MXS-1389: Fix rule reloading and query parsing requirements

Reloading of rules now properly uses the current rule file if no argument
was provided. The rule version counter also used atomic operations for the
sake of correctness.

The rule parsing is now only required for DML type statements that should
be fully parsed.

maxscale-system-test/fw2/pass4

@@ -1,4 +1,6 @@
-create or replace table test.t1(id int);
+drop table if exists test.t1;
+create table test.t1(id int);
+drop function if exists my_function;
 create function my_function (arg int) returns int deterministic return arg * arg;
 select "sum(1)";
 select (1);

maxscale-system-test/fw2/pass5

@@ -1 +1,2 @@
-create or replace table t1 (id int);
+drop table if exists t1;
+create table t1 (id int);

maxscale-system-test/fwf_reload.cpp

@@ -20,7 +20,7 @@ int main(int argc, char *argv[])
     char rules_dir[4096];
 
     sprintf(rules_dir, "%s/fw/", test_dir);
-    int N = 10;
+    int N = 12;
     int i;
 
     Test->stop_maxscale();

server/modules/filter/dbfwfilter/dbfwfilter.cc

@@ -376,10 +376,9 @@ TIMERANGE* split_reverse_time(TIMERANGE* tr)
 
 bool dbfw_reload_rules(const MODULECMD_ARG *argv, json_t** output)
 {
-    bool rval = true;
     MXS_FILTER_DEF *filter = argv->argv[0].value.filter;
     Dbfw *inst = (Dbfw*)filter_def_get_instance(filter);
-    std::string filename;
+    std::string filename = inst->get_rule_file();
 
     if (modulecmd_arg_is_present(argv, 1))
     {
@@ -1158,7 +1157,7 @@ std::string Dbfw::get_rule_file() const
 
 int Dbfw::get_rule_version() const
 {
-    return m_version;
+    return atomic_load_int32(&m_version);
 }
 
 bool Dbfw::do_reload_rules(std::string filename)
@@ -1173,7 +1172,7 @@ bool Dbfw::do_reload_rules(std::string filename)
         {
             rval = true;
             m_filename = filename;
-            m_version++;
+            atomic_add(&m_version, 1);
             MXS_NOTICE("Reloaded rules from: %s", filename.c_str());
         }
         else
@@ -1197,12 +1196,6 @@ bool Dbfw::reload_rules(std::string filename)
     return do_reload_rules(filename);
 }
 
-bool Dbfw::reload_rules()
-{
-    mxs::SpinLockGuard guard(m_lock);
-    return do_reload_rules(m_filename);
-}
-
 /**
  * Retrieve the user specific data for this session
  *

server/modules/filter/dbfwfilter/dbfwfilter.hh

@@ -251,7 +251,6 @@ public:
      *         error occurs, it is stored in the modulecmd error system.
      */
     bool reload_rules(std::string filename);
-    bool reload_rules();
 
     /** Diagnostic routines */
     void diagnostics(DCB *dcb) const;

server/modules/filter/dbfwfilter/rules.hh

@@ -18,6 +18,28 @@
 
 #include <maxscale/pcre2.hh>
 
+namespace
+{
+
+static bool is_dml(GWBUF* buffer)
+{
+    qc_query_op_t optype = qc_get_operation(buffer);
+
+    switch (optype)
+    {
+    case QUERY_OP_SELECT:
+    case QUERY_OP_UPDATE:
+    case QUERY_OP_INSERT:
+    case QUERY_OP_DELETE:
+        return true;
+
+    default:
+        return false;
+    }
+}
+
+}
+
 /**
  * A structure used to identify individual rules and to store their contents
  *
@@ -72,7 +94,7 @@ public:
 
     bool need_full_parsing(GWBUF* buffer) const
     {
-        return true;
+        return is_dml(buffer);
     }
 
     bool matches_query(DbfwSession* session, GWBUF* buffer, char** msg) const;
@@ -98,7 +120,7 @@ public:
 
     bool need_full_parsing(GWBUF* buffer) const
     {
-        return true;
+        return is_dml(buffer);
     }
 
     bool matches_query(DbfwSession* session, GWBUF* buffer, char** msg) const;
@@ -118,7 +140,7 @@ class ValueListRule: public Rule
 public:
     bool need_full_parsing(GWBUF* buffer) const
     {
-        return true;
+        return is_dml(buffer);
     }
 
 protected:
@@ -227,7 +249,7 @@ public:
 
     bool need_full_parsing(GWBUF* buffer) const
     {
-        return true;
+        return is_dml(buffer);
     }
 
     bool matches_query(DbfwSession* session, GWBUF* buffer, char** msg) const;