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rocksdb/thrift/lib/cpp/transport/TMemPagedTransport.h

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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
*/
#ifndef _THRIFT_TRANSPORT_TMEMPAGEDTRANSPORT_H_
#define _THRIFT_TRANSPORT_TMEMPAGEDTRANSPORT_H_ 1
#include "thrift/lib/cpp/transport/TVirtualTransport.h"
#include "thrift/lib/cpp/transport/TMemPagedFactory.h"
#include <boost/shared_ptr.hpp>
namespace apache { namespace thrift { namespace transport {
using namespace boost;
/**
* Class TTransport for direct usage of paged memory
* NOT thread safe - for a higher performance trade-off
*/
class TMemPagedTransport : public TVirtualTransport<TMemPagedTransport> {
public:
/**
* Constructor
*/
TMemPagedTransport(shared_ptr<FixedSizeMemoryPageFactory>& factory);
/**
* Destructor
*/
~TMemPagedTransport();
/**
* Whether this transport is open.
*/
virtual bool isOpen();
/**
* Opens the transport.
*/
virtual void open();
/**
* Closes the transport.
*/
virtual void close();
/**
* Called when read is completed.
* This can be over-ridden to perform a transport-specific action
* e.g. logging the request to a file
*
* @return number of bytes read if available, 0 otherwise.
*/
virtual uint32_t readEnd();
/**
* Called when write is completed.
* This can be over-ridden to perform a transport-specific action
* at the end of a request.
*
* @return number of bytes written if available, 0 otherwise
*/
virtual uint32_t writeEnd();
/**
* Implementations of the base functions
*/
inline uint32_t read(uint8_t* buf, uint32_t len);
inline void write(const uint8_t* buf, uint32_t len);
inline const uint8_t* borrow(uint8_t* buf, uint32_t* len);
inline void consume(uint32_t len);
inline uint32_t readAll(uint8_t* buf, uint32_t len);
/**
* interface extension, not part of the TTrasport
* make sure there are some bytes for write at the same page available
*/
inline uint8_t* reserve(uint32_t* len, bool throwOnError = true);
/**
* interface extension, not part of the TTrasport
* similar to consume but for the write
*/
inline void skip(uint32_t len);
/**
* Reset buffer for read
* Sets read offset to zero
*/
inline void resetForRead();
/**
* Reset buffer for write
* Sets write offset to zero and releases extra memory pages
*/
inline void resetForWrite(bool releaseAllPages = false);
/**
* Returns number of bytes already read from buffer
*/
inline uint32_t getReadBytes() const;
/**
* Returns current bytes written in buffer
*/
inline uint32_t getWrittenBytes() const;
private:
/**
* helper function
* write or skip bytes
*/
inline void set(const uint8_t* buf, uint32_t len);
/**
* helper function
* read or skip bytes
*/
inline uint32_t get(uint8_t* buf, uint32_t len);
private:
shared_ptr<FixedSizeMemoryPageFactory> factory_; //!< memory pages factory
const uint32_t pageSize_; //!< page size
FixedSizeMemoryPage* headPage_; //!< head of the stack
FixedSizeMemoryPage* currentReadPage_; //!< current read page
uint32_t currentReadOffset_; //!< bytes already read
FixedSizeMemoryPage* currentWritePage_; //!< current write page
uint32_t currentWriteOffset_; //!< bytes already written
};
}}} // apache::thrift::transport
#endif // #ifndef _THRIFT_TRANSPORT_TMEMPAGEDTRANSPORT_H_