CSHARP-5560: CSOT: Refactor IOperationExecutor to use operation context #1676

sanych-sun · 2025-04-24T00:08:36Z

No description provided.

src/MongoDB.Driver/OperationExecutor.cs

src/MongoDB.Driver/ReadOperationOptions.cs

src/MongoDB.Driver/MongoCollectionImpl.cs

adelinowona

Looks good! left some minor comments

src/MongoDB.Driver/AggregateHelper.cs

src/MongoDB.Driver/MongoClient.cs

src/MongoDB.Driver/OperationExecutor.cs

src/MongoDB.Driver/MongoCollectionImpl.cs

src/MongoDB.Driver/MongoDatabase.cs

tests/MongoDB.Driver.Tests/ReadOperationOptionsTests.cs

tests/MongoDB.Driver.Tests/OperationExecutorTests.cs

BorisDog

partial review: minor comments so far.

BorisDog · 2025-05-23T01:57:35Z

src/MongoDB.Driver/MongoCollectionImpl.cs

@@ -58,6 +58,8 @@ private MongoCollectionImpl(IMongoDatabase database, CollectionNamespace collect
            _documentSerializer = Ensure.IsNotNull(documentSerializer, nameof(documentSerializer));

            _messageEncoderSettings = GetMessageEncoderSettings();
+            _readOperationOptions = new ReadOperationOptions(DefaultReadPreference: _settings.ReadPreference);
+            _writeOperationOptions = new WriteOperationOptions();


minor:

_readOperationOptions = new() _writeOperationOptions = new(...)

BorisDog · 2025-05-23T02:33:26Z

src/MongoDB.Driver/MongoCollectionImpl.cs

+                Ensure.IsNotNullOrEmpty(name, nameof(name));
+                if (name == "*")
+                {
+                    throw new ArgumentException("Cannot specify '*' for the index name. Use DropAllAsync to drop all indexes.", "name");


minor: mistake in the original code, should be DropAll and DropAllAsync.

BorisDog · 2025-05-23T18:11:13Z

src/MongoDB.Driver/MongoDatabase.cs

@@ -50,6 +51,9 @@ public MongoDatabase(IMongoClient client, DatabaseNamespace databaseNamespace, M
            _settings = Ensure.IsNotNull(settings, nameof(settings)).Freeze();
            _cluster = Ensure.IsNotNull(cluster, nameof(cluster));
            _operationExecutor = Ensure.IsNotNull(operationExecutor, nameof(operationExecutor));
+
+            _readOperationOptions = new ReadOperationOptions(DefaultReadPreference: _settings.ReadPreference);
+            _writeOperationOptions = new WriteOperationOptions();


minor: new(...) ?

BorisDog · 2025-05-23T20:22:23Z

src/MongoDB.Driver/OperationExecutor.cs

+
+        private IReadWriteBindingHandle CreateReadWriteBinding(IClientSessionHandle session)
+        {
+            // TODO: CreateReadWriteBinding from MongoClient did not used ChannelPinningHelper, double-check if it's OK to start using it


Need to address this TODO.

Add parameter to disable channel pinning + ticket to investigate why do we need that: https://jira.mongodb.org/browse/CSHARP-5600

BorisDog · 2025-05-23T20:24:47Z

src/MongoDB.Driver/MongoClient.cs

@@ -100,7 +104,7 @@ public MongoClient(string connectionString)
        internal MongoClient(IOperationExecutor operationExecutor, MongoClientSettings settings)
            : this(settings)
        {
-            _operationExecutor = operationExecutor;
+            _operationExecutor = new OperationExecutorWrapper(operationExecutor);


Consider using the Fork approach.

@BorisDog what is the Fork approach?

The problem here is: MongoClient implements IDisposable, and disposed mongo client throws ObjectDisposedException. MongoDatabase and MongoCollection are not disposable on other hand. However most of work regarding commands execution is implemented in OperationExecutor, that is passed into Database and Collection. OperationExecutor holds reference to mongo client, but not used to implement IDisposable - which means that operation executor passed to database would be half-operational after the mongo client would be disposed. By half-operational I mean it will throw on any code path which require accessing mongo client: for example any implicit session creation will require that.

This is what I've tried to address here - I've made OperationExecutor disposable and move all disposed checks there. So now we will have consistent behaviour: once mongo client will be disposed - all databases and collections created from the client will throw. So this is a good part.

The bed part: mongo client has a number of methods to clone itself, by adjusting some settings (like WithReadConcern). Such method should create a new copy of mongo client with separate operation executor - so disposal of the original mongo client will not affect the created one. Plus we have a tests that wants to substitute implementation of the OperationExcecutor with the mock.

The only option to achieve all of that is to introduce the OperationExecutorFactory parameter - the factory method that accepts IMongoClient and returns OperationExecutor. So tests could substitute it, and clonning methods could ask for the fresh OperationExecutor.

BorisDog · 2025-05-23T20:36:07Z

tests/MongoDB.Driver.Tests/OperationExecutorTests.cs

+    {
+        [Theory]
+        [ParameterAttributeData]
+        public async Task StartImplicitSession_should_call_cluster([Values(true, false)]bool isAsync)


minor: _cluster_StartSession

adelinowona · 2025-05-27T18:54:15Z

src/MongoDB.Driver/WriteOperationOptions.cs

+
+namespace MongoDB.Driver
+{
+    internal record class WriteOperationOptions();


remove class here too

BorisDog

LGTM!

adelinowona

LGTM!

rstam · 2025-06-02T22:02:04Z

src/MongoDB.Driver/MongoDatabase.cs

-            return UsingImplicitSession(session => ListCollectionNames(session, options, cancellationToken), cancellationToken);
+            var cursor = _operationExecutor.ExecuteReadOperation(
+                CreateListCollectionNamesOperation(options),
+                _readOperationOptions with { DefaultReadPreference = ReadPreference.Primary },


Why DefaultReadPreference instead of ExplicitReadPreference?

This came from ListCollectionNames method, see line 358 before the changes.

rstam · 2025-06-02T23:11:42Z

src/MongoDB.Driver/MongoCollectionImpl.cs

        {
+            Ensure.IsNotNull((object)requests, nameof(requests));


Usually arguments are validated by public methods only, to alert the user that they passed an invalid value.

When WE call private methods WE should never pass an invalid argument, so it is odd to be calling Ensure.IsNotNull here in a private method.

The idea was to convert most of the public methods to expression-body methods (see other methods, for example FindOneAndDelete). Therefore I've decided to move some parameters validation inside of CreateXXXOperation methods.

rstam · 2025-06-03T21:07:16Z

src/MongoDB.Driver/MongoCollectionImpl.cs

+                _readOperationOptions,
+                session: null,
+                allowChannelPinning: true,
+                cancellationToken: cancellationToken);


Why did you suddenly switch from using var session ... to this?

Wouldn't it be better to do:

public override long Count(FilterDefinition<TDocument> filter, CountOptions options, CancellationToken cancellationToken = default) { using var session = _operationExecutor.StartImplicitSession(cancellationToken: cancellationToken); return CountDocuments(session, filter, options, cancellationToken); }

rstam · 2025-06-03T21:10:44Z

src/MongoDB.Driver/MongoClient.cs

+                _writeOperationOptions,
+                session: null,
+                allowChannelPinning: false,
+                cancellationToken: cancellationToken);


Why not use the using var session ... approach you used in parts of MongoClientImpl.cs?

public ClientBulkWriteResult BulkWrite(IReadOnlyList<BulkWriteModel> models, ClientBulkWriteOptions options = null, CancellationToken cancellationToken = default) { using var session = _operationExecutor.StartImplicitSession(cancellationToken); return BulkWrite(session, models, options, cancellationToken); }

It's less code duplication (specifically not duplicating the tricky part of whether to pass null or not for session and what value to pass for allowChannelPinning.

It very clearly emphasizes that the only difference between this method and the next is that an implicit session is being used.

rstam · 2025-06-03T21:12:52Z

src/MongoDB.Driver/OperationExecutor.cs

-            return await operation.ExecuteAsync(binding, cancellationToken).ConfigureAwait(false);
+            ThrowIfDisposed();
+            var isOwnSession = session == null;
+            session ??= StartImplicitSession(cancellationToken);


Change implementation to NOT allow passing null for session.

Let callers create implicit session instead (see other comments).

rstam

I'm going to stop my review here to see what you think of the suggestions so far. If you agree I will wait for a further commit.

rstam · 2025-06-04T17:11:47Z

src/MongoDB.Driver/MongoClient.cs

+                _writeOperationOptions,
+                Ensure.IsNotNull(session, nameof(session)),
+                allowChannelPinning: false,
+                cancellationToken: cancellationToken);


I think converting this to an expression valued body is a mistake. The result is a complicated expression with lots of things happening in one single expression.

I propose the following:

public ClientBulkWriteResult BulkWrite(IClientSessionHandle session, IReadOnlyList<BulkWriteModel> models, ClientBulkWriteOptions options = null, CancellationToken cancellationToken = default) { Ensure.IsNotNull(session, nameof(session)); var operation = CreateClientBulkWriteOperation(models, options); return ExecuteWriteOperation<ClientBulkWriteResult>(session, operation, cancellationToken); }

and keeping the ExecuteWriteOperation helper method but refactoring to:

private TResult ExecuteWriteOperation<TResult>(IClientSessionHandle session, IWriteOperation<TResult> operation, CancellationToken cancellationToken = default(CancellationToken)) { return _operationExecutor.ExecuteWriteOperation(session, operation, _writeOperationOptions, allowChannelPinning: false, cancellationToken); }

This allows the decomposing the various things going on into separate statements.

It also simplifies the code because the options and the allowChannelPinning values are the same for the entire file, and can be supplied once in the ExecuteWrite helper method.

Same for many other methods.

src/MongoDB.Driver/IOperationExecutor.cs

src/MongoDB.Driver/MongoClient.cs

rstam · 2025-06-04T20:34:35Z

src/MongoDB.Driver/MongoClient.cs

            var operation = CreateClientBulkWriteOperation(models, options);
-            return ExecuteWriteOperation<ClientBulkWriteResult>(session, operation, cancellationToken);
+            return ExecuteWriteOperation<ClientBulkWriteResult>(session, operation, _writeOperationOptions, cancellationToken);


_writeOperationOptions argument is unnecessary. It's always the same.

src/MongoDB.Driver/MongoClient.cs

rstam · 2025-06-04T20:54:19Z

src/MongoDB.Driver/MongoClient.cs

-
-            return UsingImplicitSession(session => ListDatabaseNames(session, options, cancellationToken), cancellationToken);
+            var listDatabasesOptions = CreateListDatabasesOptionsFromListDatabaseNamesOptions(options);
+            var databases = ListDatabases(listDatabasesOptions, cancellationToken);


Where did the implicit session go?

For consistency you should create the implicit session and call the other ListDatabaseNames overload.

I think you are trying to short circuit something here but don't think you should.

I'll double-check the difference.

rstam · 2025-06-04T20:56:36Z

src/MongoDB.Driver/MongoClient.cs

-
-            return UsingImplicitSessionAsync(session => ListDatabaseNamesAsync(session, options, cancellationToken), cancellationToken);
+            var listDatabasesOptions = CreateListDatabasesOptionsFromListDatabaseNamesOptions(options);
+            var databases = await ListDatabasesAsync(listDatabasesOptions, cancellationToken).ConfigureAwait(false);


What happened to the implicit session here?

I think you are trying to short circuit something but it would be better to create the implicit session and call the other overlaod of ListDatabaseNamesAsync.

I'll double-check the difference.

rstam · 2025-06-04T20:59:59Z

src/MongoDB.Driver/MongoClient.cs

-            return ListDatabases(session, null, cancellationToken);
+            Ensure.IsNotNull(session, nameof(session));
+            var operation = CreateListDatabaseOperation(null);
+            return ExecuteReadOperation(session, operation, _readOperationOptions, cancellationToken);


Just call the other overload passing null for options.

It's not a good idea to copy/paste the body of the other method here as an "optimization". If we ever change something in the other overload we could forget to make the same change here.

rstam · 2025-06-04T21:02:10Z

src/MongoDB.Driver/MongoClient.cs

-            return ListDatabasesAsync(session, null, cancellationToken);
+            Ensure.IsNotNull(session, nameof(session));
+            var operation = CreateListDatabaseOperation(null);
+            return ExecuteReadOperationAsync(session, operation, _readOperationOptions, cancellationToken);


Just call the other overload of ListDatabasesAsync like before. No need to copy/paste the implementation from that method to this one.

src/MongoDB.Driver/MongoClient.cs

src/MongoDB.Driver/MongoCollectionImpl.cs

rstam · 2025-06-04T21:47:28Z

src/MongoDB.Driver/MongoCollectionImpl.cs

+        private Task<TResult> ExecuteReadOperationAsync<TResult>(IClientSessionHandle session, IReadOperation<TResult> operation, ReadOperationOptions options, CancellationToken cancellationToken)
+            => _operationExecutor.ExecuteReadOperationAsync(session, operation, options, true, cancellationToken);
+
+        private TResult ExecuteWriteOperation<TResult>(IClientSessionHandle session, IWriteOperation<TResult> operation, WriteOperationOptions options, CancellationToken cancellationToken)


Remove options parameter?

Every single caller passes _writeOperationOptions.

src/MongoDB.Driver/MongoClient.cs

src/MongoDB.Driver/MongoCollectionImpl.cs

rstam

It's VERY close! Looking good.

rstam · 2025-06-04T23:16:41Z

src/MongoDB.Driver/MongoCollectionImpl.cs

+            if (update is PipelineUpdateDefinition<TDocument> && (options.ArrayFilters != null && options.ArrayFilters.Any()))
+            {
+                throw new NotSupportedException("An arrayfilter is not supported in the pipeline-style update.");
+            }


Does this argument validation need to be moved back to the public method?

src/MongoDB.Driver/MongoCollectionImpl.cs

rstam · 2025-06-05T00:01:11Z

src/MongoDB.Driver/MongoCollectionImpl.cs

            {
                Ensure.IsNotNull(session, nameof(session));
                Ensure.IsNotNullOrEmpty(name, nameof(name));
                if (name == "*")
                {
-                    throw new ArgumentException("Cannot specify '*' for the index name. Use DropAllAsync to drop all indexes.", "name");
+                    throw new ArgumentException("Cannot specify '*' for the index name. Use DropAll and DropAllAsync to drop all indexes.", "name");


Do we really want to mention DropAllAsync here?

They called DropOne, so the correct alternative method is DropAll.

@BorisDog as far as I remember you've asked to change the error message. Could you please confirm?

As it was discussed with Boris, I'll update wording to mention DropAll in DropOne, and DropAllAsync in DropOneAsync.

rstam · 2025-06-05T00:01:36Z

src/MongoDB.Driver/MongoCollectionImpl.cs

            {
                Ensure.IsNotNull(session, nameof(session));
                Ensure.IsNotNullOrEmpty(name, nameof(name));
                if (name == "*")
                {
-                    throw new ArgumentException("Cannot specify '*' for the index name. Use DropAllAsync to drop all indexes.", "name");
+                    throw new ArgumentException("Cannot specify '*' for the index name. Use DropAll and DropAllAsync to drop all indexes.", "name");


Do we really want to mention DropAll here?

They called DropOneAsync, so the correct alternative method is DropAllAsync.

@BorisDog as far as I remember you've asked to change the error message. Could you please confirm?

rstam · 2025-06-05T00:05:48Z

src/MongoDB.Driver/MongoCollectionImpl.cs

            {
                Ensure.IsNotNull(session, nameof(session));
-                Ensure.IsNotNull(models, nameof(models));
+                Ensure.IsNotNull((object)models, nameof(models));


Took me awhile to figure out why this cast to (object) was added.

At first glance it makes no sense!

As it was discussed, this prevents warning about possible multiple enumeration. Will revert.

rstam · 2025-06-05T00:35:10Z

src/MongoDB.Driver/MongoDatabase.cs

        }

-        private T ExecuteWriteOperation<T>(IClientSessionHandle session, IWriteOperation<T> operation, CancellationToken cancellationToken)
+        private BsonDocument GetEncryptedFields(IClientSessionHandle session, CollectionNamespace collectionNamespace, DropCollectionOptions options, CancellationToken cancellationToken)


I don't know the difference between "encrypted fields" and "effective encrypted fields", but

return effectiveEncryptedFields;

makes me think this method should be called GetEffectiveEncryptedField.

Same for async version.

src/MongoDB.Driver/MongoCollectionImpl.cs

src/MongoDB.Driver/MongoDatabase.cs

rstam · 2025-06-05T00:37:25Z

src/MongoDB.Driver/MongoDatabase.cs

-            return collections.Select(collection => collection["name"].AsString);
-        }
+        private TResult ExecuteReadOperation<TResult>(IClientSessionHandle session, IReadOperation<TResult> operation, CancellationToken cancellationToken)
+            => _operationExecutor.ExecuteReadOperation(session, operation, _readOperationOptions, true, cancellationToken);


Maybe call the other overload instead of _operationExecutor directly?

=> ExecuteReadOperation(session, operation, _readOperationOptions, cancellationToken);

rstam · 2025-06-05T00:37:49Z

src/MongoDB.Driver/MongoDatabase.cs

-            return ExecuteReadOperation(session, operation, readPreference, cancellationToken);
-        }
+        private Task<TResult> ExecuteReadOperationAsync<TResult>(IClientSessionHandle session, IReadOperation<TResult> operation, CancellationToken cancellationToken)
+            => _operationExecutor.ExecuteReadOperationAsync(session, operation, _readOperationOptions, true, cancellationToken);


Maybe call the other overload instead of _operationExecutor directly?

=> ExecuteReadOperationAsync(session, operation, _readOperationOptions, cancellationToken);

rstam

LGTM

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

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Fix nullreference exception.

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CSHARP-5560: CSOT: Refactor IOperationExecutor to use operation context #1676

CSHARP-5560: CSOT: Refactor IOperationExecutor to use operation context #1676

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sanych-sun commented Apr 24, 2025

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