#region Copyright notice and license
// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
// https://developers.google.com/protocol-buffers/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#endregion
using System;
using System.Buffers;
using System.IO;
using System.Runtime.CompilerServices;
using System.Security;
namespace Google.Protobuf
{
/// <summary>
/// Abstraction for writing to a steam / IBufferWriter
/// </summary>
[SecuritySafeCritical]
internal struct WriteBufferHelper
{
private IBufferWriter<byte> bufferWriter;
private CodedOutputStream codedOutputStream;
public CodedOutputStream CodedOutputStream => codedOutputStream;
/// <summary>
/// Initialize an instance with a coded output stream.
/// This approach is faster than using a constructor because the instance to initialize is passed by reference
/// and we can write directly into it without copying.
/// </summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static void Initialize(CodedOutputStream codedOutputStream, out WriteBufferHelper instance)
{
instance.bufferWriter = null;
instance.codedOutputStream = codedOutputStream;
}
/// <summary>
/// Initialize an instance with a buffer writer.
/// This approach is faster than using a constructor because the instance to initialize is passed by reference
/// and we can write directly into it without copying.
/// </summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static void Initialize(IBufferWriter<byte> bufferWriter, out WriteBufferHelper instance, out Span<byte> buffer)
{
instance.bufferWriter = bufferWriter;
instance.codedOutputStream = null;
buffer = default; // TODO: initialize the initial buffer so that the first write is not via slowpath.
}
/// <summary>
/// Initialize an instance with a buffer represented by a single span (i.e. buffer cannot be refreshed)
/// This approach is faster than using a constructor because the instance to initialize is passed by reference
/// and we can write directly into it without copying.
/// </summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static void InitializeNonRefreshable(out WriteBufferHelper instance)
{
instance.bufferWriter = null;
instance.codedOutputStream = null;
}
/// <summary>
/// Verifies that SpaceLeft returns zero.
/// </summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static void CheckNoSpaceLeft(ref WriterInternalState state)
{
if (GetSpaceLeft(ref state) != 0)
{
throw new InvalidOperationException("Did not write as much data as expected.");
}
}
/// <summary>
/// If writing to a flat array, returns the space left in the array. Otherwise,
/// throws an InvalidOperationException.
/// </summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static int GetSpaceLeft(ref WriterInternalState state)
{
if (state.writeBufferHelper.codedOutputStream?.InternalOutputStream == null && state.writeBufferHelper.bufferWriter == null)
{
return state.limit - state.position;
}
else
{
throw new InvalidOperationException(
"SpaceLeft can only be called on CodedOutputStreams that are " +
"writing to a flat array or when writing to a single span.");
}
}
[MethodImpl(MethodImplOptions.NoInlining)]
public static void RefreshBuffer(ref Span<byte> buffer, ref WriterInternalState state)
{
if (state.writeBufferHelper.codedOutputStream?.InternalOutputStream != null)
{
// because we're using coded output stream, we know that "buffer" and codedOutputStream.InternalBuffer are identical.
state.writeBufferHelper.codedOutputStream.InternalOutputStream.Write(state.writeBufferHelper.codedOutputStream.InternalBuffer, 0, state.position);
// reset position, limit stays the same because we are reusing the codedOutputStream's internal buffer.
state.position = 0;
}
else if (state.writeBufferHelper.bufferWriter != null)
{
// commit the bytes and get a new buffer to write to.
state.writeBufferHelper.bufferWriter.Advance(state.position);
state.position = 0;
buffer = state.writeBufferHelper.bufferWriter.GetSpan();
state.limit = buffer.Length;
}
else
{
// We're writing to a single buffer.
throw new CodedOutputStream.OutOfSpaceException();
}
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static void Flush(ref Span<byte> buffer, ref WriterInternalState state)
{
if (state.writeBufferHelper.codedOutputStream?.InternalOutputStream != null)
{
// because we're using coded output stream, we know that "buffer" and codedOutputStream.InternalBuffer are identical.
state.writeBufferHelper.codedOutputStream.InternalOutputStream.Write(state.writeBufferHelper.codedOutputStream.InternalBuffer, 0, state.position);
state.position = 0;
}
else if (state.writeBufferHelper.bufferWriter != null)
{
// calling Advance invalidates the current buffer and we must not continue writing to it,
// so we set the current buffer to point to an empty Span. If any subsequent writes happen,
// the first subsequent write will trigger refresing of the buffer.
state.writeBufferHelper.bufferWriter.Advance(state.position);
state.position = 0;
state.limit = 0;
buffer = default; // invalidate the current buffer
}
}
}
}
Codebase Browser
chromium