diff options
Diffstat (limited to 'db.go')
| -rw-r--r-- | db.go | 143 |
1 files changed, 43 insertions, 100 deletions
@@ -15,7 +15,9 @@ const ( IntegerDupKey ) -var DatabaseAlreadyOpenedError = &Error{"Database already open", nil} +var DatabaseNotOpenError = &Error{"db is not open", nil} +var DatabaseAlreadyOpenedError = &Error{"db already open", nil} +var TransactionInProgressError = &Error{"writable transaction is already in progress", nil} // TODO: #define MDB_FATAL_ERROR 0x80000000U /** Failed to update the meta page. Probably an I/O error. */ // TODO: #define MDB_ENV_ACTIVE 0x20000000U /** Some fields are initialized. */ @@ -44,9 +46,9 @@ type DB struct { mmapSize int /**< size of the data memory map */ size int /**< current file size */ pbuf []byte - transaction *transaction /**< current write transaction */ + transaction *Transaction /**< current write transaction */ maxPageNumber int /**< me_mapsize / me_psize */ - pageState pageState /**< state of old pages from freeDB */ + pagestate pagestate /**< state of old pages from freeDB */ dpages []*page /**< list of malloc'd blocks for re-use */ freePages []int /** IDL of pages that became unused in a write txn */ dirtyPages []int /** ID2L of pages written during a write txn. Length MDB_IDL_UM_SIZE. */ @@ -203,12 +205,50 @@ func (db *DB) close() { // TODO } +// Transaction creates a transaction that's associated with this database. +func (db *DB) Transaction(writable bool) (*Transaction, error) { + db.Lock() + defer db.Unlock() + + // Exit if the database is not open yet. + if !db.opened { + return nil, DatabaseNotOpenError + } + // Exit if a writable transaction is currently in progress. + if writable && db.transaction != nil { + return nil, TransactionInProgressError + } + + // Create a transaction associated with the database. + t := &Transaction{ + db: db, + writable: writable, + } + + // We only allow one writable transaction at a time so save the reference. + if writable { + db.transaction = t + } + + return t, nil +} + // page retrieves a page reference from a given byte array based on the current page size. func (db *DB) page(b []byte, id int) *page { return (*page)(unsafe.Pointer(&b[id*db.pageSize])) } +// // +// // +// // +// // +// // // ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ CONVERTED ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ // +// // +// // +// // +// // +// // func (db *DB) freePage(p *page) { /* @@ -266,103 +306,6 @@ func (db *DB) sync(force bool) error { return nil } -func (db *DB) Transaction(parent *transaction, flags int) (*transaction, error) { - /* - MDB_txn *txn; - MDB_ntxn *ntxn; - int rc, size, tsize = sizeof(MDB_txn); - - if (env->me_flags & MDB_FATAL_ERROR) { - DPUTS("environment had fatal error, must shutdown!"); - return MDB_PANIC; - } - if ((env->me_flags & MDB_RDONLY) && !(flags & MDB_RDONLY)) - return EACCES; - if (parent) { - // Nested transactions: Max 1 child, write txns only, no writemap - if (parent->mt_child || - (flags & MDB_RDONLY) || - (parent->mt_flags & (MDB_TXN_RDONLY|MDB_TXN_ERROR)) || - (env->me_flags & MDB_WRITEMAP)) - { - return (parent->mt_flags & MDB_TXN_RDONLY) ? EINVAL : MDB_BAD_TXN; - } - tsize = sizeof(MDB_ntxn); - } - size = tsize + env->me_maxdbs * (sizeof(MDB_db)+1); - if (!(flags & MDB_RDONLY)) - size += env->me_maxdbs * sizeof(MDB_cursor *); - - if ((txn = calloc(1, size)) == NULL) { - DPRINTF(("calloc: %s", strerror(ErrCode()))); - return ENOMEM; - } - txn->mt_dbs = (MDB_db *) ((char *)txn + tsize); - if (flags & MDB_RDONLY) { - txn->mt_flags |= MDB_TXN_RDONLY; - txn->mt_dbflags = (unsigned char *)(txn->mt_dbs + env->me_maxdbs); - } else { - txn->mt_cursors = (MDB_cursor **)(txn->mt_dbs + env->me_maxdbs); - txn->mt_dbflags = (unsigned char *)(txn->mt_cursors + env->me_maxdbs); - } - txn->mt_env = env; - - if (parent) { - unsigned int i; - txn->mt_u.dirty_list = malloc(sizeof(MDB_ID2)*MDB_IDL_UM_SIZE); - if (!txn->mt_u.dirty_list || - !(txn->mt_free_pgs = mdb_midl_alloc(MDB_IDL_UM_MAX))) - { - free(txn->mt_u.dirty_list); - free(txn); - return ENOMEM; - } - txn->mt_txnid = parent->mt_txnid; - txn->mt_dirty_room = parent->mt_dirty_room; - txn->mt_u.dirty_list[0].mid = 0; - txn->mt_spill_pgs = NULL; - txn->mt_next_pgno = parent->mt_next_pgno; - parent->mt_child = txn; - txn->mt_parent = parent; - txn->mt_numdbs = parent->mt_numdbs; - txn->mt_flags = parent->mt_flags; - txn->mt_dbxs = parent->mt_dbxs; - memcpy(txn->mt_dbs, parent->mt_dbs, txn->mt_numdbs * sizeof(MDB_db)); - // Copy parent's mt_dbflags, but clear DB_NEW - for (i=0; i<txn->mt_numdbs; i++) - txn->mt_dbflags[i] = parent->mt_dbflags[i] & ~DB_NEW; - rc = 0; - ntxn = (MDB_ntxn *)txn; - ntxn->mnt_pgstate = env->me_pgstate; // save parent me_pghead & co - if (env->me_pghead) { - size = MDB_IDL_SIZEOF(env->me_pghead); - env->me_pghead = mdb_midl_alloc(env->me_pghead[0]); - if (env->me_pghead) - memcpy(env->me_pghead, ntxn->mnt_pgstate.mf_pghead, size); - else - rc = ENOMEM; - } - if (!rc) - rc = mdb_cursor_shadow(parent, txn); - if (rc) - mdb_txn_reset0(txn, "beginchild-fail"); - } else { - rc = mdb_txn_renew0(txn); - } - if (rc) - free(txn); - else { - *ret = txn; - DPRINTF(("begin txn %"Z"u%c %p on mdbenv %p, root page %"Z"u", - txn->mt_txnid, (txn->mt_flags & MDB_TXN_RDONLY) ? 'r' : 'w', - (void *) txn, (void *) env, txn->mt_dbs[MAIN_DBI].md_root)); - } - - return rc; - */ - return nil, nil -} - // Check both meta pages to see which one is newer. // @param[in] env the environment handle // @return meta toggle (0 or 1). |