/*- * 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 #include #include #include #include #include #include #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)); }