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111 lines
3.5 KiB
C++
111 lines
3.5 KiB
C++
/* Copyright (C) 2014 InfiniDB, Inc.
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; version 2 of
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the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, USA. */
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/*
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* InfiniDB FOSS License Exception
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* We want free and open source software applications under certain
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* licenses to be able to use the GPL-licensed InfiniDB idbhdfs
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* libraries despite the fact that not all such FOSS licenses are
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* compatible with version 2 of the GNU General Public License.
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* Therefore there are special exceptions to the terms and conditions
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* of the GPLv2 as applied to idbhdfs libraries, which are
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* identified and described in more detail in the FOSS License
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* Exception in the file utils/idbhdfs/FOSS-EXCEPTION.txt
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*/
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#ifndef HDFSRDWRMEMBUFFER_H_
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#define HDFSRDWRMEMBUFFER_H_
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#include <stdexcept>
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#include <boost/utility.hpp>
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#include "hdfs.h"
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#include "IDBDataFile.h"
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namespace idbdatafile
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{
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class HdfsRdwrFileBuffer;
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/**
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* HdfsRdwrMemBuffer implements IDBDataFile for a file in the Hadoop file system
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* (HDFS). This file type is special in that it allows random access to a
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* file open for writing - this is not typically allowed by HDFS. It does
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* this by maintaining an internal buffer. All operations occur in memory
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* until the final write to disk upon close().
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*/
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class HdfsRdwrMemBuffer: public IDBDataFile, boost::noncopyable
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{
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public:
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HdfsRdwrMemBuffer(const char* fname, const char* mode, unsigned opts, unsigned defsize);
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/* virtual */ ~HdfsRdwrMemBuffer();
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/* virtual */ ssize_t pread(void* ptr, off64_t offset, size_t count);
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/* virtual */ ssize_t read(void* ptr, size_t count);
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/* virtual */ ssize_t write(const void* ptr, size_t count);
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/* virtual */ int seek(off64_t offset, int whence);
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/* virtual */ int truncate(off64_t length);
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/* virtual */ off64_t size();
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/* virtual */ off64_t tell();
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/* virtual */ int flush();
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/* virtual */ time_t mtime();
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/* virtual */ int fallocate(int mode, off64_t offset, off64_t length);
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// Returns the total size of all currently allocated HdfsRdwrMemBuffers
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static size_t getTotalBuff()
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{
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return t_totalbuff;
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}
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// This is used by HdfsRdwrFileBuffer constructor to dump our buffer
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// contents to a file when we run out of memory
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const unsigned char* getbuffer() const
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{
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return m_buffer;
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}
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off64_t getSize()
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{
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return m_size; // TODO: remove after debug
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}
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protected:
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/* virtual */
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int close();
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private:
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void allocBuffer(size_t size);
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// the size parm should be understood as 'needs at least size more bytes from the current position'
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void checkRealloc(size_t size);
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void releaseBuffer();
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int flushImpl();
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uint8_t* m_buffer;
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off64_t m_cur;
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off64_t m_last;
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off64_t m_size;
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bool m_dirty;
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bool m_new;
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bool m_noflush;
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static int64_t t_totalbuff;
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HdfsRdwrFileBuffer* m_pFileBuffer;
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};
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}
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#endif /* HDFSRDWRMEMBUFFER_H_ */
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