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Query hint to influence Consistent Critical Read Filter

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MXS-1067. The CCRFilter will now look at the hints in a write-type
query. The parameter-value combinations "ccr=match" and "ccr=ignore"
are recognized and will override any regex match and ignore settings.

For the hints to work, the HintFilter needs to be present in the filter
chain before the CCRFilter.

Also ran astyle and updated documentation.
This commit is contained in:
Esa Korhonen
2017-06-07 11:51:49 +03:00
parent 2778056212
commit bff5e96b1a
2 changed files with 125 additions and 23 deletions
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123
server/modules/filter/ccrfilter/ccrfilter.c
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@ -103,6 +103,15 @@ static const MXS_ENUM_VALUE option_values[] =
{NULL}
};
typedef enum ccr_hint_value_t
{
CCR_HINT_NONE,
CCR_HINT_MATCH,
CCR_HINT_IGNORE
} CCR_HINT_VALUE;
static CCR_HINT_VALUE search_ccr_hint(GWBUF* buffer);
/**
* The module entry point routine. It is this routine that
* must populate the structure that is referred to as the
@ -148,11 +157,11 @@ MXS_MODULE* MXS_CREATE_MODULE()
{"match", MXS_MODULE_PARAM_STRING},
{"ignore", MXS_MODULE_PARAM_STRING},
{
"options",
MXS_MODULE_PARAM_ENUM,
"ignorecase",
MXS_MODULE_OPT_NONE,
option_values
"options",
MXS_MODULE_PARAM_ENUM,
"ignorecase",
MXS_MODULE_OPT_NONE,
option_values
},
{MXS_END_MODULE_PARAMS}
}
@ -299,28 +308,49 @@ routeQuery(MXS_FILTER *instance, MXS_FILTER_SESSION *session, GWBUF *queue)
{
if ((sql = modutil_get_SQL(queue)) != NULL)
{
if (my_instance->nomatch == NULL ||
(my_instance->nomatch && regexec(&my_instance->nore, sql, 0, NULL, 0) != 0))
bool trigger_ccr = true;
bool decided = false; // Set by hints to take precedence.
CCR_HINT_VALUE ccr_hint_val = search_ccr_hint(queue);
if (ccr_hint_val == CCR_HINT_IGNORE)
{
if (my_instance->match == NULL ||
(my_instance->match && regexec(&my_instance->re, sql, 0, NULL, 0) == 0))
trigger_ccr = false;
decided = true;
}
else if (ccr_hint_val == CCR_HINT_MATCH)
{
decided = true;
}
if (!decided)
{
if (my_instance->nomatch &&
regexec(&my_instance->nore, sql, 0, NULL, 0) == 0)
{
if (my_instance->count)
{
my_session->hints_left = my_instance->count;
MXS_INFO("Write operation detected, next %d queries routed to master", my_instance->count);
}
if (my_instance->time)
{
my_session->last_modification = now;
MXS_INFO("Write operation detected, queries routed to master for %d seconds", my_instance->time);
}
my_instance->stats.n_modified++;
// Nomatch was present and sql matched it.
trigger_ccr = false;
}
else if (my_instance->match &&
(regexec(&my_instance->re, sql, 0, NULL, 0) != 0))
{
// Match was present but sql did *not* match it.
trigger_ccr = false;
}
}
if (trigger_ccr)
{
if (my_instance->count)
{
my_session->hints_left = my_instance->count;
MXS_INFO("Write operation detected, next %d queries routed to master", my_instance->count);
}
if (my_instance->time)
{
my_session->last_modification = now;
MXS_INFO("Write operation detected, queries routed to master for %d seconds", my_instance->time);
}
my_instance->stats.n_modified++;
}
MXS_FREE(sql);
}
}
@ -429,3 +459,52 @@ static uint64_t getCapabilities(MXS_FILTER* instance)
{
return RCAP_TYPE_NONE;
}
/**
* Find the first CCR filter hint. The hint is removed from the buffer and the
* contents returned.
*
* @param buffer Input buffer
* @return The found ccr hint value
*/
static CCR_HINT_VALUE search_ccr_hint(GWBUF* buffer)
{
const char CCR[] = "ccr";
CCR_HINT_VALUE rval = CCR_HINT_NONE;
bool found_ccr = false;
HINT** prev_ptr = &buffer->hint;
HINT* hint = buffer->hint;
while (hint && !found_ccr)
{
if (hint->type == HINT_PARAMETER && strcasecmp(hint->data, CCR) == 0)
{
found_ccr = true;
if (strcasecmp(hint->value, "match") == 0)
{
rval = CCR_HINT_MATCH;
}
else if (strcasecmp(hint->value, "ignore") == 0)
{
rval = CCR_HINT_IGNORE;
}
else
{
MXS_ERROR("Unknown value for hint parameter %s: '%s'.",
CCR, (char*)hint->value);
}
}
else
{
prev_ptr = &hint->next;
hint = hint->next;
}
}
// Remove the ccr-hint from the hint chain. Otherwise rwsplit will complain.
if (found_ccr)
{
*prev_ptr = hint->next;
hint_free(hint);
}
return rval;
}