/*
* __wt_txn_config --
* Configure a transaction.
*/
int
__wt_txn_config(WT_SESSION_IMPL *session, const char *cfg[])
{
WT_CONFIG_ITEM cval;
WT_TXN *txn;
txn = &session->txn;
WT_RET(__wt_config_gets_def(session, cfg, "isolation", 0, &cval));
if (cval.len != 0)
txn->isolation =
WT_STRING_MATCH("snapshot", cval.str, cval.len) ?
WT_ISO_SNAPSHOT :
WT_STRING_MATCH("read-committed", cval.str, cval.len) ?
WT_ISO_READ_COMMITTED : WT_ISO_READ_UNCOMMITTED;
/*
* The default sync setting is inherited from the connection, but can
* be overridden by an explicit "sync" setting for this transaction.
*
* We want to distinguish between inheriting implicitly and explicitly.
*/
F_CLR(txn, WT_TXN_SYNC_SET);
WT_RET(__wt_config_gets_def(
session, cfg, "sync", (int)UINT_MAX, &cval));
if (cval.val == 0 || cval.val == 1)
/*
* This is an explicit setting of sync. Set the flag so
* that we know not to overwrite it in commit_transaction.
*/
F_SET(txn, WT_TXN_SYNC_SET);
/*
* If sync is turned off explicitly, clear the transaction's sync field.
*/
if (cval.val == 0)
txn->txn_logsync = 0;
WT_RET(__wt_config_gets_def(session, cfg, "snapshot", 0, &cval));
if (cval.len > 0)
/*
* The layering here isn't ideal - the named snapshot get
* function does both validation and setup. Otherwise we'd
* need to walk the list of named snapshots twice during
* transaction open.
*/
WT_RET(__wt_txn_named_snapshot_get(session, &cval));
return (0);
}
/*
* __wt_txn_config --
* Configure a transaction.
*/
int
__wt_txn_config(WT_SESSION_IMPL *session, const char *cfg[])
{
WT_CONFIG_ITEM cval;
WT_TXN *txn;
txn = &session->txn;
WT_RET(__wt_config_gets_def(session, cfg, "isolation", 0, &cval));
if (cval.len != 0)
txn->isolation =
WT_STRING_MATCH("snapshot", cval.str, cval.len) ?
WT_ISO_SNAPSHOT :
WT_STRING_MATCH("read-committed", cval.str, cval.len) ?
WT_ISO_READ_COMMITTED : WT_ISO_READ_UNCOMMITTED;
/*
* The default sync setting is inherited from the connection, but can
* be overridden by an explicit "sync" setting for this transaction.
*
* We want to distinguish between inheriting implicitly and explicitly.
*/
F_CLR(txn, WT_TXN_SYNC_SET);
WT_RET(__wt_config_gets_def(
session, cfg, "sync", (int)UINT_MAX, &cval));
if (cval.val == 0 || cval.val == 1)
/*
* This is an explicit setting of sync. Set the flag so
* that we know not to overwrite it in commit_transaction.
*/
F_SET(txn, WT_TXN_SYNC_SET);
/*
* If sync is turned off explicitly, clear the transaction's sync field.
*/
if (cval.val == 0)
txn->txn_logsync = 0;
WT_RET(__wt_config_gets_def(session, cfg, "snapshot", 0, &cval));
if (cval.len > 0)
/*
* The layering here isn't ideal - the named snapshot get
* function does both validation and setup. Otherwise we'd
* need to walk the list of named snapshots twice during
* transaction open.
*/
WT_RET(__wt_txn_named_snapshot_get(session, &cval));
WT_RET(__wt_config_gets_def(session, cfg, "read_timestamp", 0, &cval));
if (cval.len > 0) {
#ifdef HAVE_TIMESTAMPS
wt_timestamp_t ts;
WT_TXN_GLOBAL *txn_global;
char timestamp_buf[2 * WT_TIMESTAMP_SIZE + 1];
bool round_to_oldest;
txn_global = &S2C(session)->txn_global;
WT_RET(__wt_txn_parse_timestamp(session, "read", &ts, &cval));
/*
* Read the configuration here to reduce the span of the
* critical section.
*/
WT_RET(__wt_config_gets_def(session,
cfg, "round_to_oldest", 0, &cval));
round_to_oldest = cval.val;
/*
* This code is not using the timestamp validate function to
* avoid a race between checking and setting transaction
* timestamp.
*/
__wt_readlock(session, &txn_global->rwlock);
if (__wt_timestamp_cmp(&ts, &txn_global->oldest_timestamp) < 0)
{
WT_RET(__wt_timestamp_to_hex_string(session,
timestamp_buf, &ts));
/*
* If given read timestamp is earlier than oldest
* timestamp then round the read timestamp to
* oldest timestamp.
*/
if (round_to_oldest)
__wt_timestamp_set(&txn->read_timestamp,
&txn_global->oldest_timestamp);
else {
__wt_readunlock(session, &txn_global->rwlock);
WT_RET_MSG(session, EINVAL, "read timestamp "
"%s older than oldest timestamp",
timestamp_buf);
}
} else {
__wt_timestamp_set(&txn->read_timestamp, &ts);
/*
* Reset to avoid a verbose message as read
* timestamp is not rounded to oldest timestamp.
*/
round_to_oldest = false;
}
__wt_txn_set_read_timestamp(session);
__wt_readunlock(session, &txn_global->rwlock);
txn->isolation = WT_ISO_SNAPSHOT;
if (round_to_oldest) {
/*
* This message is generated here to reduce the span of
* critical section.
*/
__wt_verbose(session, WT_VERB_TIMESTAMP, "Read "
"timestamp %s : Rounded to oldest timestamp",
timestamp_buf);
}
#else
WT_RET_MSG(session, EINVAL, "read_timestamp requires a "
"version of WiredTiger built with timestamp support");
#endif
}
return (0);
}
