polardbxengine/plugin/x/protocol/plugin/file_output.h

109 lines
3.1 KiB
C++

/*
* Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License, version 2.0,
* as published by the Free Software Foundation.
*
* This program is also distributed with certain software (including
* but not limited to OpenSSL) that is licensed under separate terms,
* as designated in a particular file or component or in included license
* documentation. The authors of MySQL hereby grant you an additional
* permission to link the program and your derivative works with the
* separately licensed software that they have included with MySQL.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License, version 2.0, for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef PLUGIN_X_PROTOCOL_PLUGIN_FILE_OUTPUT_H_
#define PLUGIN_X_PROTOCOL_PLUGIN_FILE_OUTPUT_H_
#include <google/protobuf/compiler/code_generator.h>
#include <google/protobuf/descriptor.h>
#include <google/protobuf/io/zero_copy_stream.h>
#include <algorithm>
#include <memory>
#include <set>
#include <string>
#include <utility>
#include <vector>
class File_output {
public:
using ZeroCopyOutputStream = google::protobuf::io::ZeroCopyOutputStream;
using Context = google::protobuf::compiler::GeneratorContext;
public:
explicit File_output(const std::string &name) : m_name(name) {}
virtual ~File_output() { close(); }
void close() {
if (m_file) {
write_footer(nullptr);
}
m_file.reset();
}
template <typename... Types>
void write_to_context(Context *context, Types &&... values) {
if (!m_file && context) {
m_file.reset(context->Open(m_name));
write_header(context);
}
writeln(std::forward<Types>(values)...);
}
virtual void write_header(Context *context) = 0;
virtual void write_footer(Context *context) = 0;
private:
bool write_bin(const char *buffer, size_t size) {
void *data;
int data_size;
if (!m_file) return false;
while (0 < size && m_file->Next(&data, &data_size)) {
const int pushed = std::min(data_size, static_cast<int>(size));
memcpy(data, buffer, pushed);
buffer += pushed;
size -= pushed;
if (pushed < data_size) m_file->BackUp(data_size - pushed);
}
return 0 == size;
}
bool write() { return true; }
template <typename... Types>
bool write(const std::string &value, Types &&... values) {
if (!write_bin(value.c_str(), value.length())) return false;
return write(std::forward<Types>(values)...);
}
template <typename... Types>
bool writeln(Types &&... values) {
return write(std::forward<Types>(values)..., "\n");
}
std::unique_ptr<ZeroCopyOutputStream> m_file;
std::string m_name;
};
#endif // PLUGIN_X_PROTOCOL_PLUGIN_FILE_OUTPUT_H_