/*- * See the file LICENSE for redistribution information. * * Copyright (c) 1996-2003 * Sleepycat Software. All rights reserved. */ #include "db_config.h" #ifndef lint static const char revid[] = "$Id: mp_sync.c,v 1.2 2004/03/30 01:23:44 jtownsen Exp $"; #endif /* not lint */ #ifndef NO_SYSTEM_INCLUDES #include <sys/types.h> #include <stdlib.h> #endif #include "db_int.h" #include "dbinc/db_shash.h" #include "dbinc/log.h" #include "dbinc/mp.h" typedef struct { DB_MPOOL_HASH *track_hp; /* Hash bucket. */ roff_t track_off; /* Page file offset. */ db_pgno_t track_pgno; /* Page number. */ } BH_TRACK; static int __bhcmp __P((const void *, const void *)); static int __memp_close_flush_files __P((DB_ENV *, DB_MPOOL *)); static int __memp_sync_files __P((DB_ENV *, DB_MPOOL *)); /* * __memp_sync_pp -- * DB_ENV->memp_sync pre/post processing. * * PUBLIC: int __memp_sync_pp __P((DB_ENV *, DB_LSN *)); */ int __memp_sync_pp(dbenv, lsnp) DB_ENV *dbenv; DB_LSN *lsnp; { int rep_check, ret; PANIC_CHECK(dbenv); ENV_REQUIRES_CONFIG(dbenv, dbenv->mp_handle, "memp_sync", DB_INIT_MPOOL); /* * If no LSN is provided, flush the entire cache (reasonable usage * even if there's no log subsystem configured). */ if (lsnp != NULL) ENV_REQUIRES_CONFIG(dbenv, dbenv->lg_handle, "memp_sync", DB_INIT_LOG); rep_check = IS_ENV_REPLICATED(dbenv) ? 1 : 0; if (rep_check) __env_rep_enter(dbenv); ret = __memp_sync(dbenv, lsnp); if (rep_check) __env_rep_exit(dbenv); return (ret); } /* * __memp_sync -- * DB_ENV->memp_sync. * * PUBLIC: int __memp_sync __P((DB_ENV *, DB_LSN *)); */ int __memp_sync(dbenv, lsnp) DB_ENV *dbenv; DB_LSN *lsnp; { DB_MPOOL *dbmp; MPOOL *mp; int ret; dbmp = dbenv->mp_handle; mp = dbmp->reginfo[0].primary; /* If we've flushed to the requested LSN, return that information. */ if (lsnp != NULL) { R_LOCK(dbenv, dbmp->reginfo); if (log_compare(lsnp, &mp->lsn) <= 0) { *lsnp = mp->lsn; R_UNLOCK(dbenv, dbmp->reginfo); return (0); } R_UNLOCK(dbenv, dbmp->reginfo); } if ((ret = __memp_sync_int(dbenv, NULL, 0, DB_SYNC_CACHE, NULL)) != 0) return (ret); if (lsnp != NULL) { R_LOCK(dbenv, dbmp->reginfo); if (log_compare(lsnp, &mp->lsn) > 0) mp->lsn = *lsnp; R_UNLOCK(dbenv, dbmp->reginfo); } return (0); } /* * __memp_fsync_pp -- * DB_MPOOLFILE->sync pre/post processing. * * PUBLIC: int __memp_fsync_pp __P((DB_MPOOLFILE *)); */ int __memp_fsync_pp(dbmfp) DB_MPOOLFILE *dbmfp; { DB_ENV *dbenv; int rep_check, ret; dbenv = dbmfp->dbenv; PANIC_CHECK(dbenv); MPF_ILLEGAL_BEFORE_OPEN(dbmfp, "DB_MPOOLFILE->sync"); if ((rep_check = IS_ENV_REPLICATED(dbenv)) != 0) __env_rep_enter(dbenv); ret = __memp_fsync(dbmfp); if (rep_check) __env_rep_exit(dbenv); return (ret); } /* * __memp_fsync -- * DB_MPOOLFILE->sync. * * PUBLIC: int __memp_fsync __P((DB_MPOOLFILE *)); */ int __memp_fsync(dbmfp) DB_MPOOLFILE *dbmfp; { /* * 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); if (F_ISSET(dbmfp->mfp, MP_TEMP)) return (0); return (__memp_sync_int(dbmfp->dbenv, dbmfp, 0, DB_SYNC_FILE, NULL)); } /* * __mp_xxx_fh -- * Return a file descriptor for DB 1.85 compatibility locking. * * PUBLIC: int __mp_xxx_fh __P((DB_MPOOLFILE *, DB_FH **)); */ int __mp_xxx_fh(dbmfp, fhp) DB_MPOOLFILE *dbmfp; DB_FH **fhp; { /* * 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. */ if ((*fhp = dbmfp->fhp) != NULL) return (0); return (__memp_sync_int(dbmfp->dbenv, dbmfp, 0, DB_SYNC_FILE, NULL)); } /* * __memp_sync_int -- * Mpool sync internal function. * * PUBLIC: int __memp_sync_int * PUBLIC: __P((DB_ENV *, DB_MPOOLFILE *, int, db_sync_op, int *)); */ int __memp_sync_int(dbenv, dbmfp, trickle_max, op, wrotep) DB_ENV *dbenv; DB_MPOOLFILE *dbmfp; int trickle_max, *wrotep; db_sync_op op; { BH *bhp; BH_TRACK *bharray; DB_MPOOL *dbmp; DB_MPOOL_HASH *hp; DB_MUTEX *mutexp; MPOOL *c_mp, *mp; MPOOLFILE *mfp; u_int32_t n_cache; int ar_cnt, ar_max, hb_lock, i, pass, remaining, ret, t_ret; int wait_cnt, write_cnt, wrote; dbmp = dbenv->mp_handle; mp = dbmp->reginfo[0].primary; pass = wrote = 0; /* Assume one dirty page per bucket. */ ar_max = mp->nreg * mp->htab_buckets; if ((ret = __os_malloc(dbenv, ar_max * sizeof(BH_TRACK), &bharray)) != 0) return (ret); /* * Walk each cache's list of buffers and mark all dirty buffers to be * written and all pinned buffers to be potentially written, depending * on our flags. */ for (ar_cnt = 0, n_cache = 0; n_cache < mp->nreg; ++n_cache) { c_mp = dbmp->reginfo[n_cache].primary; hp = R_ADDR(&dbmp->reginfo[n_cache], c_mp->htab); for (i = 0; i < c_mp->htab_buckets; i++, hp++) { /* * We can check for empty buckets before locking as we * only care if the pointer is zero or non-zero. We * can ignore empty buckets because we only need write * buffers that were dirty before we started. */ if (SH_TAILQ_FIRST(&hp->hash_bucket, __bh) == NULL) continue; MUTEX_LOCK(dbenv, &hp->hash_mutex); for (bhp = SH_TAILQ_FIRST(&hp->hash_bucket, __bh); bhp != NULL; bhp = SH_TAILQ_NEXT(bhp, hq, __bh)) { /* Always ignore unreferenced, clean pages. */ if (bhp->ref == 0 && !F_ISSET(bhp, BH_DIRTY)) continue; /* * Checkpoints have to wait on all pinned pages, * as pages may be marked dirty when returned to * the cache. * * File syncs only wait on pages both pinned and * dirty. (We don't care if pages are marked * dirty when returned to the cache, that means * there's another writing thread and flushing * the cache for this handle is meaningless.) */ if (op == DB_SYNC_FILE && !F_ISSET(bhp, BH_DIRTY)) continue; mfp = R_ADDR(dbmp->reginfo, bhp->mf_offset); /* * Ignore temporary files -- this means you * can't even flush temporary files by handle. * (Checkpoint doesn't require temporary files * be flushed and the underlying buffer write * write routine may not be able to write it * anyway.) */ if (F_ISSET(mfp, MP_TEMP)) continue; /* * If we're flushing a specific file, see if * this page is from that file. */ if (dbmfp != NULL && mfp != dbmfp->mfp) continue; /* * Ignore files that aren't involved in DB's * transactional operations during checkpoints. */ if (dbmfp == NULL && mfp->lsn_off == -1) continue; /* Track the buffer, we want it. */ bharray[ar_cnt].track_hp = hp; bharray[ar_cnt].track_pgno = bhp->pgno; bharray[ar_cnt].track_off = bhp->mf_offset; ar_cnt++; /* * If we run out of space, double and continue. * Don't stop at trickle_max, we want to sort * as large a sample set as possible in order * to minimize disk seeks. */ if (ar_cnt >= ar_max) { if ((ret = __os_realloc(dbenv, (ar_max * 2) * sizeof(BH_TRACK), &bharray)) != 0) break; ar_max *= 2; } } MUTEX_UNLOCK(dbenv, &hp->hash_mutex); if (ret != 0) goto err; } } /* If there no buffers to write, we're done. */ if (ar_cnt == 0) goto done; /* * Write the buffers in file/page order, trying to reduce seeks by the * filesystem and, when pages are smaller than filesystem block sizes, * reduce the actual number of writes. */ if (ar_cnt > 1) qsort(bharray, ar_cnt, sizeof(BH_TRACK), __bhcmp); /* * If we're trickling buffers, only write enough to reach the correct * percentage. */ if (op == DB_SYNC_TRICKLE && ar_cnt > trickle_max) ar_cnt = trickle_max; /* * Flush the log. We have to ensure the log records reflecting the * changes on the database pages we're writing have already made it * to disk. We still have to check the log each time we write a page * (because pages we are about to write may be modified after we have * flushed the log), but in general this will at least avoid any I/O * on the log's part. */ if (LOGGING_ON(dbenv) && (ret = __log_flush(dbenv, NULL)) != 0) goto err; /* * Walk the array, writing buffers. When we write a buffer, we NULL * out its hash bucket pointer so we don't process a slot more than * once. */ for (i = pass = write_cnt = 0, remaining = ar_cnt; remaining > 0; ++i) { if (i >= ar_cnt) { i = 0; ++pass; (void)__os_sleep(dbenv, 1, 0); } if ((hp = bharray[i].track_hp) == NULL) continue; /* Lock the hash bucket and find the buffer. */ mutexp = &hp->hash_mutex; MUTEX_LOCK(dbenv, mutexp); for (bhp = SH_TAILQ_FIRST(&hp->hash_bucket, __bh); bhp != NULL; bhp = SH_TAILQ_NEXT(bhp, hq, __bh)) if (bhp->pgno == bharray[i].track_pgno && bhp->mf_offset == bharray[i].track_off) break; /* * If we can't find the buffer we're done, somebody else had * to have written it. * * If the buffer isn't pinned or dirty, we're done, there's * no work needed. */ if (bhp == NULL || (bhp->ref == 0 && !F_ISSET(bhp, BH_DIRTY))) { MUTEX_UNLOCK(dbenv, mutexp); --remaining; bharray[i].track_hp = NULL; continue; } /* * If the buffer is locked by another thread, ignore it, we'll * come back to it. * * If the buffer is pinned and it's only the first or second * time we have looked at it, ignore it, we'll come back to * it. * * In either case, skip the buffer if we're not required to * write it. */ if (F_ISSET(bhp, BH_LOCKED) || (bhp->ref != 0 && pass < 2)) { MUTEX_UNLOCK(dbenv, mutexp); if (op != DB_SYNC_CACHE && op != DB_SYNC_FILE) { --remaining; bharray[i].track_hp = NULL; } continue; } /* * The buffer is either pinned or dirty. * * Set the sync wait-for count, used to count down outstanding * references to this buffer as they are returned to the cache. */ bhp->ref_sync = bhp->ref; /* Pin the buffer into memory and lock it. */ ++bhp->ref; F_SET(bhp, BH_LOCKED); MUTEX_LOCK(dbenv, &bhp->mutex); /* * Unlock the hash bucket and wait for the wait-for count to * go to 0. No new thread can acquire the buffer because we * have it locked. * * If a thread attempts to re-pin a page, the wait-for count * will never go to 0 (the thread spins on our buffer lock, * while we spin on the thread's ref count). Give up if we * don't get the buffer in 3 seconds, we can try again later. * * If, when the wait-for count goes to 0, the buffer is found * to be dirty, write it. */ MUTEX_UNLOCK(dbenv, mutexp); for (wait_cnt = 1; bhp->ref_sync != 0 && wait_cnt < 4; ++wait_cnt) (void)__os_sleep(dbenv, 1, 0); MUTEX_LOCK(dbenv, mutexp); hb_lock = 1; /* * If the ref_sync count has gone to 0, we're going to be done * with this buffer no matter what happens. */ if (bhp->ref_sync == 0) { --remaining; bharray[i].track_hp = NULL; } /* * If the ref_sync count has gone to 0 and the buffer is still * dirty, we write it. We only try to write the buffer once. * Any process checkpointing or trickle-flushing the pool * must be able to write any underlying file -- if the write * fails, error out. It would be very strange if file sync * failed to write, but we don't care if it happens. */ if (bhp->ref_sync == 0 && F_ISSET(bhp, BH_DIRTY)) { hb_lock = 0; MUTEX_UNLOCK(dbenv, mutexp); mfp = R_ADDR(dbmp->reginfo, bhp->mf_offset); if ((ret = __memp_bhwrite(dbmp, hp, mfp, bhp, 1)) == 0) ++wrote; else if (op == DB_SYNC_CACHE || op == DB_SYNC_TRICKLE) __db_err(dbenv, "%s: unable to flush page: %lu", __memp_fns(dbmp, mfp), (u_long)bhp->pgno); else ret = 0; /* * Avoid saturating the disk, sleep once we've done * some number of writes. */ if (dbenv->mp_maxwrite != 0 && ++write_cnt >= dbenv->mp_maxwrite) { write_cnt = 0; (void)__os_sleep( dbenv, 0, dbenv->mp_maxwrite_sleep); } } /* * If ref_sync count never went to 0, the buffer was written * by another thread, or the write failed, we still have the * buffer locked. * * We may or may not currently hold the hash bucket mutex. If * the __memp_bhwrite -> __memp_pgwrite call was successful, * then __memp_pgwrite will have swapped the buffer lock for * the hash lock. All other call paths will leave us without * the hash bucket lock. * * The order of mutexes above was to acquire the buffer lock * while holding the hash bucket lock. Don't deadlock here, * release the buffer lock and then acquire the hash bucket * lock. */ if (F_ISSET(bhp, BH_LOCKED)) { F_CLR(bhp, BH_LOCKED); MUTEX_UNLOCK(dbenv, &bhp->mutex); if (!hb_lock) MUTEX_LOCK(dbenv, mutexp); } /* * Reset the ref_sync count regardless of our success, we're * done with this buffer for now. */ bhp->ref_sync = 0; /* Discard our reference and unlock the bucket. */ --bhp->ref; MUTEX_UNLOCK(dbenv, mutexp); if (ret != 0) break; } done: /* * If doing a checkpoint or flushing a file for the application, we * have to force the pages to disk. We don't do this as we go along * because we want to give the OS as much time as possible to lazily * flush, and because we have to flush files that might not even have * had dirty buffers in the cache, so we have to walk the files list. */ if (ret == 0 && (op == DB_SYNC_CACHE || op == DB_SYNC_FILE)) { if (dbmfp == NULL) ret = __memp_sync_files(dbenv, dbmp); else ret = __os_fsync(dbenv, dbmfp->fhp); } /* If we've opened files to flush pages, close them. */ if ((t_ret = __memp_close_flush_files(dbenv, dbmp)) != 0 && ret == 0) ret = t_ret; err: __os_free(dbenv, bharray); if (wrotep != NULL) *wrotep = wrote; return (ret); } /* * __memp_sync_files -- * Sync all the files in the environment, open or not. */ static int __memp_sync_files(dbenv, dbmp) DB_ENV *dbenv; DB_MPOOL *dbmp; { DB_MPOOLFILE *dbmfp; MPOOL *mp; MPOOLFILE *mfp; int final_ret, ret; final_ret = 0; mp = dbmp->reginfo[0].primary; R_LOCK(dbenv, dbmp->reginfo); for (mfp = SH_TAILQ_FIRST(&mp->mpfq, __mpoolfile); mfp != NULL; mfp = SH_TAILQ_NEXT(mfp, q, __mpoolfile)) { if (!mfp->file_written || mfp->deadfile || F_ISSET(mfp, MP_TEMP)) continue; /* * Look for an already open, writeable handle (fsync doesn't * work on read-only Windows handles). */ ret = 0; MUTEX_THREAD_LOCK(dbenv, dbmp->mutexp); for (dbmfp = TAILQ_FIRST(&dbmp->dbmfq); dbmfp != NULL; dbmfp = TAILQ_NEXT(dbmfp, q)) { if (dbmfp->mfp != mfp || F_ISSET(dbmfp, MP_READONLY)) continue; ret = __os_fsync(dbenv, dbmfp->fhp); break; } MUTEX_THREAD_UNLOCK(dbenv, dbmp->mutexp); /* If we don't find one, open one. */ if (dbmfp == NULL) ret = __memp_mf_sync(dbmp, mfp); if (ret != 0) { __db_err(dbenv, "%s: unable to flush: %s", (char *)R_ADDR(dbmp->reginfo, mfp->path_off), db_strerror(ret)); if (final_ret == 0) final_ret = ret; } } R_UNLOCK(dbenv, dbmp->reginfo); return (final_ret); } /* * __memp_close_flush_files -- * Close files opened only to flush buffers. */ static int __memp_close_flush_files(dbenv, dbmp) DB_ENV *dbenv; DB_MPOOL *dbmp; { DB_MPOOLFILE *dbmfp; int ret; /* * The routine exists because we must close files opened by sync to * flush buffers. There are two cases: first, extent files have to * be closed so they may be removed when empty. Second, regular * files have to be closed so we don't run out of descriptors (for * example, and application partitioning its data into databases * based on timestamps, so there's a continually increasing set of * files). * * We mark files opened in the __memp_bhwrite() function with the * MP_FLUSH flag. Here we walk through our file descriptor list, * and, if a file was opened by __memp_bhwrite(), we close it. */ retry: MUTEX_THREAD_LOCK(dbenv, dbmp->mutexp); for (dbmfp = TAILQ_FIRST(&dbmp->dbmfq); dbmfp != NULL; dbmfp = TAILQ_NEXT(dbmfp, q)) if (F_ISSET(dbmfp, MP_FLUSH)) { F_CLR(dbmfp, MP_FLUSH); MUTEX_THREAD_UNLOCK(dbenv, dbmp->mutexp); if ((ret = __memp_fclose(dbmfp, 0)) != 0) return (ret); goto retry; } MUTEX_THREAD_UNLOCK(dbenv, dbmp->mutexp); return (0); } static int __bhcmp(p1, p2) const void *p1, *p2; { BH_TRACK *bhp1, *bhp2; bhp1 = (BH_TRACK *)p1; bhp2 = (BH_TRACK *)p2; /* Sort by file (shared memory pool offset). */ if (bhp1->track_off < bhp2->track_off) return (-1); if (bhp1->track_off > bhp2->track_off) return (1); /* * !!! * Defend against badly written quicksort code calling the comparison * function with two identical pointers (e.g., WATCOM C++ (Power++)). */ if (bhp1->track_pgno < bhp2->track_pgno) return (-1); if (bhp1->track_pgno > bhp2->track_pgno) return (1); return (0); }