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#region Copyright notice and license
// Copyright 2015 gRPC authors.
//
// 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.
#endregion
using System;
using Grpc.Core.Utils;
namespace Grpc.Core
{
/// <summary>
/// Encapsulates the logic for serializing and deserializing messages.
/// </summary>
public class Marshaller<T>
{
readonly Func<T, byte[]> serializer;
readonly Func<byte[], T> deserializer;
readonly Action<T, SerializationContext> contextualSerializer;
readonly Func<DeserializationContext, T> contextualDeserializer;
/// <summary>
/// Initializes a new marshaller from simple serialize/deserialize functions.
/// </summary>
/// <param name="serializer">Function that will be used to serialize messages.</param>
/// <param name="deserializer">Function that will be used to deserialize messages.</param>
public Marshaller(Func<T, byte[]> serializer, Func<byte[], T> deserializer)
{
this.serializer = GrpcPreconditions.CheckNotNull(serializer, nameof(serializer));
this.deserializer = GrpcPreconditions.CheckNotNull(deserializer, nameof(deserializer));
this.contextualSerializer = EmulateContextualSerializer;
this.contextualDeserializer = EmulateContextualDeserializer;
}
/// <summary>
/// Initializes a new marshaller from serialize/deserialize fuctions that can access serialization and deserialization
/// context. Compared to the simple serializer/deserializer functions, using the contextual version provides more
/// flexibility and can lead to increased efficiency (and better performance).
/// Note: This constructor is part of an experimental API that can change or be removed without any prior notice.
/// </summary>
/// <param name="serializer">Function that will be used to serialize messages.</param>
/// <param name="deserializer">Function that will be used to deserialize messages.</param>
public Marshaller(Action<T, SerializationContext> serializer, Func<DeserializationContext, T> deserializer)
{
this.contextualSerializer = GrpcPreconditions.CheckNotNull(serializer, nameof(serializer));
this.contextualDeserializer = GrpcPreconditions.CheckNotNull(deserializer, nameof(deserializer));
// TODO(jtattermusch): once gRPC C# library switches to using contextual (de)serializer,
// emulating the simple (de)serializer will become unnecessary.
this.serializer = EmulateSimpleSerializer;
this.deserializer = EmulateSimpleDeserializer;
}
/// <summary>
/// Gets the serializer function.
/// </summary>
public Func<T, byte[]> Serializer => this.serializer;
/// <summary>
/// Gets the deserializer function.
/// </summary>
public Func<byte[], T> Deserializer => this.deserializer;
/// <summary>
/// Gets the serializer function.
/// Note: experimental API that can change or be removed without any prior notice.
/// </summary>
public Action<T, SerializationContext> ContextualSerializer => this.contextualSerializer;
/// <summary>
/// Gets the serializer function.
/// Note: experimental API that can change or be removed without any prior notice.
/// </summary>
public Func<DeserializationContext, T> ContextualDeserializer => this.contextualDeserializer;
// for backward compatibility, emulate the simple serializer using the contextual one
private byte[] EmulateSimpleSerializer(T msg)
{
// TODO(jtattermusch): avoid the allocation by passing a thread-local instance
// This code will become unnecessary once gRPC C# library switches to using contextual (de)serializer.
var context = new EmulatedSerializationContext();
this.contextualSerializer(msg, context);
return context.GetPayload();
}
// for backward compatibility, emulate the simple deserializer using the contextual one
private T EmulateSimpleDeserializer(byte[] payload)
{
// TODO(jtattermusch): avoid the allocation by passing a thread-local instance
// This code will become unnecessary once gRPC C# library switches to using contextual (de)serializer.
var context = new EmulatedDeserializationContext(payload);
return this.contextualDeserializer(context);
}
// for backward compatibility, emulate the contextual serializer using the simple one
private void EmulateContextualSerializer(T message, SerializationContext context)
{
var payload = this.serializer(message);
context.Complete(payload);
}
// for backward compatibility, emulate the contextual deserializer using the simple one
private T EmulateContextualDeserializer(DeserializationContext context)
{
return this.deserializer(context.PayloadAsNewBuffer());
}
internal class EmulatedSerializationContext : SerializationContext
{
bool isComplete;
byte[] payload;
public override void Complete(byte[] payload)
{
GrpcPreconditions.CheckState(!isComplete);
this.isComplete = true;
this.payload = payload;
}
internal byte[] GetPayload()
{
return this.payload;
}
}
internal class EmulatedDeserializationContext : DeserializationContext
{
readonly byte[] payload;
bool alreadyCalledPayloadAsNewBuffer;
public EmulatedDeserializationContext(byte[] payload)
{
this.payload = GrpcPreconditions.CheckNotNull(payload);
}
public override int PayloadLength => payload.Length;
public override byte[] PayloadAsNewBuffer()
{
GrpcPreconditions.CheckState(!alreadyCalledPayloadAsNewBuffer);
alreadyCalledPayloadAsNewBuffer = true;
return payload;
}
}
}
/// <summary>
/// Utilities for creating marshallers.
/// </summary>
public static class Marshallers
{
/// <summary>
/// Creates a marshaller from specified serializer and deserializer.
/// </summary>
public static Marshaller<T> Create<T>(Func<T, byte[]> serializer, Func<byte[], T> deserializer)
{
return new Marshaller<T>(serializer, deserializer);
}
/// <summary>
/// Creates a marshaller from specified contextual serializer and deserializer.
/// Note: This method is part of an experimental API that can change or be removed without any prior notice.
/// </summary>
public static Marshaller<T> Create<T>(Action<T, SerializationContext> serializer, Func<DeserializationContext, T> deserializer)
{
return new Marshaller<T>(serializer, deserializer);
}
/// <summary>
/// Returns a marshaller for <c>string</c> type. This is useful for testing.
/// </summary>
public static Marshaller<string> StringMarshaller
{
get
{
return new Marshaller<string>(System.Text.Encoding.UTF8.GetBytes,
System.Text.Encoding.UTF8.GetString);
}
}
}
}
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