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Backport hint priority change to 2.0

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The change in readwritesplit routing priorities, where hints have the
highest priority, gives users more options to control how readwritesplit
acts.

For example, this allows read-only stored procedures to be routed to
slaves by adding a hint to the query:

       CALL myproc(); -- maxscale route to slave

The readwritesplit documentation also warns the user not to use routing
hints unless they can be absolutely sure that no damage will be done.
This commit is contained in:
Markus Makela
2016-08-31 10:44:17 +03:00
parent 94aecf4ada
commit d337aa0476
3 changed files with 131 additions and 55 deletions
Download Patch File Download Diff File Expand all files Collapse all files

110
server/modules/routing/readwritesplit/readwritesplit.c
View File

@ -1375,59 +1375,7 @@ static route_target_t get_route_target(ROUTER_CLIENT_SES *rses,
{
target = TARGET_MASTER;
}
/** process routing hints */
while (hint != NULL)
{
if (hint->type == HINT_ROUTE_TO_MASTER)
{
target = TARGET_MASTER; /*< override */
MXS_DEBUG("%lu [get_route_target] Hint: route to master.",
pthread_self());
break;
}
else if (hint->type == HINT_ROUTE_TO_NAMED_SERVER)
{
/**
* Searching for a named server. If it can't be
* found, the oroginal target is chosen.
*/
target |= TARGET_NAMED_SERVER;
MXS_DEBUG("%lu [get_route_target] Hint: route to "
"named server : ",
pthread_self());
}
else if (hint->type == HINT_ROUTE_TO_UPTODATE_SERVER)
{
/** not implemented */
}
else if (hint->type == HINT_ROUTE_TO_ALL)
{
/** not implemented */
}
else if (hint->type == HINT_PARAMETER)
{
if (strncasecmp((char *)hint->data, "max_slave_replication_lag",
strlen("max_slave_replication_lag")) == 0)
{
target |= TARGET_RLAG_MAX;
}
else
{
MXS_ERROR("Unknown hint parameter "
"'%s' when 'max_slave_replication_lag' "
"was expected.",
(char *)hint->data);
}
}
else if (hint->type == HINT_ROUTE_TO_SLAVE)
{
target = TARGET_SLAVE;
MXS_DEBUG("%lu [get_route_target] Hint: route to "
"slave.",
pthread_self());
}
hint = hint->next;
} /*< while (hint != NULL) */
/** If nothing matches then choose the master */
if ((target & (TARGET_ALL | TARGET_SLAVE | TARGET_MASTER)) == 0)
{
@ -1436,7 +1384,6 @@ static route_target_t get_route_target(ROUTER_CLIENT_SES *rses,
}
else
{
/** hints don't affect on routing */
ss_dassert(trx_active ||
(QUERY_IS_TYPE(qtype, QUERY_TYPE_WRITE) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_MASTER_READ) ||
@ -1460,6 +1407,61 @@ static route_target_t get_route_target(ROUTER_CLIENT_SES *rses,
QUERY_IS_TYPE(qtype, QUERY_TYPE_UNKNOWN)));
target = TARGET_MASTER;
}
/** process routing hints */
while (hint != NULL)
{
if (hint->type == HINT_ROUTE_TO_MASTER)
{
target = TARGET_MASTER; /*< override */
MXS_DEBUG("%lu [get_route_target] Hint: route to master.",
pthread_self());
break;
}
else if (hint->type == HINT_ROUTE_TO_NAMED_SERVER)
{
/**
* Searching for a named server. If it can't be
* found, the oroginal target is chosen.
*/
target |= TARGET_NAMED_SERVER;
MXS_DEBUG("%lu [get_route_target] Hint: route to "
"named server : ",
pthread_self());
}
else if (hint->type == HINT_ROUTE_TO_UPTODATE_SERVER)
{
/** not implemented */
}
else if (hint->type == HINT_ROUTE_TO_ALL)
{
/** not implemented */
}
else if (hint->type == HINT_PARAMETER)
{
if (strncasecmp((char *)hint->data, "max_slave_replication_lag",
strlen("max_slave_replication_lag")) == 0)
{
target |= TARGET_RLAG_MAX;
}
else
{
MXS_ERROR("Unknown hint parameter "
"'%s' when 'max_slave_replication_lag' "
"was expected.",
(char *)hint->data);
}
}
else if (hint->type == HINT_ROUTE_TO_SLAVE)
{
target = TARGET_SLAVE;
MXS_DEBUG("%lu [get_route_target] Hint: route to "
"slave.",
pthread_self());
}
hint = hint->next;
} /*< while (hint != NULL) */
#if defined(SS_EXTRA_DEBUG)
MXS_INFO("Selected target \"%s\"", STRTARGET(target));
#endif