The following code fragment uses a cursor to store a new key in the cats
database with four associated data items. The key is a name. The data
items are a company name and a list of the breeds of cat owned. Each
of the data entries is stored as a duplicate data item. In this
example, transactions are necessary to ensure that either all or none
of the data items appear in case of system or application failure.
int
main(int argc, char *argv)
{
extern int optind;
DB *db_cats, *db_color, *db_fruit;
DB_ENV *dbenv;
int ch;
while ((ch = getopt(argc, argv, "")) != EOF)
switch (ch) {
case '?':
default:
usage();
}
argc -= optind;
argv += optind;
env_dir_create();
env_open(&dbenv);
/* Open database: Key is fruit class; Data is specific type. */
db_open(dbenv, &db_fruit, "fruit", 0);
/* Open database: Key is a color; Data is an integer. */
db_open(dbenv, &db_color, "color", 0);
/*
* Open database:
* Key is a name; Data is: company name, cat breeds.
*/
db_open(dbenv, &db_cats, "cats", 1);
add_fruit(dbenv, db_fruit, "apple", "yellow delicious");
add_color(dbenv, db_color, "blue", 0);
add_color(dbenv, db_color, "blue", 3);
add_cat(dbenv, db_cats,
"Amy Adams",
"Sleepycat Software",
"abyssinian",
"bengal",
"chartreaux",
NULL);
return (0);
}
int
add_cat(DB_ENV *dbenv, DB *db, char *name, ...)
{
va_list ap;
DBC *dbc;
DBT key, data;
DB_TXN *tid;
int fail, ret, t_ret;
char *s;
/* Initialization. */
fail = 0;
memset(&key, 0, sizeof(key));
memset(&data, 0, sizeof(data));
key.data = name;
key.size = strlen(name);
retry: /* Begin the transaction. */
if ((ret = dbenv->txn_begin(dbenv, NULL, &tid, 0)) != 0) {
dbenv->err(dbenv, ret, "DB_ENV->txn_begin");
exit (1);
}
/* Delete any previously existing item. */
switch (ret = db->del(db, tid, &key, 0)) {
case 0:
case DB_NOTFOUND:
break;
case DB_LOCK_DEADLOCK:
default:
/* Retry the operation. */
if ((t_ret = tid->abort(tid)) != 0) {
dbenv->err(dbenv, t_ret, "DB_TXN->abort");
exit (1);
}
if (fail++ == MAXIMUM_RETRY)
return (ret);
goto retry;
}
/* Create a cursor. */
if ((ret = db->cursor(db, tid, &dbc, 0)) != 0) {
dbenv->err(dbenv, ret, "db->cursor");
exit (1);
}
/* Append the items, in order. */
va_start(ap, name);
while ((s = va_arg(ap, char *)) != NULL) {
data.data = s;
data.size = strlen(s);
switch (ret = dbc->c_put(dbc, &key, &data, DB_KEYLAST)) {
case 0:
break;
case DB_LOCK_DEADLOCK:
default:
va_end(ap);
/* Retry the operation. */
if ((t_ret = dbc->c_close(dbc)) != 0) {
dbenv->err(
dbenv, t_ret, "dbc->c_close");
exit (1);
}
if ((t_ret = tid->abort(tid)) != 0) {
dbenv->err(dbenv, t_ret, "DB_TXN->abort");
exit (1);
}
if (fail++ == MAXIMUM_RETRY)
return (ret);
goto retry;
}
}
va_end(ap);
/* Success: commit the change. */
if ((ret = dbc->c_close(dbc)) != 0) {
dbenv->err(dbenv, ret, "dbc->c_close");
exit (1);
}
if ((ret = tid->commit(tid, 0)) != 0) {
dbenv->err(dbenv, ret, "DB_TXN->commit");
exit (1);
}
return (0);
}
