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MXS-1507: Replay read-only transaction

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Read-only transactions are now replayed if the node in question fails.
This commit is contained in:
Markus Mäkelä 2018-04-23 11:29:15 +03:00
parent 2848f96945
commit 7de7e7b2fe
No known key found for this signature in database
GPG Key ID: 72D48FCE664F7B19
2 changed files with 45 additions and 44 deletions
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81
server/modules/routing/readwritesplit/rwsplitsession.cc
View File

@ -525,22 +525,33 @@ void check_and_log_backend_state(const SRWBackend& backend, DCB* problem_dcb)
}
}
void RWSplitSession::start_trx_replay()
bool RWSplitSession::start_trx_replay()
{
MXS_INFO("Starting transaction replay");
m_is_replay_active = true;
bool rval = false;
/**
* Copy the transaction for replaying and finalize it. This
* allows the checksums to be compared. The current transaction
* is closed as the replaying opens a new transaction.
*/
m_replayed_trx = m_trx;
m_replayed_trx.finalize();
m_trx.close();
if (!m_is_replay_active && m_config.transaction_replay)
{
// Stash any interrupted queries while we replay the transaction
m_interrupted_query.reset(m_current_query.release());
// Pop the first statement and start replaying the transaction
retry_query(m_replayed_trx.pop_stmt(), 0);
MXS_INFO("Starting transaction replay");
m_is_replay_active = true;
/**
* Copy the transaction for replaying and finalize it. This
* allows the checksums to be compared. The current transaction
* is closed as the replaying opens a new transaction.
*/
m_replayed_trx = m_trx;
m_replayed_trx.finalize();
m_trx.close();
// Pop the first statement and start replaying the transaction
retry_query(m_replayed_trx.pop_stmt(), 0);
rval = true;
}
return rval;
}
/**
@ -573,11 +584,11 @@ void RWSplitSession::handleError(GWBUF *errmsgbuf, DCB *problem_dcb,
{
case ERRACT_NEW_CONNECTION:
{
bool can_continue = false;
if (m_current_master && m_current_master->in_use() && m_current_master == backend)
{
/** The connection to the master has failed */
SERVER *srv = m_current_master->server();
bool can_continue = false;
if (!backend->is_waiting_result())
{
@ -615,9 +626,9 @@ void RWSplitSession::handleError(GWBUF *errmsgbuf, DCB *problem_dcb,
send_readonly_error(m_client);
}
if (!can_continue && !SERVER_IS_MASTER(srv) && !srv->master_err_is_logged)
if (!can_continue && !backend->is_master() &&
!backend->server()->master_err_is_logged)
{
ss_dassert(backend);
MXS_ERROR("Server %s (%s) lost the master status while waiting"
" for a result. Client sessions will be closed.",
backend->name(), backend->uri());
@ -625,27 +636,11 @@ void RWSplitSession::handleError(GWBUF *errmsgbuf, DCB *problem_dcb,
}
}
if (m_is_replay_active)
if (session_trx_is_active(session))
{
MXS_INFO("Failed to replay transaction. Closing connection.");
can_continue = false;
}
else if (session_trx_is_active(session))
{
if (m_config.transaction_replay)
{
// Stash any interrupted queries while we replay the transaction
m_interrupted_query.reset(m_current_query.release());
can_continue = true;
start_trx_replay();
}
else
{
can_continue = false;
}
can_continue = start_trx_replay();
}
*succp = can_continue;
backend->close();
}
else
@ -653,21 +648,21 @@ void RWSplitSession::handleError(GWBUF *errmsgbuf, DCB *problem_dcb,
if (m_target_node && m_target_node == backend &&
session_trx_is_read_only(problem_dcb->session))
{
/**
* We were locked to a single node but the node died. Currently
* this only happens with read-only transactions so the only
* thing we can do is to close the connection.
*/
*succp = false;
backend->close(mxs::Backend::CLOSE_FATAL);
// We're no longer locked to this server as it failed
m_target_node.reset();
// Try to replay the transaction on another node
can_continue = start_trx_replay();
backend->close();
}
else
{
/** Try to replace the failed connection with a new one */
*succp = handle_error_new_connection(problem_dcb, errmsgbuf);
can_continue = handle_error_new_connection(problem_dcb, errmsgbuf);
}
}
*succp = can_continue;
check_and_log_backend_state(backend, problem_dcb);
break;
}

8
server/modules/routing/readwritesplit/rwsplitsession.hh
View File

@ -185,7 +185,13 @@ private:
bool handle_error_new_connection(DCB *backend_dcb, GWBUF *errmsg);
void handle_trx_replay();
void start_trx_replay();
/**
* Start the replaying of the latest transaction
*
* @return True if the session can continue. False if the session must be closed.
*/
bool start_trx_replay();
private:
// QueryClassifier::Handler