fix: Avoid materializing S3 lib in memory (#288)

Worker/src/Common/Adapter/S3Adapter.cs

@@ -16,12 +16,14 @@
 
 using System;
 using System.IO;
+using System.Threading;
 using System.Threading.Tasks;
 
 using Amazon.S3;
 using Amazon.S3.Model;
 
 using ArmoniK.DevelopmentKit.Common;
+using ArmoniK.Utils;
 
 namespace ArmoniK.DevelopmentKit.Worker.Common.Adapter;
 
@@ -83,48 +85,42 @@ public S3Adapter(string endPointRegion,
   /// <param name="fileName">The filename with extension and without directory path</param>
   /// <returns>Returns the path where the file has been downloaded</returns>
   public string DownloadFile(string fileName)
-  {
-    DownloadFileAsync(fileName)
-      .Wait();
-
-    return Path.Combine(DestinationDirPath,
-                        fileName);
-  }
+    => DownloadFileAsync(fileName)
+      .WaitSync();
 
-
-  public async Task DownloadFileAsync(string fileName)
+  /// <summary>
+  ///   The method to download file from form remote server
+  /// </summary>
+  /// <param name="fileName">The filename with extension and without directory path</param>
+  /// <param name="cancellationToken">Abort download of the file</param>
+  /// <returns>Returns the path where the file has been downloaded</returns>
+  public async Task<string> DownloadFileAsync(string            fileName,
+                                              CancellationToken cancellationToken = default)
   {
-    var ms = new MemoryStream();
-
     var r = await Client.GetObjectAsync(new GetObjectRequest
                                         {
                                           BucketName = BucketName,
                                           Key        = fileName,
-                                        });
-    var stream2 = new BufferedStream(r.ResponseStream);
+                                        },
+                                        cancellationToken);
 
-    var materializedFileName = fileName + Guid.NewGuid();
+    var materializedFileName = Path.Combine(LocalZipDir,
+                                            fileName + Guid.NewGuid());
+
+    var targetFileName = Path.Combine(DestinationDirPath,
+                                      fileName);
 
-    var file = new FileStream(Path.Combine(LocalZipDir,
-                                           materializedFileName),
-                              FileMode.Create,
-                              FileAccess.Write);
     try
     {
-      var buffer = new byte[0x2000];
-      var count  = 0;
-      while ((count = stream2.Read(buffer,
-                                   0,
-                                   buffer.Length)) > 0)
-      {
-        ms.Write(buffer,
-                 0,
-                 count);
-      }
+      await r.WriteResponseStreamToFileAsync(materializedFileName,
+                                             false,
+                                             cancellationToken)
+             .ConfigureAwait(false);
 
-      ms.WriteTo(file);
-      file.Close();
-      ms.Close();
+      File.Move(materializedFileName,
+                targetFileName);
+
+      return targetFileName;
     }
     catch (AmazonS3Exception amazonS3Exception)
     {
@@ -135,10 +131,12 @@ public async Task DownloadFileAsync(string fileName)
 
       throw new Exception("Error occurred: " + amazonS3Exception.Message);
     }
-
-    File.Move(Path.Combine(LocalZipDir,
-                           materializedFileName),
-              Path.Combine(LocalZipDir,
-                           fileName));
+    finally
+    {
+      if (File.Exists(materializedFileName))
+      {
+        File.Delete(materializedFileName);
+      }
+    }
   }
 }