file_hash.h

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/*
 * Copyright 2008 Search Solution Corporation
 * Copyright 2016 CUBRID Corporation
 *
 *  Licensed 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.
 *
 */


/*
 *      file_hash.h: File Hashing
 */

#ifndef _FILE_HASH_H_
#define _FILE_HASH_H_

#ident "$Id$"

#include "config.h"
#include "error_manager.h"
#include "oid.h"

/* hash key and data */
typedef struct fh_info
{
  union
  {
    struct
    {
      OID key;
      char data;
    } fh_oidkey;
    struct
    {
      int key;
      char data;
    } fh_intkey;
  } fh_key_data;
} FH_INFO;

#define fh_oidk_key  fh_key_data.fh_oidkey.key
#define fh_oidk_data fh_key_data.fh_oidkey.data
#define fh_intk_key  fh_key_data.fh_intkey.key
#define fh_intk_data fh_key_data.fh_intkey.data

typedef unsigned int FH_FILE_POS;
#define INVALID_FILE_POS (FH_FILE_POS)~0

/* A hash table entry.  */
typedef struct fh_entry
{
  FH_FILE_POS next;     /* Collision chain */
  FH_INFO info;         /* Key & data */
} FH_ENTRY;

typedef struct fh_entry *FH_ENTRY_PTR;

/* header for a page of fh_entry's */
typedef struct fh_page_hdr
{
  struct fh_page_hdr *next; /* Next header */
  struct fh_page_hdr *prev; /* Previous header */
  struct fh_entry *fh_entries;  /* Location of fh_entry's */
  FH_FILE_POS page;     /* Hash file page number */
} FH_PAGE_HDR;

typedef unsigned int (*HASH_FUNC) (const void *info, unsigned int htsize);
typedef int (*CMP_FUNC) (const void *key1, const void *key2);

typedef enum
{
  FH_OID_KEY = 1,
  FH_INT_KEY = 2
} FH_KEY_TYPE;

/* Hash table */
typedef struct fh_table
{
  HASH_FUNC hfun;       /* Hash function */
  CMP_FUNC cmpfun;      /* How to compare keys */
  const char *name;     /* Name of Table */
  FH_PAGE_HDR *pg_hdr;      /* The page headers */
  FH_PAGE_HDR *pg_hdr_last; /* The last page's header */
  FH_PAGE_HDR *pg_hdr_free; /* The first free pages's header */
  FH_PAGE_HDR *pg_hdr_alloc;    /* The page header address allocated */
  int size;         /* Better if prime number */
  int page_size;        /* Number of bytes per page */
  int data_size;        /* Number of bytes of data per entry */
  int entry_size;       /* Number of bytes per entry */
  int entries_per_page;     /* Number of fh_entry's per page */
  int cached_pages;     /* Number of cached pages */
  FH_FILE_POS overflow;     /* Page & entry for overflow */
  int nentries;         /* Actual number of entries */
  int ncollisions;      /* Number of collisions */
  char *hash_filename;      /* Hash file pathname */
  int fd;           /* Hash file file descriptor */
  FH_KEY_TYPE key_type;     /* Type of key */
  char *bitmap;         /* Bitmap for used pages */
  int bitmap_size;      /* Size of page bitmap */
} FH_TABLE;

typedef void *FH_KEY;
typedef void *FH_DATA;

FH_TABLE *fh_create (const char *, int, int, int, const char *, FH_KEY_TYPE, int, HASH_FUNC, CMP_FUNC);
int fh_put (FH_TABLE * ht, FH_KEY key, FH_DATA data);
int fh_get (FH_TABLE * ht, FH_KEY key, FH_DATA * data);
void fh_destroy (FH_TABLE * ht);
void fh_dump (FH_TABLE * ht);

#endif /* _FILE_HASH_H_ */