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* Enclose most operations that update the database in transactions.
* Open all database tables (Db objects) at initialisation time, not every time they are used. This is necessary because tables have to outlive all transactions that refer to them.
This commit is contained in:
Eelco Dolstra
parent
177a7782ae
commit
06d3d7355d
6 changed files with 145 additions and 96 deletions
131
src/db.cc
131
src/db.cc
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@ -5,15 +5,6 @@
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/* Wrapper class to ensure proper destruction. */
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class DestroyDb
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{
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Db * db;
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public:
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DestroyDb(Db * _db) : db(_db) { }
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~DestroyDb() { db->close(0); delete db; }
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};
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class DestroyDbc
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{
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Dbc * dbc;
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@ -38,24 +29,39 @@ Transaction::Transaction()
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Transaction::Transaction(Database & db)
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{
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db.requireEnv();
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db.env->txn_begin(0, &txn, 0);
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try {
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db.env->txn_begin(0, &txn, 0);
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} catch (DbException e) { rethrow(e); }
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}
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Transaction::~Transaction()
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{
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if (txn) {
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txn->abort();
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txn = 0;
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}
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if (txn) abort();
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}
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void Transaction::commit()
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{
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if (!txn) throw Error("commit called on null transaction");
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txn->commit(0);
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debug(format("committing transaction %1%") % (void *) txn);
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DbTxn * txn2 = txn;
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txn = 0;
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try {
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txn2->commit(0);
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} catch (DbException e) { rethrow(e); }
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}
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void Transaction::abort()
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{
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if (!txn) throw Error("abort called on null transaction");
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debug(format("aborting transaction %1%") % (void *) txn);
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DbTxn * txn2 = txn;
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txn = 0;
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try {
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txn2->abort();
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} catch (DbException e) { rethrow(e); }
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}
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@ -65,28 +71,18 @@ void Database::requireEnv()
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}
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Db * Database::openDB(const Transaction & txn,
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const string & table, bool create)
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Db * Database::getDb(TableId table)
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{
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requireEnv();
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Db * db = new Db(env, 0);
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try {
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// !!! fixme when switching to BDB 4.1: use txn.
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db->open(table.c_str(), 0,
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DB_HASH, create ? DB_CREATE : 0, 0666);
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} catch (...) {
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delete db;
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throw;
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}
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return db;
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map<TableId, Db *>::iterator i = tables.find(table);
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if (i == tables.end())
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throw Error("unknown table id");
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return i->second;
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}
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Database::Database()
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: env(0)
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, nextId(1)
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{
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}
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@ -95,8 +91,23 @@ Database::~Database()
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{
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if (env) {
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debug(format("closing database environment"));
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env->txn_checkpoint(0, 0, 0);
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env->close(0);
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try {
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for (map<TableId, Db *>::iterator i = tables.begin();
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i != tables.end(); i++)
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{
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debug(format("closing table %1%") % i->first);
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Db * db = i->second;
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db->close(0);
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delete db;
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}
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env->txn_checkpoint(0, 0, 0);
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env->close(0);
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} catch (DbException e) { rethrow(e); }
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delete env;
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}
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}
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@ -112,8 +123,9 @@ void Database::open(const string & path)
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env->set_lg_bsize(32 * 1024); /* default */
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env->set_lg_max(256 * 1024); /* must be > 4 * lg_bsize */
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env->set_lk_detect(DB_LOCK_DEFAULT);
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env->open(path.c_str(),
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env->open(path.c_str(),
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DB_INIT_LOCK | DB_INIT_LOG | DB_INIT_MPOOL | DB_INIT_TXN |
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DB_CREATE,
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0666);
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@ -122,22 +134,36 @@ void Database::open(const string & path)
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}
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void Database::createTable(const string & table)
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TableId Database::openTable(const string & tableName)
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{
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requireEnv();
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TableId table = nextId++;
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try {
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Db * db = openDB(noTxn, table, true);
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DestroyDb destroyDb(db);
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Db * db = new Db(env, 0);
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try {
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// !!! fixme when switching to BDB 4.1: use txn.
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db->open(tableName.c_str(), 0, DB_HASH, DB_CREATE, 0666);
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} catch (...) {
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delete db;
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throw;
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}
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tables[table] = db;
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} catch (DbException e) { rethrow(e); }
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return table;
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}
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bool Database::queryString(const Transaction & txn, const string & table,
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bool Database::queryString(const Transaction & txn, TableId table,
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const string & key, string & data)
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{
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try {
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Db * db = openDB(txn, table, false);
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DestroyDb destroyDb(db);
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Db * db = getDb(table);
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Dbt kt((void *) key.c_str(), key.length());
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Dbt dt;
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@ -156,7 +182,7 @@ bool Database::queryString(const Transaction & txn, const string & table,
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}
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bool Database::queryStrings(const Transaction & txn, const string & table,
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bool Database::queryStrings(const Transaction & txn, TableId table,
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const string & key, Strings & data)
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{
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string d;
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@ -190,13 +216,11 @@ bool Database::queryStrings(const Transaction & txn, const string & table,
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}
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void Database::setString(const Transaction & txn, const string & table,
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void Database::setString(const Transaction & txn, TableId table,
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const string & key, const string & data)
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{
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try {
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Db * db = openDB(txn, table, false);
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DestroyDb destroyDb(db);
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Db * db = getDb(table);
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Dbt kt((void *) key.c_str(), key.length());
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Dbt dt((void *) data.c_str(), data.length());
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db->put(txn.txn, &kt, &dt, 0);
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@ -204,7 +228,7 @@ void Database::setString(const Transaction & txn, const string & table,
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}
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void Database::setStrings(const Transaction & txn, const string & table,
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void Database::setStrings(const Transaction & txn, TableId table,
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const string & key, const Strings & data)
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{
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string d;
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@ -227,28 +251,25 @@ void Database::setStrings(const Transaction & txn, const string & table,
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}
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void Database::delPair(const Transaction & txn, const string & table,
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void Database::delPair(const Transaction & txn, TableId table,
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const string & key)
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{
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try {
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Db * db = openDB(txn, table, false);
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DestroyDb destroyDb(db);
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Db * db = getDb(table);
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Dbt kt((void *) key.c_str(), key.length());
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db->del(txn.txn, &kt, 0);
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} catch (DbException e) { rethrow(e); }
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}
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void Database::enumTable(const Transaction & txn, const string & table,
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void Database::enumTable(const Transaction & txn, TableId table,
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Strings & keys)
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{
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try {
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Db * db = openDB(txn, table, false);
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DestroyDb destroyDb(db);
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Db * db = getDb(table);
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Dbc * dbc;
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db->cursor(0, &dbc, 0);
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db->cursor(txn.txn, &dbc, 0);
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DestroyDbc destroyDbc(dbc);
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Dbt kt, dt;
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