnd;
+using Microsoft.Build.Execution;
+using Microsoft.Build.Framework;
+using Microsoft.Build.Internal;
+using Microsoft.Build.Shared;
+using Xunit;
+
+#nullable disable
+
+namespace Microsoft.Build.UnitTests.BackEnd
+{
+    public class CacheSerialization_Tests
+    {
+        public static IEnumerable<object[]> CacheData
+        {
+            get
+            {
+                var configCache = new ConfigCache();
+                var brq1 = new BuildRequestConfiguration(
+                   1,
+                   new BuildRequestData("path1", new Dictionary<string, string> { ["a1"] = "b1" }, Constants.defaultToolsVersion, new[] { "target1" }, null),
+                   Constants.defaultToolsVersion);
+
+                var brq2 = new BuildRequestConfiguration(
+                    2,
+                    new BuildRequestData("path2", new Dictionary<string, string> { ["a2"] = "b2" }, Constants.defaultToolsVersion, new[] { "target2" }, null),
+                    Constants.defaultToolsVersion);
+                var brq3 = new BuildRequestConfiguration(
+                   3,
+                   new BuildRequestData("path3", new Dictionary<string, string> { ["a3"] = "b3" }, Constants.defaultToolsVersion, new[] { "target3" }, null),
+                   Constants.defaultToolsVersion);
+
+                configCache.AddConfiguration(brq1);
+                configCache.AddConfiguration(brq2);
+                configCache.AddConfiguration(brq3);
+
+                var resultsCache = new ResultsCache();
+                var request1 = new BuildRequest(1, 0, 1, new string[] { "target1" }, null, BuildEventContext.Invalid, null);
+                var request2 = new BuildRequest(2, 0, 2, new string[] { "target2" }, null, BuildEventContext.Invalid, null);
+                var request3 = new BuildRequest(3, 0, 3, new string[] { "target3" }, null, BuildEventContext.Invalid, null);
+
+                resultsCache.AddResult(new BuildResult(request1));
+                resultsCache.AddResult(new BuildResult(request2));
+                resultsCache.AddResult(new BuildResult(request3));
+
+                return new List<object[]>
+                {
+                    new object[] { configCache, resultsCache },
+                };
+            }
+        }
+
+        [Theory]
+        [MemberData(nameof(CacheData))]
+        public void OnlySerializeCacheEntryWithSmallestConfigId(object configCache, object resultsCache)
+        {
+            string cacheFile = null;
+            try
+            {
+                cacheFile = FileUtilities.GetTemporaryFile("MSBuildResultsCache");
+                Assert.Null(CacheSerialization.SerializeCaches((ConfigCache)configCache, (ResultsCache)resultsCache, cacheFile));
+
+                var result = CacheSerialization.DeserializeCaches(cacheFile);
+                Assert.True(result.ConfigCache.HasConfiguration(1));
+                Assert.False(result.ConfigCache.HasConfiguration(2));
+                Assert.False(result.ConfigCache.HasConfiguration(3));
+            }
+            finally
+            {
+                File.Delete(cacheFile);
+            }
+        }
+    }
+}

src/Build.UnitTests/BackEnd/ConfigCache_Tests.cs

@@ -5,6 +5,7 @@
 using System.Linq;
 using Microsoft.Build.BackEnd;
 using Microsoft.Build.Execution;
+using Microsoft.Build.Framework;
 using Microsoft.Build.Internal;
 using Shouldly;
 using Xunit;
@@ -55,6 +56,38 @@ public static IEnumerable<object[]> CacheSerializationTestData
             }
         }
 
+        public static IEnumerable<object[]> CacheSerializationTestDataNoConfigs
+        {
+            get
+            {
+                yield return new[] { new ConfigCache() };
+            }
+        }
+
+        public static IEnumerable<object[]> CacheSerializationTestDataMultipleConfigs
+        {
+            get
+            {
+                var configCache = new ConfigCache();
+                var brq1 = new BuildRequestConfiguration(
+                  1,
+                  new BuildRequestData("path1", new Dictionary<string, string> { ["a1"] = "b1" }, Constants.defaultToolsVersion, new[] { "target1" }, null),
+                  Constants.defaultToolsVersion);
+                var brq2 = new BuildRequestConfiguration(
+                  2,
+                  new BuildRequestData("path2", new Dictionary<string, string> { ["a2"] = "b2" }, Constants.defaultToolsVersion, new[] { "target2" }, null),
+                  Constants.defaultToolsVersion);
+                var brq3 = new BuildRequestConfiguration(
+                  3,
+                  new BuildRequestData("path3", new Dictionary<string, string> { ["a3"] = "b3" }, Constants.defaultToolsVersion, new[] { "target3" }, null),
+                  Constants.defaultToolsVersion);
+                configCache.AddConfiguration(brq1.ShallowCloneWithNewId(1));
+                configCache.AddConfiguration(brq2.ShallowCloneWithNewId(2));
+                configCache.AddConfiguration(brq3.ShallowCloneWithNewId(3));
+                yield return new[] { configCache };
+            }
+        }
+
         [Theory]
         [MemberData(nameof(CacheSerializationTestData))]
         public void ConfigCacheShouldBeTranslatable(object obj)
@@ -84,5 +117,19 @@ public void ConfigCacheShouldBeTranslatable(object obj)
                 copy[initialConfiguration.ConfigurationId].ProjectInitialTargets.ShouldBe(initialConfiguration.ProjectInitialTargets);
             }
         }
+
+        [Theory]
+        [MemberData(nameof(CacheSerializationTestDataNoConfigs))]
+        public void GetSmallestConfigIdThrows(object obj)
+        {
+            Assert.Throws<InternalErrorException>(() => ((ConfigCache)obj).GetSmallestConfigId());
+        }
+
+        [Theory]
+        [MemberData(nameof(CacheSerializationTestDataMultipleConfigs))]
+        public void HappyGetSmallestConfigId(object obj)
+        {
+            Assert.Equal(1, ((ConfigCache)obj).GetSmallestConfigId());
+        }
     }
 }

src/Build/BackEnd/BuildManager/CacheSerialization.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.IO;
+using System.Linq;
 using Microsoft.Build.BackEnd;
 using Microsoft.Build.Shared;
 
@@ -61,6 +62,27 @@ public static string SerializeCaches(IConfigCache configCache, IResultsCache res
                             break;
                     }
 
+                    // Avoid creating new config and results caches if no projects were built in violation
+                    // of isolation mode.
+                    if (configCacheToSerialize.Count() > 1)
+                    {
+                        // We need to preserve all configurations to enable the scheduler to dump them and their
+                        // associated requests, so create new caches to serialize storing solely data
+                        // associated with the project specified to be built in isolation (and not any
+                        // data associated with referenced projects needed for said project to complete
+                        // its build).
+                        var tempConfigCacheToSerialize = new ConfigCache();
+
+                        // The project that was built in isolation mode has the
+                        // smallest configuration id.
+                        int smallestCacheConfigId = configCacheToSerialize.GetSmallestConfigId();
+                        tempConfigCacheToSerialize.AddConfiguration(configCacheToSerialize[smallestCacheConfigId]);
+                        configCacheToSerialize = tempConfigCacheToSerialize;
+                        var tempResultsCacheToSerialize = new ResultsCache();
+                        tempResultsCacheToSerialize.AddResult(resultsCacheToSerialize.GetResultsForConfiguration(smallestCacheConfigId));
+                        resultsCacheToSerialize = tempResultsCacheToSerialize;
+                    }
+
                     translator.Translate(ref configCacheToSerialize);
                     translator.Translate(ref resultsCacheToSerialize);
                 }

src/Build/BackEnd/Components/Caching/ConfigCache.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using Microsoft.Build.Shared;
 
 #nullable disable
@@ -200,6 +201,21 @@ public void ClearConfigurations()
             }
         }
 
+        /// <summary>
+        /// Gets the smallest configuration id of any configuration
+        /// in this cache.
+        /// </summary>
+        /// <returns>Gets the smallest configuration id of any
+        /// configuration in this cache.</returns>
+        public int GetSmallestConfigId()
+        {
+            lock (_lockObject)
+            {
+                ErrorUtilities.VerifyThrow(_configurations.Count > 0, "No configurations exist from which to obtain the smallest configuration id.");
+                return _configurations.OrderBy(kvp => kvp.Key).First().Key;
+            }
+        }
+
         /// <summary>
         /// Clears configurations from the configuration cache which have not been explicitly loaded.
         /// </summary>