Update implementation to be TCS based

src/Microsoft.Tye.Hosting/Model/Application.cs

@@ -3,11 +3,12 @@
 // See the LICENSE file in the project root for more information.
 
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Globalization;
 using System.IO;
 using System.Linq;
-using System.Threading;
+using System.Threading.Tasks;
 
 namespace Microsoft.Tye.Hosting.Model
 {
@@ -18,18 +19,6 @@ namespace Microsoft.Tye.Hosting.Model
             Source = source.FullName;
             ContextDirectory = source.DirectoryName!;
             Services = services;
-
-            foreach (var s in Services.Values)
-            {
-                if (s.Description.RunInfo is ProjectRunInfo projectRunInfo)
-                {
-                    var projectFileName = projectRunInfo.ProjectFile.FullName;
-                    if (!ProjectFileLocks.ContainsKey(projectFileName))
-                    {
-                        ProjectFileLocks[projectFileName] = new SemaphoreSlim(1, 1);
-                    }
-                }
-            }
         }
 
         public string Source { get; }
@@ -38,7 +27,7 @@ namespace Microsoft.Tye.Hosting.Model
 
         public Dictionary<string, Service> Services { get; }
 
-        internal Dictionary<string, SemaphoreSlim> ProjectFileLocks { get; } = new Dictionary<string, SemaphoreSlim>();
+        internal ConcurrentDictionary<string, TaskCompletionSource<ProcessResult>> ProjectProcesses { get; } = new ConcurrentDictionary<string, TaskCompletionSource<ProcessResult>>();
 
         public Dictionary<object, object> Items { get; } = new Dictionary<object, object>();
 

src/Microsoft.Tye.Hosting/ProcessRunner.cs

@@ -361,22 +361,25 @@ namespace Microsoft.Tye.Hosting
                             {
                                 if (service.Description.RunInfo is ProjectRunInfo projectRunInfo)
                                 {
-                                    ProcessResult buildResult;
-
                                     var projectFile = projectRunInfo.ProjectFile.FullName;
-                                    var projectSemaphore = application.ProjectFileLocks[projectFile];
-                                    await projectSemaphore.WaitAsync();
-                                    try
-                                    {
-                                        _logger.LogDebug($"[{replica}] Building project {projectFile}:");
-                                        buildResult = await ProcessUtil.RunAsync("dotnet", $"build \"{service.Status.ProjectFilePath}\" /nologo", throwOnError: false, workingDirectory: application.ContextDirectory);
-                                    }
-                                    finally
+                                    var newProcess = new TaskCompletionSource<ProcessResult>();
+                                    var ongoingProcess = application.ProjectProcesses.GetOrAdd(projectFile, newProcess);
+
+                                    if (ongoingProcess != newProcess)
                                     {
-                                        _logger.LogDebug($"[{replica}] Finished Building project {projectFile}:");
-                                        projectSemaphore.Release();
+                                        return (await ongoingProcess.Task).ExitCode;
                                     }
 
+                                    _logger.LogDebug($"[{replica}] Building project {projectFile}:");
+                                    var buildResult = await ProcessUtil.RunAsync("dotnet", $"build \"{service.Status.ProjectFilePath}\" /nologo", throwOnError: false, workingDirectory: application.ContextDirectory);
+                                    _logger.LogDebug($"[{replica}] Finished Building project {projectFile}:");
+
+                                    ongoingProcess.SetResult(buildResult);
+
+                                    // Cannot remove a specific KVP until net5.0. Workaround is to cast to ICollection<KVP<>>
+                                    ICollection<KeyValuePair<string, TaskCompletionSource<ProcessResult>>> projectProcesses = application.ProjectProcesses;
+                                    projectProcesses.Remove(KeyValuePair.Create(projectFile, ongoingProcess));
+
                                     if (buildResult.ExitCode != 0)
                                     {
                                         _logger.LogInformation("Building projects failed with exit code {ExitCode}: \r\n" + buildResult.StandardOutput, buildResult.ExitCode);