Measure and send update time to UMA.

update_attempter.cc

Index: update_attempter.cc
diff --git a/update_attempter.cc b/update_attempter.cc
index b5d9644970e94abc67efd75a35cca9247f839654..76a0d6349a10fd9e2ef63c0af9c8079deb13c88d 100644
--- a/update_attempter.cc
+++ b/update_attempter.cc
@@ -13,7 +13,10 @@
 #include <tr1/memory>
 #include <string>
 #include <vector>
+
 #include <glib.h>
+
+#include "metrics/metrics_library.h"
 #include "update_engine/dbus_service.h"
 #include "update_engine/download_action.h"
 #include "update_engine/filesystem_copier_action.h"
@@ -205,6 +208,14 @@ void UpdateAttempter::ProcessingDone(const ActionProcessor* processor,
   if (code == kActionCodeSuccess) {
     SetStatusAndNotify(UPDATE_STATUS_UPDATED_NEED_REBOOT);
     utils::WriteFile(kUpdateCompletedMarker, "", 0);
+
+    // Report the time it took to update the system.
+    int64_t update_time = time(NULL) - last_checked_time_;
+    metrics_lib_->SendToUMA("Installer.UpdateTime",

[adlr, 2010/07/20 00:08:57]

s/Installer/UpdateEngine/?

[petkov, 2010/07/20 00:19:44]

The convention we've been trying to follow is to keep the group name the same as
the issue tracker focus area. I believe the focus area for the update engine is
Area-Installer?

We have, however, diverged from that convention on a few occasions. So, if you
believe that the tracker area doesn't make sense in this context, I'll switch.
Please confirm.

+                            static_cast<int>(update_time),  // sample
+                            1,  // min = 1 second
+                            20 * 60,  // max = 20 minutes

[adlr, 2010/07/20 00:08:57]

i could definitely see the long tail of updates taking much longer, esp on a
very slow network. Can we do a log scale, or some other non-uniform scale?

[petkov, 2010/07/20 00:19:44]

The default histogram layout is exponential -- smaller bucket ranges at the
lower end and bigger bucket ranges at the higher end.

+                            50);  // buckets
   } else {
     LOG(INFO) << "Update failed.";
     SetStatusAndNotify(UPDATE_STATUS_IDLE);