diff options
Diffstat (limited to 'db2/mp/mp_sync.c')
| -rw-r--r-- | db2/mp/mp_sync.c | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/db2/mp/mp_sync.c b/db2/mp/mp_sync.c new file mode 100644 index 0000000..4f12056 --- /dev/null +++ b/db2/mp/mp_sync.c @@ -0,0 +1,205 @@ +/*- + * 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_sync.c 10.8 (Sleepycat) 7/2/97"; +#endif /* not lint */ + +#ifndef NO_SYSTEM_INCLUDES +#include <sys/types.h> + +#include <errno.h> +#include <string.h> +#endif + +#include "db_int.h" +#include "shqueue.h" +#include "db_shash.h" +#include "mp.h" +#include "common_ext.h" + +/* + * memp_sync -- + * Mpool sync function. + */ +int +memp_sync(dbmp, lsnp) + DB_MPOOL *dbmp; + DB_LSN *lsnp; +{ + BH *bhp; + DB_ENV *dbenv; + MPOOL *mp; + MPOOLFILE *mfp; + int can_write, wrote, lsn_cnt, restart, ret; + + dbenv = dbmp->dbenv; + + if (dbmp->dbenv->lg_info == NULL) { + __db_err(dbenv, "memp_sync requires logging"); + return (EINVAL); + } + + LOCKREGION(dbmp); + + /* + * If the application is asking about a previous call, 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, then we return based on the count for that LSN. + */ + mp = dbmp->mp; + 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; + + UNLOCKREGION(dbmp); + return (ret); + } + + /* 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 do this in + * single fell swoop 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. + */ + can_write = lsn_cnt = 0; + for (lsn_cnt = 0, 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); + + if (bhp->ref == 0) + can_write = 1; + + mfp = ADDR(dbmp, bhp->mf_offset); + ++mfp->lsn_cnt; + + ++lsn_cnt; + } else + F_CLR(bhp, BH_WRITE); + + mp->lsn_cnt = lsn_cnt; + + /* If there no buffers we can write, we're done. */ + if (!can_write) { + UNLOCKREGION(dbmp); + return (mp->lsn_cnt ? DB_INCOMPLETE : 0); + } + + /* + * Write any buffers that we can. Restart the walk after each write, + * __memp_pgwrite() discards and reacquires the region lock during I/O. + */ +retry: for (bhp = SH_TAILQ_FIRST(&mp->bhq, __bh); + bhp != NULL; bhp = SH_TAILQ_NEXT(bhp, q, __bh)) { + /* Ignore pinned or locked buffers. */ + if (!F_ISSET(bhp, BH_WRITE) || + bhp->ref != 0 || F_ISSET(bhp, BH_LOCKED)) + continue; + + mfp = ADDR(dbmp, bhp->mf_offset); + if ((ret = + __memp_bhwrite(dbmp, mfp, bhp, &restart, &wrote)) != 0) + goto err; + if (wrote) { + if (restart) + goto retry; + continue; + } + __db_err(dbenv, "%s: unable to flush page: %lu", + ADDR(dbmp, mfp->path_off), (u_long)bhp->pgno); + ret = EPERM; + goto err; + } + ret = mp->lsn_cnt ? DB_INCOMPLETE : 0; + +err: UNLOCKREGION(dbmp); + return (ret); +} + +/* + * memp_fsync -- + * Mpool file sync function. + */ +int +memp_fsync(dbmfp) + DB_MPOOLFILE *dbmfp; +{ + BH *bhp; + DB_MPOOL *dbmp; + size_t mf_offset; + int pincnt, restart, ret, wrote; + + /* We don't sync temporary files -- what's the use? */ + if (F_ISSET(dbmfp, MP_PATH_TEMP)) + return (0); + + dbmp = dbmfp->dbmp; + ret = 0; + + mf_offset = OFFSET(dbmp, dbmfp->mfp); + + LOCKREGION(dbmp); + + /* + * Walk the list of buffer headers for the MPOOLFILE, and write out any + * dirty buffers that we can. + */ +retry: pincnt = 0; + for (bhp = SH_TAILQ_FIRST(&dbmp->mp->bhq, __bh); + bhp != NULL; bhp = SH_TAILQ_NEXT(bhp, q, __bh)) + if (F_ISSET(bhp, BH_DIRTY) && bhp->mf_offset == mf_offset) { + if (bhp->ref != 0 || F_ISSET(bhp, BH_LOCKED)) { + ++pincnt; + continue; + } + if ((ret = + __memp_pgwrite(dbmfp, bhp, &restart, &wrote)) != 0) + goto err; + if (!wrote) + ++pincnt; + if (restart) + goto retry; + } + + UNLOCKREGION(dbmp); + +err: return (ret == 0 ? (pincnt ? DB_INCOMPLETE : 0) : ret); +} |