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SizeLimitingBatchableSourceSerializer.cs
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SizeLimitingBatchableSourceSerializer.cs
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/* Copyright 2017-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 MongoDB.Bson.IO;
using MongoDB.Bson.Serialization;
using MongoDB.Bson.Serialization.Serializers;
namespace MongoDB.Driver.Core.Misc
{
/// <summary>
/// A serializer for BatchableSource that serializes as much of the BatchableSource as fits in the max batch count and size.
/// </summary>
/// <typeparam name="TItem">The type of the items.</typeparam>
public class SizeLimitingBatchableSourceSerializer<TItem> : SerializerBase<BatchableSource<TItem>>
{
// private fields
private readonly IElementNameValidator _itemElementNameValidator;
private readonly IBsonSerializer<TItem> _itemSerializer;
private readonly int _maxBatchCount;
private readonly int _maxBatchSize;
private readonly int _maxItemSize;
// constructors
/// <summary>
/// Initializes a new instance of the <see cref="SizeLimitingBatchableSourceSerializer{TItem}" /> class.
/// </summary>
/// <param name="itemSerializer">The item serializer.</param>
/// <param name="itemElementNameValidator">The item element name validator.</param>
/// <param name="maxBatchCount">The maximum batch count.</param>
/// <param name="maxItemSize">The maximum size of a serialized item.</param>
/// <param name="maxBatchSize">The maximum size of the batch.</param>
public SizeLimitingBatchableSourceSerializer(
IBsonSerializer<TItem> itemSerializer,
IElementNameValidator itemElementNameValidator,
int maxBatchCount,
int maxItemSize,
int maxBatchSize)
{
_itemSerializer = Ensure.IsNotNull(itemSerializer, nameof(itemSerializer));
_itemElementNameValidator = Ensure.IsNotNull(itemElementNameValidator, nameof(itemElementNameValidator));
_maxBatchCount = Ensure.IsGreaterThanZero(maxBatchCount, nameof(maxBatchCount));
_maxItemSize = Ensure.IsGreaterThanZero(maxItemSize, nameof(maxItemSize));
_maxBatchSize = Ensure.IsGreaterThanZero(maxBatchSize, nameof(maxBatchSize));
}
// public methods
/// <inheritdoc />
public override void Serialize(BsonSerializationContext context, BsonSerializationArgs args, BatchableSource<TItem> value)
{
Ensure.IsNotNull(value, nameof(value));
var writer = context.Writer;
while (writer is WrappingBsonWriter)
{
writer = ((WrappingBsonWriter)writer).Wrapped;
}
var binaryWriter = writer as BsonBinaryWriter;
var startPosition = binaryWriter?.Position;
writer.PushSettings(s => { var bs = s as BsonBinaryWriterSettings; if (bs != null) { bs.MaxDocumentSize = _maxItemSize; } });
writer.PushElementNameValidator(_itemElementNameValidator);
try
{
var batchCount = Math.Min(value.Count, _maxBatchCount);
if (batchCount != value.Count && !value.CanBeSplit)
{
throw new ArgumentException("Batch is too large.");
}
for (var i = 0; i < batchCount; i++)
{
var itemPosition = binaryWriter?.Position;
var item = value.Items[value.Offset + i];
_itemSerializer.Serialize(context, args, item);
// always process at least one item
if (i > 0)
{
var batchSize = binaryWriter?.Position - startPosition;
if (batchSize > _maxBatchSize)
{
if (value.CanBeSplit)
{
binaryWriter.BaseStream.Position = itemPosition.Value; // remove the last item
binaryWriter.BaseStream.SetLength(itemPosition.Value);
value.SetProcessedCount(i);
return;
}
else
{
throw new ArgumentException("Batch is too large.");
}
}
}
}
value.SetProcessedCount(batchCount);
}
finally
{
writer.PopElementNameValidator();
writer.PopSettings();
}
}
}
}