diff options
Diffstat (limited to 'db2/mp/mp_sync.c')
| -rw-r--r-- | db2/mp/mp_sync.c | 549 |
1 files changed, 0 insertions, 549 deletions
diff --git a/db2/mp/mp_sync.c b/db2/mp/mp_sync.c deleted file mode 100644 index 535348517c..0000000000 --- a/db2/mp/mp_sync.c +++ /dev/null @@ -1,549 +0,0 @@ -/*- - * See the file LICENSE for redistribution information. - * - * Copyright (c) 1996, 1997, 1998 - * Sleepycat Software. All rights reserved. - */ -#include "config.h" - -#ifndef lint -static const char sccsid[] = "@(#)mp_sync.c 10.31 (Sleepycat) 12/11/98"; -#endif /* not lint */ - -#ifndef NO_SYSTEM_INCLUDES -#include <sys/types.h> - -#include <errno.h> -#include <stdlib.h> -#endif - -#include "db_int.h" -#include "shqueue.h" -#include "db_shash.h" -#include "mp.h" -#include "common_ext.h" - -static int __bhcmp __P((const void *, const void *)); -static int __memp_fsync __P((DB_MPOOLFILE *)); - -/* - * memp_sync -- - * Mpool sync function. - */ -int -memp_sync(dbmp, lsnp) - DB_MPOOL *dbmp; - DB_LSN *lsnp; -{ - BH *bhp, **bharray; - DB_ENV *dbenv; - MPOOL *mp; - MPOOLFILE *mfp; - int ar_cnt, nalloc, next, maxpin, ret, wrote; - - MP_PANIC_CHECK(dbmp); - - dbenv = dbmp->dbenv; - mp = dbmp->mp; - - if (dbenv->lg_info == NULL) { - __db_err(dbenv, "memp_sync: requires logging"); - return (EINVAL); - } - - /* - * We try and write the buffers in page order: it should reduce seeks - * by the underlying filesystem and possibly reduce the actual number - * of writes. We don't want to hold the region lock while we write - * the buffers, so only hold it lock while we create a list. Get a - * good-size block of memory to hold buffer pointers, we don't want - * to run out. - */ - LOCKREGION(dbmp); - nalloc = mp->stat.st_page_dirty + mp->stat.st_page_dirty / 2 + 10; - UNLOCKREGION(dbmp); - - if ((ret = __os_malloc(nalloc * sizeof(BH *), NULL, &bharray)) != 0) - return (ret); - - LOCKREGION(dbmp); - - /* - * If the application is asking about a previous call to memp_sync(), - * and we haven't found any buffers that the application holding the - * pin couldn't write, return yes or no based on the current count. - * Note, if the application is asking about a LSN *smaller* than one - * we've already handled or are currently handling, then we return a - * result based on the count for the larger LSN. - */ - if (!F_ISSET(mp, MP_LSN_RETRY) && log_compare(lsnp, &mp->lsn) <= 0) { - if (mp->lsn_cnt == 0) { - *lsnp = mp->lsn; - ret = 0; - } else - ret = DB_INCOMPLETE; - goto done; - } - - /* Else, it's a new checkpoint. */ - F_CLR(mp, MP_LSN_RETRY); - - /* - * Save the LSN. We know that it's a new LSN or larger than the one - * for which we were already doing a checkpoint. (BTW, I don't expect - * to see multiple LSN's from the same or multiple processes, but You - * Just Never Know. Responding as if they all called with the largest - * of the LSNs specified makes everything work.) - * - * We don't currently use the LSN we save. We could potentially save - * the last-written LSN in each buffer header and use it to determine - * what buffers need to be written. The problem with this is that it's - * sizeof(LSN) more bytes of buffer header. We currently write all the - * dirty buffers instead. - * - * Walk the list of shared memory segments clearing the count of - * buffers waiting to be written. - */ - mp->lsn = *lsnp; - mp->lsn_cnt = 0; - for (mfp = SH_TAILQ_FIRST(&dbmp->mp->mpfq, __mpoolfile); - mfp != NULL; mfp = SH_TAILQ_NEXT(mfp, q, __mpoolfile)) - mfp->lsn_cnt = 0; - - /* - * Walk the list of buffers and mark all dirty buffers to be written - * and all pinned buffers to be potentially written (we can't know if - * we'll need to write them until the holding process returns them to - * the cache). We do this in one pass while holding the region locked - * so that processes can't make new buffers dirty, causing us to never - * finish. Since the application may have restarted the sync, clear - * any BH_WRITE flags that appear to be left over from previous calls. - * - * We don't want to pin down the entire buffer cache, otherwise we'll - * starve threads needing new pages. Don't pin down more than 80% of - * the cache. - * - * Keep a count of the total number of buffers we need to write in - * MPOOL->lsn_cnt, and for each file, in MPOOLFILE->lsn_count. - */ - ar_cnt = 0; - maxpin = ((mp->stat.st_page_dirty + mp->stat.st_page_clean) * 8) / 10; - for (bhp = SH_TAILQ_FIRST(&mp->bhq, __bh); - bhp != NULL; bhp = SH_TAILQ_NEXT(bhp, q, __bh)) - if (F_ISSET(bhp, BH_DIRTY) || bhp->ref != 0) { - F_SET(bhp, BH_WRITE); - - ++mp->lsn_cnt; - - mfp = R_ADDR(dbmp, bhp->mf_offset); - ++mfp->lsn_cnt; - - /* - * If the buffer isn't in use, we should be able to - * write it immediately, so increment the reference - * count to lock it and its contents down, and then - * save a reference to it. - * - * If we've run out space to store buffer references, - * we're screwed. We don't want to realloc the array - * while holding a region lock, so we set the flag to - * force the checkpoint to be done again, from scratch, - * later. - * - * If we've pinned down too much of the cache stop, and - * set a flag to force the checkpoint to be tried again - * later. - */ - if (bhp->ref == 0) { - ++bhp->ref; - bharray[ar_cnt] = bhp; - if (++ar_cnt >= nalloc || ar_cnt >= maxpin) { - F_SET(mp, MP_LSN_RETRY); - break; - } - } - } else - if (F_ISSET(bhp, BH_WRITE)) - F_CLR(bhp, BH_WRITE); - - /* If there no buffers we can write immediately, we're done. */ - if (ar_cnt == 0) { - ret = mp->lsn_cnt ? DB_INCOMPLETE : 0; - goto done; - } - - UNLOCKREGION(dbmp); - - /* Sort the buffers we're going to write. */ - qsort(bharray, ar_cnt, sizeof(BH *), __bhcmp); - - LOCKREGION(dbmp); - - /* Walk the array, writing buffers. */ - for (next = 0; next < ar_cnt; ++next) { - /* - * It's possible for a thread to have gotten the buffer since - * we listed it for writing. If the reference count is still - * 1, we're the only ones using the buffer, go ahead and write. - * If it's >1, then skip the buffer and assume that it will be - * written when it's returned to the cache. - */ - if (bharray[next]->ref > 1) { - --bharray[next]->ref; - continue; - } - - /* Write the buffer. */ - mfp = R_ADDR(dbmp, bharray[next]->mf_offset); - ret = __memp_bhwrite(dbmp, mfp, bharray[next], NULL, &wrote); - - /* Release the buffer. */ - --bharray[next]->ref; - - /* If there's an error, release the rest of the buffers. */ - if (ret != 0 || !wrote) { - /* - * Any process syncing the shared memory buffer pool - * had better be able to write to any underlying file. - * Be understanding, but firm, on this point. - */ - if (ret == 0) { - __db_err(dbenv, "%s: unable to flush page: %lu", - __memp_fns(dbmp, mfp), - (u_long)bharray[next]->pgno); - ret = EPERM; - } - - while (++next < ar_cnt) - --bharray[next]->ref; - goto err; - } - } - ret = mp->lsn_cnt != 0 || - F_ISSET(mp, MP_LSN_RETRY) ? DB_INCOMPLETE : 0; - -done: - if (0) { -err: /* - * On error, clear: - * MPOOL->lsn_cnt (the total sync count) - * MPOOLFILE->lsn_cnt (the per-file sync count) - * BH_WRITE flag (the scheduled for writing flag) - */ - mp->lsn_cnt = 0; - for (mfp = SH_TAILQ_FIRST(&dbmp->mp->mpfq, __mpoolfile); - mfp != NULL; mfp = SH_TAILQ_NEXT(mfp, q, __mpoolfile)) - mfp->lsn_cnt = 0; - for (bhp = SH_TAILQ_FIRST(&mp->bhq, __bh); - bhp != NULL; bhp = SH_TAILQ_NEXT(bhp, q, __bh)) - F_CLR(bhp, BH_WRITE); - } - UNLOCKREGION(dbmp); - __os_free(bharray, nalloc * sizeof(BH *)); - return (ret); -} - -/* - * memp_fsync -- - * Mpool file sync function. - */ -int -memp_fsync(dbmfp) - DB_MPOOLFILE *dbmfp; -{ - DB_MPOOL *dbmp; - int is_tmp; - - dbmp = dbmfp->dbmp; - - MP_PANIC_CHECK(dbmp); - - /* - * If this handle doesn't have a file descriptor that's open for - * writing, or if the file is a temporary, there's no reason to - * proceed further. - */ - if (F_ISSET(dbmfp, MP_READONLY)) - return (0); - - LOCKREGION(dbmp); - is_tmp = F_ISSET(dbmfp->mfp, MP_TEMP); - UNLOCKREGION(dbmp); - if (is_tmp) - return (0); - - return (__memp_fsync(dbmfp)); -} - -/* - * __mp_xxx_fd -- - * Return a file descriptor for DB 1.85 compatibility locking. - * - * PUBLIC: int __mp_xxx_fd __P((DB_MPOOLFILE *, int *)); - */ -int -__mp_xxx_fd(dbmfp, fdp) - DB_MPOOLFILE *dbmfp; - int *fdp; -{ - int ret; - - /* - * This is a truly spectacular layering violation, intended ONLY to - * support compatibility for the DB 1.85 DB->fd call. - * - * Sync the database file to disk, creating the file as necessary. - * - * We skip the MP_READONLY and MP_TEMP tests done by memp_fsync(3). - * The MP_READONLY test isn't interesting because we will either - * already have a file descriptor (we opened the database file for - * reading) or we aren't readonly (we created the database which - * requires write privileges). The MP_TEMP test isn't interesting - * because we want to write to the backing file regardless so that - * we get a file descriptor to return. - */ - ret = dbmfp->fd == -1 ? __memp_fsync(dbmfp) : 0; - - return ((*fdp = dbmfp->fd) == -1 ? ENOENT : ret); -} - -/* - * __memp_fsync -- - * Mpool file internal sync function. - */ -static int -__memp_fsync(dbmfp) - DB_MPOOLFILE *dbmfp; -{ - BH *bhp, **bharray; - DB_MPOOL *dbmp; - MPOOL *mp; - size_t mf_offset; - int ar_cnt, incomplete, nalloc, next, ret, wrote; - - ret = 0; - dbmp = dbmfp->dbmp; - mp = dbmp->mp; - mf_offset = R_OFFSET(dbmp, dbmfp->mfp); - - /* - * We try and write the buffers in page order: it should reduce seeks - * by the underlying filesystem and possibly reduce the actual number - * of writes. We don't want to hold the region lock while we write - * the buffers, so only hold it lock while we create a list. Get a - * good-size block of memory to hold buffer pointers, we don't want - * to run out. - */ - LOCKREGION(dbmp); - nalloc = mp->stat.st_page_dirty + mp->stat.st_page_dirty / 2 + 10; - UNLOCKREGION(dbmp); - - if ((ret = __os_malloc(nalloc * sizeof(BH *), NULL, &bharray)) != 0) - return (ret); - - LOCKREGION(dbmp); - - /* - * Walk the LRU list of buffer headers, and get a list of buffers to - * write for this MPOOLFILE. - */ - ar_cnt = incomplete = 0; - for (bhp = SH_TAILQ_FIRST(&mp->bhq, __bh); - bhp != NULL; bhp = SH_TAILQ_NEXT(bhp, q, __bh)) { - if (!F_ISSET(bhp, BH_DIRTY) || bhp->mf_offset != mf_offset) - continue; - if (bhp->ref != 0 || F_ISSET(bhp, BH_LOCKED)) { - incomplete = 1; - continue; - } - - ++bhp->ref; - bharray[ar_cnt] = bhp; - - /* - * If we've run out space to store buffer references, we're - * screwed, as we don't want to realloc the array holding a - * region lock. Set the incomplete flag -- the only way we - * can get here is if the file is active in the buffer cache, - * which is the same thing as finding pinned buffers. - */ - if (++ar_cnt >= nalloc) { - incomplete = 1; - break; - } - } - - UNLOCKREGION(dbmp); - - /* Sort the buffers we're going to write. */ - if (ar_cnt != 0) - qsort(bharray, ar_cnt, sizeof(BH *), __bhcmp); - - LOCKREGION(dbmp); - - /* Walk the array, writing buffers. */ - for (next = 0; next < ar_cnt; ++next) { - /* - * It's possible for a thread to have gotten the buffer since - * we listed it for writing. If the reference count is still - * 1, we're the only ones using the buffer, go ahead and write. - * If it's >1, then skip the buffer. - */ - if (bharray[next]->ref > 1) { - incomplete = 1; - - --bharray[next]->ref; - continue; - } - - /* Write the buffer. */ - ret = __memp_pgwrite(dbmfp, bharray[next], NULL, &wrote); - - /* Release the buffer. */ - --bharray[next]->ref; - - /* If there's an error, release the rest of the buffers. */ - if (ret != 0) { - while (++next < ar_cnt) - --bharray[next]->ref; - goto err; - } - - /* - * If we didn't write the buffer for some reason, don't return - * success. - */ - if (!wrote) - incomplete = 1; - } - -err: UNLOCKREGION(dbmp); - - __os_free(bharray, nalloc * sizeof(BH *)); - - /* - * Sync the underlying file as the last thing we do, so that the OS - * has maximal opportunity to flush buffers before we request it. - * - * XXX: - * Don't lock the region around the sync, fsync(2) has no atomicity - * issues. - */ - if (ret == 0) - return (incomplete ? DB_INCOMPLETE : __os_fsync(dbmfp->fd)); - return (ret); -} - -/* - * memp_trickle -- - * Keep a specified percentage of the buffers clean. - */ -int -memp_trickle(dbmp, pct, nwrotep) - DB_MPOOL *dbmp; - int pct, *nwrotep; -{ - BH *bhp; - MPOOL *mp; - MPOOLFILE *mfp; - u_long total; - int ret, wrote; - - MP_PANIC_CHECK(dbmp); - - mp = dbmp->mp; - if (nwrotep != NULL) - *nwrotep = 0; - - if (pct < 1 || pct > 100) - return (EINVAL); - - LOCKREGION(dbmp); - - /* - * If there are sufficient clean buffers, or no buffers or no dirty - * buffers, we're done. - * - * XXX - * Using st_page_clean and st_page_dirty is our only choice at the - * moment, but it's not as correct as we might like in the presence - * of pools with more than one buffer size, as a free 512-byte buffer - * isn't the same as a free 8K buffer. - */ -loop: total = mp->stat.st_page_clean + mp->stat.st_page_dirty; - if (total == 0 || mp->stat.st_page_dirty == 0 || - (mp->stat.st_page_clean * 100) / total >= (u_long)pct) { - UNLOCKREGION(dbmp); - return (0); - } - - /* Loop until we write a buffer. */ - for (bhp = SH_TAILQ_FIRST(&mp->bhq, __bh); - bhp != NULL; bhp = SH_TAILQ_NEXT(bhp, q, __bh)) { - if (bhp->ref != 0 || - !F_ISSET(bhp, BH_DIRTY) || F_ISSET(bhp, BH_LOCKED)) - continue; - - mfp = R_ADDR(dbmp, bhp->mf_offset); - - /* - * We can't write to temporary files -- see the comment in - * mp_bh.c:__memp_bhwrite(). - */ - if (F_ISSET(mfp, MP_TEMP)) - continue; - - if ((ret = __memp_bhwrite(dbmp, mfp, bhp, NULL, &wrote)) != 0) - goto err; - - /* - * Any process syncing the shared memory buffer pool had better - * be able to write to any underlying file. Be understanding, - * but firm, on this point. - */ - if (!wrote) { - __db_err(dbmp->dbenv, "%s: unable to flush page: %lu", - __memp_fns(dbmp, mfp), (u_long)bhp->pgno); - ret = EPERM; - goto err; - } - - ++mp->stat.st_page_trickle; - if (nwrotep != NULL) - ++*nwrotep; - goto loop; - } - - /* No more buffers to write. */ - ret = 0; - -err: UNLOCKREGION(dbmp); - return (ret); -} - -static int -__bhcmp(p1, p2) - const void *p1, *p2; -{ - BH *bhp1, *bhp2; - - bhp1 = *(BH * const *)p1; - bhp2 = *(BH * const *)p2; - - /* Sort by file (shared memory pool offset). */ - if (bhp1->mf_offset < bhp2->mf_offset) - return (-1); - if (bhp1->mf_offset > bhp2->mf_offset) - return (1); - - /* - * !!! - * Defend against badly written quicksort code calling the comparison - * function with two identical pointers (e.g., WATCOM C++ (Power++)). - */ - if (bhp1->pgno < bhp2->pgno) - return (-1); - if (bhp1->pgno > bhp2->pgno) - return (1); - return (0); -} |