diff options
Diffstat (limited to 'db2/mp/mp_bh.c')
| -rw-r--r-- | db2/mp/mp_bh.c | 131 |
1 files changed, 89 insertions, 42 deletions
diff --git a/db2/mp/mp_bh.c b/db2/mp/mp_bh.c index 578abedcb6..c23abdda24 100644 --- a/db2/mp/mp_bh.c +++ b/db2/mp/mp_bh.c @@ -7,7 +7,7 @@ #include "config.h" #ifndef lint -static const char sccsid[] = "@(#)mp_bh.c 10.23 (Sleepycat) 11/26/97"; +static const char sccsid[] = "@(#)mp_bh.c 10.28 (Sleepycat) 1/8/98"; #endif /* not lint */ #ifndef NO_SYSTEM_INCLUDES @@ -193,30 +193,28 @@ __memp_pgread(dbmfp, bhp, can_create) /* Call any pgin function. */ pgin: ret = mfp->ftype == 0 ? 0 : __memp_pg(dbmfp, bhp, 1); - /* Reacquire the region lock. */ + /* Unlock the buffer and reacquire the region lock. */ +err: UNLOCKBUFFER(dbmp, bhp); LOCKREGION(dbmp); - /* If the pgin function succeeded, the data is now valid. */ - if (ret == 0) + /* + * If no errors occurred, the data is now valid, clear the BH_TRASH + * flag; regardless, clear the lock bit and let other threads proceed. + */ + F_CLR(bhp, BH_LOCKED); + if (ret == 0) { F_CLR(bhp, BH_TRASH); - /* Update the statistics. */ - if (can_create) { - ++dbmp->mp->stat.st_page_create; - ++mfp->stat.st_page_create; - } else { - ++dbmp->mp->stat.st_page_in; - ++mfp->stat.st_page_in; - } - - if (0) { -err: LOCKREGION(dbmp); + /* Update the statistics. */ + if (can_create) { + ++dbmp->mp->stat.st_page_create; + ++mfp->stat.st_page_create; + } else { + ++dbmp->mp->stat.st_page_in; + ++mfp->stat.st_page_in; + } } - /* Release the buffer. */ - F_CLR(bhp, BH_LOCKED); - UNLOCKBUFFER(dbmp, bhp); - return (ret); } @@ -240,7 +238,7 @@ __memp_pgwrite(dbmfp, bhp, restartp, wrotep) MPOOLFILE *mfp; size_t pagesize; ssize_t nw; - int callpgin, ret; + int callpgin, ret, syncfail; const char *fail; dbmp = dbmfp->dbmp; @@ -255,8 +253,32 @@ __memp_pgwrite(dbmfp, bhp, restartp, wrotep) callpgin = 0; pagesize = mfp->stat.st_pagesize; - F_SET(bhp, BH_LOCKED); + /* + * Check the dirty bit -- this buffer may have been written since we + * decided to write it. + */ + if (!F_ISSET(bhp, BH_DIRTY)) { + if (wrotep != NULL) + *wrotep = 1; + return (0); + } + LOCKBUFFER(dbmp, bhp); + + /* + * If there were two writers, we may have just been waiting while the + * other writer completed I/O on this buffer. Check the dirty bit one + * more time. + */ + if (!F_ISSET(bhp, BH_DIRTY)) { + UNLOCKBUFFER(dbmp, bhp); + + if (wrotep != NULL) + *wrotep = 1; + return (0); + } + + F_SET(bhp, BH_LOCKED); UNLOCKREGION(dbmp); if (restartp != NULL) @@ -272,8 +294,9 @@ __memp_pgwrite(dbmfp, bhp, restartp, wrotep) goto err; /* - * Call any pgout function. We set the callpgin flag so that on - * error we flag that the contents of the buffer may be trash. + * Call any pgout function. We set the callpgin flag so that we flag + * that the contents of the buffer will need to be passed through pgin + * before they are reused. */ if (mfp->ftype == 0) ret = 0; @@ -307,7 +330,7 @@ __memp_pgwrite(dbmfp, bhp, restartp, wrotep) * between the failing clauses to __db_lseek and __db_write and * this ret != 0. */ - fail = NULL; + COMPQUIET(fail, NULL); goto syserr; } @@ -320,18 +343,20 @@ __memp_pgwrite(dbmfp, bhp, restartp, wrotep) if (wrotep != NULL) *wrotep = 1; - /* Reacquire the region lock. */ + /* Unlock the buffer and reacquire the region lock. */ + UNLOCKBUFFER(dbmp, bhp); LOCKREGION(dbmp); - /* Clean up the flags based on a successful write. */ - F_SET(bhp, BH_CALLPGIN); + /* + * Clean up the flags based on a successful write. + * + * If we rewrote the page, it will need processing by the pgin + * routine before reuse. + */ + if (callpgin) + F_SET(bhp, BH_CALLPGIN); F_CLR(bhp, BH_DIRTY | BH_LOCKED); - ++mp->stat.st_page_clean; - --mp->stat.st_page_dirty; - - UNLOCKBUFFER(dbmp, bhp); - /* * If we write a buffer for which a checkpoint is waiting, update * the count of pending buffers (both in the mpool as a whole and @@ -344,23 +369,36 @@ __memp_pgwrite(dbmfp, bhp, restartp, wrotep) * * XXX: * We ignore errors from the sync -- it makes no sense to return an - * error to the calling process, so set a flag causing the sync to - * be retried later. - * - * If the buffer we wrote has a LSN larger than the current largest - * we've written for this checkpoint, update the saved value. + * error to the calling process, so set a flag causing the checkpoint + * to be retried later. */ if (F_ISSET(bhp, BH_WRITE)) { + if (mfp->lsn_cnt == 1) { + UNLOCKREGION(dbmp); + syncfail = __db_fsync(dbmfp->fd) != 0; + LOCKREGION(dbmp); + if (syncfail) + F_SET(mp, MP_LSN_RETRY); + + } + + F_CLR(bhp, BH_WRITE); + + /* + * If the buffer just written has a larger LSN than the current + * max LSN written for this checkpoint, update the saved value. + */ if (log_compare(&lsn, &mp->lsn) > 0) mp->lsn = lsn; - F_CLR(bhp, BH_WRITE); --mp->lsn_cnt; - - if (--mfp->lsn_cnt == 0 && __db_fsync(dbmfp->fd) != 0) - F_SET(mp, MP_LSN_RETRY); + --mfp->lsn_cnt; } + /* Update the page clean/dirty statistics. */ + ++mp->stat.st_page_clean; + --mp->stat.st_page_dirty; + /* Update I/O statistics. */ ++mp->stat.st_page_out; ++mfp->stat.st_page_out; @@ -370,11 +408,20 @@ __memp_pgwrite(dbmfp, bhp, restartp, wrotep) syserr: __db_err(dbenv, "%s: %s failed for page %lu", __memp_fn(dbmfp), fail, (u_long)bhp->pgno); -err: UNLOCKBUFFER(dbmp, bhp); +err: /* Unlock the buffer and reacquire the region lock. */ + UNLOCKBUFFER(dbmp, bhp); LOCKREGION(dbmp); + + /* + * Clean up the flags based on a failure. + * + * The page remains dirty but we remove our lock. If we rewrote the + * page, it will need processing by the pgin routine before reuse. + */ if (callpgin) F_SET(bhp, BH_CALLPGIN); F_CLR(bhp, BH_LOCKED); + return (ret); } |