Replace null comparisons with pattern matching

benchmark/StoragesBenchmark/OrchestrationBenchmark.cs

@@ -80,7 +80,7 @@ public async Task RunOrchestrations()
         foreach (var instance in instances)
         {
             var state = await taskHubClient.WaitForOrchestrationAsync(instance, TimeSpan.FromMinutes(30));
-            if (state == null || state.OrchestrationStatus != OrchestrationStatus.Completed)
+            if (state is null || state.OrchestrationStatus != OrchestrationStatus.Completed)
                 throw new Exception("Orchestration did not complete");
         }
     }

samples/BpmnWorker/Activities/HttpRequestActivity.cs

@@ -1,9 +1,4 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Net.Http;
-using System.Text;
-using System.Threading.Tasks;
+using System.Text;
 using LLL.DurableTask.Worker;
 using LLL.DurableTask.Worker.Attributes;
 using Newtonsoft.Json;
@@ -21,15 +16,15 @@ public override async Task<Output> ExecuteAsync(Input input)
             Method = input.Method
         };
 
-        if (input.Headers != null)
+        if (input.Headers is not null)
         {
             foreach (var header in input.Headers)
             {
                 httpRequest.Headers.Add(header.Key, header.Value);
             }
         }
 
-        if (input.Content != null)
+        if (input.Content is not null)
         {
             var json = JsonConvert.SerializeObject(input.Content);
             httpRequest.Content = new StringContent(json, Encoding.UTF8, "application/json");
@@ -41,7 +36,7 @@ public override async Task<Output> ExecuteAsync(Input input)
         string contentRaw = null;
         object content = null;
 
-        if (httpResponse.Content != null)
+        if (httpResponse.Content is not null)
         {
             contentRaw = await httpResponse.Content.ReadAsStringAsync();
 

samples/BpmnWorker/Orchestrations/BPMNOrchestrator.cs

@@ -1,18 +1,11 @@
-using System;
-using System.Collections.Concurrent;
-using System.Collections.Generic;
-using System.IO;
-using System.Linq;
+using System.Collections.Concurrent;
 using System.Text.RegularExpressions;
-using System.Threading;
-using System.Threading.Tasks;
 using System.Xml;
 using System.Xml.Serialization;
 using BpmnWorker.Activities;
 using BpmnWorker.Providers;
 using LLL.DurableTask.Worker;
 using LLL.DurableTask.Worker.Attributes;
-using Microsoft.Extensions.Logging;
 using Newtonsoft.Json.Linq;
 using Spec.BPMN.MODEL;
 
@@ -218,14 +211,14 @@ private async Task VisitServiceTask(TServiceTask serviceTask)
     private async Task<JObject> PrepareInput(XmlElement element)
     {
         var input = default(JObject);
-        if (element != null)
+        if (element is not null)
         {
             input = new JObject();
             foreach (var inputParameter in element.ChildNodes.OfType<XmlElement>().Where(x => x.LocalName == "inputParameter"))
             {
                 var name = inputParameter.GetAttribute("name");
                 var script = inputParameter.ChildNodes.OfType<XmlElement>().FirstOrDefault(x => x.LocalName == "script");
-                if (script != null)
+                if (script is not null)
                 {
                     var scriptFormat = script.GetAttribute("scriptFormat");
                     var scriptContent = script.InnerText;
@@ -247,14 +240,14 @@ private async Task<JObject> PrepareInput(XmlElement element)
 
     private async Task ProcessOutput(XmlElement element, JToken output)
     {
-        if (element == null)
+        if (element is null)
             return;
 
         foreach (var outputParameter in element.ChildNodes.OfType<XmlElement>().Where(x => x.LocalName == "outputParameter"))
         {
             var name = outputParameter.GetAttribute("name");
             var script = outputParameter.ChildNodes.OfType<XmlElement>().FirstOrDefault(x => x.LocalName == "script");
-            if (script != null)
+            if (script is not null)
             {
                 var scriptFormat = script.GetAttribute("scriptFormat");
                 var scriptContent = script.InnerText;
@@ -286,7 +279,7 @@ private async Task VisitScriptTask(TScriptTask scriptTask)
         var output = await Context.ScheduleTask<JToken>("Script", string.Empty, input);
 
         var resultVariable = scriptTask.AnyAttribute.FirstOrDefault(a => a.LocalName == "resultVariable")?.Value;
-        if (resultVariable != null)
+        if (resultVariable is not null)
         {
             _variables[resultVariable] = output;
         }
@@ -357,7 +350,7 @@ private async Task VisitIntermediateCatchTimerEvent(
         TIntermediateCatchEvent intermediateCatchEvent,
         TTimerEventDefinition timerEventDefinition)
     {
-        if (timerEventDefinition.TimeDate != null)
+        if (timerEventDefinition.TimeDate is not null)
         {
             var fireAt = XmlConvert.ToDateTime(timerEventDefinition.TimeDate.Text.First(), XmlDateTimeSerializationMode.Local);
             _logger.LogWarning("Waiting for timer {fireAt}", fireAt);
@@ -366,7 +359,7 @@ private async Task VisitIntermediateCatchTimerEvent(
 
             await VisitFlowNodes(GetParallelOutgoingNodes(intermediateCatchEvent));
         }
-        else if (timerEventDefinition.TimeDuration != null)
+        else if (timerEventDefinition.TimeDuration is not null)
         {
             var duration = XmlConvert.ToTimeSpan(timerEventDefinition.TimeDuration.Text.First());
             var fireAt = Context.CurrentUtcDateTime.Add(duration);
@@ -385,16 +378,16 @@ private async Task VisitIntermediateCatchTimerEvent(
     private TFlowNode GetExclusiveOutgoingNode(TFlowNode flowNode)
     {
         var sequence = FindByIds<TSequenceFlow>(flowNode.Outgoing.Select(x => x.Name))
-            .Where(x => x.ConditionExpression != null)
+            .Where(x => x.ConditionExpression is not null)
             .FirstOrDefault(EvaluateSequence);
 
-        if (sequence != null)
+        if (sequence is not null)
             return FindById<TFlowNode>(sequence.TargetRef);
 
         var defaultSequence = FindByIds<TSequenceFlow>(flowNode.Outgoing.Select(x => x.Name))
-            .FirstOrDefault(x => x.ConditionExpression == null);
+            .FirstOrDefault(x => x.ConditionExpression is null);
 
-        if (defaultSequence == null)
+        if (defaultSequence is null)
             throw new Exception("No applicable exclusive outgoing node");
 
         return FindById<TFlowNode>(defaultSequence.TargetRef);
@@ -403,17 +396,17 @@ private TFlowNode GetExclusiveOutgoingNode(TFlowNode flowNode)
     private TFlowNode[] GetInclusiveOutgoingNodes(TFlowNode flowNode)
     {
         var sequences = FindByIds<TSequenceFlow>(flowNode.Outgoing.Select(x => x.Name))
-            .Where(x => x.ConditionExpression != null)
+            .Where(x => x.ConditionExpression is not null)
             .Where(EvaluateSequence)
             .ToArray();
 
         if (sequences.Length > 0)
             return FindByIds<TFlowNode>(sequences.Select(s => s.TargetRef));
 
         var defaultSequence = FindByIds<TSequenceFlow>(flowNode.Outgoing.Select(x => x.Name))
-            .FirstOrDefault(x => x.ConditionExpression == null);
+            .FirstOrDefault(x => x.ConditionExpression is null);
 
-        if (defaultSequence == null)
+        if (defaultSequence is null)
             throw new Exception("No applicable invlusive outgoing node");
 
         return new TFlowNode[] {
@@ -451,7 +444,7 @@ private TFlowNode[] GetBoundaryFlowNodes(TBoundaryEvent boundaryEvent)
     private bool EvaluateSequence(TSequenceFlow sequenceFlow)
     {
         var expression = sequenceFlow.ConditionExpression?.Text?.FirstOrDefault();
-        if (expression == null)
+        if (expression is null)
             return true;
 
         var result = _scriptExecutor.Execute<bool>("javascript", expression, new Dictionary<string, object>

samples/BpmnWorker/Scripting/CSharpScriptEngine.cs

@@ -1,6 +1,4 @@
-using System.Collections.Generic;
-using System.Threading.Tasks;
-using Microsoft.CodeAnalysis.CSharp.Scripting;
+using Microsoft.CodeAnalysis.CSharp.Scripting;
 using Newtonsoft.Json;
 
 namespace BpmnWorker.Scripting;
@@ -10,7 +8,7 @@ public class CSharpScriptEngine : IScriptEngine
     public async Task<T> Execute<T>(string script, IDictionary<string, object> variables)
     {
         var output = await CSharpScript.EvaluateAsync(script);
-        if (output == null)
+        if (output is null)
             return default;
 
         if (output is T t)

samples/BpmnWorker/Scripting/JavaScriptScriptEngine.cs

@@ -1,7 +1,4 @@
-using System;
-using System.Collections.Generic;
-using System.Threading.Tasks;
-using Microsoft.ClearScript.V8;
+using Microsoft.ClearScript.V8;
 using Newtonsoft.Json;
 
 namespace BpmnWorker.Scripting;
@@ -11,11 +8,11 @@ public class JavaScriptScriptEngine : IScriptEngine
     public Task<T> Execute<T>(string script, IDictionary<string, object> variables)
     {
         using var engine = new V8ScriptEngine();
-        if (variables != null)
+        if (variables is not null)
         {
             foreach (var kv in variables)
             {
-                if (kv.Value != null)
+                if (kv.Value is not null)
                 {
                     var inputJson = JsonConvert.SerializeObject(kv.Value);
                     var inputJs = engine.Script.JSON.parse(inputJson);
@@ -27,7 +24,7 @@ public Task<T> Execute<T>(string script, IDictionary<string, object> variables)
         engine.AddHostType("Console", typeof(Console));
 
         var outputJs = engine.Evaluate(script);
-        if (outputJs == null)
+        if (outputJs is null)
             return Task.FromResult(default(T));
 
         if (engine.Script.JSON.stringify(outputJs) is not string outputJson)

src/LLL.DurableTask.Api/DependencyInjection/DurableTaskApiServiceCollectionExtensions.cs

@@ -11,7 +11,7 @@ public static IServiceCollection AddDurableTaskApi(
     {
         services.AddOptions<DurableTaskApiOptions>();
 
-        if (configure != null)
+        if (configure is not null)
             services.Configure<DurableTaskApiOptions>(configure);
 
         return services;

src/LLL.DurableTask.Api/Endpoints/EntrypointEndpoint.cs

@@ -33,14 +33,14 @@ public static IReadOnlyList<IEndpointConventionBuilder> MapEntrypointEndpoint(
             {
                 var durableTaskEndpointMetadata = endpoint.Metadata.GetMetadata<DurableTaskEndpointMetadata>();
 
-                if (durableTaskEndpointMetadata == null)
+                if (durableTaskEndpointMetadata is null)
                     continue;
 
                 var authorized = true;
 
                 var policies = endpoint.Metadata.OfType<AuthorizeAttribute>()
                     .Select(a => a.Policy)
-                    .Where(p => p != null)
+                    .Where(p => p is not null)
                     .ToArray();
 
                 if (policies.Length > 0)

src/LLL.DurableTask.Api/Endpoints/OrchestrationsEndpoints.cs

@@ -81,7 +81,7 @@ public static IReadOnlyList<IEndpointConventionBuilder> MapOrchestrationEndpoint
 
             var state = await taskHubClient.GetOrchestrationStateAsync(instanceId);
 
-            if (state == null)
+            if (state is null)
             {
                 context.Response.StatusCode = 404;
                 return;
@@ -104,7 +104,7 @@ public static IReadOnlyList<IEndpointConventionBuilder> MapOrchestrationEndpoint
 
             var state = await taskHubClient.GetOrchestrationStateAsync(instanceId, executionId);
 
-            if (state == null)
+            if (state is null)
             {
                 context.Response.StatusCode = 404;
                 return;

src/LLL.DurableTask.Core/Serializing/HistoryEventConverter.cs

@@ -45,7 +45,7 @@ public override object ReadJson(JsonReader reader, Type objectType, object exist
 
         var eventTypeToken = jObject.GetValue("EventType", StringComparison.OrdinalIgnoreCase);
 
-        if (eventTypeToken == null)
+        if (eventTypeToken is null)
             throw new Exception("Expected EventType field in HistoryEvent");
 
         var eventType = eventTypeToken.ToObject<EventType>();

src/LLL.DurableTask.EFCore.InMemory/InMemoryOrchestrationDbContextExtensions.cs

@@ -29,7 +29,7 @@ public override async Task<Instance> LockInstanceForUpdate(OrchestrationDbContex
     {
         var instance = dbContext.Instances.Find(instanceId);
 
-        if (instance == null)
+        if (instance is null)
             return null;
 
         var lockedInstances = _lockedInstanes.GetOrAdd(dbContext, (d) => new HashSet<string>());
@@ -65,7 +65,7 @@ orderby b.AvailableAt
                 select b.Instance
             ).FirstOrDefault();
 
-            if (instance == null)
+            if (instance is null)
                 return Task.FromResult(default(Instance));
 
             instance.LockId = Guid.NewGuid().ToString();
@@ -92,7 +92,7 @@ orderby b.AvailableAt
                 select b.Instance
             ).FirstOrDefault();
 
-            if (instance == null)
+            if (instance is null)
                 return Task.FromResult(default(Instance));
 
             instance.LockId = Guid.NewGuid().ToString();
@@ -116,7 +116,7 @@ orderby message.LockedUntil
                 select message
             ).FirstOrDefault();
 
-            if (activityMessage == null)
+            if (activityMessage is null)
                 return Task.FromResult(default(ActivityMessage));
 
             activityMessage.LockId = Guid.NewGuid().ToString();
@@ -142,7 +142,7 @@ orderby message.LockedUntil
                 select message
             ).FirstOrDefault();
 
-            if (activityMessage == null)
+            if (activityMessage is null)
                 return Task.FromResult(default(ActivityMessage));
 
             activityMessage.LockId = Guid.NewGuid().ToString();

src/LLL.DurableTask.EFCore.MySql/MySqlOrchestrationDbContextExtensions.cs

@@ -52,7 +52,7 @@ LIMIT 1
                 FOR UPDATE SKIP LOCKED
             ", DateTime.UtcNow).WithStraightJoin().ToArrayAsync()).FirstOrDefault();
 
-        if (instance == null)
+        if (instance is null)
             return null;
 
         instance.LockId = Guid.NewGuid().ToString();
@@ -84,7 +84,7 @@ LIMIT 1
                 FOR UPDATE SKIP LOCKED
             ", parameters).WithStraightJoin().ToArrayAsync()).FirstOrDefault();
 
-        if (instance == null)
+        if (instance is null)
             return null;
 
         instance.LockId = Guid.NewGuid().ToString();
@@ -106,7 +106,7 @@ LIMIT 1
                 FOR UPDATE SKIP LOCKED
             ", DateTime.UtcNow).ToArrayAsync()).FirstOrDefault();
 
-        if (instance == null)
+        if (instance is null)
             return null;
 
         instance.LockId = Guid.NewGuid().ToString();
@@ -133,7 +133,7 @@ LIMIT 1
                 FOR UPDATE SKIP LOCKED
             ", parameters).ToArrayAsync()).FirstOrDefault();
 
-        if (instance == null)
+        if (instance is null)
             return null;
 
         instance.LockId = Guid.NewGuid().ToString();
@@ -174,10 +174,10 @@ SELECT Executions.ExecutionId
                     FROM Executions
                         INNER JOIN Instances ON Executions.InstanceId = Instances.InstanceId
                     WHERE Executions.CreatedTime > {parameters.Add(filter.CreatedTimeFrom)}
-                    {(filter.CreatedTimeTo != null ? $"AND Executions.CreatedTime < {parameters.Add(filter.CreatedTimeTo)}" : "")}
+                    {(filter.CreatedTimeTo is not null ? $"AND Executions.CreatedTime < {parameters.Add(filter.CreatedTimeTo)}" : "")}
                     {(filter.RuntimeStatus.Any() ? $"AND Executions.Status IN ({string.Join(",", filter.RuntimeStatus.Select(s => parameters.Add(s.ToString())))})" : "")}
                     ORDER BY Executions.CreatedTime
-                    {(limit != null ? $"LIMIT {parameters.Add(limit)}" : null)}
+                    {(limit is not null ? $"LIMIT {parameters.Add(limit)}" : null)}
                     FOR UPDATE SKIP LOCKED
                 ) T
             );