/*- * See the file LICENSE for redistribution information. * * Copyright (c) 1996, 1997, 1998 * Sleepycat Software. All rights reserved. * * @(#)mp.h 10.37 (Sleepycat) 1/1/99 */ struct __bh; typedef struct __bh BH; struct __db_mpreg; typedef struct __db_mpreg DB_MPREG; struct __mpool; typedef struct __mpool MPOOL; struct __mpoolfile; typedef struct __mpoolfile MPOOLFILE; /* Default mpool name. */ #define DB_DEFAULT_MPOOL_FILE "__db_mpool.share" /* * We default to 256K (32 8K pages) if the user doesn't specify, and * require a minimum of 20K. */ #ifndef DB_CACHESIZE_DEF #define DB_CACHESIZE_DEF (256 * 1024) #endif #define DB_CACHESIZE_MIN ( 20 * 1024) #define INVALID 0 /* Invalid shared memory offset. */ /* * There are three ways we do locking in the mpool code: * * Locking a handle mutex to provide concurrency for DB_THREAD operations. * Locking the region mutex to provide mutual exclusion while reading and * writing structures in the shared region. * Locking buffer header mutexes during I/O. * * The first will not be further described here. We use the shared mpool * region lock to provide mutual exclusion while reading/modifying all of * the data structures, including the buffer headers. We use a per-buffer * header lock to wait on buffer I/O. The order of locking is as follows: * * Searching for a buffer: * Acquire the region lock. * Find the buffer header. * Increment the reference count (guarantee the buffer stays). * While the BH_LOCKED flag is set (I/O is going on) { * Release the region lock. * Explicitly yield the processor if it's not the first pass * through this loop, otherwise, we can simply spin because * we'll be simply switching between the two locks. * Request the buffer lock. * The I/O will complete... * Acquire the buffer lock. * Release the buffer lock. * Acquire the region lock. * } * Return the buffer. * * Reading/writing a buffer: * Acquire the region lock. * Find/create the buffer header. * If reading, increment the reference count (guarantee the buffer stays). * Set the BH_LOCKED flag. * Acquire the buffer lock (guaranteed not to block). * Release the region lock. * Do the I/O and/or initialize the buffer contents. * Release the buffer lock. * At this point, the buffer lock is available, but the logical * operation (flagged by BH_LOCKED) is not yet completed. For * this reason, among others, threads checking the BH_LOCKED flag * must loop around their test. * Acquire the region lock. * Clear the BH_LOCKED flag. * Release the region lock. * Return/discard the buffer. * * Pointers to DB_MPOOL, MPOOL, DB_MPOOLFILE and MPOOLFILE structures are not * reacquired when a region lock is reacquired because they couldn't have been * closed/discarded and because they never move in memory. */ #define LOCKINIT(dbmp, mutexp) \ if (F_ISSET(dbmp, MP_LOCKHANDLE | MP_LOCKREGION)) \ (void)__db_mutex_init(mutexp, \ MUTEX_LOCK_OFFSET((dbmp)->reginfo.addr, mutexp)) #define LOCKHANDLE(dbmp, mutexp) \ if (F_ISSET(dbmp, MP_LOCKHANDLE)) \ (void)__db_mutex_lock(mutexp, (dbmp)->reginfo.fd) #define UNLOCKHANDLE(dbmp, mutexp) \ if (F_ISSET(dbmp, MP_LOCKHANDLE)) \ (void)__db_mutex_unlock(mutexp, (dbmp)->reginfo.fd) #define LOCKREGION(dbmp) \ if (F_ISSET(dbmp, MP_LOCKREGION)) \ (void)__db_mutex_lock(&((RLAYOUT *)(dbmp)->mp)->lock, \ (dbmp)->reginfo.fd) #define UNLOCKREGION(dbmp) \ if (F_ISSET(dbmp, MP_LOCKREGION)) \ (void)__db_mutex_unlock(&((RLAYOUT *)(dbmp)->mp)->lock, \ (dbmp)->reginfo.fd) #define LOCKBUFFER(dbmp, bhp) \ if (F_ISSET(dbmp, MP_LOCKREGION)) \ (void)__db_mutex_lock(&(bhp)->mutex, (dbmp)->reginfo.fd) #define UNLOCKBUFFER(dbmp, bhp) \ if (F_ISSET(dbmp, MP_LOCKREGION)) \ (void)__db_mutex_unlock(&(bhp)->mutex, (dbmp)->reginfo.fd) /* Check for region catastrophic shutdown. */ #define MP_PANIC_CHECK(dbmp) { \ if ((dbmp)->mp->rlayout.panic) \ return (DB_RUNRECOVERY); \ } /* * DB_MPOOL -- * Per-process memory pool structure. */ struct __db_mpool { /* These fields need to be protected for multi-threaded support. */ db_mutex_t *mutexp; /* Structure 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 protected. */ DB_ENV *dbenv; /* Reference to error information. */ REGINFO reginfo; /* Region information. */ MPOOL *mp; /* Address of the shared MPOOL. */ void *addr; /* Address of shalloc() region. */ DB_HASHTAB *htab; /* Hash table of bucket headers. */ #define MP_LOCKHANDLE 0x01 /* Threaded, lock handles and region. */ #define MP_LOCKREGION 0x02 /* Concurrent access, lock region. */ u_int32_t flags; }; /* * 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 (DB_CALLBACK *pgin) __P((db_pgno_t, void *, DBT *)); int (DB_CALLBACK *pgout) __P((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. */ db_mutex_t *mutexp; /* Structure lock. */ int fd; /* Underlying file descriptor. */ 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. */ /* These fields are not protected. */ TAILQ_ENTRY(__db_mpoolfile) q; /* Linked list of DB_MPOOLFILE's. */ 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; }; /* * MPOOL -- * Shared memory pool region. One of these is allocated in shared * memory, and describes the pool. */ struct __mpool { RLAYOUT rlayout; /* General region information. */ SH_TAILQ_HEAD(__bhq) bhq; /* LRU list of buckets. */ SH_TAILQ_HEAD(__bhfq) bhfq; /* Free buckets. */ SH_TAILQ_HEAD(__mpfq) mpfq; /* List of MPOOLFILEs. */ /* * We make the assumption that the early pages of the file are far * more likely to be retrieved than the later pages, which means * that the top bits are more interesting for hashing since they're * less likely to collide. On the other hand, since 512 4K pages * represents a 2MB file, only the bottom 9 bits of the page number * are likely to be set. We XOR in the offset in the MPOOL of the * MPOOLFILE that backs this particular page, since that should also * be unique for the page. */ #define BUCKET(mp, mf_offset, pgno) \ (((pgno) ^ ((mf_offset) << 9)) % (mp)->htab_buckets) size_t htab; /* Hash table offset. */ size_t htab_buckets; /* Number of hash table entries. */ DB_LSN lsn; /* Maximum checkpoint LSN. */ u_int32_t lsn_cnt; /* Checkpoint buffers left to write. */ DB_MPOOL_STAT stat; /* Global mpool statistics. */ #define MP_LSN_RETRY 0x01 /* Retry all BH_WRITE buffers. */ u_int32_t flags; }; /* * MPOOLFILE -- * Shared DB_MPOOLFILE information. */ struct __mpoolfile { SH_TAILQ_ENTRY q; /* List of MPOOLFILEs */ u_int32_t ref; /* Reference count. */ int ftype; /* File type. */ int32_t lsn_off; /* Page's LSN offset. */ u_int32_t clear_len; /* Bytes to clear on page create. */ size_t path_off; /* File name location. */ size_t fileid_off; /* File identification location. */ size_t pgcookie_len; /* Pgin/pgout cookie length. */ size_t pgcookie_off; /* Pgin/pgout cookie location. */ u_int32_t lsn_cnt; /* Checkpoint buffers left to write. */ db_pgno_t last_pgno; /* Last page in the file. */ db_pgno_t orig_last_pgno; /* Original last page in the file. */ #define MP_CAN_MMAP 0x01 /* If the file can be mmap'd. */ #define MP_TEMP 0x02 /* Backing file is a temporary. */ u_int32_t flags; DB_MPOOL_FSTAT stat; /* Per-file mpool statistics. */ }; /* * BH -- * Buffer header. */ struct __bh { db_mutex_t mutex; /* Structure 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_TRASH 0x010 /* Page is garbage. */ #define BH_WRITE 0x020 /* Page scheduled for writing. */ 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. */ size_t mf_offset; /* Associated MPOOLFILE offset. */ /* * !!! * This array must be size_t aligned -- the DB access methods put PAGE * and other structures into it, and expect to be able to access them * directly. (We guarantee size_t alignment in the db_mpool(3) manual * page as well.) */ u_int8_t buf[1]; /* Variable length data. */ }; #include "mp_ext.h"
