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Refactor readwritesplit connection creation

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The connections for a router session can now be done without a constructed
router session. This simplifies the creation of new router session by
removing the need to handle memory allocations.

Readwritesplit router sessions are now created in the static `create`
function which handles the actual creation of the connections and
allocation of the session itself.
This commit is contained in:
Markus Mäkelä
2017-08-17 08:18:16 +03:00
parent 46b7db1d45
commit ca4dbf5d0d
4 changed files with 108 additions and 87 deletions
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69
server/modules/routing/readwritesplit/rwsplit_select_backends.cc
View File

@ -54,15 +54,15 @@ static bool valid_for_slave(const SERVER *server, const SERVER *master)
*
* @return The best slave backend reference or NULL if no candidates could be found
*/
SRWBackend get_slave_candidate(RWSplitSession* rses, const SERVER *master,
SRWBackend get_slave_candidate(const SRWBackendList& backends, const SERVER *master,
int (*cmpfun)(const SRWBackend&, const SRWBackend&))
{
SRWBackend candidate;
for (SRWBackendList::iterator it = rses->backends.begin();
it != rses->backends.end(); it++)
for (SRWBackendList::const_iterator it = backends.begin();
it != backends.end(); it++)
{
SRWBackend& backend = *it;
const SRWBackend& backend = *it;
if (!backend->in_use() && backend->can_connect() &&
valid_for_slave(backend->server(), master))
@ -197,14 +197,12 @@ int (*criteria_cmpfun[LAST_CRITERIA])(const SRWBackend&, const SRWBackend&) =
* @param criteria Slave selection criteria
* @param rses Router client session
*/
static void log_server_connections(select_criteria_t criteria,
RWSplitSession* rses)
static void log_server_connections(select_criteria_t criteria, const SRWBackendList& backends)
{
MXS_INFO("Servers and %s connection counts:",
criteria == LEAST_GLOBAL_CONNECTIONS ? "all MaxScale" : "router");
for (SRWBackendList::iterator it = rses->backends.begin();
it != rses->backends.end(); it++)
for (SRWBackendList::const_iterator it = backends.begin(); it != backends.end(); it++)
{
SERVER_REF* b = (*it)->backend();
@ -246,12 +244,12 @@ static void log_server_connections(select_criteria_t criteria,
*
* @return The root master reference or NULL if no master is found
*/
static SERVER_REF* get_root_master(RWSplitSession* rses)
static SERVER_REF* get_root_master(const SRWBackendList& backends)
{
SERVER_REF *master_host = NULL;
for (SRWBackendList::iterator it = rses->backends.begin();
it != rses->backends.end(); it++)
for (SRWBackendList::const_iterator it = backends.begin();
it != backends.end(); it++)
{
SERVER_REF* b = (*it)->backend();
@ -288,17 +286,19 @@ static SERVER_REF* get_root_master(RWSplitSession* rses)
*/
bool select_connect_backend_servers(int router_nservers,
int max_nslaves,
select_criteria_t select_criteria,
MXS_SESSION *session,
RWSplit *router,
RWSplitSession *rses,
const Config& config,
SRWBackendList& backends,
SRWBackend& current_master,
mxs::SessionCommandList* sescmd_list,
int* expected_responses,
connection_type type)
{
/* get the root Master */
SERVER_REF *master_backend = get_root_master(rses);
SERVER_REF *master_backend = get_root_master(backends);
SERVER *master_host = master_backend ? master_backend->server : NULL;
if (router->config().master_failure_mode == RW_FAIL_INSTANTLY &&
if (config.master_failure_mode == RW_FAIL_INSTANTLY &&
(master_host == NULL || SERVER_IS_DOWN(master_host)))
{
MXS_ERROR("Couldn't find suitable Master from %d candidates.", router_nservers);
@ -315,15 +315,16 @@ bool select_connect_backend_servers(int router_nservers,
* Master is already connected or we don't have a master. The function was
* called because new slaves must be selected to replace failed ones.
*/
bool master_connected = type == SLAVE || rses->current_master;
bool master_connected = type == SLAVE || current_master;
/** Check slave selection criteria and set compare function */
select_criteria_t select_criteria = config.slave_selection_criteria;
int (*cmpfun)(const SRWBackend&, const SRWBackend&) = criteria_cmpfun[select_criteria];
ss_dassert(cmpfun);
if (MXS_LOG_PRIORITY_IS_ENABLED(LOG_INFO))
{
log_server_connections(select_criteria, rses);
log_server_connections(select_criteria, backends);
}
int slaves_found = 0;
@ -334,26 +335,24 @@ bool select_connect_backend_servers(int router_nservers,
if (!master_connected)
{
/** Find a master server */
for (SRWBackendList::iterator it = rses->backends.begin();
it != rses->backends.end(); it++)
for (SRWBackendList::const_iterator it = backends.begin(); it != backends.end(); it++)
{
SRWBackend& backend = *it;
const SRWBackend& backend = *it;
if (backend->can_connect() && master_host && backend->server() == master_host)
{
if (backend->connect(session))
{
rses->current_master = backend;
current_master = backend;
}
}
}
}
/** Calculate how many connections we already have */
for (SRWBackendList::iterator it = rses->backends.begin();
it != rses->backends.end(); it++)
for (SRWBackendList::const_iterator it = backends.begin(); it != backends.end(); it++)
{
SRWBackend& backend = *it;
const SRWBackend& backend = *it;
if (backend->can_connect() && valid_for_slave(backend->server(), master_host))
{
@ -369,19 +368,22 @@ bool select_connect_backend_servers(int router_nservers,
ss_dassert(slaves_connected < max_nslaves || max_nslaves == 0);
/** Connect to all possible slaves */
for (SRWBackend backend(get_slave_candidate(rses, master_host, cmpfun));
for (SRWBackend backend(get_slave_candidate(backends, master_host, cmpfun));
backend && slaves_connected < max_nslaves;
backend = get_slave_candidate(rses, master_host, cmpfun))
backend = get_slave_candidate(backends, master_host, cmpfun))
{
if (backend->can_connect() && backend->connect(session))
{
if (rses->sescmd_list.size())
if (sescmd_list && sescmd_list->size())
{
backend->append_session_command(rses->sescmd_list);
backend->append_session_command(*sescmd_list);
if (backend->execute_session_command())
{
rses->expected_responses++;
if (expected_responses)
{
(*expected_responses)++;
}
slaves_connected++;
}
}
@ -405,10 +407,9 @@ bool select_connect_backend_servers(int router_nservers,
"of %d of them.", slaves_connected, slaves_found);
}
for (SRWBackendList::iterator it = rses->backends.begin();
it != rses->backends.end(); it++)
for (SRWBackendList::const_iterator it = backends.begin(); it != backends.end(); it++)
{
SRWBackend& backend = *it;
const SRWBackend& backend = *it;
if (backend->in_use())
{
MXS_INFO("Selected %s in \t%s", STRSRVSTATUS(backend->server()),
@ -422,7 +423,7 @@ bool select_connect_backend_servers(int router_nservers,
MXS_ERROR("Couldn't establish required amount of slave connections for "
"router session. Would need between %d and %d slaves but only have %d.",
min_nslaves, max_nslaves, slaves_connected);
close_all_connections(rses);
close_all_connections(backends);
}
return succp;