CSHARP-5560: CSOT: Refactor IOperationExecutor to use operation context

.editorconfig

@@ -47,10 +47,10 @@ dotnet_style_qualification_for_property = false:suggestion
 dotnet_style_qualification_for_method = false:suggestion
 dotnet_style_qualification_for_event = false:suggestion
 
-# Types: use keywords instead of BCL types, and permit var only when the type is clear
-csharp_style_var_for_built_in_types = false:suggestion
-csharp_style_var_when_type_is_apparent = false:none
-csharp_style_var_elsewhere = false:suggestion
+# Types: use keywords instead of BCL types, and prefer var instead of the explicit type
+csharp_style_var_for_built_in_types = true:suggestion
+csharp_style_var_when_type_is_apparent = true:suggestion
+csharp_style_var_elsewhere = true:suggestion
 dotnet_style_predefined_type_for_locals_parameters_members = true:suggestion
 dotnet_style_predefined_type_for_member_access = true:suggestion
 

src/MongoDB.Driver/AggregateHelper.cs

@@ -0,0 +1,96 @@
+/* Copyright 2010-present MongoDB Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+using System;
+using System.Linq;
+using MongoDB.Bson;
+
+namespace MongoDB.Driver
+{
+    internal static class AggregateHelper
+    {
+        public static RenderedPipelineDefinition<TResult> RenderAggregatePipeline<TDocument, TResult>(PipelineDefinition<TDocument, TResult> pipeline, RenderArgs<TDocument> renderArgs, out bool isAggregateToCollection)
+        {
+            var renderedPipeline = pipeline.Render(renderArgs);
+
+            var lastStage = renderedPipeline.Documents.LastOrDefault();
+            var lastStageName = lastStage?.GetElement(0).Name;
+            isAggregateToCollection = lastStageName == "$out" || lastStageName == "$merge";
+
+            return renderedPipeline;
+        }
+
+        public static CollectionNamespace GetOutCollection(BsonDocument outStage, DatabaseNamespace defaultDatabaseNamespace)
+        {
+            var stageName = outStage.GetElement(0).Name;
+            switch (stageName)
+            {
+                case "$out":
+                    {
+                        var outValue = outStage[0];
+                        DatabaseNamespace outputDatabaseNamespace;
+                        string outputCollectionName;
+                        if (outValue.IsString)
+                        {
+                            outputDatabaseNamespace = defaultDatabaseNamespace;
+                            outputCollectionName = outValue.AsString;
+                        }
+                        else
+                        {
+                            outputDatabaseNamespace = new DatabaseNamespace(outValue["db"].AsString);
+                            outputCollectionName = outValue["coll"].AsString;
+                        }
+                        return new CollectionNamespace(outputDatabaseNamespace, outputCollectionName);
+                    }
+                case "$merge":
+                    {
+                        var mergeArguments = outStage[0];
+                        DatabaseNamespace outputDatabaseNamespace;
+                        string outputCollectionName;
+                        if (mergeArguments.IsString)
+                        {
+                            outputDatabaseNamespace = defaultDatabaseNamespace;
+                            outputCollectionName = mergeArguments.AsString;
+                        }
+                        else
+                        {
+                            var into = mergeArguments.AsBsonDocument["into"];
+                            if (into.IsString)
+                            {
+                                outputDatabaseNamespace = defaultDatabaseNamespace;
+                                outputCollectionName = into.AsString;
+                            }
+                            else
+                            {
+                                if (into.AsBsonDocument.Contains("db"))
+                                {
+                                    outputDatabaseNamespace = new DatabaseNamespace(into["db"].AsString);
+                                }
+                                else
+                                {
+                                    outputDatabaseNamespace = defaultDatabaseNamespace;
+                                }
+                                outputCollectionName = into["coll"].AsString;
+                            }
+                        }
+                        return new CollectionNamespace(outputDatabaseNamespace, outputCollectionName);
+                    }
+                default:
+                    throw new ArgumentException($"Unexpected stage name: {stageName}.");
+            }
+        }
+    }
+}
+

src/MongoDB.Driver/IOperationExecutor.cs

@@ -16,20 +16,36 @@
 using System;
 using System.Threading;
 using System.Threading.Tasks;
-using MongoDB.Driver.Core.Bindings;
 using MongoDB.Driver.Core.Operations;
 
 namespace MongoDB.Driver
 {
-    internal interface IOperationExecutor
+    internal interface IOperationExecutor : IDisposable
     {
-        TResult ExecuteReadOperation<TResult>(IReadBinding binding, IReadOperation<TResult> operation, CancellationToken cancellationToken);
-        Task<TResult> ExecuteReadOperationAsync<TResult>(IReadBinding binding, IReadOperation<TResult> operation, CancellationToken cancellationToken);
+        TResult ExecuteReadOperation<TResult>(IReadOperation<TResult> operation,
+            ReadOperationOptions options,
+            IClientSessionHandle session,
+            bool allowChannelPinning,
+            CancellationToken cancellationToken);
 
-        TResult ExecuteWriteOperation<TResult>(IWriteBinding binding, IWriteOperation<TResult> operation, CancellationToken cancellationToken);
-        Task<TResult> ExecuteWriteOperationAsync<TResult>(IWriteBinding binding, IWriteOperation<TResult> operation, CancellationToken cancellationToken);
+        Task<TResult> ExecuteReadOperationAsync<TResult>(IReadOperation<TResult> operation,
+            ReadOperationOptions options,
+            IClientSessionHandle session,
+            bool allowChannelPinning,
+            CancellationToken cancellationToken);
 
-        IClientSessionHandle StartImplicitSession(CancellationToken cancellationToken);
-        Task<IClientSessionHandle> StartImplicitSessionAsync(CancellationToken cancellationToken);
+        TResult ExecuteWriteOperation<TResult>(IWriteOperation<TResult> operation,
+            WriteOperationOptions options,
+            IClientSessionHandle session,
+            bool allowChannelPinning,
+            CancellationToken cancellationToken);
+
+        Task<TResult> ExecuteWriteOperationAsync<TResult>(IWriteOperation<TResult> operation,
+            WriteOperationOptions options,
+            IClientSessionHandle session,
+            bool allowChannelPinning,
+            CancellationToken cancellationToken);
+
+        IClientSessionHandle StartImplicitSession();
     }
 }