[Storage] [DataMovement] Fixed bug where adding multiple transfer in parallel could cause a Dictionary Collision in the transfers stored

sdk/storage/Azure.Storage.DataMovement.Blobs/tests/PauseResumeTransferTests.cs

@@ -1255,7 +1255,7 @@ public async Task PauseAllTriggersCorrectPauses()
                 {
                     unpausable.Add(transfer);
                 }
-                manager._dataTransfers.Add(Guid.NewGuid().ToString(), transfer.Object);
+                manager._dataTransfers.TryAdd(Guid.NewGuid().ToString(), transfer.Object);
             }
 
             await manager.PauseAllRunningTransfersAsync(_mockingToken);

sdk/storage/Azure.Storage.DataMovement/CHANGELOG.md

@@ -7,6 +7,7 @@
 ### Breaking Changes
 
 ### Bugs Fixed
+- Fixed bug where adding multiple transfers in parallel could cause a collision (`InvalidOperationException`) in the data transfers stored within the `TransferManager`.
 
 ### Other Changes
 

sdk/storage/Azure.Storage.DataMovement/src/Shared/Errors.DataMovement.cs

@@ -131,5 +131,8 @@ public static ArgumentException UnexpectedPropertyType(string propertyName, para
 
         public static InvalidOperationException CheckpointerDisabled(string method)
             => new InvalidOperationException($"Unable to perform {method}. The transfer checkpointer is disabled.");
+
+        public static InvalidOperationException CollisionTransferId(string id)
+            => new InvalidOperationException($"Transfer Id Collision: The transfer id, {id}, already exists in the transfer manager.");
     }
 }

sdk/storage/Azure.Storage.DataMovement/src/TransferManager.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Buffers;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Linq;
 using System.Runtime.CompilerServices;
@@ -28,7 +29,7 @@ public class TransferManager : IAsyncDisposable
         /// <summary>
         /// Ongoing transfers indexed at the transfer id.
         /// </summary>
-        internal readonly Dictionary<string, DataTransfer> _dataTransfers = new();
+        internal readonly ConcurrentDictionary<string, DataTransfer> _dataTransfers = new();
 
         /// <summary>
         /// Designated checkpointer for the respective transfer manager.
@@ -290,12 +291,11 @@ bool TryGetStorageResourceProvider(DataTransferProperties properties, bool getSo
 
             transferOptions ??= new DataTransferOptions();
 
-            if (_dataTransfers.ContainsKey(dataTransferProperties.TransferId))
-            {
-                // Remove the stale DataTransfer so we can pass a new DataTransfer object
-                // to the user and also track the transfer from the DataTransfer object
-                _dataTransfers.Remove(dataTransferProperties.TransferId);
-            }
+            // Remove the stale DataTransfer so we can pass a new DataTransfer object
+            // to the user and also track the transfer from the DataTransfer object
+            // No need to check if we were able to remove the transfer or not.
+            // If there's no stale DataTransfer to remove, move on.
+            _dataTransfers.TryRemove(dataTransferProperties.TransferId, out DataTransfer transfer);
 
             if (!TryGetStorageResourceProvider(dataTransferProperties, getSource: true, out StorageResourceProvider sourceProvider))
             {
@@ -409,7 +409,10 @@ private async Task<DataTransfer> BuildAndAddTransferJobAsync(
                 .ConfigureAwait(false);
 
             transfer.TransferManager = this;
-            _dataTransfers.Add(transfer.Id, transfer);
+            if (!_dataTransfers.TryAdd(transfer.Id, transfer))
+            {
+                throw Errors.CollisionTransferId(transfer.Id);
+            }
             await _jobsProcessor.QueueAsync(transferJobInternal, cancellationToken).ConfigureAwait(false);
 
             return transfer;
@@ -424,12 +427,17 @@ private async Task SetDataTransfers(CancellationToken cancellationToken = defaul
             foreach (string transferId in storedTransfers)
             {
                 DataTransferStatus jobStatus = await _checkpointer.GetJobStatusAsync(transferId, cancellationToken).ConfigureAwait(false);
-                _dataTransfers.Add(transferId, new DataTransfer(
+                // If TryAdd fails here, we need to check if in other places where we are
+                // adding that every transferId is unique.
+                if (!_dataTransfers.TryAdd(transferId, new DataTransfer(
                     id: transferId,
                     status: jobStatus)
                 {
                     TransferManager = this,
-                });
+                }))
+                {
+                    throw Errors.CollisionTransferId(transferId);
+                }
             }
         }
 

sdk/storage/Azure.Storage.DataMovement/tests/GetTransfersTests.cs

@@ -222,9 +222,10 @@ public async Task GetTransfers_LocalCheckpointer()
 
             // Act
             IList<DataTransfer> result = await manager.GetTransfersAsync().ToListAsync();
+            List<string> resultIds = result.Select(t => t.Id).ToList();
 
             // Assert
-            Assert.AreEqual(checkpointerTransfers, result.Select(d => d.Id).ToList());
+            Assert.IsTrue(Enumerable.SequenceEqual(checkpointerTransfers.OrderBy(id => id), result.Select(t => t.Id).OrderBy(id => id)));
         }
 
         [Test]

sdk/storage/Azure.Storage.DataMovement/tests/Models/StepProcessor.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License.
 
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
@@ -14,7 +15,7 @@ namespace Azure.Storage.DataMovement.Tests
     /// <typeparam name="T"></typeparam>
     internal class StepProcessor<T> : IProcessor<T>
     {
-        private readonly Queue<T> _queue = new();
+        private readonly ConcurrentQueue<T> _queue = new();
 
         public int ItemsInQueue => _queue.Count;
 
@@ -39,7 +40,8 @@ public async ValueTask<bool> TryStepAsync(CancellationToken cancellationToken =
         {
             if (_queue.Count > 0)
             {
-                await Process?.Invoke(_queue.Dequeue(), cancellationToken);
+                _queue.TryDequeue(out T result);
+                await Process?.Invoke(result, cancellationToken);
                 return true;
             }
             else

sdk/storage/Azure.Storage.DataMovement/tests/TransferManagerTests.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Buffers;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
@@ -430,6 +431,38 @@ public async Task TransferFailAtPartProcess(
         // TODO determine checkpointer status of job chunks
         //      need checkpointer API refactor for this
     }
+
+    [Test]
+    [TestCase(5)]
+    [TestCase(10)]
+    [TestCase(12345)]
+    public async Task MultipleTransfersAddedCheckpointer(int numJobs)
+    {
+        Uri srcUri = new("file:///foo/bar");
+        Uri dstUri = new("https://example.com/fizz/buzz");
+
+        (var jobsProcessor, var partsProcessor, var chunksProcessor) = StepProcessors();
+        JobBuilder jobBuilder = new(ArrayPool<byte>.Shared, default, new(ClientOptions.Default));
+        Mock<ITransferCheckpointer> checkpointer = new(MockBehavior.Loose);
+
+        (StorageResource srcResource, StorageResource dstResource, Func<IDisposable> srcThrowScope, Func<IDisposable> dstThrowScope)
+            = GetBasicSetupResources(false, srcUri, dstUri);
+
+        await using TransferManager transferManager = new(
+            jobsProcessor,
+            partsProcessor,
+            chunksProcessor,
+            jobBuilder,
+            checkpointer.Object,
+            default);
+
+        // Add jobs on separate Tasks
+        var loopResult = Parallel.For(0, numJobs, i =>
+        {
+            Task<DataTransfer> task = transferManager.StartTransferAsync(srcResource, dstResource);
+        });
+        Assert.That(jobsProcessor.ItemsInQueue, Is.EqualTo(numJobs), "Error during initial Job queueing.");
+    }
 }
 
 internal static partial class MockExtensions