From e67bdd411ee6e6271085f522ca646106033bf2be Mon Sep 17 00:00:00 2001
From: Pranav K <prkrishn@hotmail.com>
Date: Sat, 11 Mar 2017 17:38:30 -0800
Subject: [PATCH] Add options to build a subgraph of repos

---
 build/repo.targets               | 10 +++++++---
 tools/BuildGraph/GraphBuilder.cs | 26 +++++++++++++++++++++++++-
 tools/BuildGraph/Program.cs      |  7 +++++--
 3 files changed, 37 insertions(+), 6 deletions(-)

diff --git a/build/repo.targets b/build/repo.targets
index 08b47f286e..0228877720 100644
--- a/build/repo.targets
+++ b/build/repo.targets
@@ -152,8 +152,12 @@
   </Target>
 
   <Target Name="_GenerateBuildGraph" DependsOnTargets="_FindDotNetPath">
+    <PropertyGroup>
+      <BuildGrapArgs>$(DotNetPath) run -r &quot;$(_CloneRepositoryRoot) &quot; --graph-specs-root &quot;$(_RestoreGraphSpecsDirectory) &quot; &quot;$(_BuildGraphFile)&quot;</BuildGrapArgs>
+      <BuildGrapArgs Condition="'$(BuildGraphOf)'!=''">$(BuildGrapArgs) --start-at $(BuildGraphOf)</BuildGrapArgs>
+    </PropertyGroup>
     <Exec
-      Command="$(DotNetPath) run -r &quot;$(_CloneRepositoryRoot) &quot; --graph-specs-root &quot;$(_RestoreGraphSpecsDirectory) &quot; &quot;$(_BuildGraphFile)&quot;"
+      Command="$(BuildGrapArgs)"
       WorkingDirectory="$(RepositoryRoot)tools\BuildGraph\" />
   </Target>
 
@@ -192,10 +196,10 @@
       <RepositoryCloneDirectory>$(_CloneRepositoryRoot)%(Repository.Identity)</RepositoryCloneDirectory>
     </PropertyGroup>
 
-    <Error Text="%(Repository.Identity) has not been cloned."
+    <Warning Text="%(Repository.Identity) has not been cloned."
       Condition="!Exists('$(RepositoryCloneDirectory)')" />
 
-    <GetGitCommitInfo WorkingDirectory="$(RepositoryCloneDirectory)">
+    <GetGitCommitInfo WorkingDirectory="$(RepositoryCloneDirectory)" Condition="Exists('$(RepositoryCloneDirectory)')">
       <Output TaskParameter="CommitHash" PropertyName="_Hash" />
     </GetGitCommitInfo>
 
diff --git a/tools/BuildGraph/GraphBuilder.cs b/tools/BuildGraph/GraphBuilder.cs
index 283a01e278..0cf9fc7f24 100644
--- a/tools/BuildGraph/GraphBuilder.cs
+++ b/tools/BuildGraph/GraphBuilder.cs
@@ -6,7 +6,7 @@ namespace BuildGraph
 {
     public static class GraphBuilder
     {
-        public static IList<GraphNode> Generate(IList<Repository> repositories)
+        public static IList<GraphNode> Generate(IList<Repository> repositories, string root)
         {
             // Build global list of primary projects
             var primaryProjects = repositories.SelectMany(c => c.Projects)
@@ -14,9 +14,15 @@ namespace BuildGraph
             var graphNodes = repositories.Select(r => new GraphNode { Repository = r })
                 .ToDictionary(r => r.Repository);
 
+            GraphNode searchRoot = null;
+
             foreach (var project in repositories.SelectMany(r => r.AllProjects))
             {
                 var thisProjectRepositoryNode = graphNodes[project.Repository];
+                if (root != null && string.Equals(root, project.Repository.Name, StringComparison.OrdinalIgnoreCase))
+                {
+                    searchRoot = thisProjectRepositoryNode;
+                }
 
                 foreach (var packageDependency in project.PackageReferences)
                 {
@@ -31,7 +37,25 @@ namespace BuildGraph
                 }
             }
 
+            var results = new HashSet<GraphNode>();
+            if (searchRoot != null)
+            {
+                Visit(results, searchRoot);
+                return results.ToList();
+            }
+
             return graphNodes.Values.ToList();
         }
+
+        private static void Visit(HashSet<GraphNode> results, GraphNode searchRoot)
+        {
+            if (results.Add(searchRoot))
+            {
+                foreach (var node in searchRoot.Outgoing)
+                {
+                    Visit(results, node);
+                }
+            }
+        }
     }
 }
\ No newline at end of file
diff --git a/tools/BuildGraph/Program.cs b/tools/BuildGraph/Program.cs
index 81d0a44de5..3271204a7c 100644
--- a/tools/BuildGraph/Program.cs
+++ b/tools/BuildGraph/Program.cs
@@ -23,6 +23,10 @@ namespace BuildGraph
                 "Directory containing package specs. (Optional)",
                 CommandOptionType.SingleValue);
 
+            var graphRoot = app.Option("--start-at",
+                "Calculate the build graph starting at the specified repo. (Optional)",
+                CommandOptionType.SingleValue);
+
             var outputPathArgument = app.Argument("Output path", "Output path");
 
             app.OnExecute(() =>
@@ -45,7 +49,6 @@ namespace BuildGraph
 
                 var outputType = outputTypeOption.Value() ?? "msbuild";
 
-
                 var graphSpecProvider = packageSpecsDirectoryOption.HasValue()
                     ? new DependencyGraphSpecProvider(packageSpecsDirectoryOption.Value().Trim())
                     : DependencyGraphSpecProvider.Default;
@@ -55,7 +58,7 @@ namespace BuildGraph
                     repositories = Repository.ReadAllRepositories(repositoriesRootOption.Value().Trim(), graphSpecProvider);
                 }
 
-                var graph = GraphBuilder.Generate(repositories);
+                var graph = GraphBuilder.Generate(repositories, graphRoot.Value());
                 GraphFormatter formatter;
                 switch (outputType)
                 {