.NET: [Feature Branch] Add basic durable workflow support (#3648)

* Add basic durable workflow support. * PR feedback fixes * Add conditional edge sample. * PR feedback fixes. * Minor cleanup. * Minor cleanup * Minor formatting improvements. * Improve comments/documentation on the execution flow.
2026-06-16 21:04:09 +08:00 · 2026-02-06 16:02:42 -08:00
parent 98cd72839e
commit e8d0bd9051
54 changed files with 4863 additions and 505 deletions
@@ -0,0 +1,156 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+// Routing decision flow for a single edge.
+// Example: the B→D edge from a workflow like below:
+//
+//     [A] ──► [B] ──► [C] ──► [E]          (B→D has condition: x => x.NeedsReview)
+//              │               ▲
+//              └──► [D] ──────┘
+//
+//   (condition: x => x.NeedsReview, _sourceOutputType: typeof(Order))
+//
+//  RouteMessage(envelope)          envelope.Message = "{\"NeedsReview\":true, ...}"
+//       │
+//       ▼
+//  Has condition? ──── No ────► Enqueue to sink's queue
+//       │
+//      Yes  (B→D has one)
+//       │
+//       ▼
+//  Deserialize message             JSON string → Order object using _sourceOutputType
+//       │
+//       ▼
+//  Evaluate _condition(order)      order => order.NeedsReview
+//       │
+//    ┌──┴──┐
+//  true   false
+//    │      │
+//    ▼      └──► Skip (log and return, D will not run)
+//  Enqueue to
+//  D's queue
+
+using System.Diagnostics.CodeAnalysis;
+using System.Text.Json;
+using Microsoft.Extensions.Logging;
+
+namespace Microsoft.Agents.AI.DurableTask.Workflows.EdgeRouters;
+
+/// <summary>
+/// Routes messages from a source executor to a single target executor with optional condition evaluation.
+/// </summary>
+/// <remarks>
+/// <para>
+/// Created by <see cref="DurableEdgeMap"/> during construction — one instance per (source, sink) edge.
+/// When an edge has a condition (e.g., <c>order =&gt; order.Total &gt; 1000</c>), the router deserialises
+/// the serialised JSON message back to the source executor's output type so the condition delegate
+/// can evaluate it against strongly-typed properties. If the condition returns <c>false</c>, the
+/// message is not forwarded and the target executor will not run for this edge.
+/// </para>
+/// <para>
+/// For sources with multiple successors, individual <see cref="DurableDirectEdgeRouter"/> instances
+/// are wrapped in a <see cref="DurableFanOutEdgeRouter"/> so a single <c>RouteMessage</c> call
+/// fans the same message out to all targets, each evaluating its own condition independently.
+/// </para>
+/// </remarks>
+internal sealed class DurableDirectEdgeRouter : IDurableEdgeRouter
+{
+    private readonly string _sourceId;
+    private readonly string _sinkId;
+    private readonly Func<object?, bool>? _condition;
+    private readonly Type? _sourceOutputType;
+
+    /// <summary>
+    /// Initializes a new instance of <see cref="DurableDirectEdgeRouter"/>.
+    /// </summary>
+    /// <param name="sourceId">The source executor ID.</param>
+    /// <param name="sinkId">The target executor ID.</param>
+    /// <param name="condition">Optional condition function to evaluate before routing.</param>
+    /// <param name="sourceOutputType">The output type of the source executor for deserialization.</param>
+    internal DurableDirectEdgeRouter(
+        string sourceId,
+        string sinkId,
+        Func<object?, bool>? condition,
+        Type? sourceOutputType)
+    {
+        this._sourceId = sourceId;
+        this._sinkId = sinkId;
+        this._condition = condition;
+        this._sourceOutputType = sourceOutputType;
+    }
+
+    /// <inheritdoc />
+    public void RouteMessage(
+        DurableMessageEnvelope envelope,
+        Dictionary<string, Queue<DurableMessageEnvelope>> messageQueues,
+        ILogger logger)
+    {
+        if (this._condition is not null)
+        {
+            try
+            {
+                object? messageObj = DeserializeForCondition(envelope.Message, this._sourceOutputType);
+                if (!this._condition(messageObj))
+                {
+                    logger.LogEdgeConditionFalse(this._sourceId, this._sinkId);
+                    return;
+                }
+            }
+            catch (Exception ex)
+            {
+                logger.LogEdgeConditionEvaluationFailed(ex, this._sourceId, this._sinkId);
+                return;
+            }
+        }
+
+        logger.LogEdgeRoutingMessage(this._sourceId, this._sinkId);
+        EnqueueMessage(messageQueues, this._sinkId, envelope);
+    }
+
+    /// <summary>
+    /// Deserializes a JSON message to an object for condition evaluation.
+    /// </summary>
+    /// <remarks>
+    /// Messages travel through the durable workflow as serialized JSON strings, but condition
+    /// delegates need typed objects to evaluate (e.g., order => order.Status == "Approved").
+    /// This method converts the JSON back to an object the condition delegate can evaluate.
+    /// </remarks>
+    /// <param name="json">The JSON string representation of the message.</param>
+    /// <param name="targetType">
+    /// The expected type of the message. When provided, enables strongly-typed deserialization
+    /// so the condition function receives the correct type to evaluate against.
+    /// </param>
+    /// <returns>
+    /// The deserialized object, or null if the JSON is empty.
+    /// </returns>
+    /// <exception cref="JsonException">Thrown when the JSON is invalid or cannot be deserialized to the target type.</exception>
+    [UnconditionalSuppressMessage("AOT", "IL3050", Justification = "Deserializing workflow types registered at startup.")]
+    [UnconditionalSuppressMessage("Trimming", "IL2026", Justification = "Deserializing workflow types registered at startup.")]
+    private static object? DeserializeForCondition(string json, Type? targetType)
+    {
+        if (string.IsNullOrEmpty(json))
+        {
+            return null;
+        }
+
+        // If we know the source executor's output type, deserialize to that specific type
+        // so the condition function can access strongly-typed properties.
+        // Otherwise, deserialize as a generic object for basic inspection.
+        return targetType is null
+            ? JsonSerializer.Deserialize<object>(json)
+            : JsonSerializer.Deserialize(json, targetType);
+    }
+
+    private static void EnqueueMessage(
+        Dictionary<string, Queue<DurableMessageEnvelope>> queues,
+        string executorId,
+        DurableMessageEnvelope envelope)
+    {
+        if (!queues.TryGetValue(executorId, out Queue<DurableMessageEnvelope>? queue))
+        {
+            queue = new Queue<DurableMessageEnvelope>();
+            queues[executorId] = queue;
+        }
+
+        queue.Enqueue(envelope);
+    }
+}