LCOV - lcov.info - /usr/include/tagcoll-2.0.11/tagcoll/diskindex/mmap.h

LTP GCOV extension - code coverage report
Current view: | directory - usr/include/tagcoll-2.0.11/tagcoll/diskindex - mmap.h
Test: | lcov.info
Date: | 2008-08-14 |  | Instrumented lines: | 4
Code covered: | 100.0 % |  | Executed lines: | 4

           1                 : #ifndef TAGCOLL_DISKINDEX_MMAP_H
           2                 : #define TAGCOLL_DISKINDEX_MMAP_H
           3                 :
           4                 : /** \file
           5                 :  * Basic infrastructure for implementing mmapped indexes
           6                 :  */
           7                 :
           8                 : /*
           9                 :  * Copyright (C) 2006  Enrico Zini <enrico@debian.org>
          10                 :  *
          11                 :  * This program is free software; you can redistribute it and/or modify
          12                 :  * it under the terms of the GNU General Public License as published by
          13                 :  * the Free Software Foundation; either version 2 of the License, or
          14                 :  * (at your option) any later version.
          15                 :  *
          16                 :  * This program is distributed in the hope that it will be useful,
          17                 :  * but WITHOUT ANY WARRANTY; without even the implied warranty of
          18                 :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
          19                 :  * GNU General Public License for more details.
          20                 :  *
          21                 :  * You should have received a copy of the GNU General Public License
          22                 :  * along with this program; if not, write to the Free Software
          23                 :  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
          24                 :  */
          25                 :
          26                 : #include <string>
          27                 :
          28                 : namespace tagcoll {
          29                 : namespace diskindex {
          30                 :
          31                 : class mmap;
          32                 :
          33                 : /**
          34                 :  * Performs the memory management and mmapping tasks for mmapped indexes.
          35                 :  *
          36                 :  * One MMap can contain many indexes.  Indexes come chained one after the
          37                 :  * other, prefixed by an int that specifies their length:
          38                 :  *
          39                 :  * [size of index 1][index1][size of index 2][index]...
          40                 :  *
          41                 :  * Every index must make sure that its size is int-aligned, otherwise accessing
          42                 :  * it would cause a bus error in many architectures.
          43                 :  */
          44                 : class MasterMMap
          45                 : {
          46                 : protected:
          47                 :         std::string m_filename;
          48                 :         size_t m_size;
          49                 :         int m_fd;
          50                 :         const char* m_buf;
          51                 :
          52                 : public:
          53                 :         MasterMMap();
          54                 :         MasterMMap(const std::string& filename);
          55                 :         ~MasterMMap();
          56                 :
          57                 :         void init(const std::string& filename);
          58                 :
          59                 :         friend class MMap;
          60                 : };
          61                 :
          62                 : class MMap
          63                 : {
          64                 : protected:
          65                 :         const MasterMMap* m_master;
          66                 :         const char* m_buf;
          67                 :         size_t m_size;
          68                 :
          69                 : public:
          70                 :         MMap();
          71                 :         MMap(const char* buf, int size);
          72                 :         MMap(const MasterMMap& master, size_t idx);
          73                 :
          74                 :         void init(const char* buf, int size);
          75                 :         void init(const MasterMMap& master, size_t idx);
          76                 :
          77                 :         /// Round a value to the next word size in the current architecture
          78                 :         template<class INT>
          79              12 :         static inline INT align(INT val)
          80                 :         {
          81              12 :                 return (val + sizeof(int) - 1) & ~(sizeof(int) - 1);
          82                 :         }
          83                 : };
          84                 :
          85                 : /**
          86                 :  * Interface for indexers.
          87                 :  */
          88                 : class MMapIndexer
          89              20 : {
          90                 : public:
          91              20 :         virtual ~MMapIndexer() {}
          92                 :
          93                 :         /// Return the size of the encoded index data (in bytes)
          94                 :         virtual int encodedSize() const = 0;
          95                 :
          96                 :         /// Write the index data in the given buffer, which should be at least
          97                 :         /// encodedSize bytes
          98                 :         virtual void encode(char* buf) const = 0;
          99                 : };
         100                 :
         101                 : /**
         102                 :  * Master index writer.  It allows to write many indexes in the same file,
         103                 :  * atomically: the file will be created as a tempfile and atomically renamed to
         104                 :  * the destination filename on class destruction.
         105                 :  */
         106                 : class MasterMMapIndexer
         107                 : {
         108                 : protected:
         109                 :         std::string finalname;
         110                 :         std::string tmpname;
         111                 :         int fd;
         112                 :
         113                 : public:
         114                 :         MasterMMapIndexer(const std::string& filename);
         115                 :         ~MasterMMapIndexer();
         116                 :
         117                 :         /// Close the file and perform the final rename
         118                 :         void commit();
         119                 :
         120                 :         /// Append one subindex
         121                 :         void append(const MMapIndexer& idx);
         122                 : };
         123                 :
         124                 :
         125                 : }
         126                 : }
         127                 :
         128                 : // vim:set ts=4 sw=4:
         129                 : #endif

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