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Diffstat (limited to 'src/google/protobuf/io/zero_copy_stream_impl.h')
| -rw-r--r-- | src/google/protobuf/io/zero_copy_stream_impl.h | 356 |
1 files changed, 356 insertions, 0 deletions
diff --git a/src/google/protobuf/io/zero_copy_stream_impl.h b/src/google/protobuf/io/zero_copy_stream_impl.h new file mode 100644 index 0000000..64e96cd --- /dev/null +++ b/src/google/protobuf/io/zero_copy_stream_impl.h @@ -0,0 +1,356 @@ +// Protocol Buffers - Google's data interchange format +// Copyright 2008 Google Inc. All rights reserved. +// http://code.google.com/p/protobuf/ +// +// 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. + +// Author: kenton@google.com (Kenton Varda) +// Based on original Protocol Buffers design by +// Sanjay Ghemawat, Jeff Dean, and others. +// +// This file contains common implementations of the interfaces defined in +// zero_copy_stream.h which are only included in the full (non-lite) +// protobuf library. These implementations include Unix file descriptors +// and C++ iostreams. See also: zero_copy_stream_impl_lite.h + +#ifndef GOOGLE_PROTOBUF_IO_ZERO_COPY_STREAM_IMPL_H__ +#define GOOGLE_PROTOBUF_IO_ZERO_COPY_STREAM_IMPL_H__ + +#include <string> +#include <iosfwd> +#include <google/protobuf/io/zero_copy_stream.h> +#include <google/protobuf/io/zero_copy_stream_impl_lite.h> +#include <google/protobuf/stubs/common.h> + + +namespace google { +namespace protobuf { +namespace io { + + +// =================================================================== + +// A ZeroCopyInputStream which reads from a file descriptor. +// +// FileInputStream is preferred over using an ifstream with IstreamInputStream. +// The latter will introduce an extra layer of buffering, harming performance. +// Also, it's conceivable that FileInputStream could someday be enhanced +// to use zero-copy file descriptors on OSs which support them. +class LIBPROTOBUF_EXPORT FileInputStream : public ZeroCopyInputStream { + public: + // Creates a stream that reads from the given Unix file descriptor. + // If a block_size is given, it specifies the number of bytes that + // should be read and returned with each call to Next(). Otherwise, + // a reasonable default is used. + explicit FileInputStream(int file_descriptor, int block_size = -1); + ~FileInputStream(); + + // Flushes any buffers and closes the underlying file. Returns false if + // an error occurs during the process; use GetErrno() to examine the error. + // Even if an error occurs, the file descriptor is closed when this returns. + bool Close(); + + // By default, the file descriptor is not closed when the stream is + // destroyed. Call SetCloseOnDelete(true) to change that. WARNING: + // This leaves no way for the caller to detect if close() fails. If + // detecting close() errors is important to you, you should arrange + // to close the descriptor yourself. + void SetCloseOnDelete(bool value) { copying_input_.SetCloseOnDelete(value); } + + // If an I/O error has occurred on this file descriptor, this is the + // errno from that error. Otherwise, this is zero. Once an error + // occurs, the stream is broken and all subsequent operations will + // fail. + int GetErrno() { return copying_input_.GetErrno(); } + + // implements ZeroCopyInputStream ---------------------------------- + bool Next(const void** data, int* size); + void BackUp(int count); + bool Skip(int count); + int64 ByteCount() const; + + private: + class LIBPROTOBUF_EXPORT CopyingFileInputStream : public CopyingInputStream { + public: + CopyingFileInputStream(int file_descriptor); + ~CopyingFileInputStream(); + + bool Close(); + void SetCloseOnDelete(bool value) { close_on_delete_ = value; } + int GetErrno() { return errno_; } + + // implements CopyingInputStream --------------------------------- + int Read(void* buffer, int size); + int Skip(int count); + + private: + // The file descriptor. + const int file_; + bool close_on_delete_; + bool is_closed_; + + // The errno of the I/O error, if one has occurred. Otherwise, zero. + int errno_; + + // Did we try to seek once and fail? If so, we assume this file descriptor + // doesn't support seeking and won't try again. + bool previous_seek_failed_; + + GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(CopyingFileInputStream); + }; + + CopyingFileInputStream copying_input_; + CopyingInputStreamAdaptor impl_; + + GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(FileInputStream); +}; + +// =================================================================== + +// A ZeroCopyOutputStream which writes to a file descriptor. +// +// FileInputStream is preferred over using an ofstream with OstreamOutputStream. +// The latter will introduce an extra layer of buffering, harming performance. +// Also, it's conceivable that FileInputStream could someday be enhanced +// to use zero-copy file descriptors on OSs which support them. +class LIBPROTOBUF_EXPORT FileOutputStream : public ZeroCopyOutputStream { + public: + // Creates a stream that writes to the given Unix file descriptor. + // If a block_size is given, it specifies the size of the buffers + // that should be returned by Next(). Otherwise, a reasonable default + // is used. + explicit FileOutputStream(int file_descriptor, int block_size = -1); + ~FileOutputStream(); + + // Flushes any buffers and closes the underlying file. Returns false if + // an error occurs during the process; use GetErrno() to examine the error. + // Even if an error occurs, the file descriptor is closed when this returns. + bool Close(); + + // Flushes FileOutputStream's buffers but does not close the + // underlying file. No special measures are taken to ensure that + // underlying operating system file object is synchronized to disk. + bool Flush(); + + // By default, the file descriptor is not closed when the stream is + // destroyed. Call SetCloseOnDelete(true) to change that. WARNING: + // This leaves no way for the caller to detect if close() fails. If + // detecting close() errors is important to you, you should arrange + // to close the descriptor yourself. + void SetCloseOnDelete(bool value) { copying_output_.SetCloseOnDelete(value); } + + // If an I/O error has occurred on this file descriptor, this is the + // errno from that error. Otherwise, this is zero. Once an error + // occurs, the stream is broken and all subsequent operations will + // fail. + int GetErrno() { return copying_output_.GetErrno(); } + + // implements ZeroCopyOutputStream --------------------------------- + bool Next(void** data, int* size); + void BackUp(int count); + int64 ByteCount() const; + + private: + class LIBPROTOBUF_EXPORT CopyingFileOutputStream : public CopyingOutputStream { + public: + CopyingFileOutputStream(int file_descriptor); + ~CopyingFileOutputStream(); + + bool Close(); + void SetCloseOnDelete(bool value) { close_on_delete_ = value; } + int GetErrno() { return errno_; } + + // implements CopyingOutputStream -------------------------------- + bool Write(const void* buffer, int size); + + private: + // The file descriptor. + const int file_; + bool close_on_delete_; + bool is_closed_; + + // The errno of the I/O error, if one has occurred. Otherwise, zero. + int errno_; + + GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(CopyingFileOutputStream); + }; + + CopyingFileOutputStream copying_output_; + CopyingOutputStreamAdaptor impl_; + + GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(FileOutputStream); +}; + +// =================================================================== + +// A ZeroCopyInputStream which reads from a C++ istream. +// +// Note that for reading files (or anything represented by a file descriptor), +// FileInputStream is more efficient. +class LIBPROTOBUF_EXPORT IstreamInputStream : public ZeroCopyInputStream { + public: + // Creates a stream that reads from the given C++ istream. + // If a block_size is given, it specifies the number of bytes that + // should be read and returned with each call to Next(). Otherwise, + // a reasonable default is used. + explicit IstreamInputStream(istream* stream, int block_size = -1); + ~IstreamInputStream(); + + // implements ZeroCopyInputStream ---------------------------------- + bool Next(const void** data, int* size); + void BackUp(int count); + bool Skip(int count); + int64 ByteCount() const; + + private: + class LIBPROTOBUF_EXPORT CopyingIstreamInputStream : public CopyingInputStream { + public: + CopyingIstreamInputStream(istream* input); + ~CopyingIstreamInputStream(); + + // implements CopyingInputStream --------------------------------- + int Read(void* buffer, int size); + // (We use the default implementation of Skip().) + + private: + // The stream. + istream* input_; + + GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(CopyingIstreamInputStream); + }; + + CopyingIstreamInputStream copying_input_; + CopyingInputStreamAdaptor impl_; + + GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(IstreamInputStream); +}; + +// =================================================================== + +// A ZeroCopyOutputStream which writes to a C++ ostream. +// +// Note that for writing files (or anything represented by a file descriptor), +// FileOutputStream is more efficient. +class LIBPROTOBUF_EXPORT OstreamOutputStream : public ZeroCopyOutputStream { + public: + // Creates a stream that writes to the given C++ ostream. + // If a block_size is given, it specifies the size of the buffers + // that should be returned by Next(). Otherwise, a reasonable default + // is used. + explicit OstreamOutputStream(ostream* stream, int block_size = -1); + ~OstreamOutputStream(); + + // implements ZeroCopyOutputStream --------------------------------- + bool Next(void** data, int* size); + void BackUp(int count); + int64 ByteCount() const; + + private: + class LIBPROTOBUF_EXPORT CopyingOstreamOutputStream : public CopyingOutputStream { + public: + CopyingOstreamOutputStream(ostream* output); + ~CopyingOstreamOutputStream(); + + // implements CopyingOutputStream -------------------------------- + bool Write(const void* buffer, int size); + + private: + // The stream. + ostream* output_; + + GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(CopyingOstreamOutputStream); + }; + + CopyingOstreamOutputStream copying_output_; + CopyingOutputStreamAdaptor impl_; + + GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(OstreamOutputStream); +}; + +// =================================================================== + +// A ZeroCopyInputStream which reads from several other streams in sequence. +// ConcatenatingInputStream is unable to distinguish between end-of-stream +// and read errors in the underlying streams, so it assumes any errors mean +// end-of-stream. So, if the underlying streams fail for any other reason, +// ConcatenatingInputStream may do odd things. It is suggested that you do +// not use ConcatenatingInputStream on streams that might produce read errors +// other than end-of-stream. +class LIBPROTOBUF_EXPORT ConcatenatingInputStream : public ZeroCopyInputStream { + public: + // All streams passed in as well as the array itself must remain valid + // until the ConcatenatingInputStream is destroyed. + ConcatenatingInputStream(ZeroCopyInputStream* const streams[], int count); + ~ConcatenatingInputStream(); + + // implements ZeroCopyInputStream ---------------------------------- + bool Next(const void** data, int* size); + void BackUp(int count); + bool Skip(int count); + int64 ByteCount() const; + + + private: + // As streams are retired, streams_ is incremented and count_ is + // decremented. + ZeroCopyInputStream* const* streams_; + int stream_count_; + int64 bytes_retired_; // Bytes read from previous streams. + + GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(ConcatenatingInputStream); +}; + +// =================================================================== + +// A ZeroCopyInputStream which wraps some other stream and limits it to +// a particular byte count. +class LIBPROTOBUF_EXPORT LimitingInputStream : public ZeroCopyInputStream { + public: + LimitingInputStream(ZeroCopyInputStream* input, int64 limit); + ~LimitingInputStream(); + + // implements ZeroCopyInputStream ---------------------------------- + bool Next(const void** data, int* size); + void BackUp(int count); + bool Skip(int count); + int64 ByteCount() const; + + + private: + ZeroCopyInputStream* input_; + int64 limit_; // Decreases as we go, becomes negative if we overshoot. + + GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(LimitingInputStream); +}; + +// =================================================================== + +} // namespace io +} // namespace protobuf + +} // namespace google +#endif // GOOGLE_PROTOBUF_IO_ZERO_COPY_STREAM_IMPL_H__ |