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/*-
* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)mpool.h 8.1 (Berkeley) 6/2/93
*/
/*
* The memory pool scheme is a simple one. Each in memory page is referenced
* by a bucket which is threaded in three ways. All active pages are threaded
* on a hash chain (hashed by the page number) and an lru chain. Inactive
* pages are threaded on a free chain. Each reference to a memory pool is
* handed an MPOOL which is the opaque cookie passed to all of the memory
* routines.
*/
#define HASHSIZE 128
#define HASHKEY(pgno) ((pgno - 1) % HASHSIZE)
/* The BKT structures are the elements of the lists. */
typedef struct BKT {
struct BKT *hnext; /* next hash bucket */
struct BKT *hprev; /* previous hash bucket */
struct BKT *cnext; /* next free/lru bucket */
struct BKT *cprev; /* previous free/lru bucket */
void *page; /* page */
pgno_t pgno; /* page number */
#define MPOOL_DIRTY 0x01 /* page needs to be written */
#define MPOOL_PINNED 0x02 /* page is pinned into memory */
unsigned long flags; /* flags */
} BKT;
/* The BKTHDR structures are the heads of the lists. */
typedef struct BKTHDR {
struct BKT *hnext; /* next hash bucket */
struct BKT *hprev; /* previous hash bucket */
struct BKT *cnext; /* next free/lru bucket */
struct BKT *cprev; /* previous free/lru bucket */
} BKTHDR;
typedef struct MPOOL {
BKTHDR free; /* The free list. */
BKTHDR lru; /* The LRU list. */
BKTHDR hashtable[HASHSIZE]; /* Hashed list by page number. */
pgno_t curcache; /* Current number of cached pages. */
pgno_t maxcache; /* Max number of cached pages. */
pgno_t npages; /* Number of pages in the file. */
u_long pagesize; /* File page size. */
int fd; /* File descriptor. */
/* Page in conversion routine. */
void (*pgin) __P((void *, pgno_t, void *));
/* Page out conversion routine. */
void (*pgout) __P((void *, pgno_t, void *));
void *pgcookie; /* Cookie for page in/out routines. */
#ifdef STATISTICS
unsigned long cachehit;
unsigned long cachemiss;
unsigned long pagealloc;
unsigned long pageflush;
unsigned long pageget;
unsigned long pagenew;
unsigned long pageput;
unsigned long pageread;
unsigned long pagewrite;
#endif
} MPOOL;
#ifdef __MPOOLINTERFACE_PRIVATE
/* Macros to insert/delete into/from hash chain. */
#define rmhash(bp) { \
(bp)->hprev->hnext = (bp)->hnext; \
(bp)->hnext->hprev = (bp)->hprev; \
}
#define inshash(bp, pg) { \
hp = &mp->hashtable[HASHKEY(pg)]; \
(bp)->hnext = hp->hnext; \
(bp)->hprev = (struct BKT *)hp; \
hp->hnext->hprev = (bp); \
hp->hnext = (bp); \
}
/* Macros to insert/delete into/from lru and free chains. */
#define rmchain(bp) { \
(bp)->cprev->cnext = (bp)->cnext; \
(bp)->cnext->cprev = (bp)->cprev; \
}
#define inschain(bp, dp) { \
(bp)->cnext = (dp)->cnext; \
(bp)->cprev = (struct BKT *)(dp); \
(dp)->cnext->cprev = (bp); \
(dp)->cnext = (bp); \
}
#endif
__BEGIN_DECLS
MPOOL *mpool_open __P((DBT *, int, pgno_t, pgno_t));
void mpool_filter __P((MPOOL *, void (*)(void *, pgno_t, void *),
void (*)(void *, pgno_t, void *), void *));
void *mpool_new __P((MPOOL *, pgno_t *));
void *mpool_get __P((MPOOL *, pgno_t, u_int));
int mpool_put __P((MPOOL *, void *, u_int));
int mpool_sync __P((MPOOL *));
int mpool_close __P((MPOOL *));
#ifdef STATISTICS
void mpool_stat __P((MPOOL *));
#endif
__END_DECLS
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