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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 1996, 1997, 1998, 1999, 2000
* Sleepycat Software. All rights reserved.
*
* $Id: mp.h,v 11.16 2001/01/10 04:50:53 ubell Exp $
*/
struct __bh; typedef struct __bh BH;
struct __db_mpool; typedef struct __db_mpool DB_MPOOL;
struct __db_mpreg; typedef struct __db_mpreg DB_MPREG;
struct __mpool; typedef struct __mpool MPOOL;
struct __mpoolfile; typedef struct __mpoolfile MPOOLFILE;
/* We require at least 40K of cache. */
#define DB_CACHESIZE_MIN (20 * 1024)
/*
* DB_MPOOL --
* Per-process memory pool structure.
*/
struct __db_mpool {
/* These fields need to be protected for multi-threaded support. */
MUTEX *mutexp; /* Structure thread lock. */
/* List of pgin/pgout routines. */
LIST_HEAD(__db_mpregh, __db_mpreg) dbregq;
/* List of DB_MPOOLFILE's. */
TAILQ_HEAD(__db_mpoolfileh, __db_mpoolfile) dbmfq;
/* These fields are not thread-protected. */
DB_ENV *dbenv; /* Reference to error information. */
u_int32_t nreg; /* N underlying cache regions. */
REGINFO *reginfo; /* Underlying cache regions. */
};
/*
* DB_MPREG --
* DB_MPOOL registry of pgin/pgout functions.
*/
struct __db_mpreg {
LIST_ENTRY(__db_mpreg) q; /* Linked list. */
int ftype; /* File type. */
/* Pgin, pgout routines. */
int (*pgin) __P((DB_ENV *, db_pgno_t, void *, DBT *));
int (*pgout) __P((DB_ENV *, db_pgno_t, void *, DBT *));
};
/*
* DB_MPOOLFILE --
* Per-process DB_MPOOLFILE information.
*/
struct __db_mpoolfile {
/* These fields need to be protected for multi-threaded support. */
MUTEX *mutexp; /* Structure thread lock. */
DB_FH fh; /* Underlying file handle. */
u_int32_t ref; /* Reference count. */
/*
* !!!
* This field is a special case -- it's protected by the region lock
* NOT the thread lock. The reason for this is that we always have
* the region lock immediately before or after we modify the field,
* and we don't want to use the structure lock to protect it because
* then I/O (which is done with the structure lock held because of
* the race between the seek and write of the file descriptor) will
* block any other put/get calls using this DB_MPOOLFILE structure.
*/
u_int32_t pinref; /* Pinned block reference count. */
/*
* !!!
* This field is a special case -- it's protected by the region lock
* since it's manipulated only when new files are added to the list.
*/
TAILQ_ENTRY(__db_mpoolfile) q; /* Linked list of DB_MPOOLFILE's. */
/* These fields are not thread-protected. */
DB_MPOOL *dbmp; /* Overlying DB_MPOOL. */
MPOOLFILE *mfp; /* Underlying MPOOLFILE. */
void *addr; /* Address of mmap'd region. */
size_t len; /* Length of mmap'd region. */
/* These fields need to be protected for multi-threaded support. */
#define MP_READONLY 0x01 /* File is readonly. */
#define MP_UPGRADE 0x02 /* File descriptor is readwrite. */
#define MP_UPGRADE_FAIL 0x04 /* Upgrade wasn't possible. */
u_int32_t flags;
};
/*
* NCACHE --
* Select a cache based on the page number. This assumes accesses are
* uniform across pages, which is probably OK -- what we really want to
* avoid is anything that puts all the pages for any single file in the
* same cache, as we expect that file access will be bursty.
*/
#define NCACHE(mp, pgno) \
((pgno) % ((MPOOL *)mp)->nreg)
/*
* NBUCKET --
* We make the assumption that early pages of the file are more likely
* to be retrieved than the later pages, which means the top bits will
* be more interesting for hashing as they're less likely to collide.
* That said, as 512 8K pages represents a 4MB file, so only reasonably
* large files will have page numbers with any other than the bottom 9
* bits set. We XOR in the MPOOL offset of the MPOOLFILE that backs the
* page, since that should also be unique for the page. We don't want
* to do anything very fancy -- speed is more important to us than using
* good hashing.
*/
#define NBUCKET(mc, mf_offset, pgno) \
(((pgno) ^ ((mf_offset) << 9)) % (mc)->htab_buckets)
/*
* MPOOL --
* Shared memory pool region.
*/
struct __mpool {
/*
* The memory pool can be broken up into individual pieces/files.
* Not what we would have liked, but on Solaris you can allocate
* only a little more than 2GB of memory in a contiguous chunk,
* and I expect to see more systems with similar issues.
*
* The first of these pieces/files describes the entire pool, all
* subsequent ones only describe a part of the cache.
*
* We single-thread memp_sync and memp_fsync calls.
*
* This mutex is intended *only* to single-thread access to the call,
* it is not used to protect the lsn and lsn_cnt fields, the region
* lock is used to protect them.
*/
MUTEX sync_mutex; /* Checkpoint lock. */
DB_LSN lsn; /* Maximum checkpoint LSN. */
u_int32_t lsn_cnt; /* Checkpoint buffers left to write. */
SH_TAILQ_HEAD(__mpfq) mpfq; /* List of MPOOLFILEs. */
u_int32_t nreg; /* Number of underlying REGIONS. */
roff_t regids; /* Array of underlying REGION Ids. */
#define MP_LSN_RETRY 0x01 /* Retry all BH_WRITE buffers. */
u_int32_t flags;
/*
* The following structure fields only describe the cache portion of
* the region.
*/
SH_TAILQ_HEAD(__bhq) bhq; /* LRU list of buffer headers. */
int htab_buckets; /* Number of hash table entries. */
roff_t htab; /* Hash table offset. */
DB_MPOOL_STAT stat; /* Per-cache mpool statistics. */
#ifdef MUTEX_SYSTEM_RESOURCES
roff_t maint_off; /* Maintenance information offset */
#endif
};
/*
* MPOOLFILE --
* Shared DB_MPOOLFILE information.
*/
struct __mpoolfile {
SH_TAILQ_ENTRY q; /* List of MPOOLFILEs */
db_pgno_t mpf_cnt; /* Ref count: DB_MPOOLFILEs. */
db_pgno_t block_cnt; /* Ref count: blocks in cache. */
db_pgno_t lsn_cnt; /* Checkpoint buffers left to write. */
int ftype; /* File type. */
int32_t lsn_off; /* Page's LSN offset. */
u_int32_t clear_len; /* Bytes to clear on page create. */
roff_t path_off; /* File name location. */
roff_t fileid_off; /* File identification location. */
roff_t pgcookie_len; /* Pgin/pgout cookie length. */
roff_t pgcookie_off; /* Pgin/pgout cookie location. */
db_pgno_t last_pgno; /* Last page in the file. */
db_pgno_t orig_last_pgno; /* Original last page in the file. */
DB_MPOOL_FSTAT stat; /* Per-file mpool statistics. */
#define MP_CAN_MMAP 0x01 /* If the file can be mmap'd. */
#define MP_DEADFILE 0x02 /* Dirty pages can simply be trashed. */
#define MP_TEMP 0x04 /* Backing file is a temporary. */
#define MP_UNLINK 0x08 /* Unlink file on last close. */
u_int32_t flags;
};
/*
* BH_TO_CACHE --
* Return the cache where we can find the specified buffer header.
*/
#define BH_TO_CACHE(dbmp, bhp) \
(dbmp)->reginfo[NCACHE((dbmp)->reginfo[0].primary, (bhp)->pgno)].primary
/*
* BH --
* Buffer header.
*/
struct __bh {
MUTEX mutex; /* Buffer thread/process lock. */
u_int16_t ref; /* Reference count. */
#define BH_CALLPGIN 0x001 /* Page needs to be reworked... */
#define BH_DIRTY 0x002 /* Page was modified. */
#define BH_DISCARD 0x004 /* Page is useless. */
#define BH_LOCKED 0x008 /* Page is locked (I/O in progress). */
#define BH_SYNC 0x010 /* memp sync: write the page */
#define BH_SYNC_LOGFLSH 0x020 /* memp sync: also flush the log */
#define BH_TRASH 0x040 /* Page is garbage. */
u_int16_t flags;
SH_TAILQ_ENTRY q; /* LRU queue. */
SH_TAILQ_ENTRY hq; /* MPOOL hash bucket queue. */
db_pgno_t pgno; /* Underlying MPOOLFILE page number. */
roff_t mf_offset; /* Associated MPOOLFILE offset. */
/*
* !!!
* This array must be at least size_t aligned -- the DB access methods
* put PAGE and other structures into it, and then access them directly.
* (We guarantee size_t alignment to applications in the documentation,
* too.)
*/
u_int8_t buf[1]; /* Variable length data. */
};
#include "mp_ext.h"
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