NVcontainer.h

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#ifndef _NVcontainer_h_
#define _NVcontainer_h_

#include <fcntl.h>
#include <sys/file.h>
#include <sys/param.h>
#include <unistd.h>

#include "Debug.h"

#define NVcontainer_LOCKSTACKSIZE 16

typedef unsigned long nvtime_t;
typedef unsigned long nvoff_t;

extern nvtime_t nvtime(nvtime_t * nvt);

class NVcontainer {
        struct Header {
                unsigned int hlen;      /* 32 */
                unsigned int version;   /* 32 */
                nvoff_t size;           /* 32/64 */
                nvtime_t mtime;         /* 32/64 */
                nvoff_t freelist;       /* 32/64 */
                nvoff_t bytes_free;     /* 32/64 */
                nvoff_t userdata;       /* 32/64 */
                 Header() {
                        clear();
                } void clear() {
                        hlen = sizeof(Header);
                        version = 2;
                        size = hlen;
                        mtime = 0;
                        freelist = userdata = 0;
                        bytes_free = 0;
        }};
        struct FreeList {
                nvoff_t next;   /* 32/64 */
                nvoff_t size;   /* 32/64 */
        };
        int lck_stack[NVcontainer_LOCKSTACKSIZE];
        int lck_stackp;

        char mem_fn[MAXPATHLEN];
        int mem_fd;
        Header *mem_hdr;

        FreeList *o2fl(nvoff_t o) {
                return (FreeList *) (o ? mem_p + o : NULL);
        }
        nvoff_t fl2o(FreeList * r) {
                return r ? (char *) r - mem_p : 0;
        }

      protected:
        NVcontainer(void);
        NVcontainer(const char *dbname, int flags = 0);
        virtual ~ NVcontainer(void);

        char *mem_p;
        size_t mem_sz;

        /*
         * The method make_current map the database file into shared memory.
         * It does some sanety checks. If a error occours then the database
         * file ist renamed and close with rename_to_bad_and_close. If the
         * database filesize is changed, then it is necessary to 
         * \throw Error and SystemError
         */
        virtual void make_current(void);

        /*
         * Check if the the the file size is equal the memory mapped size.
         */
        virtual int is_current(void) {
                return mem_sz == mem_hdr->size;
        }
        virtual size_t resize(size_t nsz);

        nvoff_t getdata();
        nvoff_t getdatap();
        void setdata(nvoff_t d);

        nvoff_t nvalloc(size_t rsz);
        void nvfree(nvoff_t f);
      public:
        enum {
                UnLock = F_UNLCK,
                ShrdLock = F_RDLCK,
                ExclLock = F_WRLCK
        };
        enum {
                Block = 0x0,
                NoBlock = 0x1
        };

        int lock(int command, int block = Block);
        int get_lock(void);

        virtual void open(const char *dbname, int flags = 0);
        virtual int is_open(void);
        
        /*
         * Close the file and reset the internal data.
         */
        virtual void close(void);

        /*
         * If th sanity check signals a bad state of the database file,
         * then the rename_to_bad_close methods tries to rename the database.
         * It append .bad to the current filename. 
         * \author Herbert Straub
         * \date 2004
         */
        void rename_to_bad_and_close (void);

        void setmtime(nvtime_t tm, int force = 0);
        void getmtime(nvtime_t * tm);
};

/* We should add a general iterator class */
/*
class NVcontainterIter {
...
};
*/

#endif

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