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Use references instead of copies of SRWBackend

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As the DCB passed as the clientReply parameter is guaranteed to match one
of the DCBs in the RWBackends. By using a reference, the need to copy a
shared_ptr is removed (along with the atomic operation that it implies)
thus reducing the overhead in the clientReply and the functions it uses.
This commit is contained in:
Markus Mäkelä
2017-10-06 11:34:33 +03:00
parent 5f13f1d358
commit 81f9425c9b
3 changed files with 39 additions and 39 deletions
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74
server/modules/routing/readwritesplit/readwritesplit.cc
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@ -124,6 +124,30 @@ SRWBackend get_backend_from_dcb(RWSplitSession *rses, DCB *dcb)
return SRWBackend();
}
static SRWBackend emptyref;
static SRWBackend& get_backend_ref_from_dcb(RWSplitSession *rses, DCB *dcb)
{
ss_dassert(dcb->dcb_role == DCB_ROLE_BACKEND_HANDLER);
CHK_DCB(dcb);
CHK_CLIENT_RSES(rses);
for (SRWBackendList::iterator it = rses->backends.begin();
it != rses->backends.end(); it++)
{
SRWBackend& backend = *it;
if (backend->dcb() == dcb)
{
return backend;
}
}
/** We should always have a valid backend reference */
ss_dassert(false);
return emptyref;
}
/**
* @brief Process router options
*
@ -562,22 +586,13 @@ static inline bool is_result_set(GWBUF *buffer)
*
* @return True if the complete response has been received
*/
bool reply_is_complete(SRWBackend backend, GWBUF *buffer)
bool reply_is_complete(SRWBackend& backend, GWBUF *buffer)
{
if (GWBUF_IS_COLLECTED_RESULT(buffer))
if (backend->get_reply_state() == REPLY_STATE_START &&
(!is_result_set(buffer) || GWBUF_IS_COLLECTED_RESULT(buffer)))
{
// This branch should only be taken with a PS response
ss_dassert(backend->get_reply_state() == REPLY_STATE_START);
ss_dassert(backend->current_command() == MXS_COM_STMT_PREPARE ||
backend->current_command() == MXS_COM_QUERY);
// This is a complete result of a request
LOG_RS(backend, REPLY_STATE_DONE);
backend->set_reply_state(REPLY_STATE_DONE);
}
else if (backend->get_reply_state() == REPLY_STATE_START && !is_result_set(buffer))
{
if (backend->current_command() == MXS_COM_STMT_PREPARE ||
if (GWBUF_IS_COLLECTED_RESULT(buffer) ||
backend->current_command() == MXS_COM_STMT_PREPARE ||
!is_ok(buffer) || !more_results_exist(buffer))
{
/** Not a result set, we have the complete response */
@ -1190,16 +1205,10 @@ static void clientReply(MXS_ROUTER *instance,
GWBUF_IS_COLLECTED_RESULT(writebuf));
RWSplitSession *rses = (RWSplitSession *)router_session;
DCB *client_dcb = backend_dcb->session->client_dcb;
CHK_CLIENT_RSES(rses);
ss_dassert(!rses->rses_closed);
if (rses->rses_closed)
{
gwbuf_free(writebuf);
return;
}
SRWBackend backend = get_backend_from_dcb(rses, backend_dcb);
SRWBackend& backend = get_backend_ref_from_dcb(rses, backend_dcb);
if (backend->get_reply_state() == REPLY_STATE_DONE)
{
@ -1253,32 +1262,23 @@ static void clientReply(MXS_ROUTER *instance,
bool queue_routed = false;
if (rses->expected_responses == 0)
if (rses->expected_responses == 0 && rses->query_queue)
{
for (SRWBackendList::iterator it = rses->backends.begin();
it != rses->backends.end(); it++)
{
ss_dassert((*it)->get_reply_state() == REPLY_STATE_DONE || (*it)->is_closed());
}
queue_routed = rses->query_queue != NULL;
queue_routed = true;
route_stored_query(rses);
}
else
{
ss_dassert(rses->expected_responses > 0);
}
if (writebuf && client_dcb)
if (writebuf)
{
ss_dassert(client_dcb);
/** Write reply to client DCB */
MXS_SESSION_ROUTE_REPLY(backend_dcb->session, writebuf);
}
/** Check pending session commands */
else if (!queue_routed && backend->session_command_count())
{
MXS_INFO("Backend %s processed reply and starts to execute active cursor.",
backend->uri());
MXS_DEBUG("Backend %s processed reply and starts to execute active cursor.",
backend->uri());
if (backend->execute_session_command())
{