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Diffstat (limited to 'db/mpool.h')
| -rw-r--r-- | db/mpool.h | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/db/mpool.h b/db/mpool.h new file mode 100644 index 0000000000..40d1022309 --- /dev/null +++ b/db/mpool.h @@ -0,0 +1,99 @@ +/*- + * Copyright (c) 1991, 1993, 1994 + * 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 8.2 (Berkeley) 7/14/94 + */ + +#include <sys/queue.h> + +/* + * The memory pool scheme is a simple one. Each in-memory page is referenced + * by a bucket which is threaded in up to two of three ways. All active pages + * are threaded on a hash chain (hashed by page number) and an lru chain. + * Inactive pages are threaded on a free chain. Each reference to a memory + * pool is handed an opaque MPOOL cookie which stores all of this information. + */ +#define HASHSIZE 128 +#define HASHKEY(pgno) ((pgno - 1) % HASHSIZE) + +/* The BKT structures are the elements of the queues. */ +typedef struct _bkt { + CIRCLEQ_ENTRY(_bkt) hq; /* hash queue */ + CIRCLEQ_ENTRY(_bkt) q; /* lru queue */ + 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 */ + u_int8_t flags; /* flags */ +} BKT; + +typedef struct MPOOL { + CIRCLEQ_HEAD(_lqh, _bkt) lqh; /* lru queue head */ + /* hash queue array */ + CIRCLEQ_HEAD(_hqh, _bkt) hqh[HASHSIZE]; + 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 + u_long cachehit; + u_long cachemiss; + u_long pagealloc; + u_long pageflush; + u_long pageget; + u_long pagenew; + u_long pageput; + u_long pageread; + u_long pagewrite; +#endif +} MPOOL; + +__BEGIN_DECLS +MPOOL *mpool_open __P((void *, 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 |