Add explicit buffering options (Azure#19115)

Author: pakrym

sdk/storage/Azure.Storage.Blobs.Batch/src/ContainerRestClient.cs

@@ -15,7 +15,6 @@ internal HttpMessage CreateSubmitBatchRequest(string containerName, long content
         {
             var message = _pipeline.CreateMessage();
             var request = message.Request;
-            message.BufferResponse = false;
             request.Method = RequestMethod.Post;
             var uri = new RawRequestUriBuilder();
             uri.AppendRaw(url, false);

sdk/storage/Azure.Storage.Blobs.Batch/src/autorest.md

@@ -205,4 +205,13 @@ directive:
   transform: >
     $.Blob["x-ms-skip-url-encoding"] = true;
     $.ContainerName["x-ms-skip-url-encoding"] = true;
+```
+
+### Buffer batch responses
+
+``` yaml
+directive:
+- from: swagger-document
+  where: $..[?(@.operationId=='Service_SubmitBatch' || @.operationId=='Container_SubmitBatch')]
+  transform: $["x-csharp-buffer-response"] = true;
 ```

sdk/storage/Azure.Storage.Blobs/src/BlobBaseClient.cs

@@ -1006,7 +1006,7 @@ private async Task<Response<BlobDownloadInfo>> StartDownloadAsync(
             }
 
             // Watch out for exploding Responses
-            long length = response.IsUnavailable() ? 0 : response.Value.Length;
+            long length = response.IsUnavailable() ? 0 : response.Headers.ContentLength ?? 0;
             ClientConfiguration.Pipeline.LogTrace($"Response: {response.GetRawResponse().Status}, ContentLength: {length}");
 
             return Response.FromValue(

sdk/storage/Azure.Storage.Blobs/src/Generated/BlobRestClient.cs

@@ -276,4 +276,13 @@ directive:
       "x-az-response-name": "ConditionNotMetError",
       "headers": { "x-ms-error-code": { "x-ms-client-name": "ErrorCode", "type": "string" } }
     };
+```
+
+### Don't buffer downloads and query
+
+``` yaml
+directive:
+- from: swagger-document
+  where: $..[?(@.operationId=='Blob_Query' || @.operationId=='Blob_Download')]
+  transform: $["x-csharp-buffer-response"] = false;
 ```

sdk/storage/Azure.Storage.Blobs/src/autorest.md

@@ -90,4 +90,13 @@ directive:
     $.patch.consumes = [
       "application/octet-stream"
     ]
+```
+
+### Don't buffer downloads
+
+``` yaml
+directive:
+- from: swagger-document
+  where: $..[?(@.operationId=='Path_Read')]
+  transform: $["x-csharp-buffer-response"] = false;
 ```

sdk/storage/Azure.Storage.Files.DataLake/src/autorest.md

@@ -121,4 +121,13 @@ directive:
        delete $[id];
      }
    });
+```
+
+### Don't buffer downloads
+
+``` yaml
+directive:
+- from: swagger-document
+  where: $..[?(@.operationId=='File_Download')]
+  transform: $["x-csharp-buffer-response"] = false;
 ```