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Fix handling of transactions with large results

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If transaction replaying was enabled and a result was returned in more
than one call to clientReply, a NULL value would be added to the statement
which in turn would trigger a debug assertion.

Similarly any following statements in the transaction would be executed
regardless of whether the result was complete.

Renamed the statement execution function to better describe what it does.

Extended the basic functional test case to cover this.
This commit is contained in:
Markus Mäkelä
2018-07-07 01:42:11 +03:00
parent 77a1417479
commit 0614ff4c9d
3 changed files with 32 additions and 4 deletions
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21
server/modules/routing/readwritesplit/rwsplitsession.cc
View File

@ -376,7 +376,7 @@ GWBUF* RWSplitSession::handle_causal_read_reply(GWBUF *writebuf, SRWBackend& bac
return writebuf;
}
void RWSplitSession::handle_trx_replay()
void RWSplitSession::trx_replay_next_stmt()
{
if (m_replayed_trx.have_stmts())
{
@ -495,8 +495,17 @@ void RWSplitSession::clientReply(GWBUF *writebuf, DCB *backend_dcb)
{
/** Transaction size is OK, store the statement for replaying and
* update the checksum of the result */
m_trx.add_stmt(m_current_query.release());
m_trx.add_result(writebuf);
if (m_current_query.get())
{
// TODO: Don't replay transactions interrupted mid-result. Currently
// the client will receive a `Packets out of order` error if this happens.
// Add the statement to the transaction once the first part
// of the result is received.
m_trx.add_stmt(m_current_query.release());
}
}
else
{
@ -561,7 +570,12 @@ void RWSplitSession::clientReply(GWBUF *writebuf, DCB *backend_dcb)
else if (m_is_replay_active)
{
ss_dassert(m_config->transaction_replay);
handle_trx_replay();
if (m_expected_responses == 0)
{
// Current statement is complete, continue with the next one
trx_replay_next_stmt();
}
/**
* If the start of the transaction was interrupted, we need to return
@ -598,6 +612,7 @@ void RWSplitSession::clientReply(GWBUF *writebuf, DCB *backend_dcb)
}
else if (m_expected_responses == 0 && m_query_queue)
{
ss_dassert(!m_is_replay_active); // Note: We might currently end up here
// All replies received, route any stored queries
route_stored_query();
}

2
server/modules/routing/readwritesplit/rwsplitsession.hh
View File

@ -202,7 +202,7 @@ private:
void handle_error_reply_client(DCB *backend_dcb, GWBUF *errmsg);
bool handle_error_new_connection(DCB *backend_dcb, GWBUF *errmsg);
void handle_trx_replay();
void trx_replay_next_stmt();
// Do we have at least one open slave connection
bool have_connected_slaves() const;