Factor out caching decision making

server/modules/filter/cache/cachefiltersession.cc

@@ -130,66 +130,7 @@ int CacheFilterSession::routeQuery(GWBUF* pPacket)
         break;
 
     case MYSQL_COM_QUERY:
-        {
+        if (should_consult_cache(pPacket))
-            bool consult_cache = false;
-
-            uint32_t type_mask = qc_get_type_mask(pPacket);
-
-            if (qc_query_is_type(type_mask, QUERY_TYPE_BEGIN_TRX))
-            {
-                // When a transaction is started, we initially assume it is read-only.
-                m_is_read_only = true;
-            }
-            else if (!qc_query_is_type(type_mask, QUERY_TYPE_READ))
-            {
-                // Thereafter, if there's any non-read statement we mark it as non-readonly.
-                // Note that the state of m_is_read_only is not consulted if there is no
-                // on-going transaction of if there is an explicitly read-only transaction.
-                m_is_read_only = false;
-            }
-
-            if (!session_trx_is_active(m_pSession))
-            {
-                if (log_decisions())
-                {
-                    MXS_NOTICE("Cache can be used and stored to, since there is no transaction.");
-                }
-                consult_cache = true;
-            }
-            else if (session_trx_is_read_only(m_pSession))
-            {
-                if (log_decisions())
-                {
-                    MXS_NOTICE("Cache can be used and stored to since there is an explicitly "
-                               "read-only transaction.");
-                }
-                consult_cache = true;
-            }
-            else if (m_is_read_only)
-            {
-                if (log_decisions())
-                {
-                    MXS_NOTICE("Cache can be used and stored to, since the current transaction "
-                               "(not explicitly read-only) has so far been read-only.");
-                }
-                consult_cache = true;
-            }
-            else
-            {
-                if (log_decisions())
-                {
-                    MXS_NOTICE("Cache can not be used, since a not explicitly read-only transaction "
-                               "is active and the transaction has executed non-read statements.");
-                }
-            }
-
-            if (consult_cache)
-            {
-                // 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)
         {
             if (m_pCache->should_store(m_zDefaultDb, pPacket))
             {
@@ -267,8 +208,6 @@ int CacheFilterSession::routeQuery(GWBUF* pPacket)
                 m_state = CACHE_IGNORING_RESPONSE;
             }
         }
-            }
-        }
         break;
 
     default:
@@ -704,3 +643,79 @@ void CacheFilterSession::store_result()
         m_refreshing = false;
     }
 }
+
+/**
+ * Whether the cache should be consulted.
+ *
+ * @param pParam The GWBUF being handled.
+ *
+ * @return True, if the cache should be consulted, false otherwise.
+ */
+bool CacheFilterSession::should_consult_cache(GWBUF* pPacket)
+{
+    bool consult_cache = false;
+
+    uint32_t type_mask = qc_get_type_mask(pPacket);
+
+    if (qc_query_is_type(type_mask, QUERY_TYPE_BEGIN_TRX))
+    {
+        // When a transaction is started, we initially assume it is read-only.
+        m_is_read_only = true;
+    }
+    else if (!qc_query_is_type(type_mask, QUERY_TYPE_READ))
+    {
+        // Thereafter, if there's any non-read statement we mark it as non-readonly.
+        // Note that the state of m_is_read_only is not consulted if there is no
+        // on-going transaction of if there is an explicitly read-only transaction.
+        m_is_read_only = false;
+    }
+
+    if (!session_trx_is_active(m_pSession))
+    {
+        if (log_decisions())
+        {
+            MXS_NOTICE("Cache can be used and stored to, since there is no transaction.");
+        }
+        consult_cache = true;
+    }
+    else if (session_trx_is_read_only(m_pSession))
+    {
+        if (log_decisions())
+        {
+            MXS_NOTICE("Cache can be used and stored to since there is an explicitly "
+                       "read-only transaction.");
+        }
+        consult_cache = true;
+    }
+    else if (m_is_read_only)
+    {
+        if (log_decisions())
+        {
+            MXS_NOTICE("Cache can be used and stored to, since the current transaction "
+                       "(not explicitly read-only) has so far been read-only.");
+        }
+        consult_cache = true;
+    }
+    else
+    {
+        if (log_decisions())
+        {
+            MXS_NOTICE("Cache can not be used, since a not explicitly read-only transaction "
+                       "is active and the transaction has executed non-read statements.");
+        }
+    }
+
+    if (consult_cache)
+    {
+        // 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;
+        }
+    }
+
+    return consult_cache;
+}

server/modules/filter/cache/cachefiltersession.hh

@@ -105,6 +105,8 @@ private:
 
     void store_result();
 
+    bool should_consult_cache(GWBUF* pPacket);
+
 private:
     CacheFilterSession(MXS_SESSION* pSession, Cache* pCache, char* zDefaultDb);