Add SignalsQueries sample (#58)

README.md

@@ -23,6 +23,7 @@ Prerequisites:
 * [Polling](src/Polling) - Recommended implementation of an activity that needs to periodically poll an external resource waiting its successful completion.
 * [Saga](src/Saga) - Demonstrates how to implement a saga pattern.
 * [Schedules](src/Schedules) - How to schedule workflows to be run at specific times in the future.
+* [SignalsQueries](src/SignalsQueries) - A loyalty program using Signals and Queries.
 * [Timer](src/Timer) - Use a timer to implement a monthly subscription; handle workflow cancellation.
 * [WorkerSpecificTaskQueues](src/WorkerSpecificTaskQueues) - Use a unique task queue per Worker to have certain Activities only run on that specific Worker.
 * [WorkerVersioning](src/WorkerVersioning) - How to use the Worker Versioning feature to more easily deploy changes to Workflow & other code.

src/SignalsQueries/LoyaltyProgram.workflow.cs

@@ -0,0 +1,47 @@
+namespace TemporalioSamples.SignalsQueries;
+
+using Microsoft.Extensions.Logging;
+using Temporalio.Workflows;
+
+public record Purchase(string Id, int TotalCents);
+
+[Workflow]
+public class LoyaltyProgram
+{
+    private readonly Queue<Purchase> toProcess = new();
+
+    [WorkflowQuery]
+    public int Points { get; private set; }
+
+    [WorkflowRun]
+    public async Task RunAsync(string userId)
+    {
+        while (true)
+        {
+            // Wait for purchase
+            await Workflow.WaitConditionAsync(() => toProcess.Count > 0);
+
+            // Process
+            var purchase = toProcess.Dequeue();
+            Points += purchase.TotalCents;
+            Workflow.Logger.LogInformation("Added {TotalCents} points, total: {Points}", purchase.TotalCents, Points);
+            if (Points >= 10_000)
+            {
+                await Workflow.ExecuteActivityAsync(
+                    () => MyActivities.SendCoupon(userId),
+                    new() { ScheduleToCloseTimeout = TimeSpan.FromMinutes(5) });
+                Points -= 10_000;
+                Workflow.Logger.LogInformation("Remaining points: {Points}", Points);
+            }
+        }
+    }
+
+    [WorkflowSignal]
+    public async Task NotifyPurchaseAsync(Purchase purchase)
+    {
+        if (!toProcess.Contains(purchase))
+        {
+            toProcess.Enqueue(purchase);
+        }
+    }
+}

src/SignalsQueries/MyActivities.cs

@@ -0,0 +1,13 @@
+namespace TemporalioSamples.SignalsQueries;
+
+using Microsoft.Extensions.Logging;
+using Temporalio.Activities;
+
+public static class MyActivities
+{
+    [Activity]
+    public static void SendCoupon(string? userId)
+    {
+        ActivityExecutionContext.Current.Logger.LogInformation("Sending coupon to user {UserId}", userId);
+    }
+}

src/SignalsQueries/Program.cs

@@ -0,0 +1,80 @@
+using Microsoft.Extensions.Logging;
+using Temporalio.Client;
+using Temporalio.Worker;
+using TemporalioSamples.SignalsQueries;
+
+// Create a client to localhost on default namespace
+var client = await TemporalClient.ConnectAsync(new("localhost:7233")
+{
+    LoggerFactory = LoggerFactory.Create(builder =>
+        builder.
+            AddSimpleConsole(options => options.TimestampFormat = "[HH:mm:ss] ").
+            SetMinimumLevel(LogLevel.Information)),
+});
+
+async Task RunWorkerAsync()
+{
+    // Cancellation token cancelled on ctrl+c
+    using var tokenSource = new CancellationTokenSource();
+    Console.CancelKeyPress += (_, eventArgs) =>
+    {
+        tokenSource.Cancel();
+        eventArgs.Cancel = true;
+    };
+
+    // Run worker until cancelled
+    Console.WriteLine("Running worker");
+    using var worker = new TemporalWorker(
+        client,
+        new TemporalWorkerOptions(taskQueue: "signals-queries-sample").
+            AddActivity(MyActivities.SendCoupon).
+            AddWorkflow<LoyaltyProgram>());
+    try
+    {
+        await worker.ExecuteAsync(tokenSource.Token);
+    }
+    catch (OperationCanceledException)
+    {
+        Console.WriteLine("Worker cancelled");
+    }
+}
+
+async Task ExecuteWorkflowAsync()
+{
+    // If the workflow is already running from a previous run, terminate it
+    try
+    {
+        await client.GetWorkflowHandle("signals-queries-workflow-id").TerminateAsync();
+    }
+    catch (Temporalio.Exceptions.RpcException ex) when (ex.Code == Temporalio.Exceptions.RpcException.StatusCode.NotFound)
+    {
+        // Ignore
+    }
+
+    Console.WriteLine("Executing workflow");
+    var handle = await client.StartWorkflowAsync(
+        (LoyaltyProgram wf) => wf.RunAsync("user-id-123"),
+        new(id: "signals-queries-workflow-id", taskQueue: "signals-queries-sample"));
+
+    Console.WriteLine("Signal: Purchase made for $80");
+    await handle.SignalAsync(wf => wf.NotifyPurchaseAsync(new Purchase("purchase-1", 8_000)));
+    Console.WriteLine("Signal: Purchase made for $40");
+    await handle.SignalAsync(wf => wf.NotifyPurchaseAsync(new Purchase("purchase-1", 4_000)));
+
+    // Wait for workflow to process the signals
+    await Task.Delay(1000);
+    var points = await handle.QueryAsync(wf => wf.Points);
+    Console.WriteLine("Remaining points: {0}", points);
+}
+
+switch (args.ElementAtOrDefault(0))
+{
+    case "worker":
+        await RunWorkerAsync();
+        break;
+    case "workflow":
+        await ExecuteWorkflowAsync();
+        break;
+    default:
+        throw new ArgumentException("Must pass 'worker' or 'workflow' as the single argument");
+}

src/SignalsQueries/README.md

@@ -0,0 +1,14 @@
+# SignalsQueries
+
+A loyalty program implemented with Signals and Queries.
+
+To run, first see [README.md](../../README.md) for prerequisites. Then, run the following from this directory
+in a separate terminal to start the worker:
+
+    dotnet run worker
+
+Then in another terminal, run the workflow from this directory:
+
+    dotnet run workflow
+
+The worker terminal will show logs from running the workflow.

src/SignalsQueries/TemporalioSamples.SignalsQueries.csproj

@@ -0,0 +1,7 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+  </PropertyGroup>
+
+</Project>