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Add better cache debugging

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Now the statement and the decision is logged. Easier to figure
out why something is or is not cached.
This commit is contained in:
Johan Wikman
2017-03-02 10:12:34 +02:00
parent 4902ed7cf5
commit 923ed9329d
1 changed files with 48 additions and 19 deletions
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61
server/modules/filter/cache/cachefiltersession.cc vendored
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@ -15,8 +15,9 @@
#include "cachefiltersession.hh" #include "cachefiltersession.hh"
#include <new> #include <new>
#include <maxscale/alloc.h> #include <maxscale/alloc.h>
#include <maxscale/query_classifier.h> #include <maxscale/modutil.h>
#include <maxscale/mysql_utils.h> #include <maxscale/mysql_utils.h>
#include <maxscale/query_classifier.h>
#include "storage.hh" #include "storage.hh"
namespace namespace
@ -657,6 +658,8 @@ bool CacheFilterSession::should_consult_cache(GWBUF* pPacket)
uint32_t type_mask = qc_get_type_mask(pPacket); uint32_t type_mask = qc_get_type_mask(pPacket);
const char* zReason = NULL;
if (qc_query_is_type(type_mask, QUERY_TYPE_BEGIN_TRX)) if (qc_query_is_type(type_mask, QUERY_TYPE_BEGIN_TRX))
{ {
// When a transaction is started, we initially assume it is read-only. // When a transaction is started, we initially assume it is read-only.
@ -674,7 +677,7 @@ bool CacheFilterSession::should_consult_cache(GWBUF* pPacket)
{ {
if (log_decisions()) if (log_decisions())
{ {
MXS_NOTICE("Cache can be used and stored to, since there is no transaction."); zReason = "no transaction";
} }
consult_cache = true; consult_cache = true;
} }
@ -682,8 +685,7 @@ bool CacheFilterSession::should_consult_cache(GWBUF* pPacket)
{ {
if (log_decisions()) if (log_decisions())
{ {
MXS_NOTICE("Cache can be used and stored to since there is an explicitly " zReason = "explicitly read-only transaction";
"read-only transaction.");
} }
consult_cache = true; consult_cache = true;
} }
@ -691,8 +693,7 @@ bool CacheFilterSession::should_consult_cache(GWBUF* pPacket)
{ {
if (log_decisions()) if (log_decisions())
{ {
MXS_NOTICE("Cache can be used and stored to, since the current transaction " zReason = "ordinary transaction that has so far been read-only";
"(not explicitly read-only) has so far been read-only.");
} }
consult_cache = true; consult_cache = true;
} }
@ -700,29 +701,57 @@ bool CacheFilterSession::should_consult_cache(GWBUF* pPacket)
{ {
if (log_decisions()) if (log_decisions())
{ {
MXS_NOTICE("Cache can not be used, since a not explicitly read-only transaction " zReason = "ordinary transaction with non-read statements";
"is active and the transaction has executed non-read statements.");
} }
} }
if (consult_cache) if (consult_cache)
{ {
if (qc_query_is_type(type_mask, QUERY_TYPE_USERVAR_READ) || if (qc_get_operation(pPacket) == QUERY_OP_SELECT)
qc_query_is_type(type_mask, QUERY_TYPE_SYSVAR_READ)) {
if (qc_query_is_type(type_mask, QUERY_TYPE_USERVAR_READ))
{ {
consult_cache = false; consult_cache = false;
zReason = "user variables are read";
}
else if (qc_query_is_type(type_mask, QUERY_TYPE_SYSVAR_READ))
{
consult_cache = false;
zReason = "system variables are read";
}
} }
else else
{
// We do not care whether the query was fully parsed or not.
// If a query cannot be fully parsed, the worst thing that can
// happen is that caching is not used, even though it would be
// possible.
if (qc_get_operation(pPacket) != QUERY_OP_SELECT)
{ {
consult_cache = false; consult_cache = false;
zReason = "statement is not SELECT";
} }
} }
if (log_decisions())
{
char* pSql;
int length;
const int max_length = 40;
// At this point we know it's a COM_QUERY and that the buffer is contiguous
modutil_extract_SQL(pPacket, &pSql, &length);
const char* zFormat;
if (length <= max_length)
{
zFormat = "%s, \"%.*s\", %s.";
}
else
{
zFormat = "%s, \"%.*s...\", %s.";
length = max_length - 3; // strlen("...");
}
const char* zDecision = (consult_cache ? "CONSULT" : "IGNORE ");
ss_dassert(zReason);
MXS_NOTICE(zFormat, zDecision, length, pSql, zReason);
} }
return consult_cache; return consult_cache;