Make query_classifier a wrapper.

The query_classifier library is now only a wrapper that loads an
actual query classifier implementation. Currently it is hardwired
to load qc_mysqlembedded, which implements the query classifier
API using MySQL embedded.

This will be changed, so that the library to load is specified
when qc_init() is called. That will then allow the query classifier
to be specified in the config file.

Currently there seems to be a conflict between the mysql_library_end()
call made in qc_mysqlembedded and the mysql_library_end() call made in
gateway.c. The reason is that they both finalize a shared library.
For the time being mysql_library_end() is not called in gateway.c.
This problem is likely to go away by switching from the client
library to the connector-c library.

query_classifier/CMakeLists.txt

@@ -3,7 +3,7 @@ add_library(query_classifier SHARED query_classifier.cc)
 target_link_libraries(query_classifier ${MYSQL_EMBEDDED_LIB} aio crypt crypto dl m ${PCRE_LINK_FLAGS} ssl stdc++ z)
 set_target_properties(query_classifier PROPERTIES VERSION "1.0.0")
 set_target_properties(query_classifier PROPERTIES LINK_FLAGS -Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/query_classifier.map)
-#set_target_properties(query_classifier PROPERTIES LINK_FLAGS -Wl,-z,defs)
+set_target_properties(query_classifier PROPERTIES LINK_FLAGS -Wl,-z,defs)
 install(TARGETS query_classifier COMPONENT lib DESTINATION ${MAXSCALE_LIBDIR})
 
 add_subdirectory(qc_mysqlembedded)

query_classifier/qc_mysqlembedded/qc_mysqlembedded.cc

@@ -1818,6 +1818,9 @@ void qc_thread_end()
  * EXPORTS
  */
 
+extern "C"
+{
+
 static char version_string[] = "V1.0.0";
 
 static QUERY_CLASSIFIER qc =
@@ -1862,4 +1865,4 @@ QUERY_CLASSIFIER* GetModuleObject()
     return &qc;
 }
 
-
+}

query_classifier/qc_mysqlembedded/qc_mysqlembedded.map

@@ -2,7 +2,7 @@
     global:
         info;
         version;
-        GetModuleInfo;
+        GetModuleObject;
         ModuleInit;
     local:
         *;

server/core/gateway.c

@@ -507,7 +507,15 @@ static void libmysqld_done(void)
 {
     if (libmysqld_started)
     {
-        mysql_library_end();
+        // TODO: qc_end() (if qc_mysqlembedded is used) also calls mysql_library_end(),
+        // TODO: which refers to the mysql_library_end() in the embedded library. This
+        // TODO: one would call the mysql_library_end() in the client library. It seems
+        // TODO: that would work, but for the fact that both de-initialize some lower
+        // TODO: level library, which in turn does not work. Thus, for the time being
+        // TODO: this call is not made.
+        // TODO: Linking MaxScale with Connector-C would likely make this problem
+        // TODO: go away.
+        //mysql_library_end();
     }
 }
 
@@ -2012,6 +2020,8 @@ int main(int argc, char **argv)
     /** Release mysql thread context*/
     mysql_thread_end();
 
+    qc_end();
+
     utils_end();
     datadir_cleanup();
     MXS_NOTICE("MaxScale shutdown completed.");

server/modules/routing/binlog/CMakeLists.txt

@@ -4,7 +4,9 @@ target_link_libraries(binlogrouter maxscale-common)
 install(TARGETS binlogrouter DESTINATION ${MAXSCALE_LIBDIR})
 
 add_executable(maxbinlogcheck maxbinlogcheck.c blr_file.c blr_cache.c blr_master.c blr_slave.c blr.c)
-target_link_libraries(maxbinlogcheck maxscale-common query_classifier)
+# maxbinlogcheck refers to my_uuid_init and my_uuin. They are non-public functions and
+# should not be used. They are found only from the embedded lib.
+target_link_libraries(maxbinlogcheck maxscale-common query_classifier ${EMBEDDED_LIB})
 
 install(TARGETS maxbinlogcheck DESTINATION bin)
 

server/modules/routing/binlog/test/CMakeLists.txt

@@ -1,5 +1,7 @@
 if(BUILD_TESTS)
   add_executable(testbinlogrouter testbinlog.c ../blr.c ../blr_slave.c ../blr_master.c ../blr_file.c ../blr_cache.c)
-  target_link_libraries(testbinlogrouter maxscale-common query_classifier)
+  # testbinlogrouter refers to my_uuid_init and my_uuin. They are non-public functions and
+  # should not be used. They are found only from the embedded lib.
+  target_link_libraries(testbinlogrouter maxscale-common query_classifier ${EMBEDDED_LIB})
   add_test(TestBinlogRouter ${CMAKE_CURRENT_BINARY_DIR}/testbinlogrouter)
 endif()