serialize-packed.h 5.27 KB
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// Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributors
// Licensed under the MIT License:
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
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#pragma once
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#if defined(__GNUC__) && !defined(CAPNP_HEADER_WARNINGS)
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#pragma GCC system_header
#endif

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#include "serialize.h"

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namespace capnp {
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namespace _ {  // private
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class PackedInputStream: public kj::InputStream {
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  // An input stream that unpacks packed data with a picky constraint:  The caller must read data
  // in the exact same size and sequence as the data was written to PackedOutputStream.

public:
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  explicit PackedInputStream(kj::BufferedInputStream& inner);
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  KJ_DISALLOW_COPY(PackedInputStream);
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  ~PackedInputStream() noexcept(false);
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  // implements InputStream ------------------------------------------
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  size_t tryRead(void* buffer, size_t minBytes, size_t maxBytes) override;
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  void skip(size_t bytes) override;

private:
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  kj::BufferedInputStream& inner;
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};

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class PackedOutputStream: public kj::OutputStream {
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  // An output stream that packs data. Buffers passed to `write()` must be word-aligned.
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public:
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  explicit PackedOutputStream(kj::BufferedOutputStream& inner);
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  KJ_DISALLOW_COPY(PackedOutputStream);
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  ~PackedOutputStream() noexcept(false);
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  // implements OutputStream -----------------------------------------
  void write(const void* buffer, size_t bytes) override;

private:
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  kj::BufferedOutputStream& inner;
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};

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}  // namespace _ (private)
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class PackedMessageReader: private _::PackedInputStream, public InputStreamMessageReader {
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public:
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  PackedMessageReader(kj::BufferedInputStream& inputStream, ReaderOptions options = ReaderOptions(),
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                      kj::ArrayPtr<word> scratchSpace = nullptr);
  KJ_DISALLOW_COPY(PackedMessageReader);
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  ~PackedMessageReader() noexcept(false);
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};

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class PackedFdMessageReader: private kj::FdInputStream, private kj::BufferedInputStreamWrapper,
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                             public PackedMessageReader {
public:
  PackedFdMessageReader(int fd, ReaderOptions options = ReaderOptions(),
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                        kj::ArrayPtr<word> scratchSpace = nullptr);
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  // Read message from a file descriptor, without taking ownership of the descriptor.
  // Note that if you want to reuse the descriptor after the reader is destroyed, you'll need to
  // seek it, since otherwise the position is unspecified.

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  PackedFdMessageReader(kj::AutoCloseFd fd, ReaderOptions options = ReaderOptions(),
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                        kj::ArrayPtr<word> scratchSpace = nullptr);
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  // Read a message from a file descriptor, taking ownership of the descriptor.

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  KJ_DISALLOW_COPY(PackedFdMessageReader);
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  ~PackedFdMessageReader() noexcept(false);
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};

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void writePackedMessage(kj::BufferedOutputStream& output, MessageBuilder& builder);
void writePackedMessage(kj::BufferedOutputStream& output,
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                        kj::ArrayPtr<const kj::ArrayPtr<const word>> segments);
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// Write a packed message to a buffered output stream.

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void writePackedMessage(kj::OutputStream& output, MessageBuilder& builder);
void writePackedMessage(kj::OutputStream& output,
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                        kj::ArrayPtr<const kj::ArrayPtr<const word>> segments);
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// Write a packed message to an unbuffered output stream.  If you intend to write multiple messages
// in succession, consider wrapping your output in a buffered stream in order to reduce system
// call overhead.

void writePackedMessageToFd(int fd, MessageBuilder& builder);
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void writePackedMessageToFd(int fd, kj::ArrayPtr<const kj::ArrayPtr<const word>> segments);
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// Write a single packed message to the file descriptor.

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size_t computeUnpackedSizeInWords(kj::ArrayPtr<const byte> packedBytes);
// Computes the number of words to which the given packed bytes will unpack. Not intended for use
// in performance-sensitive situations.

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// =======================================================================================
// inline stuff

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inline void writePackedMessage(kj::BufferedOutputStream& output, MessageBuilder& builder) {
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  writePackedMessage(output, builder.getSegmentsForOutput());
}

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inline void writePackedMessage(kj::OutputStream& output, MessageBuilder& builder) {
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  writePackedMessage(output, builder.getSegmentsForOutput());
}

inline void writePackedMessageToFd(int fd, MessageBuilder& builder) {
  writePackedMessageToFd(fd, builder.getSegmentsForOutput());
}

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}  // namespace capnp