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MXS-1474 Refactor for forthcoming changes

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This commit is contained in:
Johan Wikman 2017-10-25 14:52:52 +03:00
parent 93edc230f9
commit e45ee22ec3
2 changed files with 101 additions and 81 deletions
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181
server/modules/filter/cache/cachefiltersession.cc vendored
View File

@ -897,7 +897,7 @@ bool CacheFilterSession::should_consult_cache(GWBUF* pPacket)
/**
* Routes a COM_QUERY packet.
*
* @param pPacket A contiguousCOM_QUERY packet.
* @param pPacket A contiguous COM_QUERY packet.
*
* @return ROUTING_ABORT if the processing of the packet should be aborted
* (as the data is obtained from the cache) or
@ -918,86 +918,7 @@ CacheFilterSession::routing_action_t CacheFilterSession::route_COM_QUERY(GWBUF*
if (CACHE_RESULT_IS_OK(result))
{
if (m_pCache->should_use(m_pSession))
{
uint32_t flags = CACHE_FLAGS_INCLUDE_STALE;
GWBUF* pResponse;
result = m_pCache->get_value(m_key, flags, &pResponse);
if (CACHE_RESULT_IS_OK(result))
{
if (CACHE_RESULT_IS_STALE(result))
{
// The value was found, but it was stale. Now we need to
// figure out whether somebody else is already fetching it.
if (m_pCache->must_refresh(m_key, this))
{
// We were the first ones who hit the stale item. It's
// our responsibility now to fetch it.
if (log_decisions())
{
MXS_NOTICE("Cache data is stale, fetching fresh from server.");
}
// As we don't use the response it must be freed.
gwbuf_free(pResponse);
m_refreshing = true;
action = ROUTING_CONTINUE;
}
else
{
// Somebody is already fetching the new value. So, let's
// use the stale value. No point in hitting the server twice.
if (log_decisions())
{
MXS_NOTICE("Cache data is stale but returning it, fresh "
"data is being fetched already.");
}
action = ROUTING_ABORT;
}
}
else
{
if (log_decisions())
{
MXS_NOTICE("Using fresh data from cache.");
}
action = ROUTING_ABORT;
}
}
else
{
action = ROUTING_CONTINUE;
}
if (action == ROUTING_CONTINUE)
{
m_state = CACHE_EXPECTING_RESPONSE;
}
else
{
m_state = CACHE_EXPECTING_NOTHING;
gwbuf_free(pPacket);
DCB *dcb = m_pSession->client_dcb;
// TODO: This is not ok. Any filters before this filter, will not
// TODO: see this data.
dcb->func.write(dcb, pResponse);
}
}
else
{
// We will not use any value in the cache, but we will update
// the existing value.
if (log_decisions())
{
MXS_NOTICE("Unconditionally fetching data from the server, "
"refreshing cache entry.");
}
m_state = CACHE_EXPECTING_RESPONSE;
}
action = route_SELECT(pPacket);
}
else
{
@ -1013,3 +934,101 @@ CacheFilterSession::routing_action_t CacheFilterSession::route_COM_QUERY(GWBUF*
return action;
}
/**
* Routes a SELECT packet.
*
* @param pPacket A contiguous COM_QUERY packet containing a SELECT.
*
* @return ROUTING_ABORT if the processing of the packet should be aborted
* (as the data is obtained from the cache) or
* ROUTING_CONTINUE if the normal processing should continue.
*/
CacheFilterSession::routing_action_t CacheFilterSession::route_SELECT(GWBUF* pPacket)
{
routing_action_t action = ROUTING_CONTINUE;
if (m_pCache->should_use(m_pSession))
{
uint32_t flags = CACHE_FLAGS_INCLUDE_STALE;
GWBUF* pResponse;
cache_result_t result = m_pCache->get_value(m_key, flags, &pResponse);
if (CACHE_RESULT_IS_OK(result))
{
if (CACHE_RESULT_IS_STALE(result))
{
// The value was found, but it was stale. Now we need to
// figure out whether somebody else is already fetching it.
if (m_pCache->must_refresh(m_key, this))
{
// We were the first ones who hit the stale item. It's
// our responsibility now to fetch it.
if (log_decisions())
{
MXS_NOTICE("Cache data is stale, fetching fresh from server.");
}
// As we don't use the response it must be freed.
gwbuf_free(pResponse);
m_refreshing = true;
action = ROUTING_CONTINUE;
}
else
{
// Somebody is already fetching the new value. So, let's
// use the stale value. No point in hitting the server twice.
if (log_decisions())
{
MXS_NOTICE("Cache data is stale but returning it, fresh "
"data is being fetched already.");
}
action = ROUTING_ABORT;
}
}
else
{
if (log_decisions())
{
MXS_NOTICE("Using fresh data from cache.");
}
action = ROUTING_ABORT;
}
}
else
{
action = ROUTING_CONTINUE;
}
if (action == ROUTING_CONTINUE)
{
m_state = CACHE_EXPECTING_RESPONSE;
}
else
{
m_state = CACHE_EXPECTING_NOTHING;
gwbuf_free(pPacket);
DCB *dcb = m_pSession->client_dcb;
// TODO: This is not ok. Any filters before this filter, will not
// TODO: see this data.
dcb->func.write(dcb, pResponse);
}
}
else
{
// We will not use any value in the cache, but we will update
// the existing value.
if (log_decisions())
{
MXS_NOTICE("Unconditionally fetching data from the server, "
"refreshing cache entry.");
}
m_state = CACHE_EXPECTING_RESPONSE;
}
return action;
}

1
server/modules/filter/cache/cachefiltersession.hh vendored
View File

@ -118,6 +118,7 @@ private:
};
routing_action_t route_COM_QUERY(GWBUF* pPacket);
routing_action_t route_SELECT(GWBUF* pPacket);
private:
CacheFilterSession(MXS_SESSION* pSession, Cache* pCache, char* zDefaultDb);