MXS-1775 Change MonitorInstance::configure() prototype

Now return boolean, to allow derived class to signal a failure
to configure.

include/maxscale/monitor.hh

@@ -80,9 +80,13 @@ protected:
      *
      * When the monitor is started, this function will be called in order
      * to allow the concrete implementation to configure itself from
-     * configuration parameters. The default implementation does nothing.
+     * configuration parameters. The default implementation returns true.
+     *
+     * @return True, if the monitor could be configured, false otherwise.
+     *
+     * @note If false is returned, then the monitor will not be started.
      */
-    virtual void configure(const MXS_CONFIG_PARAMETER* pParams);
+    virtual bool configure(const MXS_CONFIG_PARAMETER* pParams);
 
     /**
      * @brief Check whether the monitor has sufficient rights

server/core/monitor.cc

@@ -2599,26 +2599,27 @@ bool MonitorInstance::start(const MXS_CONFIG_PARAMETER* pParams)
         m_events = config_get_enum(pParams, "events", mxs_monitor_event_enum_values);
         m_master = NULL;
 
-        configure(pParams);
+        if (configure(pParams))
-
-        if (thread_start(&m_thread, &maxscale::MonitorInstance::main, this, 0) == NULL)
         {
-            MXS_ERROR("Failed to start monitor thread for monitor '%s'.", m_monitor->name);
+            if (thread_start(&m_thread, &maxscale::MonitorInstance::main, this, 0) == NULL)
-        }
-        else
-        {
-            // Ok, so the thread started. Let's wait until we can be certain the
-            // state has been updated.
-            m_semaphore.wait();
-
-            started = (atomic_load_int32(&m_status) == MXS_MONITOR_RUNNING);
-
-            if (!started)
             {
-                // Ok, so the initialization failed and the thread will exit.
+                MXS_ERROR("Failed to start monitor thread for monitor '%s'.", m_monitor->name);
-                // We need to wait on it so that the thread resources will not leak.
+            }
-                thread_wait(m_thread);
+            else
-                m_thread = 0;
+            {
+                // Ok, so the thread started. Let's wait until we can be certain the
+                // state has been updated.
+                m_semaphore.wait();
+
+                started = (atomic_load_int32(&m_status) == MXS_MONITOR_RUNNING);
+
+                if (!started)
+                {
+                    // Ok, so the initialization failed and the thread will exit.
+                    // We need to wait on it so that the thread resources will not leak.
+                    thread_wait(m_thread);
+                    m_thread = 0;
+                }
             }
         }
     }
@@ -2626,13 +2627,14 @@ bool MonitorInstance::start(const MXS_CONFIG_PARAMETER* pParams)
     return started;
 }
 
-bool MonitorInstance::has_sufficient_permissions() const
+bool MonitorInstance::configure(const MXS_CONFIG_PARAMETER* pParams)
 {
     return true;
 }
 
-void MonitorInstance::configure(const MXS_CONFIG_PARAMETER* pParams)
+bool MonitorInstance::has_sufficient_permissions() const
 {
+    return true;
 }
 
 void MonitorInstance::flush_server_status()

server/modules/monitor/auroramon/auroramon.cc

@@ -49,8 +49,9 @@ json_t* AuroraMonitor::diagnostics_json() const
     return NULL;
 }
 
-void AuroraMonitor::configure(const MXS_CONFIG_PARAMETER* params)
+bool AuroraMonitor::configure(const MXS_CONFIG_PARAMETER* params)
 {
+    return true;
 }
 
 bool AuroraMonitor::has_sufficient_permissions() const

server/modules/monitor/auroramon/auroramon.hh

@@ -32,7 +32,7 @@ public:
     json_t* diagnostics_json() const;
 
 protected:
-    void configure(const MXS_CONFIG_PARAMETER* params);
+    bool configure(const MXS_CONFIG_PARAMETER* params);
     bool has_sufficient_permissions() const;
     void update_server_status(MXS_MONITORED_SERVER* monitored_server);
 

server/modules/monitor/galeramon/galeramon.cc

@@ -130,7 +130,7 @@ json_t* GaleraMonitor::diagnostics_json() const
     return rval;
 }
 
-void GaleraMonitor::configure(const MXS_CONFIG_PARAMETER* params)
+bool GaleraMonitor::configure(const MXS_CONFIG_PARAMETER* params)
 {
     m_disableMasterFailback = config_get_bool(params, "disable_master_failback");
     m_availableWhenDonor = config_get_bool(params, "available_when_donor");
@@ -142,6 +142,8 @@ void GaleraMonitor::configure(const MXS_CONFIG_PARAMETER* params)
 
     /* Reset all data in the hashtable */
     reset_cluster_info();
+
+    return true;
 }
 
 bool GaleraMonitor::has_sufficient_permissions() const

server/modules/monitor/galeramon/galeramon.hh

@@ -64,7 +64,7 @@ public:
     json_t* diagnostics_json() const;
 
 protected:
-    void configure(const MXS_CONFIG_PARAMETER* param);
+    bool configure(const MXS_CONFIG_PARAMETER* param);
     bool has_sufficient_permissions() const;
     void update_server_status(MXS_MONITORED_SERVER* monitored_server);
     void tick();

server/modules/monitor/grmon/grmon.cc

@@ -49,8 +49,9 @@ json_t* GRMon::diagnostics_json() const
     return NULL;
 }
 
-void GRMon::configure(const MXS_CONFIG_PARAMETER* params)
+bool GRMon::configure(const MXS_CONFIG_PARAMETER* params)
 {
+    return true;
 }
 
 bool GRMon::has_sufficient_permissions() const

server/modules/monitor/grmon/grmon.hh

@@ -32,7 +32,7 @@ public:
     json_t* diagnostics_json() const;
 
 protected:
-    void configure(const MXS_CONFIG_PARAMETER* params);
+    bool configure(const MXS_CONFIG_PARAMETER* params);
     bool has_sufficient_permissions() const;
     void update_server_status(MXS_MONITORED_SERVER* monitored_server);
 

server/modules/monitor/mmmon/mmmon.cc

@@ -64,9 +64,11 @@ json_t* MMMonitor::diagnostics_json() const
     return rval;
 }
 
-void MMMonitor::configure(const MXS_CONFIG_PARAMETER* params)
+bool MMMonitor::configure(const MXS_CONFIG_PARAMETER* params)
 {
     m_detectStaleMaster = config_get_bool(params, "detect_stale_master");
+
+    return true;
 }
 
 bool MMMonitor::has_sufficient_permissions() const

server/modules/monitor/mmmon/mmmon.hh

@@ -32,7 +32,7 @@ public:
     json_t* diagnostics_json() const;
 
 protected:
-    void configure(const MXS_CONFIG_PARAMETER* params);
+    bool configure(const MXS_CONFIG_PARAMETER* params);
     bool has_sufficient_permissions() const;
     void update_server_status(MXS_MONITORED_SERVER* monitored_server);
     void tick();

server/modules/monitor/ndbclustermon/ndbclustermon.cc

@@ -47,8 +47,9 @@ json_t* NDBCMonitor::diagnostics_json() const
     return NULL;
 }
 
-void NDBCMonitor::configure(const MXS_CONFIG_PARAMETER* params)
+bool NDBCMonitor::configure(const MXS_CONFIG_PARAMETER* params)
 {
+    return true;
 }
 
 bool NDBCMonitor::has_sufficient_permissions() const

server/modules/monitor/ndbclustermon/ndbclustermon.hh

@@ -32,7 +32,7 @@ public:
     json_t* diagnostics_json() const;
 
 protected:
-    void configure(const MXS_CONFIG_PARAMETER* params);
+    bool configure(const MXS_CONFIG_PARAMETER* params);
     bool has_sufficient_permissions() const;
     void update_server_status(MXS_MONITORED_SERVER* monitored_server);