commit 21030c18fc636a8887c76824ffb68ef41a3ebdd3
author Tianjie Xu <xunchang@google.com> Wed Aug 14 13:00:23 2019 -0700
committer Tianjie Xu <xunchang@google.com> Mon Aug 26 23:46:20 2019 +0000
tree aa15c8aab39072c5b2d28b85127608978ee4f247
parent 72d512c227264fcd7f5156dd64ec09316aa77f8b

Use the payload size as the base to calculate download overhead

The download_overhead_percentage was calculated based on the bytes
downloaded during the current update attempt. This may leads to large
number when the update is interrupted; and the resumed update attempt
only downloads a small portion of the payload. For example, for a 10M
payload; if we download 9M, interrupt, and resume to download the
remaining 1M; the current code will report the overhead as (10-1)/1*100%
as 900. We should switch to use the payload size as it was the intention
of the metrics.

Test: run update engine, interrupt and check the metrics
Change-Id: Ic3e1c0a0a4671ee6e7751d53fc40fd2dc8072d63

update_attempter_android_unittest.cc

diff --git a/update_attempter_android_unittest.cc b/update_attempter_android_unittest.cc
index 3be0b7e..721b735 100644
--- a/update_attempter_android_unittest.cc
+++ b/update_attempter_android_unittest.cc
@@ -18,6 +18,7 @@
 
 #include <memory>
 #include <string>
+#include <utility>
 
 #include <android-base/properties.h>
 #include <base/time/time.h>
@@ -57,6 +58,11 @@
     update_attempter_android_.status_ = status;
   }
 
+  void AddPayload(InstallPlan::Payload&& payload) {
+    update_attempter_android_.install_plan_.payloads.push_back(
+        std::move(payload));
+  }
+
   UpdateAttempterAndroid update_attempter_android_{
       &daemon_state_, &prefs_, &boot_control_, &hardware_};
 
@@ -143,9 +149,13 @@
       .Times(1);
   EXPECT_CALL(*metrics_reporter_,
               ReportSuccessfulUpdateMetrics(
-                  2, 0, _, _, _, _, duration, duration_uptime, 3, _))
+                  2, 0, _, 50, _, _, duration, duration_uptime, 3, _))
       .Times(1);
 
+  // Adds a payload of 50 bytes to the InstallPlan.
+  InstallPlan::Payload payload;
+  payload.size = 50;
+  AddPayload(std::move(payload));
   SetUpdateStatus(UpdateStatus::UPDATE_AVAILABLE);
   update_attempter_android_.ProcessingDone(nullptr, ErrorCode::kSuccess);
 
@@ -179,15 +189,20 @@
                   _,
                   _,
                   _,
-                  _,
+                  50,
                   test_utils::DownloadSourceMatcher(total_bytes),
-                  125,
+                  80,
                   _,
                   _,
                   _,
                   _))
       .Times(1);
 
+  // Adds a payload of 50 bytes to the InstallPlan.
+  InstallPlan::Payload payload;
+  payload.size = 50;
+  AddPayload(std::move(payload));
+
   // The first update fails after receiving 50 bytes in total.
   update_attempter_android_.BytesReceived(30, 50, 200);
   update_attempter_android_.ProcessingDone(nullptr, ErrorCode::kError);
@@ -199,7 +214,7 @@
       metrics_utils::GetPersistedValue(kPrefsTotalBytesDownloaded, &prefs_));
 
   // The second update succeeds after receiving 40 bytes, which leads to a
-  // overhead of 50 / 40 = 125%.
+  // overhead of (90 - 50) / 50 = 80%.
   update_attempter_android_.BytesReceived(40, 40, 50);
   update_attempter_android_.ProcessingDone(nullptr, ErrorCode::kSuccess);
   // Both prefs should be cleared.