perf: fix dictionary double-lookups, Collection.Contains, and LINQ allocations

src/Microsoft.TestPlatform.Common/Utilities/SimpleJSON.cs

@@ -856,16 +856,13 @@ public override JSONNode this[string aKey]
     {
         get
         {
-            return _dict.ContainsKey(aKey) ? _dict[aKey] : new JSONLazyCreator(this, aKey);
+            return _dict.TryGetValue(aKey, out var value) ? value : new JSONLazyCreator(this, aKey);
         }
         set
         {
             if (value == null)
                 value = JSONNull.CreateOrGet();
-            if (_dict.ContainsKey(aKey))
-                _dict[aKey] = value;
-            else
-                _dict.Add(aKey, value);
+            _dict[aKey] = value;
         }
     }
 
@@ -898,20 +895,16 @@ public override void Add(string aKey, JSONNode aItem)
 
         if (aKey != null)
         {
-            if (_dict.ContainsKey(aKey))
-                _dict[aKey] = aItem;
-            else
-                _dict.Add(aKey, aItem);
+            _dict[aKey] = aItem;
         }
         else
             _dict.Add(Guid.NewGuid().ToString(), aItem);
     }
 
     public override JSONNode Remove(string aKey)
     {
-        if (!_dict.ContainsKey(aKey))
+        if (!_dict.TryGetValue(aKey, out var tmp))
             return null;
-        JSONNode tmp = _dict[aKey];
         _dict.Remove(aKey);
         return tmp;
     }

src/Microsoft.TestPlatform.CrossPlatEngine/Client/Parallel/ParallelRunDataAggregator.cs

@@ -79,13 +79,14 @@ public ITestRunStatistics GetAggregatedRunStats()
             foreach (var runStats in _testRunStatsList)
             {
                 // TODO: we get nullref here if the stats are empty.
-                foreach (var outcome in runStats.Stats!.Keys)
+                foreach (var kvp in runStats.Stats!)
                 {
-                    if (!testOutcomeMap.ContainsKey(outcome))
+                    if (!testOutcomeMap.TryGetValue(kvp.Key, out long currentCount))
                     {
-                        testOutcomeMap.Add(outcome, 0);
+                        currentCount = 0;
                     }
-                    testOutcomeMap[outcome] += runStats.Stats[outcome];
+
+                    testOutcomeMap[kvp.Key] = currentCount + kvp.Value;
                 }
                 totalTests += runStats.ExecutedTests;
             }
@@ -198,9 +199,9 @@ public void AggregateRunDataMetrics(IDictionary<string, object>? metrics)
                 var newValue = Convert.ToDouble(metric.Value, CultureInfo.InvariantCulture);
 
                 _metricsAggregator.AddOrUpdate(
-                                    metric.Key,
-                                    newValue,
-                                    (_, oldValue) => newValue + Convert.ToDouble(oldValue, CultureInfo.InvariantCulture));
+                    metric.Key,
+                    newValue,
+                    (_, oldValue) => newValue + Convert.ToDouble(oldValue, CultureInfo.InvariantCulture));
             }
         }
     }

src/Microsoft.TestPlatform.CrossPlatEngine/DataCollection/InProcDataCollectionSink.cs

@@ -53,16 +53,12 @@ public IDictionary<string, string> GetDataCollectionDataSetForTestCase(Guid test
 
     private void AddKeyValuePairToDictionary(Guid testCaseId, string key, string value)
     {
-        if (!_testCaseDataCollectionDataMap.ContainsKey(testCaseId))
+        if (!_testCaseDataCollectionDataMap.TryGetValue(testCaseId, out var testCaseCollectionData))
         {
-            var testCaseCollectionData = new TestCaseDataCollectionData();
-            testCaseCollectionData.AddOrUpdateData(key, value);
+            testCaseCollectionData = new TestCaseDataCollectionData();
             _testCaseDataCollectionDataMap[testCaseId] = testCaseCollectionData;
         }
-        else
-        {
-            _testCaseDataCollectionDataMap[testCaseId].AddOrUpdateData(key, value);
-        }
+        testCaseCollectionData.AddOrUpdateData(key, value);
     }
 
     private class TestCaseDataCollectionData
@@ -76,15 +72,11 @@ public TestCaseDataCollectionData()
 
         internal void AddOrUpdateData(string key, string value)
         {
-            if (!CollectionData.ContainsKey(key))
-            {
-                CollectionData[key] = value;
-            }
-            else
+            if (CollectionData.ContainsKey(key))
             {
                 EqtTrace.Warning("The data for in-proc data collector with key {0} has already been set. Will be reset with new value", key);
-                CollectionData[key] = value;
             }
+            CollectionData[key] = value;
         }
     }
 }

src/Microsoft.TestPlatform.CrossPlatEngine/DataCollection/ParallelDataCollectionEventsHandler.cs

@@ -2,6 +2,8 @@
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Linq;
 using System.Threading;
 
 using Microsoft.VisualStudio.TestPlatform.CommunicationUtilities;
@@ -67,7 +69,7 @@ public override void HandleTestRunComplete(
             _runDataAggregator.IsAborted,
             _runDataAggregator.GetAggregatedException(),
             _runDataAggregator.RunContextAttachments,
-            _runDataAggregator.InvokedDataCollectors,
+            new Collection<InvokedDataCollector>(_runDataAggregator.InvokedDataCollectors.ToList()),
             _runDataAggregator.ElapsedTime);
 
         // Add Metrics from Test Host

src/Microsoft.TestPlatform.CrossPlatEngine/TestSession/ProxyTestSessionManager.cs

@@ -257,8 +257,8 @@ public virtual ProxyOperationManager DequeueProxy(string source, string? runSett
         lock (_proxyOperationLockObject)
         {
             // No proxy available means the caller will have to create its own proxy.
-            if (!_proxyMap.ContainsKey(source)
-                || !_proxyContainerList[_proxyMap[source]].IsAvailable)
+            if (!_proxyMap.TryGetValue(source, out int proxyIndex)
+                || !_proxyContainerList[proxyIndex].IsAvailable)
             {
                 throw new InvalidOperationException(CrossPlatResources.NoAvailableProxyForDeque);
             }
@@ -273,7 +273,7 @@ public virtual ProxyOperationManager DequeueProxy(string source, string? runSett
             }
 
             // Get the actual proxy.
-            proxyContainer = _proxyContainerList[_proxyMap[source]];
+            proxyContainer = _proxyContainerList[proxyIndex];
 
             // Mark the proxy as unavailable.
             proxyContainer.IsAvailable = false;

src/Microsoft.TestPlatform.CrossPlatEngine/TestSession/TestSessionPool.cs

@@ -101,13 +101,13 @@ public virtual bool KillSession(TestSessionInfo testSessionInfo, IRequestData re
         lock (_lockObject)
         {
             // Check if the session info exists.
-            if (!_sessionPool.ContainsKey(testSessionInfo))
+            if (!_sessionPool.TryGetValue(testSessionInfo, out var proxyManagerFromPool))
             {
                 return false;
             }
 
             // Remove the session from the pool.
-            proxyManager = _sessionPool[testSessionInfo];
+            proxyManager = proxyManagerFromPool;
             _sessionPool.Remove(testSessionInfo);
         }
 
@@ -136,13 +136,10 @@ public virtual bool KillSession(TestSessionInfo testSessionInfo, IRequestData re
         ProxyTestSessionManager? sessionManager;
         lock (_lockObject)
         {
-            if (!_sessionPool.ContainsKey(testSessionInfo))
+            if (!_sessionPool.TryGetValue(testSessionInfo, out sessionManager))
             {
                 return null;
             }
-
-            // Gets the session manager reference from the pool.
-            sessionManager = _sessionPool[testSessionInfo];
         }
 
         try
@@ -184,13 +181,10 @@ public virtual bool ReturnProxy(TestSessionInfo testSessionInfo, int proxyId)
         ProxyTestSessionManager? sessionManager;
         lock (_lockObject)
         {
-            if (!_sessionPool.ContainsKey(testSessionInfo))
+            if (!_sessionPool.TryGetValue(testSessionInfo, out sessionManager))
             {
                 return false;
             }
-
-            // Gets the session manager reference from the pool.
-            sessionManager = _sessionPool[testSessionInfo];
         }
 
         try

src/Microsoft.TestPlatform.ObjectModel/ConnectionInfo/TestRunnerConnectionInfoExtensions.cs

@@ -20,8 +20,7 @@ public static string ToCommandLineOptions(this TestRunnerConnectionInfo connecti
         var options = $"--port {connectionInfo.Port} --endpoint {connectionInfo.ConnectionInfo.Endpoint} --role {(connectionInfo.ConnectionInfo.Role == ConnectionRole.Client ? "client" : "host")} --parentprocessid {connectionInfo.RunnerProcessId}";
         if (!StringUtils.IsNullOrEmpty(connectionInfo.LogFile))
         {
-            options += " --diag " + connectionInfo.LogFile;
-            options += " --tracelevel " + connectionInfo.TraceLevel;
+            options = $"{options} --diag {connectionInfo.LogFile} --tracelevel {connectionInfo.TraceLevel}";
         }
 
         return options;

src/Microsoft.TestPlatform.ObjectModel/DataCollector/Events/SessionEvents.cs

@@ -75,7 +75,7 @@ public SessionStartEventArgs(DataCollectionContext context, IDictionary<string,
     {
         ValidateArg.NotNullOrEmpty(property, nameof(property));
 
-        return _properties.ContainsKey(property) ? (T?)_properties[property] : default;
+        return _properties.TryGetValue(property, out var propertyValue) ? (T?)propertyValue : default;
     }
 
     /// <summary>

src/Microsoft.TestPlatform.ObjectModel/DataCollector/InProcDataCollector/TestSessionStartArgs.cs

@@ -69,7 +69,7 @@ public TestSessionStartArgs(string configuration)
     {
         ValidateArg.NotNullOrEmpty(property, nameof(property));
         TPDebug.Assert(_properties is not null, "_properties is null");
-        return _properties.ContainsKey(property) ? (T?)_properties[property] : default;
+        return _properties.TryGetValue(property, out var propertyValue) ? (T?)propertyValue : default;
     }
 
     /// <summary>

src/Microsoft.TestPlatform.ObjectModel/Navigation/FullSymbolReader.cs

@@ -315,9 +315,9 @@ private void PopulateCacheForTypeAndMethodSymbols()
         try
         {
             typeName = typeName.Replace('+', '.');
-            if (_typeSymbols.ContainsKey(typeName))
+            if (_typeSymbols.TryGetValue(typeName, out var cachedSymbol))
             {
-                return _typeSymbols[typeName];
+                return cachedSymbol;
             }
 
             TPDebug.Assert(_session is not null, "_session is null");
@@ -384,12 +384,12 @@ private void PopulateCacheForTypeAndMethodSymbols()
         try
         {
             typeSymbol.GetName(out string symbolName);
-            if (_methodSymbols.ContainsKey(symbolName))
+            if (_methodSymbols.TryGetValue(symbolName, out var existingMethodSymbols))
             {
-                methodSymbolsForType = _methodSymbols[symbolName];
-                if (methodSymbolsForType.ContainsKey(methodName))
+                methodSymbolsForType = existingMethodSymbols;
+                if (methodSymbolsForType.TryGetValue(methodName, out var cachedMethodSymbol))
                 {
-                    return methodSymbolsForType[methodName];
+                    return cachedMethodSymbol;
                 }
             }
             else

src/Microsoft.TestPlatform.ObjectModel/Navigation/PortableSymbolReader.cs

@@ -65,17 +65,13 @@ public void Dispose()
     /// </returns>
     public INavigationData? GetNavigationData(string declaringTypeName, string methodName)
     {
-        INavigationData? navigationData = null;
-        if (_methodsNavigationDataForType.ContainsKey(declaringTypeName))
+        if (_methodsNavigationDataForType.TryGetValue(declaringTypeName, out var methodDict)
+            && methodDict.TryGetValue(methodName, out var navigationData))
         {
-            var methodDict = _methodsNavigationDataForType[declaringTypeName];
-            if (methodDict.ContainsKey(methodName))
-            {
-                navigationData = methodDict[methodName];
-            }
+            return navigationData;
         }
 
-        return navigationData;
+        return null;
     }
 
     /// <summary>

src/vstest.console/Processors/EnableBlameArgumentProcessor.cs

@@ -25,6 +25,12 @@
 
 namespace Microsoft.VisualStudio.TestPlatform.CommandLine.Processors;
 
+static file class BlameParameterNames
+{
+    public static HashSet<string> CrashDumpKeys { get; } = new HashSet<string>(StringComparer.OrdinalIgnoreCase) { "CollectAlways", "DumpType" };
+    public static HashSet<string> HangDumpKeys { get; } = new HashSet<string>(StringComparer.OrdinalIgnoreCase) { "TestTimeout", "HangDumpType" };
+}
+
 internal class EnableBlameArgumentProcessor : IArgumentProcessor
 {
     /// <summary>
@@ -208,7 +214,7 @@ private void InitializeBlame(bool enableCrashDump, bool enableHangDump, bool mon
         if (enableCrashDump)
         {
             var dumpParameters = collectDumpParameters
-                ?.Where(p => new[] { "CollectAlways", "DumpType" }.Contains(p.Key, StringComparer.OrdinalIgnoreCase))
+                ?.Where(p => BlameParameterNames.CrashDumpKeys.Contains(p.Key))
                 .ToDictionary(p => p.Key, p => p.Value, StringComparer.OrdinalIgnoreCase)
                 ?? new Dictionary<string, string>();
 
@@ -224,7 +230,7 @@ private void InitializeBlame(bool enableCrashDump, bool enableHangDump, bool mon
         if (enableHangDump)
         {
             var hangDumpParameters = collectDumpParameters
-                ?.Where(p => new[] { "TestTimeout", "HangDumpType" }.Contains(p.Key, StringComparer.OrdinalIgnoreCase))
+                ?.Where(p => BlameParameterNames.HangDumpKeys.Contains(p.Key))
                 .ToDictionary(p => p.Key, p => p.Value, StringComparer.OrdinalIgnoreCase)
                 ?? new Dictionary<string, string>();