diff options
Diffstat (limited to 'db2/mp/mp_region.c')
| -rw-r--r-- | db2/mp/mp_region.c | 340 |
1 files changed, 340 insertions, 0 deletions
diff --git a/db2/mp/mp_region.c b/db2/mp/mp_region.c new file mode 100644 index 0000000000..a5c52123b9 --- /dev/null +++ b/db2/mp/mp_region.c @@ -0,0 +1,340 @@ +/*- + * See the file LICENSE for redistribution information. + * + * Copyright (c) 1996, 1997 + * Sleepycat Software. All rights reserved. + */ +#include "config.h" + +#ifndef lint +static const char sccsid[] = "@(#)mp_region.c 10.11 (Sleepycat) 8/2/97"; +#endif /* not lint */ + +#ifndef NO_SYSTEM_INCLUDES +#include <sys/types.h> +#include <sys/stat.h> + +#include <errno.h> +#include <fcntl.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#endif + +#include "db_int.h" +#include "shqueue.h" +#include "db_shash.h" +#include "mp.h" +#include "common_ext.h" + +/* + * __memp_ralloc -- + * Allocate some space in the mpool region. + * + * PUBLIC: int __memp_ralloc __P((DB_MPOOL *, size_t, size_t *, void *)); + */ +int +__memp_ralloc(dbmp, len, offsetp, retp) + DB_MPOOL *dbmp; + size_t len, *offsetp; + void *retp; +{ + BH *bhp, *nbhp; + MPOOL *mp; + MPOOLFILE *mfp; + size_t fsize, total; + int nomore, restart, ret, wrote; + void *p; + + mp = dbmp->mp; + + nomore = 0; +alloc: if ((ret = __db_shalloc(dbmp->addr, len, MUTEX_ALIGNMENT, &p)) == 0) { + if (offsetp != NULL) + *offsetp = OFFSET(dbmp, p); + *(void **)retp = p; + return (0); + } + if (nomore) { + __db_err(dbmp->dbenv, "%s", strerror(ret)); + return (ret); + } + + /* Look for a buffer on the free list that's the right size. */ + for (bhp = + SH_TAILQ_FIRST(&mp->bhfq, __bh); bhp != NULL; bhp = nbhp) { + nbhp = SH_TAILQ_NEXT(bhp, q, __bh); + + if (__db_shsizeof(bhp) == len) { + SH_TAILQ_REMOVE(&mp->bhfq, bhp, q, __bh); + if (offsetp != NULL) + *offsetp = OFFSET(dbmp, bhp); + *(void **)retp = bhp; + return (0); + } + } + + /* Discard from the free list until we've freed enough memory. */ + total = 0; + for (bhp = + SH_TAILQ_FIRST(&mp->bhfq, __bh); bhp != NULL; bhp = nbhp) { + nbhp = SH_TAILQ_NEXT(bhp, q, __bh); + + SH_TAILQ_REMOVE(&mp->bhfq, bhp, q, __bh); + __db_shalloc_free(dbmp->addr, bhp); + + /* + * Retry as soon as we've freed up sufficient space. If we + * have to coalesce of memory to satisfy the request, don't + * try until it's likely (possible?) that we'll succeed. + */ + total += fsize = __db_shsizeof(bhp); + if (fsize >= len || total >= 3 * len) + goto alloc; + } + +retry: /* Find a buffer we can flush; pure LRU. */ + total = 0; + for (bhp = + SH_TAILQ_FIRST(&mp->bhq, __bh); bhp != NULL; bhp = nbhp) { + nbhp = SH_TAILQ_NEXT(bhp, q, __bh); + + /* Ignore pinned or locked (I/O in progress) buffers. */ + if (bhp->ref != 0 || F_ISSET(bhp, BH_LOCKED)) + continue; + + /* Find the associated MPOOLFILE. */ + mfp = ADDR(dbmp, bhp->mf_offset); + + /* + * Write the page if it's dirty. + * + * If we wrote the page, fall through and free the buffer. We + * don't have to rewalk the list to acquire the buffer because + * it was never available for any other process to modify it. + * If we didn't write the page, but we discarded and reacquired + * the region lock, restart the buffer list walk. If we neither + * wrote the buffer nor discarded the region lock, continue down + * the buffer list. + */ + if (F_ISSET(bhp, BH_DIRTY)) { + if ((ret = __memp_bhwrite(dbmp, + mfp, bhp, &restart, &wrote)) != 0) + return (ret); + + /* + * It's possible that another process wants this buffer + * and incremented the ref count while we were writing + * it. + */ + if (bhp->ref != 0) + goto retry; + + if (wrote) + ++mp->stat.st_rw_evict; + else { + if (restart) + goto retry; + else + continue; + } + } else + ++mp->stat.st_ro_evict; + + /* + * Check to see if the buffer is the size we're looking for. + * If it is, simply reuse it. + */ + total += fsize = __db_shsizeof(bhp); + if (fsize == len) { + __memp_bhfree(dbmp, mfp, bhp, 0); + + if (offsetp != NULL) + *offsetp = OFFSET(dbmp, bhp); + *(void **)retp = bhp; + return (0); + } + + /* Free the buffer. */ + __memp_bhfree(dbmp, mfp, bhp, 1); + + /* + * Retry as soon as we've freed up sufficient space. If we + * have to coalesce of memory to satisfy the request, don't + * try until it's likely (possible?) that we'll succeed. + */ + if (fsize >= len || total >= 3 * len) + goto alloc; + + /* Restart the walk if we discarded the region lock. */ + if (restart) + goto retry; + } + nomore = 1; + goto alloc; +} + +/* + * __memp_ropen -- + * Attach to, and optionally create, the mpool region. + * + * PUBLIC: int __memp_ropen + * PUBLIC: __P((DB_MPOOL *, const char *, size_t, int, int)); + */ +int +__memp_ropen(dbmp, path, cachesize, mode, flags) + DB_MPOOL *dbmp; + const char *path; + size_t cachesize; + int mode, flags; +{ + MPOOL *mp; + size_t rlen; + int fd, newregion, ret, retry_cnt; + + /* + * Unlike other DB subsystems, mpool can't simply grow the region + * because it returns pointers into the region to its clients. To + * "grow" the region, we'd have to allocate a new region and then + * store a region number in the structures that reference regional + * objects. It's reasonable that we fail regardless, as clients + * shouldn't have every page in the region pinned, so the only + * "failure" mode should be a performance penalty because we don't + * find a page in the cache that we'd like to have found. + * + * Up the user's cachesize by 25% to account for our overhead. + */ + if (cachesize < DB_CACHESIZE_MIN) + if (cachesize == 0) + cachesize = DB_CACHESIZE_DEF; + else + cachesize = DB_CACHESIZE_MIN; + rlen = cachesize + cachesize / 4; + + /* Map in the region. */ + retry_cnt = newregion = 0; +retry: if (LF_ISSET(DB_CREATE)) { + /* + * If it's a private mpool, use malloc, it's a lot faster than + * instantiating a region. + * + * XXX + * If we're doing locking and don't have spinlocks for this + * architecture, we'd have to instantiate the file, we need + * the file descriptor for locking. However, it should not + * be possible for DB_THREAD to be set if HAVE_SPINLOCKS aren't + * defined. + */ + if (F_ISSET(dbmp, MP_ISPRIVATE)) + ret = (dbmp->maddr = malloc(rlen)) == NULL ? ENOMEM : 0; + else + ret = __db_rcreate(dbmp->dbenv, DB_APP_NONE, path, + DB_DEFAULT_MPOOL_FILE, mode, rlen, &fd, + &dbmp->maddr); + if (ret == 0) { + /* Put the MPOOL structure first in the region. */ + mp = dbmp->maddr; + + SH_TAILQ_INIT(&mp->bhq); + SH_TAILQ_INIT(&mp->bhfq); + SH_TAILQ_INIT(&mp->mpfq); + + /* Initialize the rest of the region as free space. */ + dbmp->addr = (u_int8_t *)dbmp->maddr + sizeof(MPOOL); + __db_shalloc_init(dbmp->addr, rlen - sizeof(MPOOL)); + + /* + * + * Pretend that the cache will be broken up into 4K + * pages, and that we want to keep it under, say, 10 + * pages on each chain. This means a 256MB cache will + * allocate ~6500 offset pairs. + */ + mp->htab_buckets = + __db_tablesize((cachesize / (4 * 1024)) / 10); + + /* Allocate hash table space and initialize it. */ + if ((ret = __db_shalloc(dbmp->addr, + mp->htab_buckets * sizeof(DB_HASHTAB), + 0, &dbmp->htab)) != 0) + goto err; + __db_hashinit(dbmp->htab, mp->htab_buckets); + mp->htab = OFFSET(dbmp, dbmp->htab); + + memset(&mp->stat, 0, sizeof(mp->stat)); + mp->stat.st_cachesize = cachesize; + + mp->flags = 0; + + newregion = 1; + } else if (ret != EEXIST) + return (ret); + } + + /* If we didn't or couldn't create the region, try and join it. */ + if (!newregion && + (ret = __db_ropen(dbmp->dbenv, DB_APP_NONE, + path, DB_DEFAULT_MPOOL_FILE, 0, &fd, &dbmp->maddr)) != 0) { + /* + * If we failed because the file wasn't available, wait a + * second and try again. + */ + if (ret == EAGAIN && ++retry_cnt < 3) { + (void)__db_sleep(1, 0); + goto retry; + } + return (ret); + } + + /* Set up the common pointers. */ + dbmp->mp = dbmp->maddr; + dbmp->addr = (u_int8_t *)dbmp->maddr + sizeof(MPOOL); + + /* + * If not already locked, lock the region -- if it's a new region, + * then either __db_rcreate() locked it for us or we malloc'd it + * instead of creating a region, neither of which requires locking + * here. + */ + if (!newregion) + LOCKREGION(dbmp); + + /* + * Get the hash table address; it's on the shared page, so we have + * to lock first. + */ + dbmp->htab = ADDR(dbmp, dbmp->mp->htab); + + dbmp->fd = fd; + + /* If we locked the region, release it now. */ + if (!F_ISSET(dbmp, MP_ISPRIVATE)) + UNLOCKREGION(dbmp); + return (0); + +err: if (fd != -1) { + dbmp->fd = fd; + (void)__memp_rclose(dbmp); + } + + if (newregion) + (void)memp_unlink(path, 1, dbmp->dbenv); + return (ret); +} + +/* + * __memp_rclose -- + * Close the mpool region. + * + * PUBLIC: int __memp_rclose __P((DB_MPOOL *)); + */ +int +__memp_rclose(dbmp) + DB_MPOOL *dbmp; +{ + if (F_ISSET(dbmp, MP_ISPRIVATE)) { + free(dbmp->maddr); + return (0); + } + return (__db_rclose(dbmp->dbenv, dbmp->fd, dbmp->maddr)); +} |