bool
Freeze::IteratorHelperI::find(const Dbt& key) const
{
assert((key.get_flags() & DB_DBT_USERMEM) != 0);
Dbt dbKey(key);
#if (DB_VERSION_MAJOR <= 4) || (DB_VERSION_MAJOR == 5 && DB_VERSION_MINOR <= 1)
//
// When we have a custom-comparison function, Berkeley DB returns
// the key on-disk (when it finds one). We disable this behavior:
// (ref Oracle SR 5925672.992)
//
dbKey.set_flags(dbKey.get_flags() | DB_DBT_PARTIAL);
#else
//
// In DB > 5.1 we can not set DB_DBT_PARTIAL in the key Dbt,
// when using DB_SET, we must resize the Dbt key param to hold enough
// space or Dbc::get fails with DB_BUFFER_SMALL.
//
dbKey.set_ulen(dbKey.get_size());
#endif
//
// Keep 0 length since we're not interested in the data.
//
Dbt dbValue;
dbValue.set_flags(DB_DBT_USERMEM | DB_DBT_PARTIAL);
for(;;)
{
try
{
return _dbc->get(&dbKey, &dbValue, DB_SET) == 0;
}
catch(const ::DbDeadlockException& dx)
{
if(_tx != 0)
{
_tx->dead();
}
DeadlockException ex(__FILE__, __LINE__);
ex.message = dx.what();
throw ex;
}
catch(const ::DbException& dx)
{
DatabaseException ex(__FILE__, __LINE__);
ex.message = dx.what();
throw ex;
}
}
}
void test_dbt(void) {
u_int32_t size = 3;
u_int32_t flags = 5;
u_int32_t ulen = 7;
void* data = &size;
Dbt dbt;
dbt.set_size(size);
dbt.set_flags(flags);
dbt.set_data(data);
dbt.set_ulen(ulen);
assert(dbt.get_size() == size);
assert(dbt.get_flags() == flags);
assert(dbt.get_data() == data);
assert(dbt.get_ulen() == ulen);
}
void BtRecExample::run()
{
db_recno_t recno;
int ret;
char buf[1024];
// Acquire a cursor for the database.
dbp->cursor(NULL, &dbcp, 0);
//
// Prompt the user for a record number, then retrieve and display
// that record.
//
for (;;) {
// Get a record number.
cout << "recno #> ";
cout.flush();
if (fgets(buf, sizeof(buf), stdin) == NULL)
break;
recno = atoi(buf);
//
// Start with a fresh key each time,
// the dbp->get() routine returns
// the key and data pair, not just the key!
//
Dbt key(&recno, sizeof(recno));
Dbt data;
if ((ret = dbcp->get(&key, &data, DB_SET_RECNO)) != 0) {
dbp->err(ret, "DBcursor->get");
throw DbException(ret);
}
// Display the key and data.
show("k/d\t", &key, &data);
// Move the cursor a record forward.
if ((ret = dbcp->get(&key, &data, DB_NEXT)) != 0) {
dbp->err(ret, "DBcursor->get");
throw DbException(ret);
}
// Display the key and data.
show("next\t", &key, &data);
//
// Retrieve the record number for the following record into
// local memory.
//
data.set_data(&recno);
data.set_size(sizeof(recno));
data.set_ulen(sizeof(recno));
data.set_flags(data.get_flags() | DB_DBT_USERMEM);
if ((ret = dbcp->get(&key, &data, DB_GET_RECNO)) != 0) {
if (ret != DB_NOTFOUND && ret != DB_KEYEMPTY) {
dbp->err(ret, "DBcursor->get");
throw DbException(ret);
}
}
else {
cout << "retrieved recno: " << (u_long)recno << "\n";
}
}
dbcp->close();
dbcp = NULL;
}
