tdb/common/traverse.c

ソースコードを見る。

関数
static int	tdb_next_lock (struct tdb_context *tdb, struct tdb_traverse_lock *tlock, struct list_struct *rec)
static int	tdb_traverse_internal (struct tdb_context *tdb, tdb_traverse_func fn, void *private_data, struct tdb_traverse_lock *tl)
int	tdb_traverse_read (struct tdb_context *tdb, tdb_traverse_func fn, void *private_data)
int	tdb_traverse (struct tdb_context *tdb, tdb_traverse_func fn, void *private_data)
TDB_DATA	tdb_firstkey (struct tdb_context *tdb)
TDB_DATA	tdb_nextkey (struct tdb_context *tdb, TDB_DATA oldkey)

---

関数

static int tdb_next_lock	(	struct tdb_context *	tdb,
		struct tdb_traverse_lock *	tlock,
		struct list_struct *	rec
	)			[static]

traverse.c の 32 行で定義されています。

参照先 tdb_traverse_lock::hash・tdb_header::hash_size・tdb_context::header・tdb_traverse_lock::lock_rw・tdb_context::methods・list_struct::next・tdb_methods::next_hash_chain・tdb_traverse_lock::off・tdb_context::read_only・tdb・TDB_DEBUG_FATAL・tdb_do_delete()・tdb_lock()・tdb_lock_record()・tdb_ofs_read()・tdb_rec_read()・tdb_unlock()・tdb_unlock_record()・tdb_context::traverse_read.

参照元 tdb_firstkey()・tdb_nextkey()・tdb_traverse_internal().

{
        int want_next = (tlock->off != 0);

        /* Lock each chain from the start one. */
        for (; tlock->hash < tdb->header.hash_size; tlock->hash++) {
                if (!tlock->off && tlock->hash != 0) {
                        /* this is an optimisation for the common case where
                           the hash chain is empty, which is particularly
                           common for the use of tdb with ldb, where large
                           hashes are used. In that case we spend most of our
                           time in tdb_brlock(), locking empty hash chains.
                           
                           To avoid this, we do an unlocked pre-check to see
                           if the hash chain is empty before starting to look
                           inside it. If it is empty then we can avoid that
                           hash chain. If it isn't empty then we can't believe
                           the value we get back, as we read it without a
                           lock, so instead we get the lock and re-fetch the
                           value below.
                           
                           Notice that not doing this optimisation on the
                           first hash chain is critical. We must guarantee
                           that we have done at least one fcntl lock at the
                           start of a search to guarantee that memory is
                           coherent on SMP systems. If records are added by
                           others during the search then thats OK, and we
                           could possibly miss those with this trick, but we
                           could miss them anyway without this trick, so the
                           semantics don't change.
                           
                           With a non-indexed ldb search this trick gains us a
                           factor of around 80 in speed on a linux 2.6.x
                           system (testing using ldbtest).
                        */
                        tdb->methods->next_hash_chain(tdb, &tlock->hash);
                        if (tlock->hash == tdb->header.hash_size) {
                                continue;
                        }
                }

                if (tdb_lock(tdb, tlock->hash, tlock->lock_rw) == -1)
                        return -1;

                /* No previous record?  Start at top of chain. */
                if (!tlock->off) {
                        if (tdb_ofs_read(tdb, TDB_HASH_TOP(tlock->hash),
                                     &tlock->off) == -1)
                                goto fail;
                } else {
                        /* Otherwise unlock the previous record. */
                        if (tdb_unlock_record(tdb, tlock->off) != 0)
                                goto fail;
                }

                if (want_next) {
                        /* We have offset of old record: grab next */
                        if (tdb_rec_read(tdb, tlock->off, rec) == -1)
                                goto fail;
                        tlock->off = rec->next;
                }

                /* Iterate through chain */
                while( tlock->off) {
                        tdb_off_t current;
                        if (tdb_rec_read(tdb, tlock->off, rec) == -1)
                                goto fail;

                        /* Detect infinite loops. From "Shlomi Yaakobovich" <Shlomi@exanet.com>. */
                        if (tlock->off == rec->next) {
                                TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_next_lock: loop detected.\n"));
                                goto fail;
                        }

                        if (!TDB_DEAD(rec)) {
                                /* Woohoo: we found one! */
                                if (tdb_lock_record(tdb, tlock->off) != 0)
                                        goto fail;
                                return tlock->off;
                        }

                        /* Try to clean dead ones from old traverses */
                        current = tlock->off;
                        tlock->off = rec->next;
                        if (!(tdb->read_only || tdb->traverse_read) && 
                            tdb_do_delete(tdb, current, rec) != 0)
                                goto fail;
                }
                tdb_unlock(tdb, tlock->hash, tlock->lock_rw);
                want_next = 0;
        }
        /* We finished iteration without finding anything */
        return TDB_ERRCODE(TDB_SUCCESS, 0);

 fail:
        tlock->off = 0;
        if (tdb_unlock(tdb, tlock->hash, tlock->lock_rw) != 0)
                TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_next_lock: On error unlock failed!\n"));
        return -1;
}

static int tdb_traverse_internal	(	struct tdb_context *	tdb,
		tdb_traverse_func	fn,
		void *	private_data,
		struct tdb_traverse_lock *	tl
	)			[static]

traverse.c の 139 行で定義されています。

参照先 TDB_DATA::dptr・TDB_DATA::dsize・fn・tdb_traverse_lock::hash・tdb_traverse_lock::lock_rw・tdb_traverse_lock::next・tdb_traverse_lock::off・tdb・tdb_alloc_read()・TDB_DEBUG_FATAL・tdb_next_lock()・tdb_unlock()・tdb_unlock_record()・tdb_context::travlocks.

参照元 tdb_traverse()・tdb_traverse_read().

{
        TDB_DATA key, dbuf;
        struct list_struct rec;
        int ret, count = 0;

        /* This was in the initializaton, above, but the IRIX compiler
         * did not like it.  crh
         */
        tl->next = tdb->travlocks.next;

        /* fcntl locks don't stack: beware traverse inside traverse */
        tdb->travlocks.next = tl;

        /* tdb_next_lock places locks on the record returned, and its chain */
        while ((ret = tdb_next_lock(tdb, tl, &rec)) > 0) {
                count++;
                /* now read the full record */
                key.dptr = tdb_alloc_read(tdb, tl->off + sizeof(rec), 
                                          rec.key_len + rec.data_len);
                if (!key.dptr) {
                        ret = -1;
                        if (tdb_unlock(tdb, tl->hash, tl->lock_rw) != 0)
                                goto out;
                        if (tdb_unlock_record(tdb, tl->off) != 0)
                                TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_traverse: key.dptr == NULL and unlock_record failed!\n"));
                        goto out;
                }
                key.dsize = rec.key_len;
                dbuf.dptr = key.dptr + rec.key_len;
                dbuf.dsize = rec.data_len;

                /* Drop chain lock, call out */
                if (tdb_unlock(tdb, tl->hash, tl->lock_rw) != 0) {
                        ret = -1;
                        SAFE_FREE(key.dptr);
                        goto out;
                }
                if (fn && fn(tdb, key, dbuf, private_data)) {
                        /* They want us to terminate traversal */
                        ret = count;
                        if (tdb_unlock_record(tdb, tl->off) != 0) {
                                TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_traverse: unlock_record failed!\n"));;
                                ret = -1;
                        }
                        SAFE_FREE(key.dptr);
                        goto out;
                }
                SAFE_FREE(key.dptr);
        }
out:
        tdb->travlocks.next = tl->next;
        if (ret < 0)
                return -1;
        else
                return count;
}

int tdb_traverse_read	(	struct tdb_context *	tdb,
		tdb_traverse_func	fn,
		void *	private_data
	)

traverse.c の 203 行で定義されています。

参照先 tdb_context::ecode・tdb_context::methods・tdb・tdb_methods::tdb_brlock・TDB_DEBUG_ERROR・TDB_ERR_LOCK・tdb_traverse_internal()・tdb_context::traverse_read.

参照元 addrec_db()・main()・tdb_traverse().

{
        struct tdb_traverse_lock tl = { NULL, 0, 0, F_RDLCK };
        int ret;
        
        /* we need to get a read lock on the transaction lock here to
           cope with the lock ordering semantics of solaris10 */
        if (tdb->methods->tdb_brlock(tdb, TRANSACTION_LOCK, F_RDLCK, F_SETLKW, 0, 1) == -1) {
                TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_traverse_read: failed to get transaction lock\n"));
                tdb->ecode = TDB_ERR_LOCK;
                return -1;
        }

        tdb->traverse_read++;
        ret = tdb_traverse_internal(tdb, fn, private_data, &tl);
        tdb->traverse_read--;

        tdb->methods->tdb_brlock(tdb, TRANSACTION_LOCK, F_UNLCK, F_SETLKW, 0, 1);

        return ret;
}

int tdb_traverse	(	struct tdb_context *	tdb,
		tdb_traverse_func	fn,
		void *	private_data
	)

traverse.c の 230 行で定義されています。

参照先 tdb_context::ecode・tdb_context::methods・tdb_context::read_only・tdb・tdb_methods::tdb_brlock・TDB_DEBUG_ERROR・TDB_ERR_LOCK・tdb_traverse_internal()・tdb_traverse_read()・tdb_context::traverse_read.

参照元 addrec_db()・backup_tdb()・brl_forall()・clear_unexpected()・count_current_connections()・do_command()・do_daemon_stack_trace()・dump_tdb()・dump_wins_subnet_namelist()・elog_tdb_size()・enum_aliasmem()・fetch_all_active_wins_1b_names()・idmap_tdb_convert()・idmap_tdb_dump_data()・info_tdb()・init_group_mapping()・initiate_wins_processing()・load_msg()・main()・message_send_all()・net_enum_pipes()・net_idmap_dump()・net_status_sessions()・net_status_shares()・net_status_shares_parseable()・print_backend_init()・print_queue_update_internal()・privilege_enumerate_accounts()・py_tdb_hnd_keys()・py_tdb_hnd_traverse()・receive_unexpected()・session_traverse()・share_info_db_init()・share_mode_forall()・status_page()・sysjob_to_jobid()・tdb_hnd_length()・tdbsam_setsampwent()・update_c_setprinter()・upgrade_to_version_4()・upgrade_to_version_5()・verify_tdb()・wcache_count_cached_creds()・wcache_flush_cache()・wcache_invalidate_cache()・wcache_remove_oldest_cached_creds()・wins_write_database().

{
        struct tdb_traverse_lock tl = { NULL, 0, 0, F_WRLCK };
        int ret;

        if (tdb->read_only || tdb->traverse_read) {
                return tdb_traverse_read(tdb, fn, private_data);
        }
        
        if (tdb->methods->tdb_brlock(tdb, TRANSACTION_LOCK, F_WRLCK, F_SETLKW, 0, 1) == -1) {
                TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_traverse: failed to get transaction lock\n"));
                tdb->ecode = TDB_ERR_LOCK;
                return -1;
        }

        ret = tdb_traverse_internal(tdb, fn, private_data, &tl);

        tdb->methods->tdb_brlock(tdb, TRANSACTION_LOCK, F_UNLCK, F_SETLKW, 0, 1);

        return ret;
}

TDB_DATA tdb_firstkey

(

struct tdb_context *

tdb

)

traverse.c の 255 行で定義されています。

参照先 TDB_DATA::dptr・TDB_DATA::dsize・tdb_traverse_lock::hash・list_struct::key_len・tdb_traverse_lock::lock_rw・tdb_traverse_lock::off・tdb・tdb_alloc_read()・TDB_DEBUG_FATAL・tdb_next_lock()・tdb_null・tdb_unlock()・tdb_unlock_record()・tdb_context::travlocks.

参照元 compare_db()・enum_group_mapping()・first_record()・get_group_map_from_gid()・get_group_map_from_ntname()・get_ntdrivers()・get_ntforms()・py_tdb_hnd_first_key()・tdb_search_keys()・tdbsam_convert()・upgrade_to_version_3().

{
        TDB_DATA key;
        struct list_struct rec;

        /* release any old lock */
        if (tdb_unlock_record(tdb, tdb->travlocks.off) != 0)
                return tdb_null;
        tdb->travlocks.off = tdb->travlocks.hash = 0;
        tdb->travlocks.lock_rw = F_RDLCK;

        /* Grab first record: locks chain and returned record. */
        if (tdb_next_lock(tdb, &tdb->travlocks, &rec) <= 0)
                return tdb_null;
        /* now read the key */
        key.dsize = rec.key_len;
        key.dptr =tdb_alloc_read(tdb,tdb->travlocks.off+sizeof(rec),key.dsize);

        /* Unlock the hash chain of the record we just read. */
        if (tdb_unlock(tdb, tdb->travlocks.hash, tdb->travlocks.lock_rw) != 0)
                TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_firstkey: error occurred while tdb_unlocking!\n"));
        return key;
}

TDB_DATA tdb_nextkey	(	struct tdb_context *	tdb,
		TDB_DATA	oldkey
	)

traverse.c の 280 行で定義されています。

参照先 TDB_DATA::dptr・TDB_DATA::dsize・errno・list_struct::full_hash・tdb_traverse_lock::hash・tdb_context::hash_fn・list_struct::key_len・tdb_traverse_lock::lock_rw・tdb_traverse_lock::off・strerror()・tdb・tdb_alloc_read()・TDB_DEBUG_FATAL・tdb_find_lock_hash()・tdb_lock()・tdb_lock_record()・tdb_next_lock()・tdb_null・tdb_rec_read()・tdb_unlock()・tdb_unlock_record()・tdb_context::travlocks.

参照元 compare_db()・enum_group_mapping()・get_group_map_from_gid()・get_group_map_from_ntname()・get_ntdrivers()・get_ntforms()・next_record()・py_tdb_hnd_next_key()・tdb_search_keys()・tdbsam_convert()・upgrade_to_version_3().

{
        u32 oldhash;
        TDB_DATA key = tdb_null;
        struct list_struct rec;
        char *k = NULL;

        /* Is locked key the old key?  If so, traverse will be reliable. */
        if (tdb->travlocks.off) {
                if (tdb_lock(tdb,tdb->travlocks.hash,tdb->travlocks.lock_rw))
                        return tdb_null;
                if (tdb_rec_read(tdb, tdb->travlocks.off, &rec) == -1
                    || !(k = tdb_alloc_read(tdb,tdb->travlocks.off+sizeof(rec),
                                            rec.key_len))
                    || memcmp(k, oldkey.dptr, oldkey.dsize) != 0) {
                        /* No, it wasn't: unlock it and start from scratch */
                        if (tdb_unlock_record(tdb, tdb->travlocks.off) != 0) {
                                SAFE_FREE(k);
                                return tdb_null;
                        }
                        if (tdb_unlock(tdb, tdb->travlocks.hash, tdb->travlocks.lock_rw) != 0) {
                                SAFE_FREE(k);
                                return tdb_null;
                        }
                        tdb->travlocks.off = 0;
                }

                SAFE_FREE(k);
        }

        if (!tdb->travlocks.off) {
                /* No previous element: do normal find, and lock record */
                tdb->travlocks.off = tdb_find_lock_hash(tdb, oldkey, tdb->hash_fn(&oldkey), tdb->travlocks.lock_rw, &rec);
                if (!tdb->travlocks.off)
                        return tdb_null;
                tdb->travlocks.hash = BUCKET(rec.full_hash);
                if (tdb_lock_record(tdb, tdb->travlocks.off) != 0) {
                        TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_nextkey: lock_record failed (%s)!\n", strerror(errno)));
                        return tdb_null;
                }
        }
        oldhash = tdb->travlocks.hash;

        /* Grab next record: locks chain and returned record,
           unlocks old record */
        if (tdb_next_lock(tdb, &tdb->travlocks, &rec) > 0) {
                key.dsize = rec.key_len;
                key.dptr = tdb_alloc_read(tdb, tdb->travlocks.off+sizeof(rec),
                                          key.dsize);
                /* Unlock the chain of this new record */
                if (tdb_unlock(tdb, tdb->travlocks.hash, tdb->travlocks.lock_rw) != 0)
                        TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_nextkey: WARNING tdb_unlock failed!\n"));
        }
        /* Unlock the chain of old record */
        if (tdb_unlock(tdb, BUCKET(oldhash), tdb->travlocks.lock_rw) != 0)
                TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_nextkey: WARNING tdb_unlock failed!\n"));
        return key;
}

---