X-Git-Url: http://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Ftdb%2Ftransaction.c;h=34137251bce51f2697184fbd8dc515315b9d64c6;hp=6909c261a2808ca50c33cb413a5597cde8d4cbd5;hb=165727526f785b05f67f3d88f9518a0a840acbbf;hpb=bcf7916c5d694858766869dfd570e525127154a6 diff --git a/ccan/tdb/transaction.c b/ccan/tdb/transaction.c index 6909c261..34137251 100644 --- a/ccan/tdb/transaction.c +++ b/ccan/tdb/transaction.c @@ -85,11 +85,13 @@ still available, but no transaction recovery area is used and no fsync/msync calls are made. - - if TDB_NO_NESTING is passed to flags in tdb open then transaction - nesting is disabled. tdb_transaction_start() will then implicitely - cancel any pending transactions and always start a new transaction - context instead of nesting. + - if TDB_ALLOW_NESTING is passed to flags in tdb open, or added using + tdb_add_flags() transaction is enabled. + The default is that transaction nesting is not allowed and an attempt + to create a nested transaction will fail with TDB_ERR_NESTING. + Beware. when transactions are nested a transaction successfully + completed with tdb_transaction_commit() can be silently unrolled later. */ @@ -142,14 +144,6 @@ static int transaction_read(struct tdb_context *tdb, tdb_off_t off, void *buf, { uint32_t blk; - /* Only a commit is allowed on a prepared transaction */ - if (tdb->transaction->prepared) { - tdb->ecode = TDB_ERR_EINVAL; - TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_read: transaction already prepared, read not allowed\n")); - tdb->transaction->transaction_error = 1; - return -1; - } - /* break it down into block sized ops */ while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) { tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size); @@ -409,8 +403,15 @@ static int transaction_expand_file(struct tdb_context *tdb, tdb_off_t size, /* brlock during a transaction - ignore them */ -static int transaction_brlock(struct tdb_context *tdb, tdb_off_t offset, - int rw_type, int lck_type, int probe, size_t len) +static int transaction_brlock(struct tdb_context *tdb, + int rw_type, tdb_off_t offset, size_t len, + enum tdb_lock_flags flags) +{ + return 0; +} + +static int transaction_brunlock(struct tdb_context *tdb, + int rw_type, tdb_off_t offset, size_t len) { return 0; } @@ -421,7 +422,8 @@ static const struct tdb_methods transaction_methods = { transaction_next_hash_chain, transaction_oob, transaction_expand_file, - transaction_brlock + transaction_brlock, + transaction_brunlock }; /* @@ -453,7 +455,8 @@ static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t return 0; } -int tdb_transaction_cancel_internal(struct tdb_context *tdb) +/* ltype is F_WRLCK after prepare. */ +int _tdb_transaction_cancel(struct tdb_context *tdb, int ltype) { int i, ret = 0; @@ -492,15 +495,16 @@ int tdb_transaction_cancel_internal(struct tdb_context *tdb) /* remove any global lock created during the transaction */ if (tdb->global_lock.count != 0) { - tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 4*tdb->header.hash_size); + tdb_brunlock(tdb, tdb->global_lock.ltype, + FREELIST_TOP, 4*tdb->header.hash_size); tdb->global_lock.count = 0; } /* remove any locks created during the transaction */ if (tdb->num_locks != 0) { for (i=0;inum_lockrecs;i++) { - tdb_brlock(tdb,FREELIST_TOP+4*tdb->lockrecs[i].list, - F_UNLCK,F_SETLKW, 0, 1); + tdb_brunlock(tdb, tdb->lockrecs[i].ltype, + FREELIST_TOP+4*tdb->lockrecs[i].list, 1); } tdb->num_locks = 0; tdb->num_lockrecs = 0; @@ -510,8 +514,8 @@ int tdb_transaction_cancel_internal(struct tdb_context *tdb) /* restore the normal io methods */ tdb->methods = tdb->transaction->io_methods; - tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0); - tdb_transaction_unlock(tdb); + tdb_brunlock(tdb, ltype, FREELIST_TOP, 0); + tdb_transaction_unlock(tdb, F_WRLCK); SAFE_FREE(tdb->transaction->hash_heads); SAFE_FREE(tdb->transaction); @@ -533,16 +537,15 @@ int tdb_transaction_start(struct tdb_context *tdb) /* cope with nested tdb_transaction_start() calls */ if (tdb->transaction != NULL) { - tdb_trace(tdb, "tdb_transaction_start"); - if (!tdb->flags & TDB_NO_NESTING) { - tdb->transaction->nesting++; - TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n", - tdb->transaction->nesting)); - return 0; - } else { - tdb_transaction_cancel_internal(tdb); - TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: cancelling previous transaction\n")); + if (!(tdb->flags & TDB_ALLOW_NESTING)) { + tdb->ecode = TDB_ERR_NESTING; + return -1; } + tdb_trace(tdb, "tdb_transaction_start"); + tdb->transaction->nesting++; + TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n", + tdb->transaction->nesting)); + return 0; } if (tdb->num_locks != 0 || tdb->global_lock.count) { @@ -584,7 +587,7 @@ int tdb_transaction_start(struct tdb_context *tdb) /* get a read lock from the freelist to the end of file. This is upgraded to a write lock during the commit */ - if (tdb_brlock(tdb, FREELIST_TOP, F_RDLCK, F_SETLKW, 0, 0) == -1) { + if (tdb_brlock(tdb, F_RDLCK, FREELIST_TOP, 0, TDB_LOCK_WAIT) == -1) { TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to get hash locks\n")); tdb->ecode = TDB_ERR_LOCK; goto fail; @@ -620,8 +623,8 @@ int tdb_transaction_start(struct tdb_context *tdb) return 0; fail: - tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0); - tdb_transaction_unlock(tdb); + tdb_brunlock(tdb, F_RDLCK, FREELIST_TOP, 0); + tdb_transaction_unlock(tdb, F_WRLCK); SAFE_FREE(tdb->transaction->blocks); SAFE_FREE(tdb->transaction->hash_heads); SAFE_FREE(tdb->transaction); @@ -633,9 +636,12 @@ fail: cancel the current transaction */ int tdb_transaction_cancel(struct tdb_context *tdb) -{ +{ + int ltype = F_RDLCK; tdb_trace(tdb, "tdb_transaction_cancel"); - return tdb_transaction_cancel_internal(tdb); + if (tdb->transaction && tdb->transaction->prepared) + ltype = F_WRLCK; + return _tdb_transaction_cancel(tdb, ltype); } /* @@ -884,7 +890,7 @@ static int transaction_setup_recovery(struct tdb_context *tdb, return 0; } -static int tdb_transaction_prepare_commit_internal(struct tdb_context *tdb) +static int _tdb_transaction_prepare_commit(struct tdb_context *tdb) { const struct tdb_methods *methods; @@ -895,14 +901,14 @@ static int tdb_transaction_prepare_commit_internal(struct tdb_context *tdb) if (tdb->transaction->prepared) { tdb->ecode = TDB_ERR_EINVAL; - tdb_transaction_cancel(tdb); + _tdb_transaction_cancel(tdb, F_WRLCK); TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction already prepared\n")); return -1; } if (tdb->transaction->transaction_error) { tdb->ecode = TDB_ERR_IO; - tdb_transaction_cancel_internal(tdb); + _tdb_transaction_cancel(tdb, F_RDLCK); TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction error pending\n")); return -1; } @@ -913,11 +919,6 @@ static int tdb_transaction_prepare_commit_internal(struct tdb_context *tdb) return 0; } -#ifdef TDB_TRACE - /* store seqnum now, before reading becomes illegal. */ - tdb_ofs_read(tdb, TDB_SEQNUM_OFS, &tdb->transaction_prepare_seqnum); -#endif - /* check for a null transaction */ if (tdb->transaction->blocks == NULL) { return 0; @@ -930,7 +931,7 @@ static int tdb_transaction_prepare_commit_internal(struct tdb_context *tdb) if (tdb->num_locks || tdb->global_lock.count) { tdb->ecode = TDB_ERR_LOCK; TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: locks pending on commit\n")); - tdb_transaction_cancel_internal(tdb); + _tdb_transaction_cancel(tdb, F_RDLCK); return -1; } @@ -938,16 +939,16 @@ static int tdb_transaction_prepare_commit_internal(struct tdb_context *tdb) if (tdb_brlock_upgrade(tdb, FREELIST_TOP, 0) == -1) { TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to upgrade hash locks\n")); tdb->ecode = TDB_ERR_LOCK; - tdb_transaction_cancel_internal(tdb); + _tdb_transaction_cancel(tdb, F_RDLCK); return -1; } /* get the global lock - this prevents new users attaching to the database during the commit */ - if (tdb_brlock(tdb, GLOBAL_LOCK, F_WRLCK, F_SETLKW, 0, 1) == -1) { + if (tdb_brlock(tdb, F_WRLCK, GLOBAL_LOCK, 1, TDB_LOCK_WAIT) == -1) { TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get global lock\n")); tdb->ecode = TDB_ERR_LOCK; - tdb_transaction_cancel_internal(tdb); + _tdb_transaction_cancel(tdb, F_WRLCK); return -1; } @@ -955,8 +956,8 @@ static int tdb_transaction_prepare_commit_internal(struct tdb_context *tdb) /* write the recovery data to the end of the file */ if (transaction_setup_recovery(tdb, &tdb->transaction->magic_offset) == -1) { TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: failed to setup recovery data\n")); - tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1); - tdb_transaction_cancel_internal(tdb); + tdb_brunlock(tdb, F_WRLCK, GLOBAL_LOCK, 1); + _tdb_transaction_cancel(tdb, F_WRLCK); return -1; } } @@ -970,8 +971,8 @@ static int tdb_transaction_prepare_commit_internal(struct tdb_context *tdb) tdb->transaction->old_map_size) == -1) { tdb->ecode = TDB_ERR_IO; TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: expansion failed\n")); - tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1); - tdb_transaction_cancel_internal(tdb); + tdb_brunlock(tdb, F_WRLCK, GLOBAL_LOCK, 1); + _tdb_transaction_cancel(tdb, F_WRLCK); return -1; } tdb->map_size = tdb->transaction->old_map_size; @@ -989,7 +990,7 @@ static int tdb_transaction_prepare_commit_internal(struct tdb_context *tdb) int tdb_transaction_prepare_commit(struct tdb_context *tdb) { tdb_trace(tdb, "tdb_transaction_prepare_commit"); - return tdb_transaction_prepare_commit_internal(tdb); + return _tdb_transaction_prepare_commit(tdb); } /* @@ -1006,13 +1007,7 @@ int tdb_transaction_commit(struct tdb_context *tdb) return -1; } - /* If we've prepared, can't read seqnum. */ - if (tdb->transaction->prepared) { - tdb_trace_seqnum(tdb, tdb->transaction_prepare_seqnum, - "tdb_transaction_commit"); - } else { - tdb_trace(tdb, "tdb_transaction_commit"); - } + tdb_trace(tdb, "tdb_transaction_commit"); if (tdb->transaction->transaction_error) { tdb->ecode = TDB_ERR_IO; @@ -1029,12 +1024,12 @@ int tdb_transaction_commit(struct tdb_context *tdb) /* check for a null transaction */ if (tdb->transaction->blocks == NULL) { - tdb_transaction_cancel_internal(tdb); + _tdb_transaction_cancel(tdb, F_RDLCK); return 0; } if (!tdb->transaction->prepared) { - int ret = tdb_transaction_prepare_commit_internal(tdb); + int ret = _tdb_transaction_prepare_commit(tdb); if (ret) return ret; } @@ -1065,8 +1060,8 @@ int tdb_transaction_commit(struct tdb_context *tdb) tdb->methods = methods; tdb_transaction_recover(tdb); - tdb_transaction_cancel_internal(tdb); - tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1); + _tdb_transaction_cancel(tdb, F_WRLCK); + tdb_brunlock(tdb, F_WRLCK, GLOBAL_LOCK, 1); TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n")); return -1; @@ -1082,7 +1077,7 @@ int tdb_transaction_commit(struct tdb_context *tdb) return -1; } - tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1); + tdb_brunlock(tdb, F_WRLCK, GLOBAL_LOCK, 1); /* TODO: maybe write to some dummy hdr field, or write to magic @@ -1103,7 +1098,7 @@ int tdb_transaction_commit(struct tdb_context *tdb) /* use a transaction cancel to free memory and remove the transaction locks */ - tdb_transaction_cancel_internal(tdb); + _tdb_transaction_cancel(tdb, F_WRLCK); if (need_repack) { return tdb_repack(tdb);