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MXS-2025 Use PRWBackends in backend selection.

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This commit is contained in:
Niclas Antti
2018-11-29 10:41:18 +02:00
parent 20b62a3f3d
commit 91f6f374a8
3 changed files with 29 additions and 31 deletions
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6
server/modules/routing/readwritesplit/readwritesplit.hh
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@ -132,9 +132,7 @@ static const char gtid_wait_stmt[] =
/** Function that returns a "score" for a server to enable comparison. /** Function that returns a "score" for a server to enable comparison.
* Smaller numbers are better. * Smaller numbers are better.
*/ */
using SRWBackendVector = std::vector<mxs::RWBackend**>; using BackendSelectFunction = std::function<mxs::PRWBackends::iterator (mxs::PRWBackends& sBackends)>;
using BackendSelectFunction = std::function
<SRWBackendVector::iterator (SRWBackendVector& sBackends)>;
BackendSelectFunction get_backend_select_function(select_criteria_t); BackendSelectFunction get_backend_select_function(select_criteria_t);
struct Config struct Config
@ -416,7 +414,7 @@ std::pair<int, int> get_slave_counts(mxs::PRWBackends& backends, mxs::RWBackend*
* *
* @return Valid iterator into argument backends, or end(backends) if empty * @return Valid iterator into argument backends, or end(backends) if empty
*/ */
SRWBackendVector::iterator find_best_backend(SRWBackendVector& backends, mxs::PRWBackends::iterator find_best_backend(mxs::PRWBackends& backends,
BackendSelectFunction select, BackendSelectFunction select,
bool masters_accepts_reads); bool masters_accepts_reads);

8
server/modules/routing/readwritesplit/rwsplit_route_stmt.cc
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@ -578,7 +578,7 @@ RWBackend* RWSplitSession::get_slave_backend(int max_rlag)
{ {
// create a list of useable backends (includes masters, function name is a bit off), // create a list of useable backends (includes masters, function name is a bit off),
// then feed that list to compare. // then feed that list to compare.
SRWBackendVector candidates; PRWBackends candidates;
auto counts = get_slave_counts(m_backends, m_current_master); auto counts = get_slave_counts(m_backends, m_current_master);
for (auto& backend : m_backends) for (auto& backend : m_backends)
@ -597,15 +597,15 @@ RWBackend* RWSplitSession::get_slave_backend(int max_rlag)
if (server_is_candidate) if (server_is_candidate)
{ {
candidates.push_back(&backend); candidates.push_back(backend);
} }
} }
SRWBackendVector::const_iterator rval = find_best_backend(candidates, PRWBackends::const_iterator rval = find_best_backend(candidates,
m_config.backend_select_fct, m_config.backend_select_fct,
m_config.master_accept_reads); m_config.master_accept_reads);
return (rval == candidates.end()) ? nullptr : **rval; return (rval == candidates.end()) ? nullptr : *rval;
} }
RWBackend* RWSplitSession::get_master_backend() RWBackend* RWSplitSession::get_master_backend()

36
server/modules/routing/readwritesplit/rwsplit_select_backends.cc
View File

@ -57,14 +57,14 @@ static bool valid_for_slave(const RWBackend* backend, const RWBackend* master)
&& (!master || backend != master); && (!master || backend != master);
} }
SRWBackendVector::iterator best_score(SRWBackendVector& sBackends, PRWBackends::iterator best_score(PRWBackends& sBackends,
std::function<double(SERVER_REF* server)> server_score) std::function<double(SERVER_REF* server)> server_score)
{ {
double min {std::numeric_limits<double>::max()}; double min {std::numeric_limits<double>::max()};
auto best = sBackends.end(); auto best = sBackends.end();
for (auto ite = sBackends.begin(); ite != sBackends.end(); ++ite) for (auto ite = sBackends.begin(); ite != sBackends.end(); ++ite)
{ {
double score = server_score((***ite).backend()); double score = server_score((**ite).backend());
if (min > score) if (min > score)
{ {
min = score; min = score;
@ -76,7 +76,7 @@ SRWBackendVector::iterator best_score(SRWBackendVector& sBackends,
} }
/** Compare number of connections from this router in backend servers */ /** Compare number of connections from this router in backend servers */
SRWBackendVector::iterator backend_cmp_router_conn(SRWBackendVector& sBackends) PRWBackends::iterator backend_cmp_router_conn(PRWBackends& sBackends)
{ {
static auto server_score = [](SERVER_REF* server) { static auto server_score = [](SERVER_REF* server) {
return server->server_weight ? (server->connections + 1) / server->server_weight : return server->server_weight ? (server->connections + 1) / server->server_weight :
@ -87,7 +87,7 @@ SRWBackendVector::iterator backend_cmp_router_conn(SRWBackendVector& sBackends)
} }
/** Compare number of global connections in backend servers */ /** Compare number of global connections in backend servers */
SRWBackendVector::iterator backend_cmp_global_conn(SRWBackendVector& sBackends) PRWBackends::iterator backend_cmp_global_conn(PRWBackends& sBackends)
{ {
static auto server_score = [](SERVER_REF* server) { static auto server_score = [](SERVER_REF* server) {
return server->server_weight ? (server->server->stats.n_current + 1) / server->server_weight : return server->server_weight ? (server->server->stats.n_current + 1) / server->server_weight :
@ -98,7 +98,7 @@ SRWBackendVector::iterator backend_cmp_global_conn(SRWBackendVector& sBackends)
} }
/** Compare replication lag between backend servers */ /** Compare replication lag between backend servers */
SRWBackendVector::iterator backend_cmp_behind_master(SRWBackendVector& sBackends) PRWBackends::iterator backend_cmp_behind_master(PRWBackends& sBackends)
{ {
static auto server_score = [](SERVER_REF* server) { static auto server_score = [](SERVER_REF* server) {
return server->server_weight ? server->server->rlag / server->server_weight : return server->server_weight ? server->server->rlag / server->server_weight :
@ -109,7 +109,7 @@ SRWBackendVector::iterator backend_cmp_behind_master(SRWBackendVector& sBackends
} }
/** Compare number of current operations in backend servers */ /** Compare number of current operations in backend servers */
SRWBackendVector::iterator backend_cmp_current_load(SRWBackendVector& sBackends) PRWBackends::iterator backend_cmp_current_load(PRWBackends& sBackends)
{ {
static auto server_score = [](SERVER_REF* server) { static auto server_score = [](SERVER_REF* server) {
return server->server_weight ? (server->server->stats.n_current_ops + 1) / server->server_weight : return server->server_weight ? (server->server->stats.n_current_ops + 1) / server->server_weight :
@ -119,7 +119,7 @@ SRWBackendVector::iterator backend_cmp_current_load(SRWBackendVector& sBackends)
return best_score(sBackends, server_score); return best_score(sBackends, server_score);
} }
SRWBackendVector::iterator backend_cmp_response_time(SRWBackendVector& sBackends) PRWBackends::iterator backend_cmp_response_time(PRWBackends& sBackends)
{ {
const int SZ = sBackends.size(); const int SZ = sBackends.size();
double slot[SZ]; double slot[SZ];
@ -128,7 +128,7 @@ SRWBackendVector::iterator backend_cmp_response_time(SRWBackendVector& sBackends
double pre_total {0}; double pre_total {0};
for (int i = 0; i < SZ; ++i) for (int i = 0; i < SZ; ++i)
{ {
SERVER_REF* server = (**sBackends[i]).backend(); SERVER_REF* server = (*sBackends[i]).backend();
double ave = server_response_time_average(server->server); double ave = server_response_time_average(server->server);
if (ave == 0) if (ave == 0)
@ -211,17 +211,17 @@ BackendSelectFunction get_backend_select_function(select_criteria_t sc)
* *
* @return iterator to the best slave or backends.end() if none found * @return iterator to the best slave or backends.end() if none found
*/ */
SRWBackendVector::iterator find_best_backend(SRWBackendVector& backends, PRWBackends::iterator find_best_backend(PRWBackends& backends,
BackendSelectFunction select, BackendSelectFunction select,
bool masters_accepts_reads) bool masters_accepts_reads)
{ {
// Group backends by priority. The set of highest priority backends will then compete. // Group backends by priority. The set of highest priority backends will then compete.
std::map<int, SRWBackendVector> priority_map; std::map<int, PRWBackends> priority_map;
int best_priority {INT_MAX}; // low numbers are high priority int best_priority {INT_MAX}; // low numbers are high priority
for (auto& psBackend : backends) for (auto& psBackend : backends)
{ {
auto& backend = **psBackend; auto& backend = *psBackend;
bool is_busy = backend.in_use() && backend.has_session_commands(); bool is_busy = backend.in_use() && backend.has_session_commands();
bool acts_slave = backend.is_slave() || (backend.is_master() && masters_accepts_reads); bool acts_slave = backend.is_slave() || (backend.is_master() && masters_accepts_reads);
@ -420,14 +420,14 @@ bool RWSplit::select_connect_backend_servers(MXS_SESSION* session,
mxb_assert(slaves_connected <= max_nslaves || max_nslaves == 0); mxb_assert(slaves_connected <= max_nslaves || max_nslaves == 0);
SRWBackendVector candidates; PRWBackends candidates;
for (auto& sBackend : backends) for (auto& pBackend : backends)
{ {
if (!sBackend->in_use() if (!pBackend->in_use()
&& sBackend->can_connect() && pBackend->can_connect()
&& valid_for_slave(sBackend, master)) && valid_for_slave(pBackend, master))
{ {
candidates.push_back(&sBackend); candidates.push_back(pBackend);
} }
} }
@ -439,7 +439,7 @@ bool RWSplit::select_connect_backend_servers(MXS_SESSION* session,
break; break;
} }
auto& backend = **ite; auto& backend = *ite;
if (backend->connect(session, sescmd_list)) if (backend->connect(session, sescmd_list))
{ {