allow to disable sampling

triggered via the vmlist-fields/{network_traffic,disk_io} gconf keys. We do
this by replacing the sampling routines with noops. Also adjust the label in
the vm details to say "sampling disabled".

src/virtManager/details.py

@@ -814,20 +814,24 @@ class vmmDetails(gobject.GObject):
         self.window.get_widget("overview-memory-usage-text").set_text("%d MB of %d MB" % \
                                                                       (int(round(vm_memory/1024.0)), \
                                                                        int(round(host_memory/1024.0))))
-        self.window.get_widget("overview-network-traffic-text").set_markup(_rx_tx_text(
-                                                                    self.vm.network_rx_rate(), 
-                                                                    self.vm.network_tx_rate(), 
-                                                                    "KBytes/s"))
-        self.window.get_widget("overview-disk-usage-text").set_markup(_rx_tx_text(
-                                                                   self.vm.disk_read_rate(),
-                                                                   self.vm.disk_write_rate(),
-                                                                   "KBytes/s"))
 
         history_len = self.config.get_stats_history_length()
         self.cpu_usage_graph.set_property("data_array", self.vm.cpu_time_vector())
         self.memory_usage_graph.set_property("data_array", self.vm.current_memory_vector())
-        self.network_traffic_graph.set_property("data_array", self.vm.network_traffic_vector())
-        self.disk_io_graph.set_property("data_array", self.vm.disk_io_vector())
+
+        if self.config.is_vmlist_network_traffic_visible():
+            text = _rx_tx_text(self.vm.network_rx_rate(), self.vm.network_tx_rate(), "KBytes/s")
+            self.network_traffic_graph.set_property("data_array", self.vm.network_traffic_vector())
+        else:
+            text = "sampling\ndisabled"
+        self.window.get_widget("overview-network-traffic-text").set_markup(text)
+
+        if self.config.is_vmlist_disk_io_visible():
+            text = _rx_tx_text(self.vm.disk_read_rate(), self.vm.disk_write_rate(), "KBytes/s")
+            self.disk_io_graph.set_property("data_array", self.vm.disk_io_vector())
+        else:
+            text = "sampling\ndisabled"
+        self.window.get_widget("overview-disk-usage-text").set_markup(text)
 
     def refresh_config_cpu(self):
         self.window.get_widget("state-host-cpus").set_text("%d" % self.vm.get_connection().host_active_processor_count())

src/virtManager/domain.py

@@ -54,6 +54,11 @@ class vmmDomain(gobject.GObject):
         self._update_status()
         self.xml = None
 
+        self.config.on_vmlist_network_traffic_visible_changed(self.toggle_sample_network_traffic)
+        self.toggle_sample_network_traffic()
+        self.config.on_vmlist_disk_io_visible_changed(self.toggle_sample_disk_io)
+        self.toggle_sample_disk_io()
+
     def get_xml(self):
         if self.xml is None:
             self.xml = self.vm.XMLDesc(0)
@@ -155,7 +160,10 @@ class vmmDomain(gobject.GObject):
             self.lastStatus = status
             self.emit("status-changed", status)
 
-    def _network_traffic(self):
+    def _sample_network_traffic_dummy(self):
+        return 0, 0
+
+    def _sample_network_traffic(self):
         rx = 0
         tx = 0
         for netdev in self.get_network_devices():
@@ -168,7 +176,10 @@ class vmmDomain(gobject.GObject):
                     logging.error("Error reading interface stats %s" % err)
         return rx, tx
 
-    def _disk_io(self):
+    def _sample_disk_io_dummy(self):
+        return 0, 0
+
+    def _sample_disk_io(self):
         rd = 0
         wr = 0
         for disk in self.get_disk_devices():
@@ -1065,4 +1076,31 @@ class vmmDomain(gobject.GObject):
         # Invalidate cached xml
         self.xml = None
 
+    def toggle_sample_network_traffic(self, ignore1=None, ignore2=None, ignore3=None, ignore4=None):
+        if self.config.is_vmlist_network_traffic_visible():
+            if len(self.record) > 1:
+                # resample the current value before calculating the rate in
+                # self.tick() otherwise we'd get a huge spike when switching
+                # from 0 to bytes_transfered_so_far
+                rxBytes, txBytes = self._sample_network_traffic()
+                self.record[0]["netRxKB"] = rxBytes / 1024
+                self.record[0]["netTxKB"] = txBytes / 1024
+            self._network_traffic = self._sample_network_traffic
+        else:
+            self._network_traffic = self._sample_network_traffic_dummy
+
+    def toggle_sample_disk_io(self, ignore1=None, ignore2=None, ignore3=None, ignore4=None):
+        if self.config.is_vmlist_disk_io_visible():
+            if len(self.record) > 1:
+                # resample the current value before calculating the rate in
+                # self.tick() otherwise we'd get a huge spike when switching
+                # from 0 to bytes_transfered_so_far
+                rdBytes, wrBytes = self._sample_disk_io()
+                self.record[0]["diskRdKB"] = rdBytes / 1024
+                self.record[0]["diskWrKB"] = wrBytes / 1024
+            self._disk_io = self._sample_disk_io
+        else:
+            self._disk_io = self._sample_disk_io_dummy
+
+
 gobject.type_register(vmmDomain)