Exclude MXS_DEBUG in release builds

Now, MXS_DEBUG turns into a nop in release builds.

Documentation/Getting-Started/Configuration-Guide.md

@@ -247,7 +247,11 @@ To disable these messages use the value 0 and to enable them use the value 1.
 
 #### `log_debug`
 
-Enable or disable the logging of messages whose syslog priority is *debug*. This kind of messages are intended for development purposes and are disabled by default.
+Enable or disable the logging of messages whose syslog priority is *debug*.
+This kind of messages are intended for development purposes and are disabled
+by default. Note that if MariaDB MaxScale has been built in release mode, then
+debug messages are excluded from the build and this setting will not have any
+effect.
 
 ```
 # Valid options are:

include/maxscale/log_manager.h

@@ -156,7 +156,12 @@ int mxs_log_message(int priority,
 #define MXS_WARNING(format, ...) MXS_LOG_MESSAGE(LOG_WARNING, format, ##__VA_ARGS__)
 #define MXS_NOTICE(format, ...)  MXS_LOG_MESSAGE(LOG_NOTICE,  format, ##__VA_ARGS__)
 #define MXS_INFO(format, ...)    MXS_LOG_MESSAGE(LOG_INFO,    format, ##__VA_ARGS__)
+
+#if defined(SS_DEBUG)
 #define MXS_DEBUG(format, ...)   MXS_LOG_MESSAGE(LOG_DEBUG,   format, ##__VA_ARGS__)
+#else
+#define MXS_DEBUG(format, ...)
+#endif
 
 /**
  * Log an out of memory error using custom message.

server/core/dcb.c

@@ -2919,20 +2919,16 @@ dcb_create_SSL(DCB* dcb, SSL_LISTENER *ssl)
  */
 int dcb_accept_SSL(DCB* dcb)
 {
-    int ssl_rval;
-    char *remote;
-    char *user;
-
     if ((NULL == dcb->listener || NULL == dcb->listener->ssl) ||
         (NULL == dcb->ssl && dcb_create_SSL(dcb, dcb->listener->ssl) != 0))
     {
         return -1;
     }
 
-    remote = dcb->remote ? dcb->remote : "";
-    user = dcb->user ? dcb->user : "";
+    ss_debug(char *remote = dcb->remote ? dcb->remote : "");
+    ss_debug(char *user = dcb->user ? dcb->user : "");
 
-    ssl_rval = SSL_accept(dcb->ssl);
+    int ssl_rval = SSL_accept(dcb->ssl);
 
     switch (SSL_get_error(dcb->ssl, ssl_rval))
     {

server/core/poll.c

@@ -1044,9 +1044,8 @@ process_pollq(int thread_id)
 
     if (ev & EPOLLHUP)
     {
-        int eno = 0;
-        eno = gw_getsockerrno(dcb->fd);
-        char errbuf[MXS_STRERROR_BUFLEN];
+        ss_debug(int eno = gw_getsockerrno(dcb->fd));
+        ss_debug(char errbuf[MXS_STRERROR_BUFLEN]);
         MXS_DEBUG("%lu [poll_waitevents] "
                   "EPOLLHUP on dcb %p, fd %d. "
                   "Errno %d, %s.",
@@ -1080,9 +1079,8 @@ process_pollq(int thread_id)
 #ifdef EPOLLRDHUP
     if (ev & EPOLLRDHUP)
     {
-        int eno = 0;
-        eno = gw_getsockerrno(dcb->fd);
-        char errbuf[MXS_STRERROR_BUFLEN];
+        ss_debug(int eno = gw_getsockerrno(dcb->fd));
+        ss_debug(char errbuf[MXS_STRERROR_BUFLEN]);
         MXS_DEBUG("%lu [poll_waitevents] "
                   "EPOLLRDHUP on dcb %p, fd %d. "
                   "Errno %d, %s.",

server/modules/authenticator/MySQLAuth/dbusers.c

@@ -1199,7 +1199,6 @@ get_users(SERV_LISTENER *listener, USERS *users)
                              MYSQL_PASSWORD_LEN +
                              sizeof(char) +
                              MYSQL_DATABASE_MAXLEN;
-    int dbnames = 0;
     int db_grants = 0;
     char dbnm[MYSQL_DATABASE_MAXLEN + 1];
     bool anon_user = false;
@@ -1454,7 +1453,7 @@ get_users(SERV_LISTENER *listener, USERS *users)
     if (db_grants)
     {
         /* load all mysql database names */
-        dbnames = get_databases(listener, con);
+        ss_debug(int dbnames =) get_databases(listener, con);
         MXS_DEBUG("Loaded %d MySQL Database Names for service [%s]",
                   dbnames, service->name);
     }

server/modules/routing/binlog/blr.c

@@ -914,9 +914,8 @@ static void freeSession(ROUTER* router_instance,
 {
     ROUTER_INSTANCE *router = (ROUTER_INSTANCE *)router_instance;
     ROUTER_SLAVE *slave = (ROUTER_SLAVE *)router_client_ses;
-    int prev_val;
 
-    prev_val = atomic_add(&router->stats.n_slaves, -1);
+    ss_debug(int prev_val = ) atomic_add(&router->stats.n_slaves, -1);
     ss_dassert(prev_val > 0);
 
     /*

server/modules/routing/readconnroute/readconnroute.c

@@ -633,9 +633,8 @@ static void freeSession(ROUTER* router_instance, void* router_client_ses)
     ROUTER_INSTANCE* router = (ROUTER_INSTANCE *) router_instance;
     ROUTER_CLIENT_SES* router_cli_ses =
         (ROUTER_CLIENT_SES *) router_client_ses;
-    int prev_val;
 
-    prev_val = atomic_add(&router_cli_ses->backend->current_connection_count, -1);
+    ss_debug(int prev_val = ) atomic_add(&router_cli_ses->backend->current_connection_count, -1);
     ss_dassert(prev_val > 0);
 
     spinlock_acquire(&router->lock);

server/modules/routing/schemarouter/schemarouter.c

@@ -3578,17 +3578,14 @@ static void tracelog_routed_query(ROUTER_CLIENT_SES* rses,
     size_t buflen = GWBUF_LENGTH(buf);
     char* querystr;
     char* startpos = (char *)&packet[5];
-    BACKEND* b;
-    backend_type_t be_type;
-    DCB* dcb;
 
     CHK_BACKEND_REF(bref);
-    b = bref->bref_backend;
+    ss_debug(BACKEND *b = bref->bref_backend);
     CHK_BACKEND(b);
-    dcb = bref->bref_dcb;
+    ss_debug(DCB *dcb = bref->bref_dcb);
     CHK_DCB(dcb);
 
-    be_type = BACKEND_TYPE(b);
+    ss_debug(backend_type_t be_type = BACKEND_TYPE(b));
 
     if (GWBUF_IS_TYPE_MYSQL(buf))
     {