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Clean up functions that use SRWBackend

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Return values instead of objects. This removes the need to handle cases
where a reference to a "debug value" is returned.

Return SRWBackend values instead of passing output references. This
doubles as a false boolan return value when an empty reference is
returned.
This commit is contained in:
Markus Mäkelä
2017-06-19 11:36:14 +03:00
parent e5f6d00fda
commit ae1cdea802
4 changed files with 71 additions and 82 deletions
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92
server/modules/routing/readwritesplit/rwsplit_route_stmt.cc
View File

@ -175,16 +175,22 @@ bool route_single_stmt(ROUTER_INSTANCE *inst, ROUTER_CLIENT_SES *rses,
if (TARGET_IS_NAMED_SERVER(route_target) ||
TARGET_IS_RLAG_MAX(route_target))
{
succp = handle_hinted_target(rses, querybuf, route_target, target);
if ((target = handle_hinted_target(rses, querybuf, route_target)))
{
succp = true;
}
}
else if (TARGET_IS_SLAVE(route_target))
{
succp = handle_slave_is_target(inst, rses, target);
store_stmt = rses->rses_config.retry_failed_reads;
if ((target = handle_slave_is_target(inst, rses)))
{
succp = true;
store_stmt = rses->rses_config.retry_failed_reads;
}
}
else if (TARGET_IS_MASTER(route_target))
{
succp = handle_master_is_target(inst, rses, target);
succp = handle_master_is_target(inst, rses, &target);
if (!rses->rses_config.strict_multi_stmt &&
rses->target_node == rses->current_master)
@ -324,8 +330,8 @@ bool route_session_write(ROUTER_CLIENT_SES *rses, GWBUF *querybuf, uint8_t comma
*
* @return True if a backend was found
*/
bool get_target_backend(ROUTER_CLIENT_SES *rses, backend_type_t btype,
char *name, int max_rlag, SRWBackend& target)
SRWBackend get_target_backend(ROUTER_CLIENT_SES *rses, backend_type_t btype,
char *name, int max_rlag)
{
CHK_CLIENT_RSES(rses);
@ -334,8 +340,7 @@ bool get_target_backend(ROUTER_CLIENT_SES *rses, backend_type_t btype,
{
MXS_DEBUG("In READ ONLY transaction, using server '%s'",
rses->target_node->server()->unique_name);
target = rses->target_node;
return true;
return rses->target_node;
}
bool succp = false;
@ -360,8 +365,7 @@ bool get_target_backend(ROUTER_CLIENT_SES *rses, backend_type_t btype,
SERVER_IS_RELAY_SERVER(bref->server()) ||
SERVER_IS_MASTER(bref->server())))
{
target = bref;
return true;
return bref;
}
}
@ -369,10 +373,10 @@ bool get_target_backend(ROUTER_CLIENT_SES *rses, backend_type_t btype,
btype = BE_SLAVE;
}
SRWBackend rval;
if (btype == BE_SLAVE)
{
SRWBackend candidate_bref;
for (SRWBackendList::iterator it = rses->backends.begin();
it != rses->backends.end(); it++)
{
@ -391,7 +395,7 @@ bool get_target_backend(ROUTER_CLIENT_SES *rses, backend_type_t btype,
* If there are no candidates yet accept both master or
* slave.
*/
else if (!candidate_bref)
else if (!rval)
{
/**
* Ensure that master has not changed during
@ -400,8 +404,7 @@ bool get_target_backend(ROUTER_CLIENT_SES *rses, backend_type_t btype,
if (SERVER_IS_MASTER(bref->server()) && bref == rses->current_master)
{
/** found master */
candidate_bref = bref;
succp = true;
rval = bref;
}
/**
* Ensure that max replication lag is not set
@ -413,15 +416,14 @@ bool get_target_backend(ROUTER_CLIENT_SES *rses, backend_type_t btype,
bref->server()->rlag <= max_rlag))
{
/** found slave */
candidate_bref = bref;
succp = true;
rval = bref;
}
}
/**
* If candidate is master, any slave which doesn't break
* replication lag limits replaces it.
*/
else if (SERVER_IS_MASTER(candidate_bref->server()) &&
else if (SERVER_IS_MASTER(rval->server()) &&
SERVER_IS_SLAVE(bref->server()) &&
(max_rlag == MAX_RLAG_UNDEFINED ||
(bref->server()->rlag != MAX_RLAG_NOT_AVAILABLE &&
@ -429,8 +431,7 @@ bool get_target_backend(ROUTER_CLIENT_SES *rses, backend_type_t btype,
!rses->rses_config.master_accept_reads)
{
/** found slave */
candidate_bref = bref;
succp = true;
rval = bref;
}
/**
* When candidate exists, compare it against the current
@ -445,8 +446,7 @@ bool get_target_backend(ROUTER_CLIENT_SES *rses, backend_type_t btype,
(bref->server()->rlag != MAX_RLAG_NOT_AVAILABLE &&
bref->server()->rlag <= max_rlag))
{
candidate_bref = check_candidate_bref(candidate_bref, bref,
rses->rses_config.slave_selection_criteria);
rval = check_candidate_bref(rval, bref, rses->rses_config.slave_selection_criteria);
}
else
{
@ -457,13 +457,6 @@ bool get_target_backend(ROUTER_CLIENT_SES *rses, backend_type_t btype,
}
}
} /*< for */
/** Assign selected DCB's pointer value */
if (candidate_bref)
{
target = candidate_bref;
}
}
/**
* If target was originally master only then the execution jumps
@ -483,8 +476,7 @@ bool get_target_backend(ROUTER_CLIENT_SES *rses, backend_type_t btype,
{
if (SERVER_IS_MASTER(&server))
{
target = master_bref;
succp = true;
rval = master_bref;
}
else
{
@ -492,19 +484,17 @@ bool get_target_backend(ROUTER_CLIENT_SES *rses, backend_type_t btype,
"and can't be chosen as the master.",
master_bref->server()->unique_name,
STRSRVSTATUS(&server));
succp = false;
}
}
else
{
MXS_ERROR("Server '%s' is not in use and can't be chosen as the master.",
master_bref->server()->unique_name);
succp = false;
}
}
}
return succp;
return rval;
}
/**
@ -811,12 +801,11 @@ handle_multi_temp_and_load(ROUTER_CLIENT_SES *rses, GWBUF *querybuf,
*
* @return bool - true if succeeded, false otherwise
*/
bool handle_hinted_target(ROUTER_CLIENT_SES *rses, GWBUF *querybuf,
route_target_t route_target, SRWBackend& target)
SRWBackend handle_hinted_target(ROUTER_CLIENT_SES *rses, GWBUF *querybuf,
route_target_t route_target)
{
char *named_server = NULL;
int rlag_max = MAX_RLAG_UNDEFINED;
bool succp;
HINT* hint = querybuf->hint;
@ -859,9 +848,9 @@ bool handle_hinted_target(ROUTER_CLIENT_SES *rses, GWBUF *querybuf,
* Search backend server by name or replication lag.
* If it fails, then try to find valid slave or master.
*/
succp = get_target_backend(rses, btype, named_server, rlag_max, target);
SRWBackend target = get_target_backend(rses, btype, named_server, rlag_max);
if (!succp)
if (!target)
{
if (TARGET_IS_NAMED_SERVER(route_target))
{
@ -876,7 +865,8 @@ bool handle_hinted_target(ROUTER_CLIENT_SES *rses, GWBUF *querybuf,
"find such a slave.", rlag_max);
}
}
return succp;
return target;
}
/**
@ -890,24 +880,21 @@ bool handle_hinted_target(ROUTER_CLIENT_SES *rses, GWBUF *querybuf,
*
* @return bool - true if succeeded, false otherwise
*/
bool handle_slave_is_target(ROUTER_INSTANCE *inst, ROUTER_CLIENT_SES *rses,
SRWBackend& target)
SRWBackend handle_slave_is_target(ROUTER_INSTANCE *inst, ROUTER_CLIENT_SES *rses)
{
int rlag_max = rses_get_max_replication_lag(rses);
SRWBackend target = get_target_backend(rses, BE_SLAVE, NULL, rlag_max);
/**
* Search suitable backend server, get DCB in target_dcb
*/
if (get_target_backend(rses, BE_SLAVE, NULL, rlag_max, target))
if (target)
{
atomic_add_uint64(&inst->stats.n_slave, 1);
return true;
}
else
{
MXS_INFO("Was supposed to route to slave but finding suitable one failed.");
return false;
}
return target;
}
/**
@ -980,12 +967,12 @@ static void log_master_routing_failure(ROUTER_CLIENT_SES *rses, bool found,
* @return bool - true if succeeded, false otherwise
*/
bool handle_master_is_target(ROUTER_INSTANCE *inst, ROUTER_CLIENT_SES *rses,
SRWBackend& target)
SRWBackend* dest)
{
DCB *curr_master_dcb = NULL;
bool succp = get_target_backend(rses, BE_MASTER, NULL, MAX_RLAG_UNDEFINED, target);
SRWBackend target = get_target_backend(rses, BE_MASTER, NULL, MAX_RLAG_UNDEFINED);
bool succp = true;
if (succp && target == rses->current_master)
if (target && target == rses->current_master)
{
atomic_add_uint64(&inst->stats.n_master, 1);
}
@ -1008,6 +995,7 @@ bool handle_master_is_target(ROUTER_INSTANCE *inst, ROUTER_CLIENT_SES *rses,
}
}
*dest = target;
return succp;
}