Fix parallel builds

Also added unit test

10 files changed, 220 insertions, 5 deletions

diff --git a/main/src/core/MonoDevelop.Core/MonoDevelop.Projects.MSBuild/RemoteBuildEngineManager.cs b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects.MSBuild/RemoteBuildEngineManager.cs
index b024f9b48e..2c28218fa8 100644
--- a/main/src/core/MonoDevelop.Core/MonoDevelop.Projects.MSBuild/RemoteBuildEngineManager.cs
+++ b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects.MSBuild/RemoteBuildEngineManager.cs
@@ -172,21 +172,21 @@ namespace MonoDevelop.Projects.MSBuild
 
 			// Find builders which are not being shut down
 
-			var candiateBuilders = builders.GetBuilders (builderKey).Where (b => !b.IsShuttingDown);
+			var candiateBuilders = builders.GetBuilders (builderKey).Where (b => !b.IsShuttingDown && (!b.IsBusy || allowBusy));
 
 			if (buildSessionId != null) {
 
-				// Look for a builder that already started the session, no matter if the builder is busy or not.
+				// Look for a builder that already started the session.
 				// If there isn't one, pick builders which don't have any session assigned, so a new one
 				// can be started.
 
 				var sessionBuilders = candiateBuilders.Where (b => b.BuildSessionId == buildSessionId);
 				if (!sessionBuilders.Any ())
-					sessionBuilders = candiateBuilders.Where (b => b.BuildSessionId == null && (!b.IsBusy || allowBusy));
+					sessionBuilders = candiateBuilders.Where (b => b.BuildSessionId == null);
 				candiateBuilders = sessionBuilders;
 			} else
 				// Pick builders which are not bound to any session
-				candiateBuilders = candiateBuilders.Where (b => b.BuildSessionId == null && (!b.IsBusy || allowBusy));
+				candiateBuilders = candiateBuilders.Where (b => b.BuildSessionId == null);
 
 			// Prefer non-busy builders
 
diff --git a/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/Project.cs b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/Project.cs
index 0e8297e46f..f9ac9372f0 100644
--- a/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/Project.cs
+++ b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/Project.cs
@@ -1228,7 +1228,7 @@ namespace MonoDevelop.Projects
 				foreach (var err in result.Errors) {
 					FilePath file = null;
 					if (err.File != null)
-						file = Path.Combine (Path.GetDirectoryName (err.ProjectFile), err.File);
+						file = Path.Combine (Path.GetDirectoryName (err.ProjectFile ?? ItemDirectory.ToString ()), err.File);
 
 					br.Append (new BuildError (file, err.LineNumber, err.ColumnNumber, err.Code, err.Message) {
 						Subcategory = err.Subcategory,
diff --git a/main/tests/MonoDevelop.Core.Tests/MonoDevelop.Projects/BuilderManagerTests.cs b/main/tests/MonoDevelop.Core.Tests/MonoDevelop.Projects/BuilderManagerTests.cs
index f946e326a0..fdfdd35b2b 100644
--- a/main/tests/MonoDevelop.Core.Tests/MonoDevelop.Projects/BuilderManagerTests.cs
+++ b/main/tests/MonoDevelop.Core.Tests/MonoDevelop.Projects/BuilderManagerTests.cs
@@ -556,6 +556,53 @@ namespace MonoDevelop.Projects
 			}
 		}
 
+		[Test]
+		public async Task ParallelBuilds ()
+		{
+			// Check that the project system can start two builds in parallel.
+
+			await RemoteBuildEngineManager.RecycleAllBuilders ();
+			Assert.AreEqual (0, RemoteBuildEngineManager.ActiveEnginesCount);
+
+			var currentSetting = Runtime.Preferences.ParallelBuild.Value;
+			try {
+				Runtime.Preferences.ParallelBuild.Set (true);
+
+				FilePath solFile = Util.GetSampleProject ("builder-manager-tests", "builder-manager-tests.sln");
+				using (var sol = (Solution)await Services.ProjectService.ReadWorkspaceItem (Util.GetMonitor (), solFile)) {
+
+					// DepMain depends on both Dep1 and Dep2.
+
+					var demMain = sol.Items.FirstOrDefault (p => p.Name == "DepMain");
+					var dep1 = sol.Items.FirstOrDefault (p => p.Name == "Dep1");
+					var dep2 = sol.Items.FirstOrDefault (p => p.Name == "Dep2");
+
+					InitBuildSyncEvent (dep1);
+					InitBuildSyncEvent (dep2);
+
+					// Start the build
+					var build1 = demMain.Build (Util.GetMonitor (), sol.Configurations [0].Selector, true);
+
+					// Wait for sync signal from projects Dep1 and Dep2, which will mean that
+					// both projects started building in parallel
+
+					var syncAll = Task.WhenAll (WaitForBuildSyncEvent (dep1), WaitForBuildSyncEvent (dep2));
+					if (await Task.WhenAny (syncAll, Task.Delay (5000)) != syncAll)
+						Assert.Fail ("Not all builds were started");
+
+					// Finish the build
+					SignalBuildToContinue (dep1);
+					SignalBuildToContinue (dep2);
+
+					if (await Task.WhenAny (build1, Task.Delay (5000)) != build1)
+						Assert.Fail ("Build did not end in time");
+
+					Assert.AreEqual (0, build1.Result.ErrorCount);
+				}
+			} finally {
+				Runtime.Preferences.ParallelBuild.Set (currentSetting);
+			}
+		}
 		void InitBuildSyncEvent (SolutionItem p)
 		{
 			var file = p.FileName.ParentDirectory.Combine ("sync-event");
diff --git a/main/tests/test-projects/builder-manager-tests/Dep1/Dep1.csproj b/main/tests/test-projects/builder-manager-tests/Dep1/Dep1.csproj
new file mode 100644
index 0000000000..eeeeac2bfc
--- /dev/null
+++ b/main/tests/test-projects/builder-manager-tests/Dep1/Dep1.csproj
@@ -0,0 +1,37 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project DefaultTargets="Build" ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="..\SyncTask.targets" />
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
+    <ProjectGuid>{B515C1C3-9897-45FE-B350-037EECD0BDC7}</ProjectGuid>
+    <OutputType>Library</OutputType>
+    <RootNamespace>Dep1</RootNamespace>
+    <AssemblyName>Dep1</AssemblyName>
+    <TargetFrameworkVersion>v4.6.1</TargetFrameworkVersion>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
+    <DebugSymbols>true</DebugSymbols>
+    <DebugType>full</DebugType>
+    <Optimize>false</Optimize>
+    <OutputPath>bin\Debug</OutputPath>
+    <DefineConstants>DEBUG;</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+    <ConsolePause>false</ConsolePause>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
+    <Optimize>true</Optimize>
+    <OutputPath>bin\Release</OutputPath>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+    <ConsolePause>false</ConsolePause>
+  </PropertyGroup>
+  <ItemGroup>
+    <Reference Include="System" />
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="MyClass.cs" />
+  </ItemGroup>
+  <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
+</Project>
\ No newline at end of file
diff --git a/main/tests/test-projects/builder-manager-tests/Dep1/MyClass.cs b/main/tests/test-projects/builder-manager-tests/Dep1/MyClass.cs
new file mode 100644
index 0000000000..7513c54b2a
--- /dev/null
+++ b/main/tests/test-projects/builder-manager-tests/Dep1/MyClass.cs
@@ -0,0 +1,10 @@
+using System;
+namespace Dep1
+{
+    public class MyClass
+    {
+        public MyClass()
+        {
+        }
+    }
+}
diff --git a/main/tests/test-projects/builder-manager-tests/Dep2/Dep2.csproj b/main/tests/test-projects/builder-manager-tests/Dep2/Dep2.csproj
new file mode 100644
index 0000000000..3307066845
--- /dev/null
+++ b/main/tests/test-projects/builder-manager-tests/Dep2/Dep2.csproj
@@ -0,0 +1,37 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project DefaultTargets="Build" ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="..\SyncTask.targets" />
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
+    <ProjectGuid>{99329AC5-674A-4475-9431-43CAC8ED1CBF}</ProjectGuid>
+    <OutputType>Library</OutputType>
+    <RootNamespace>Dep2</RootNamespace>
+    <AssemblyName>Dep2</AssemblyName>
+    <TargetFrameworkVersion>v4.6.1</TargetFrameworkVersion>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
+    <DebugSymbols>true</DebugSymbols>
+    <DebugType>full</DebugType>
+    <Optimize>false</Optimize>
+    <OutputPath>bin\Debug</OutputPath>
+    <DefineConstants>DEBUG;</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+    <ConsolePause>false</ConsolePause>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
+    <Optimize>true</Optimize>
+    <OutputPath>bin\Release</OutputPath>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+    <ConsolePause>false</ConsolePause>
+  </PropertyGroup>
+  <ItemGroup>
+    <Reference Include="System" />
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="MyClass.cs" />
+  </ItemGroup>
+  <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
+</Project>
\ No newline at end of file
diff --git a/main/tests/test-projects/builder-manager-tests/Dep2/MyClass.cs b/main/tests/test-projects/builder-manager-tests/Dep2/MyClass.cs
new file mode 100644
index 0000000000..b93930601e
--- /dev/null
+++ b/main/tests/test-projects/builder-manager-tests/Dep2/MyClass.cs
@@ -0,0 +1,10 @@
+using System;
+namespace Dep2
+{
+    public class MyClass
+    {
+        public MyClass()
+        {
+        }
+    }
+}
diff --git a/main/tests/test-projects/builder-manager-tests/DepMain/DepMain.csproj b/main/tests/test-projects/builder-manager-tests/DepMain/DepMain.csproj
new file mode 100644
index 0000000000..318f73a010
--- /dev/null
+++ b/main/tests/test-projects/builder-manager-tests/DepMain/DepMain.csproj
@@ -0,0 +1,46 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project DefaultTargets="Build" ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
+    <ProjectGuid>{12D301E7-3AAC-4375-A6DB-E3755E9892E4}</ProjectGuid>
+    <OutputType>Library</OutputType>
+    <RootNamespace>DepMain</RootNamespace>
+    <AssemblyName>DepMain</AssemblyName>
+    <TargetFrameworkVersion>v4.6.1</TargetFrameworkVersion>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
+    <DebugSymbols>true</DebugSymbols>
+    <DebugType>full</DebugType>
+    <Optimize>false</Optimize>
+    <OutputPath>bin\Debug</OutputPath>
+    <DefineConstants>DEBUG;</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+    <ConsolePause>false</ConsolePause>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
+    <Optimize>true</Optimize>
+    <OutputPath>bin\Release</OutputPath>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+    <ConsolePause>false</ConsolePause>
+  </PropertyGroup>
+  <ItemGroup>
+    <Reference Include="System" />
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="MyClass.cs" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\Dep1\Dep1.csproj">
+      <Project>{B515C1C3-9897-45FE-B350-037EECD0BDC7}</Project>
+      <Name>Dep1</Name>
+    </ProjectReference>
+    <ProjectReference Include="..\Dep2\Dep2.csproj">
+      <Project>{99329AC5-674A-4475-9431-43CAC8ED1CBF}</Project>
+      <Name>Dep2</Name>
+    </ProjectReference>
+  </ItemGroup>
+  <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
+</Project>
\ No newline at end of file
diff --git a/main/tests/test-projects/builder-manager-tests/DepMain/MyClass.cs b/main/tests/test-projects/builder-manager-tests/DepMain/MyClass.cs
new file mode 100644
index 0000000000..f6cf0a7afd
--- /dev/null
+++ b/main/tests/test-projects/builder-manager-tests/DepMain/MyClass.cs
@@ -0,0 +1,10 @@
+using System;
+namespace DepMain
+{
+    public class MyClass
+    {
+        public MyClass()
+        {
+        }
+    }
+}
diff --git a/main/tests/test-projects/builder-manager-tests/builder-manager-tests.sln b/main/tests/test-projects/builder-manager-tests/builder-manager-tests.sln
index 5f576d53ea..c160279f4a 100644
--- a/main/tests/test-projects/builder-manager-tests/builder-manager-tests.sln
+++ b/main/tests/test-projects/builder-manager-tests/builder-manager-tests.sln
@@ -7,6 +7,12 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "SyncTask", "SyncTask\SyncTa
 EndProject

 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "SyncBuildProject", "TaskTest\SyncBuildProject.csproj", "{441F02A0-E0AC-4E7E-99D9-E6E516D0B35F}"

 EndProject

+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Dep1", "Dep1\Dep1.csproj", "{B515C1C3-9897-45FE-B350-037EECD0BDC7}"

+EndProject

+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Dep2", "Dep2\Dep2.csproj", "{99329AC5-674A-4475-9431-43CAC8ED1CBF}"

+EndProject

+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "DepMain", "DepMain\DepMain.csproj", "{12D301E7-3AAC-4375-A6DB-E3755E9892E4}"

+EndProject

 Global

 	GlobalSection(SolutionConfigurationPlatforms) = preSolution

 		Debug|x86 = Debug|x86

@@ -25,5 +31,17 @@ Global
 		{441F02A0-E0AC-4E7E-99D9-E6E516D0B35F}.Debug|x86.Build.0 = Debug|Any CPU

 		{441F02A0-E0AC-4E7E-99D9-E6E516D0B35F}.Release|x86.ActiveCfg = Release|Any CPU

 		{441F02A0-E0AC-4E7E-99D9-E6E516D0B35F}.Release|x86.Build.0 = Release|Any CPU

+		{B515C1C3-9897-45FE-B350-037EECD0BDC7}.Debug|x86.ActiveCfg = Debug|Any CPU

+		{B515C1C3-9897-45FE-B350-037EECD0BDC7}.Debug|x86.Build.0 = Debug|Any CPU

+		{B515C1C3-9897-45FE-B350-037EECD0BDC7}.Release|x86.ActiveCfg = Release|Any CPU

+		{B515C1C3-9897-45FE-B350-037EECD0BDC7}.Release|x86.Build.0 = Release|Any CPU

+		{99329AC5-674A-4475-9431-43CAC8ED1CBF}.Debug|x86.ActiveCfg = Debug|Any CPU

+		{99329AC5-674A-4475-9431-43CAC8ED1CBF}.Debug|x86.Build.0 = Debug|Any CPU

+		{99329AC5-674A-4475-9431-43CAC8ED1CBF}.Release|x86.ActiveCfg = Release|Any CPU

+		{99329AC5-674A-4475-9431-43CAC8ED1CBF}.Release|x86.Build.0 = Release|Any CPU

+		{12D301E7-3AAC-4375-A6DB-E3755E9892E4}.Debug|x86.ActiveCfg = Debug|Any CPU

+		{12D301E7-3AAC-4375-A6DB-E3755E9892E4}.Debug|x86.Build.0 = Debug|Any CPU

+		{12D301E7-3AAC-4375-A6DB-E3755E9892E4}.Release|x86.ActiveCfg = Release|Any CPU

+		{12D301E7-3AAC-4375-A6DB-E3755E9892E4}.Release|x86.Build.0 = Release|Any CPU

 	EndGlobalSection

 EndGlobal