[Storage][DataMovement] Refactor download transfers (#47231)

Author: jalauzon-msft

sdk/storage/Azure.Storage.Common/src/Shared/ContentRange.cs

@@ -153,7 +153,8 @@ public static HttpRange ToHttpRange(ContentRange contentRange)
             {
                 // Because constructing HttpRange is the start value, and the length of the range
                 // increment 1 on the end value, since the end value is the end index (not the length).
-                return new HttpRange(contentRange.Start.Value, contentRange.End.Value + 1);
+                long length = contentRange.End.Value - contentRange.Start.Value + 1;
+                return new HttpRange(contentRange.Start.Value, length);
             }
             return default;
         }

sdk/storage/Azure.Storage.DataMovement.Blobs/perf-tests.yml

@@ -15,6 +15,7 @@ Tests:
   Arguments: &sizes
   - --size 1024 --count 5000 --duration 60 --concurrency 64
   - --size 10485760 --count 500 --duration 90 --concurrency 64
+  - --size 52428800 --count 200 --duration 120 --concurrency 64
   - --size 1073741824 --count 5 --duration 120 --concurrency 64
 
 - Test: upload

sdk/storage/Azure.Storage.DataMovement/api/Azure.Storage.DataMovement.net6.0.cs

@@ -220,6 +220,7 @@ public partial class StorageResourceWriteToOffsetOptions
     {
         public StorageResourceWriteToOffsetOptions() { }
         public string BlockId { get { throw null; } set { } }
+        public bool Initial { get { throw null; } set { } }
         public long? Position { get { throw null; } set { } }
         public Azure.Storage.DataMovement.StorageResourceItemProperties SourceProperties { get { throw null; } set { } }
     }

sdk/storage/Azure.Storage.DataMovement/api/Azure.Storage.DataMovement.net8.0.cs

@@ -220,6 +220,7 @@ public partial class StorageResourceWriteToOffsetOptions
     {
         public StorageResourceWriteToOffsetOptions() { }
         public string BlockId { get { throw null; } set { } }
+        public bool Initial { get { throw null; } set { } }
         public long? Position { get { throw null; } set { } }
         public Azure.Storage.DataMovement.StorageResourceItemProperties SourceProperties { get { throw null; } set { } }
     }

sdk/storage/Azure.Storage.DataMovement/api/Azure.Storage.DataMovement.netstandard2.0.cs

@@ -220,6 +220,7 @@ public partial class StorageResourceWriteToOffsetOptions
     {
         public StorageResourceWriteToOffsetOptions() { }
         public string BlockId { get { throw null; } set { } }
+        public bool Initial { get { throw null; } set { } }
         public long? Position { get { throw null; } set { } }
         public Azure.Storage.DataMovement.StorageResourceItemProperties SourceProperties { get { throw null; } set { } }
     }

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

@@ -126,17 +126,17 @@ protected internal override async Task CopyFromStreamAsync(
             CancellationHelper.ThrowIfCancellationRequested(cancellationToken);
 
             long position = options?.Position != default ? options.Position.Value : 0;
-            if (position == 0)
+            if (options?.Initial == true)
             {
                 Create(overwrite);
             }
             if (streamLength > 0)
             {
                 // Appends incoming stream to the local file resource
                 using (FileStream fileStream = new FileStream(
-                        _uri.LocalPath,
-                        FileMode.OpenOrCreate,
-                        FileAccess.Write))
+                    _uri.LocalPath,
+                    FileMode.Open,
+                    FileAccess.Write))
                 {
                     if (position > 0)
                     {

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

@@ -0,0 +1,24 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System.IO;
+
+namespace Azure.Storage.DataMovement
+{
+    internal class QueueDownloadChunkArgs
+    {
+        public long Offset { get; }
+        public long Length { get; }
+        public Stream Content { get; }
+
+        public QueueDownloadChunkArgs(
+            long offset,
+            long length,
+            Stream content)
+        {
+            Offset = offset;
+            Length = length;
+            Content = content;
+        }
+    }
+}

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

@@ -24,6 +24,11 @@ public class StorageResourceWriteToOffsetOptions
         /// </summary>
         public long? Position { get; set; }
 
+        /// <summary>
+        /// Optional. Specifies whether this write is for the initial chunk.
+        /// </summary>
+        public bool Initial { get; set; }
+
         /// <summary>
         /// Optional. Specifies the source properties to set in the destination.
         /// </summary>