db_dispatch.c

这是linux下运行的mysql软件包,可用于linux 下安装 php + mysql + apach 的网络配置

	db_pgno_t pgno;
	db_lockmode_t mode;
	DB_TXN *ptxn, *txn;
{
	DBT lock_dbt;
	DB_LOCK lock;
	DB_LOCK_ILOCK lock_obj;
	DB_LOCKREQ req;
	int ret;

	lock_obj.pgno = pgno;
	memcpy(lock_obj.fileid, fileid, DB_FILE_ID_LEN);
	lock_obj.type = DB_PAGE_LOCK;

	memset(&lock_dbt, 0, sizeof(lock_dbt));
	lock_dbt.data = &lock_obj;
	lock_dbt.size = sizeof(lock_obj);

	if ((ret = dbenv->lock_get(dbenv,
	    txn->txnid, 0, &lock_dbt, mode, &lock)) == 0) {
		memset(&req, 0, sizeof(req));
		req.lock = lock;
		req.op = DB_LOCK_TRADE;

		ret = dbenv->lock_vec(dbenv, ptxn->txnid, 0, &req, 1, NULL);
	}
	return (ret);
}

/*
 * __db_limbo_move
 *	Move just the metapage lock to the parent.
 */
static int
__db_limbo_move(dbenv, ptxn, txn, elp)
	DB_ENV *dbenv;
	DB_TXN *ptxn, *txn;
	DB_TXNLIST *elp;
{
	int ret;

	for (; elp != NULL; elp = LIST_NEXT(elp, links)) {
		if (elp->type != TXNLIST_PGNO || elp->u.p.locked == 1)
			continue;
		if ((ret = __db_lock_move(dbenv, elp->u.p.uid,
		    PGNO_BASE_MD, DB_LOCK_WRITE, ptxn, txn)) != 0)
			return (ret);
		elp->u.p.locked = 1;
	}

	return (0);
}
/*
 * __db_limbo_bucket
 *	Perform limbo processing for a single hash bucket in the txnlist.
 * txn is the transaction aborting in the case of an abort and ctxn is the
 * compensating transaction.
 */

#define T_RESTORED(txn)       ((txn) != NULL && F_ISSET(txn, TXN_RESTORED))
static int
__db_limbo_bucket(dbenv, txn, elp)
	DB_ENV *dbenv;
	DB_TXN *txn;
	DB_TXNLIST *elp;
{
	DB *dbp;
	DB_MPOOLFILE *mpf;
	DBMETA *meta;
	DB_TXN *ctxn, *t;
	db_pgno_t last_pgno, pgno;
	int dbp_created, in_retry, ret, t_ret;

	ctxn = NULL;
	in_retry = 0;
	meta = NULL;
	mpf = NULL;
	ret = 0;
	for (; elp != NULL; elp = LIST_NEXT(elp, links)) {
		if (elp->type != TXNLIST_PGNO)
			continue;
retry:		dbp_created = 0;

		/*
		 * Pick the transaction in which to potentially
		 * log compensations.
		 */
		if (!in_retry && !IS_RECOVERING(dbenv) && !T_RESTORED(txn)
		    && (ret = __txn_compensate_begin(dbenv, &ctxn)) != 0)
			return (ret);

		/*
		 * Either use the compensating transaction or
		 * the one passed in, which will be null if recovering.
		 */
		t = ctxn == NULL ? txn : ctxn;

		/* First try to get a dbp by fileid. */
		ret = __dbreg_id_to_db(dbenv, t, &dbp, elp->u.p.fileid, 0);

		/*
		 * File is being destroyed.  No need to worry about
		 * dealing with recovery of allocations.
		 */
		if (ret == DB_DELETED ||
		    (ret == 0 && F_ISSET(dbp, DB_AM_DISCARD)))
			goto next;

		if (ret != 0) {
			if ((ret = db_create(&dbp, dbenv, 0)) != 0)
				goto err;

			/*
			 * This tells the system not to lock, which is always
			 * OK, whether this is an abort or recovery.
			 */
			F_SET(dbp, DB_AM_COMPENSATE);
			dbp_created = 1;

			/* It is ok if the file is nolonger there. */
			dbp->type = DB_UNKNOWN;
			ret = __db_dbopen(dbp, t, elp->u.p.fname, NULL,
			    DB_ODDFILESIZE, __db_omode("rw----"), PGNO_BASE_MD);
			if (ret == ENOENT)
				goto next;
		}

		/*
		 * Verify that we are opening the same file that we were
		 * referring to when we wrote this log record.
		 */
		if (memcmp(elp->u.p.uid, dbp->fileid, DB_FILE_ID_LEN) != 0)
			goto next;

		mpf = dbp->mpf;
		last_pgno = PGNO_INVALID;

		if (ctxn == NULL) {
			pgno = PGNO_BASE_MD;
			if ((ret =
			    mpf->get(mpf, &pgno, 0, (PAGE **)&meta)) != 0)
				goto err;
			last_pgno = meta->free;
		}

		ret = __db_limbo_fix(dbp, ctxn, elp, &last_pgno, meta);
		/*
		 * If we were doing compensating transactions, then we are
		 * going to hope this error was due to running out of space.
		 * We'll change modes (into the sync the file mode) and keep
		 * trying.  If we weren't doing compensating transactions,
		 * then this is a real error and we're sunk.
		 */
		if (ret != 0) {
			if (ret == DB_RUNRECOVERY || ctxn == NULL)
				goto err;
			in_retry = 1;
			goto retry;
		}

		if (ctxn != NULL) {
			ret = ctxn->commit(ctxn, DB_TXN_NOSYNC);
			ctxn = NULL;
			if (ret != 0)
				goto retry;
			goto next;
		}

		/*
		 * This is where we handle the case where we're explicitly
		 * putting together a free list.  We need to decide whether
		 * we have to write the meta-data page, and if we do, then
		 * we need to sync it as well.
		 */
		if (last_pgno == meta->free) {
			/* No change to page; just put the page back. */
			if ((ret = mpf->put(mpf, meta, 0)) != 0)
				goto err;
			meta = NULL;
		} else {
			/*
			 * These changes are unlogged so we cannot have the
			 * metapage pointing at pages that are not on disk.
			 * Therefore, we flush the new free list, then update
			 * the metapage.  We have to put the meta-data page
			 * first so that it isn't pinned when we try to sync.
			 */
			if (!IS_RECOVERING(dbenv) && !T_RESTORED(txn))
				__db_err(dbenv, "Flushing free list to disk");
			if ((ret = mpf->put(mpf, meta, 0)) != 0)
				goto err;
			meta = NULL;
			dbp->sync(dbp, 0);
			pgno = PGNO_BASE_MD;
			if ((ret =
			    mpf->get(mpf, &pgno, 0, (PAGE **)&meta)) != 0)
				goto err;
			meta->free = last_pgno;
			if ((ret = mpf->put(mpf, meta, DB_MPOOL_DIRTY)) != 0)
				goto err;
			meta = NULL;
		}

next:
		/*
		 * If we get here, either we have processed the list
		 * or the db file has been deleted or could no be opened.
		 */
		if (ctxn != NULL &&
		    (t_ret = ctxn->abort(ctxn)) != 0 && ret == 0)
			ret = t_ret;

		if (dbp_created &&
		    (t_ret = __db_close_i(dbp, txn, 0)) != 0 && ret == 0)
			ret = t_ret;
		dbp = NULL;
		__os_free(dbenv, elp->u.p.fname);
		__os_free(dbenv, elp->u.p.pgno_array);
		if (ret == ENOENT)
			ret = 0;
		else if (ret != 0)
			goto err;
	}

err:	if (meta != NULL)
		(void)mpf->put(mpf, meta, 0);
	return (ret);
}

/*
 * __db_limbo_fix --
 *	Process a single limbo entry which describes all the page allocations
 * for a single file.
 */
static int
__db_limbo_fix(dbp, ctxn, elp, lastp, meta)
	DB *dbp;
	DB_TXN *ctxn;
	DB_TXNLIST *elp;
	db_pgno_t *lastp;
	DBMETA *meta;
{
	DBC *dbc;
	DB_MPOOLFILE *mpf;
	PAGE *freep, *pagep;
	db_pgno_t next, pgno;
	int i, put_page, ret, t_ret;

	/*
	 * Loop through the entries for this txnlist element and
	 * either link them into the free list or write a compensating
	 * record for each.
	 */
	put_page = 0;
	ret = 0;
	mpf = dbp->mpf;
	dbc = NULL;

	for (i = 0; i < elp->u.p.nentries; i++) {
		pgno = elp->u.p.pgno_array[i];

		if ((ret = mpf->get(mpf, &pgno, DB_MPOOL_CREATE, &pagep)) != 0)
			goto err;
		put_page = 1;

		if (IS_ZERO_LSN(LSN(pagep))) {
			if (ctxn == NULL) {
				/*
				 * If this is a fatal recovery which
				 * spans a previous crash this page may
				 * be on the free list already.
				 */
				for (next = *lastp; next != 0; ) {
					if (next == pgno)
						break;
					if ((ret = mpf->get(mpf,
					    &next, 0, &freep)) != 0)
						goto err;
					next = NEXT_PGNO(freep);
					if ((ret =
					    mpf->put(mpf, freep, 0)) != 0)
						goto err;
				}

				if (next != pgno) {
					P_INIT(pagep, dbp->pgsize, pgno,
					    PGNO_INVALID, *lastp, 0, P_INVALID);
					LSN(pagep) = LSN(meta);
					*lastp = pgno;
				}
			} else {
				P_INIT(pagep, dbp->pgsize, pgno,
				    PGNO_INVALID, *lastp, 0, P_INVALID);
				if (dbc == NULL && (ret =
				    dbp->cursor(dbp, ctxn, &dbc, 0)) != 0)
						goto err;
				/*
				 * If the dbp is compensating (because we
				 * opened it), the dbc will automatically be
				 * marked compensating, but in case we didn't
				 * do the open, we have to mark it explicitly.
				 */
				F_SET(dbc, DBC_COMPENSATE);
				ret = __db_free(dbc, pagep);
				put_page = 0;
				/*
				 * On any error, we hope that the error was
				 * caused due to running out of space, and we
				 * switch modes, doing the processing where we
				 * sync out files instead of doing compensating
				 * transactions.  If this was a real error and
				 * not out of space, we assume that some other
				 * call will fail real soon.
				 */
				if (ret != 0) {
					/* Assume that this is out of space. */
					(void)dbc->c_close(dbc);
					dbc = NULL;
					goto err;
				}
			}
		}

		if (put_page == 1) {
			ret = mpf->put(mpf, pagep, DB_MPOOL_DIRTY);
			put_page = 0;
		}
		if (ret != 0)
			goto err;
	}

err:	if (put_page &&
	    (t_ret = mpf->put(mpf, pagep, DB_MPOOL_DIRTY)) != 0 && ret == 0)
		ret = t_ret;
	if (dbc != NULL && (t_ret = dbc->c_close(dbc)) != 0 && ret == 0)
		ret = t_ret;
	return (ret);
}

#define	DB_TXNLIST_MAX_PGNO	8		/* A nice even number. */

/*
 * __db_txnlist_pgnoadd --
 *	Find the txnlist entry for a file and add this pgno, or add the list
 *	entry for the file and then add the pgno.
 */
static int
__db_txnlist_pgnoadd(dbenv, hp, fileid, uid, fname, pgno)
	DB_ENV *dbenv;
	DB_TXNHEAD *hp;
	int32_t fileid;
	u_int8_t uid[DB_FILE_ID_LEN];
	char *fname;
	db_pgno_t pgno;
{
	DB_TXNLIST *elp;
	u_int32_t hash;
	int len, ret;

	elp = NULL;

	if (__db_txnlist_find_internal(dbenv, hp,
	    TXNLIST_PGNO, 0, uid, &elp, 0) != 0) {
		if ((ret =
		    __os_malloc(dbenv, sizeof(DB_TXNLIST), &elp)) != 0)
			goto err;
		memcpy(&hash, uid, sizeof(hash));
		LIST_INSERT_HEAD(
		    &hp->head[DB_TXNLIST_MASK(hp, hash)], elp, links);
		elp->u.p.fileid = fileid;
		memcpy(elp->u.p.uid, uid, DB_FILE_ID_LEN);

		len = (int)strlen(fname) + 1;
		if ((ret = __os_malloc(dbenv, len, &elp->u.p.fname)) != 0)
			goto err;
		memcpy(elp->u.p.fname, fname, len);

		elp->u.p.maxentry = 0;
		elp->u.p.locked = 0;
		elp->type = TXNLIST_PGNO;
		if ((ret = __os_malloc(dbenv,
		    8 * sizeof(db_pgno_t), &elp->u.p.pgno_array)) != 0)
			goto err;
		elp->u.p.maxentry = DB_TXNLIST_MAX_PGNO;
		elp->u.p.nentries = 0;
	} else if (elp->u.p.nentries == elp->u.p.maxentry) {
		elp->u.p.maxentry <<= 1;
		if ((ret = __os_realloc(dbenv, elp->u.p.maxentry *
		    sizeof(db_pgno_t), &elp->u.p.pgno_array)) != 0)
			goto err;
	}

	elp->u.p.pgno_array[elp->u.p.nentries++] = pgno;

	return (0);

err:	__db_txnlist_end(dbenv, hp);
	return (ret);
}

/*
 * __db_default_getpgnos --
 *	Fill in default getpgnos information for an application-specific
 * log record.
 */
static int
__db_default_getpgnos(dbenv, lsnp, summary)
	DB_ENV *dbenv;
	DB_LSN *lsnp;
	void *summary;
{
	TXN_RECS *t;
	int ret;

	t = (TXN_RECS *)summary;

	if ((ret = __rep_check_alloc(dbenv, t, 1)) != 0)
		return (ret);

	t->array[t->npages].flags = LSN_PAGE_NOLOCK;
	t->array[t->npages].lsn = *lsnp;
	t->array[t->npages].fid = DB_LOGFILEID_INVALID;
	memset(&t->array[t->npages].pgdesc, 0,
	    sizeof(t->array[t->npages].pgdesc));

	t->npages++;

	return (0);
}

#ifdef DEBUG
/*
 * __db_txnlist_print --
 *	Print out the transaction list.
 *
 * PUBLIC: void __db_txnlist_print __P((void *));
 */
void
__db_txnlist_print(listp)
	void *listp;
{
	DB_TXNHEAD *hp;
	DB_TXNLIST *p;
	int i;
	char *stats[] = { "ok", "commit", "prepare", "abort", "notfound",
	    "ignore", "expected", "unexpected" };

	hp = (DB_TXNHEAD *)listp;

	printf("Maxid: %lu Generation: %lu\n",
	    (u_long)hp->maxid, (u_long)hp->generation);
	for (i = 0; i < hp->nslots; i++)
	for (p = LIST_FIRST(&hp->head[i]); p != NULL; p = LIST_NEXT(p, links)) {
		switch (p->type) {
		case TXNLIST_TXNID:
			printf("TXNID: %lx(%lu): %s\n",
			    (u_long)p->u.t.txnid, (u_long)p->u.t.generation,
			    stats[p->u.t.status]);
			break;
		default:
			printf("Unrecognized type: %d\n", p->type);
			break;
		}
	}
}
#endif