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