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MXS-1474 Document and act in the same way

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From the documentation:

   * `never`: When there is an active transaction, no data will be returned
     from the cache, but all requests will always be sent to the backend.
     The cache will be populated inside _explicitly_ read-only transactions.
     Inside transactions that are not explicitly read-only, the cache will
     be populated _until_ the first non-SELECT statement.
   * `read_only_transactions`: The cache will be used and populated inside
     _explicitly_ read-only transactions. Inside transactions that are not
     explicitly read-only, the cache will be populated, but not used
     _until_ the first non-SELECT statement.
   * `all_transactions`: The cache will be used and populated inside
     _explicitly_ read-only transactions. Inside transactions that are not
     explicitly read-only, the cache will be used and populated _until_ the
     first non-SELECT statement.
This commit is contained in:
Johan Wikman
2017-10-25 16:01:13 +03:00
parent e45ee22ec3
commit f52a0acbbe
3 changed files with 67 additions and 36 deletions
Download Patch File Download Diff File Expand all files Collapse all files

72
server/modules/filter/cache/cachefiltersession.cc vendored
View File

@ -740,11 +740,11 @@ void CacheFilterSession::store_result()
*
* @param pParam The GWBUF being handled.
*
* @return True, if the cache should be consulted, false otherwise.
* @return Enum value indicating appropriate action.
*/
bool CacheFilterSession::should_consult_cache(GWBUF* pPacket)
CacheFilterSession::cache_action_t CacheFilterSession::get_cache_action(GWBUF* pPacket)
{
bool consult_cache = false;
cache_action_t action = CACHE_IGNORE;
uint32_t type_mask = qc_get_trx_type_mask(pPacket); // Note, only trx-related type mask
@ -767,7 +767,7 @@ bool CacheFilterSession::should_consult_cache(GWBUF* pPacket)
{
zReason = "no transaction";
}
consult_cache = true;
action = CACHE_USE_AND_POPULATE;
}
else if (session_trx_is_read_only(m_pSession))
{
@ -777,7 +777,7 @@ bool CacheFilterSession::should_consult_cache(GWBUF* pPacket)
{
zReason = "explicitly read-only transaction";
}
consult_cache = true;
action = CACHE_USE_AND_POPULATE;
}
else
{
@ -785,8 +785,9 @@ bool CacheFilterSession::should_consult_cache(GWBUF* pPacket)
if (log_decisions())
{
zReason = "no caching inside transactions";
zReason = "populating but not using cache inside read-only transactions";
}
action = CACHE_POPULATE;
}
}
else if (m_is_read_only)
@ -800,7 +801,7 @@ bool CacheFilterSession::should_consult_cache(GWBUF* pPacket)
{
zReason = "ordinary transaction that has so far been read-only";
}
consult_cache = true;
action = CACHE_USE_AND_POPULATE;
}
else
{
@ -809,8 +810,11 @@ bool CacheFilterSession::should_consult_cache(GWBUF* pPacket)
if (log_decisions())
{
zReason = "no caching inside not explicitly read-only transactions";
zReason =
"populating but not using cache inside transaction that is not "
"explicitly read-only, but that has used only SELECTs sofar";
}
action = CACHE_POPULATE;
}
}
else
@ -821,7 +825,7 @@ bool CacheFilterSession::should_consult_cache(GWBUF* pPacket)
}
}
if (consult_cache)
if (action != CACHE_IGNORE)
{
if (is_select_statement(pPacket))
{
@ -833,22 +837,22 @@ bool CacheFilterSession::should_consult_cache(GWBUF* pPacket)
if (qc_query_is_type(type_mask, QUERY_TYPE_USERVAR_READ))
{
consult_cache = false;
action = CACHE_IGNORE;
zReason = "user variables are read";
}
else if (qc_query_is_type(type_mask, QUERY_TYPE_SYSVAR_READ))
{
consult_cache = false;
action = CACHE_IGNORE;
zReason = "system variables are read";
}
else if (uses_non_cacheable_function(pPacket))
{
consult_cache = false;
action = CACHE_IGNORE;
zReason = "uses non-cacheable function";
}
else if (uses_non_cacheable_variable(pPacket))
{
consult_cache = false;
action = CACHE_IGNORE;
zReason = "uses non-cacheable variable";
}
}
@ -857,9 +861,11 @@ bool CacheFilterSession::should_consult_cache(GWBUF* pPacket)
{
// A bit broad, as e.g. SHOW will cause the read only state to be turned
// off. However, during normal use this will always be an UPDATE, INSERT
// or DELETE.
// or DELETE. Note that 'm_is_read_only' only affects transactions that
// are not explicitly read-only.
m_is_read_only = false;
consult_cache = false;
action = CACHE_IGNORE;
zReason = "statement is not SELECT";
}
}
@ -885,13 +891,13 @@ bool CacheFilterSession::should_consult_cache(GWBUF* pPacket)
length = max_length - 3; // strlen("...");
}
const char* zDecision = (consult_cache ? "CONSULT" : "IGNORE ");
const char* zDecision = (action == CACHE_IGNORE) ? "IGNORE" : "CONSULT";
ss_dassert(zReason);
MXS_NOTICE(zFormat, zDecision, length, pSql, zReason);
}
return consult_cache;
return action;
}
/**
@ -908,9 +914,10 @@ CacheFilterSession::routing_action_t CacheFilterSession::route_COM_QUERY(GWBUF*
ss_debug(uint8_t* pData = static_cast<uint8_t*>(GWBUF_DATA(pPacket)));
ss_dassert((int)MYSQL_GET_COMMAND(pData) == MXS_COM_QUERY);
routing_action_t action = ROUTING_CONTINUE;
routing_action_t routing_action = ROUTING_CONTINUE;
cache_action_t cache_action = get_cache_action(pPacket);
if (should_consult_cache(pPacket))
if (cache_action != CACHE_IGNORE)
{
if (m_pCache->should_store(m_zDefaultDb, pPacket))
{
@ -918,7 +925,7 @@ CacheFilterSession::routing_action_t CacheFilterSession::route_COM_QUERY(GWBUF*
if (CACHE_RESULT_IS_OK(result))
{
action = route_SELECT(pPacket);
routing_action = route_SELECT(cache_action, pPacket);
}
else
{
@ -932,24 +939,25 @@ CacheFilterSession::routing_action_t CacheFilterSession::route_COM_QUERY(GWBUF*
}
}
return action;
return routing_action;
}
/**
* Routes a SELECT packet.
*
* @param pPacket A contiguous COM_QUERY packet containing a SELECT.
* @param cache_action The desired action.
* @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)
CacheFilterSession::routing_action_t CacheFilterSession::route_SELECT(cache_action_t cache_action, GWBUF* pPacket)
{
routing_action_t action = ROUTING_CONTINUE;
routing_action_t routing_action = ROUTING_CONTINUE;
if (m_pCache->should_use(m_pSession))
if (should_use(cache_action) && m_pCache->should_use(m_pSession))
{
uint32_t flags = CACHE_FLAGS_INCLUDE_STALE;
GWBUF* pResponse;
@ -975,7 +983,7 @@ CacheFilterSession::routing_action_t CacheFilterSession::route_SELECT(GWBUF* pPa
gwbuf_free(pResponse);
m_refreshing = true;
action = ROUTING_CONTINUE;
routing_action = ROUTING_CONTINUE;
}
else
{
@ -986,7 +994,7 @@ CacheFilterSession::routing_action_t CacheFilterSession::route_SELECT(GWBUF* pPa
MXS_NOTICE("Cache data is stale but returning it, fresh "
"data is being fetched already.");
}
action = ROUTING_ABORT;
routing_action = ROUTING_ABORT;
}
}
else
@ -995,15 +1003,15 @@ CacheFilterSession::routing_action_t CacheFilterSession::route_SELECT(GWBUF* pPa
{
MXS_NOTICE("Using fresh data from cache.");
}
action = ROUTING_ABORT;
routing_action = ROUTING_ABORT;
}
}
else
{
action = ROUTING_CONTINUE;
routing_action = ROUTING_CONTINUE;
}
if (action == ROUTING_CONTINUE)
if (routing_action == ROUTING_CONTINUE)
{
m_state = CACHE_EXPECTING_RESPONSE;
}
@ -1020,6 +1028,8 @@ CacheFilterSession::routing_action_t CacheFilterSession::route_SELECT(GWBUF* pPa
}
else
{
ss_dassert(should_populate(cache_action));
// We will not use any value in the cache, but we will update
// the existing value.
if (log_decisions())
@ -1030,5 +1040,5 @@ CacheFilterSession::routing_action_t CacheFilterSession::route_SELECT(GWBUF* pPa
m_state = CACHE_EXPECTING_RESPONSE;
}
return action;
return routing_action;
}

22
server/modules/filter/cache/cachefiltersession.hh vendored
View File

@ -109,7 +109,25 @@ private:
void store_result();
bool should_consult_cache(GWBUF* pPacket);
enum cache_action_t
{
CACHE_IGNORE = 0,
CACHE_USE = 1,
CACHE_POPULATE = 2,
CACHE_USE_AND_POPULATE = (CACHE_USE | CACHE_POPULATE)
};
static bool should_use(cache_action_t action)
{
return action & CACHE_USE ? true : false;
}
static bool should_populate(cache_action_t action)
{
return action & CACHE_POPULATE ? true : false;
}
cache_action_t get_cache_action(GWBUF* pPacket);
enum routing_action_t
{
@ -118,7 +136,7 @@ private:
};
routing_action_t route_COM_QUERY(GWBUF* pPacket);
routing_action_t route_SELECT(GWBUF* pPacket);
routing_action_t route_SELECT(cache_action_t action, GWBUF* pPacket);
private:
CacheFilterSession(MXS_SESSION* pSession, Cache* pCache, char* zDefaultDb);