From 9cbae0f976118472f0065eee674eacf6ab4b80c5 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Wed, 31 Aug 2011 15:39:17 +0930 Subject: [PATCH] tdb2: enhance tdb1 porting document. --- ccan/tdb2/doc/TDB1_porting.txt | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/ccan/tdb2/doc/TDB1_porting.txt b/ccan/tdb2/doc/TDB1_porting.txt index 90ba2497..ef305cab 100644 --- a/ccan/tdb2/doc/TDB1_porting.txt +++ b/ccan/tdb2/doc/TDB1_porting.txt @@ -42,3 +42,31 @@ Interface differences between TDB1 and TDB2. tdb_lockall_read(): child must call tdb_unlockall_read() tdb_chainlock(): child must call tdb_chainunlock() tdb_parse() callback: child must return from tdb_parse() + +- tdb2 will not open a non-tdb file, even if O_CREAT is specified. + +- There is no tdb_traverse_read. For operating on TDB1 files, you can + simulate it by tdb_add_flag(tdb, TDB_RDONLY); tdb_traverse(); + tdb_remove_flag(tdb, TDB_RDONLY). This may be desirable because + traverse on TDB1 files use a write lock on the entire database + unless it's read-only. + +- Failure inside a transaction (such as a lock function failing) does + not implicitly cancel the transaction; you still need to call + tdb_transaction_cancel(). + +TDB1 Compatibility: + +- tdb2's offers a tdb1_incompatible_hash function, which is the same + as the default hash with the TDB_INCOMPATIBLE_HASH flag. There is + no way of marking an old TDB incompatible with versions < 1.2.6 + while using any other hash. + +- The TDB_ATTRIBUTE_TDB1_HASHSIZE attribute can be used to control the + hash size, but only when creating (ie. O_CREAT) a TDB1 + (ie. TDB_VERSION1). + +- There is no TDB_CLEAR_IF_FIRST flag; it has severe scalability and + API problems. If necessary, you can emulate this by using the open + hook and placing a 1-byte lock at offset 4. If your program forks, + you will need to place this lock again in the child. -- 2.39.2