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GroupOperation.cs
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GroupOperation.cs
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/* Copyright 2013-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.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using MongoDB.Bson;
using MongoDB.Bson.Serialization;
using MongoDB.Bson.Serialization.Serializers;
using MongoDB.Driver.Core.Bindings;
using MongoDB.Driver.Core.Misc;
using MongoDB.Driver.Core.WireProtocol.Messages.Encoders;
namespace MongoDB.Driver.Core.Operations
{
/// <summary>
/// Represents a group operation.
/// </summary>
/// <typeparam name="TResult">The type of the result.</typeparam>
public class GroupOperation<TResult> : IReadOperation<IEnumerable<TResult>>
{
// fields
private Collation _collation;
private readonly CollectionNamespace _collectionNamespace;
private readonly BsonDocument _filter;
private BsonJavaScript _finalizeFunction;
private readonly BsonDocument _initial;
private readonly BsonDocument _key;
private readonly BsonJavaScript _keyFunction;
private TimeSpan? _maxTime;
private readonly MessageEncoderSettings _messageEncoderSettings;
private readonly BsonJavaScript _reduceFunction;
private IBsonSerializer<TResult> _resultSerializer;
// constructors
/// <summary>
/// Initializes a new instance of the <see cref="GroupOperation{TResult}"/> class.
/// </summary>
/// <param name="collectionNamespace">The collection namespace.</param>
/// <param name="key">The key.</param>
/// <param name="initial">The initial aggregation result for each group.</param>
/// <param name="reduceFunction">The reduce function.</param>
/// <param name="filter">The filter.</param>
/// <param name="messageEncoderSettings">The message encoder settings.</param>
public GroupOperation(CollectionNamespace collectionNamespace, BsonDocument key, BsonDocument initial, BsonJavaScript reduceFunction, BsonDocument filter, MessageEncoderSettings messageEncoderSettings)
{
_collectionNamespace = Ensure.IsNotNull(collectionNamespace, nameof(collectionNamespace));
_key = Ensure.IsNotNull(key, nameof(key));
_initial = Ensure.IsNotNull(initial, nameof(initial));
_reduceFunction = Ensure.IsNotNull(reduceFunction, nameof(reduceFunction));
_filter = filter; // can be null
_messageEncoderSettings = messageEncoderSettings;
}
/// <summary>
/// Initializes a new instance of the <see cref="GroupOperation{TResult}"/> class.
/// </summary>
/// <param name="collectionNamespace">The collection namespace.</param>
/// <param name="keyFunction">The key function.</param>
/// <param name="initial">The initial aggregation result for each group.</param>
/// <param name="reduceFunction">The reduce function.</param>
/// <param name="filter">The filter.</param>
/// <param name="messageEncoderSettings">The message encoder settings.</param>
public GroupOperation(CollectionNamespace collectionNamespace, BsonJavaScript keyFunction, BsonDocument initial, BsonJavaScript reduceFunction, BsonDocument filter, MessageEncoderSettings messageEncoderSettings)
{
_collectionNamespace = Ensure.IsNotNull(collectionNamespace, nameof(collectionNamespace));
_keyFunction = Ensure.IsNotNull(keyFunction, nameof(keyFunction));
_initial = Ensure.IsNotNull(initial, nameof(initial));
_reduceFunction = Ensure.IsNotNull(reduceFunction, nameof(reduceFunction));
_filter = filter;
_messageEncoderSettings = messageEncoderSettings;
}
// properties
/// <summary>
/// Gets or sets the collation.
/// </summary>
/// <value>
/// The collation.
/// </value>
public Collation Collation
{
get { return _collation; }
set { _collation = value; }
}
/// <summary>
/// Gets the collection namespace.
/// </summary>
/// <value>
/// The collection namespace.
/// </value>
public CollectionNamespace CollectionNamespace
{
get { return _collectionNamespace; }
}
/// <summary>
/// Gets the filter.
/// </summary>
/// <value>
/// The filter.
/// </value>
public BsonDocument Filter
{
get { return _filter; }
}
/// <summary>
/// Gets or sets the finalize function.
/// </summary>
/// <value>
/// The finalize function.
/// </value>
public BsonJavaScript FinalizeFunction
{
get { return _finalizeFunction; }
set { _finalizeFunction = value; }
}
/// <summary>
/// Gets the initial aggregation result for each group.
/// </summary>
/// <value>
/// The initial aggregation result for each group.
/// </value>
public BsonDocument Initial
{
get { return _initial; }
}
/// <summary>
/// Gets the key.
/// </summary>
/// <value>
/// The key.
/// </value>
public BsonDocument Key
{
get { return _key; }
}
/// <summary>
/// Gets the key function.
/// </summary>
/// <value>
/// The key function.
/// </value>
public BsonJavaScript KeyFunction
{
get { return _keyFunction; }
}
/// <summary>
/// Gets or sets the maximum time the server should spend on this operation.
/// </summary>
/// <value>
/// The maximum time the server should spend on this operation.
/// </value>
public TimeSpan? MaxTime
{
get { return _maxTime; }
set { _maxTime = Ensure.IsNullOrInfiniteOrGreaterThanOrEqualToZero(value, nameof(value)); }
}
/// <summary>
/// Gets the message encoder settings.
/// </summary>
/// <value>
/// The message encoder settings.
/// </value>
public MessageEncoderSettings MessageEncoderSettings
{
get { return _messageEncoderSettings; }
}
/// <summary>
/// Gets the reduce function.
/// </summary>
/// <value>
/// The reduce function.
/// </value>
public BsonJavaScript ReduceFunction
{
get { return _reduceFunction; }
}
/// <summary>
/// Gets or sets the result serializer.
/// </summary>
/// <value>
/// The result serializer.
/// </value>
public IBsonSerializer<TResult> ResultSerializer
{
get { return _resultSerializer; }
set { _resultSerializer = value; }
}
// public methods
/// <inheritdoc/>
public IEnumerable<TResult> Execute(IReadBinding binding, CancellationToken cancellationToken)
{
Ensure.IsNotNull(binding, nameof(binding));
using (var channelSource = binding.GetReadChannelSource(cancellationToken))
using (var channel = channelSource.GetChannel(cancellationToken))
using (var channelBinding = new ChannelReadBinding(channelSource.Server, channel, binding.ReadPreference, binding.Session.Fork()))
{
var operation = CreateOperation();
return operation.Execute(channelBinding, cancellationToken);
}
}
/// <inheritdoc/>
public async Task<IEnumerable<TResult>> ExecuteAsync(IReadBinding binding, CancellationToken cancellationToken)
{
Ensure.IsNotNull(binding, nameof(binding));
using (var channelSource = await binding.GetReadChannelSourceAsync(cancellationToken).ConfigureAwait(false))
using (var channel = await channelSource.GetChannelAsync(cancellationToken).ConfigureAwait(false))
using (var channelBinding = new ChannelReadBinding(channelSource.Server, channel, binding.ReadPreference, binding.Session.Fork()))
{
var operation = CreateOperation();
return await operation.ExecuteAsync(channelBinding, cancellationToken).ConfigureAwait(false);
}
}
// private methods
internal BsonDocument CreateCommand()
{
return new BsonDocument
{
{ "group", new BsonDocument
{
{ "ns", _collectionNamespace.CollectionName },
{ "key", _key, _key != null },
{ "$keyf", _keyFunction, _keyFunction != null },
{ "$reduce", _reduceFunction },
{ "initial", _initial },
{ "cond", _filter, _filter != null },
{ "finalize", _finalizeFunction, _finalizeFunction != null },
{ "collation", () => _collation.ToBsonDocument(), _collation != null }
}
},
{ "maxTimeMS", () => MaxTimeHelper.ToMaxTimeMS(_maxTime.Value), _maxTime.HasValue }
};
}
private ReadCommandOperation<TResult[]> CreateOperation()
{
var command = CreateCommand();
var resultSerializer = _resultSerializer ?? BsonSerializer.LookupSerializer<TResult>();
var resultArraySerializer = new ArraySerializer<TResult>(resultSerializer);
var commandResultSerializer = new ElementDeserializer<TResult[]>("retval", resultArraySerializer);
return new ReadCommandOperation<TResult[]>(_collectionNamespace.DatabaseNamespace, command, commandResultSerializer, _messageEncoderSettings)
{
RetryRequested = false
};
}
}
}