hcq/MaxScale
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

MXS-1474 Document and act in the same way

Browse Source 
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

9
Documentation/Filters/Cache.md
View File

@ -265,10 +265,13 @@ are active transactions:
* `never`: When there is an active transaction, no data will be returned * `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. from the cache, but all requests will always be sent to the backend.
The cache will be populated if the transaction is explicitly read only The cache will be populated inside _explicitly_ read-only transactions.
or if no non-SELECT statement has been encounted. 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 * `read_only_transactions`: The cache will be used and populated inside
_explicitly_ read-only transactions. _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 * `all_transactions`: The cache will be used and populated inside
_explicitly_ read-only transactions. Inside transactions that are not _explicitly_ read-only transactions. Inside transactions that are not
explicitly read-only, the cache will be used and populated _until_ the explicitly read-only, the cache will be used and populated _until_ the

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

@ -740,11 +740,11 @@ void CacheFilterSession::store_result()
* *
* @param pParam The GWBUF being handled. * @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 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"; zReason = "no transaction";
} }
consult_cache = true; action = CACHE_USE_AND_POPULATE;
} }
else if (session_trx_is_read_only(m_pSession)) 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"; zReason = "explicitly read-only transaction";
} }
consult_cache = true; action = CACHE_USE_AND_POPULATE;
} }
else else
{ {
@ -785,8 +785,9 @@ bool CacheFilterSession::should_consult_cache(GWBUF* pPacket)
if (log_decisions()) 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) 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"; zReason = "ordinary transaction that has so far been read-only";
} }
consult_cache = true; action = CACHE_USE_AND_POPULATE;
} }
else else
{ {
@ -809,8 +810,11 @@ bool CacheFilterSession::should_consult_cache(GWBUF* pPacket)
if (log_decisions()) 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 else
@ -821,7 +825,7 @@ bool CacheFilterSession::should_consult_cache(GWBUF* pPacket)
} }
} }
if (consult_cache) if (action != CACHE_IGNORE)
{ {
if (is_select_statement(pPacket)) 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)) if (qc_query_is_type(type_mask, QUERY_TYPE_USERVAR_READ))
{ {
consult_cache = false; action = CACHE_IGNORE;
zReason = "user variables are read"; zReason = "user variables are read";
} }
else if (qc_query_is_type(type_mask, QUERY_TYPE_SYSVAR_READ)) else if (qc_query_is_type(type_mask, QUERY_TYPE_SYSVAR_READ))
{ {
consult_cache = false; action = CACHE_IGNORE;
zReason = "system variables are read"; zReason = "system variables are read";
} }
else if (uses_non_cacheable_function(pPacket)) else if (uses_non_cacheable_function(pPacket))
{ {
consult_cache = false; action = CACHE_IGNORE;
zReason = "uses non-cacheable function"; zReason = "uses non-cacheable function";
} }
else if (uses_non_cacheable_variable(pPacket)) else if (uses_non_cacheable_variable(pPacket))
{ {
consult_cache = false; action = CACHE_IGNORE;
zReason = "uses non-cacheable variable"; 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 // 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 // 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; m_is_read_only = false;
consult_cache = false;
action = CACHE_IGNORE;
zReason = "statement is not SELECT"; zReason = "statement is not SELECT";
} }
} }
@ -885,13 +891,13 @@ bool CacheFilterSession::should_consult_cache(GWBUF* pPacket)
length = max_length - 3; // strlen("..."); length = max_length - 3; // strlen("...");
} }
const char* zDecision = (consult_cache ? "CONSULT" : "IGNORE "); const char* zDecision = (action == CACHE_IGNORE) ? "IGNORE" : "CONSULT";
ss_dassert(zReason); ss_dassert(zReason);
MXS_NOTICE(zFormat, zDecision, length, pSql, 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_debug(uint8_t* pData = static_cast<uint8_t*>(GWBUF_DATA(pPacket)));
ss_dassert((int)MYSQL_GET_COMMAND(pData) == MXS_COM_QUERY); 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)) 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)) if (CACHE_RESULT_IS_OK(result))
{ {
action = route_SELECT(pPacket); routing_action = route_SELECT(cache_action, pPacket);
} }
else else
{ {
@ -932,24 +939,25 @@ CacheFilterSession::routing_action_t CacheFilterSession::route_COM_QUERY(GWBUF*
} }
} }
return action; return routing_action;
} }
/** /**
* Routes a SELECT packet. * 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 * @return ROUTING_ABORT if the processing of the packet should be aborted
* (as the data is obtained from the cache) or * (as the data is obtained from the cache) or
* ROUTING_CONTINUE if the normal processing should continue. * 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; uint32_t flags = CACHE_FLAGS_INCLUDE_STALE;
GWBUF* pResponse; GWBUF* pResponse;
@ -975,7 +983,7 @@ CacheFilterSession::routing_action_t CacheFilterSession::route_SELECT(GWBUF* pPa
gwbuf_free(pResponse); gwbuf_free(pResponse);
m_refreshing = true; m_refreshing = true;
action = ROUTING_CONTINUE; routing_action = ROUTING_CONTINUE;
} }
else else
{ {
@ -986,7 +994,7 @@ CacheFilterSession::routing_action_t CacheFilterSession::route_SELECT(GWBUF* pPa
MXS_NOTICE("Cache data is stale but returning it, fresh " MXS_NOTICE("Cache data is stale but returning it, fresh "
"data is being fetched already."); "data is being fetched already.");
} }
action = ROUTING_ABORT; routing_action = ROUTING_ABORT;
} }
} }
else else
@ -995,15 +1003,15 @@ CacheFilterSession::routing_action_t CacheFilterSession::route_SELECT(GWBUF* pPa
{ {
MXS_NOTICE("Using fresh data from cache."); MXS_NOTICE("Using fresh data from cache.");
} }
action = ROUTING_ABORT; routing_action = ROUTING_ABORT;
} }
} }
else else
{ {
action = ROUTING_CONTINUE; routing_action = ROUTING_CONTINUE;
} }
if (action == ROUTING_CONTINUE) if (routing_action == ROUTING_CONTINUE)
{ {
m_state = CACHE_EXPECTING_RESPONSE; m_state = CACHE_EXPECTING_RESPONSE;
} }
@ -1020,6 +1028,8 @@ CacheFilterSession::routing_action_t CacheFilterSession::route_SELECT(GWBUF* pPa
} }
else else
{ {
ss_dassert(should_populate(cache_action));
// We will not use any value in the cache, but we will update // We will not use any value in the cache, but we will update
// the existing value. // the existing value.
if (log_decisions()) if (log_decisions())
@ -1030,5 +1040,5 @@ CacheFilterSession::routing_action_t CacheFilterSession::route_SELECT(GWBUF* pPa
m_state = CACHE_EXPECTING_RESPONSE; 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(); 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 enum routing_action_t
{ {
@ -118,7 +136,7 @@ private:
}; };
routing_action_t route_COM_QUERY(GWBUF* pPacket); 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: private:
CacheFilterSession(MXS_SESSION* pSession, Cache* pCache, char* zDefaultDb); CacheFilterSession(MXS_SESSION* pSession, Cache* pCache, char* zDefaultDb);