commit baff640d5d0a1abd95458f08017fe0e8babb8103
author Jin Qian <jinqian@google.com> Thu Feb 16 18:34:31 2017 -0800
committer Jin Qian <jinqian@google.com> Thu Feb 16 18:46:41 2017 -0800
tree 469866b12bb91b6fdc1cb4994cefc67b532a3045
parent cee1918b088d1df7e6875e495c985c2704c0ef2d

storaged: handle negative delta in io usage

When UID is uninstalled and reinstalled, IO usage of the UID is
reset. This caused problem in accounting since it assumes IO usage
is always increasing for the same UID. In such case, use the current
usage instead of negative delta for accounting.

Bug: 34198239
Change-Id: I74661feccc05d19ba8a0feff8a2e38d72c7d1465

storaged/storaged_uid_monitor.cpp

diff --git a/storaged/storaged_uid_monitor.cpp b/storaged/storaged_uid_monitor.cpp
index 3b893b5..49d0d48 100644
--- a/storaged/storaged_uid_monitor.cpp
+++ b/storaged/storaged_uid_monitor.cpp
@@ -204,18 +204,23 @@
         }
 
         struct uid_io_usage& usage = curr_io_stats[uid.name];
-        usage.bytes[READ][FOREGROUND][charger_stat] +=
-            uid.io[FOREGROUND].read_bytes -
+        int64_t fg_rd_delta = uid.io[FOREGROUND].read_bytes -
             last_uid_io_stats[uid.uid].io[FOREGROUND].read_bytes;
-        usage.bytes[READ][BACKGROUND][charger_stat] +=
-            uid.io[BACKGROUND].read_bytes -
+        int64_t bg_rd_delta = uid.io[BACKGROUND].read_bytes -
             last_uid_io_stats[uid.uid].io[BACKGROUND].read_bytes;
-        usage.bytes[WRITE][FOREGROUND][charger_stat] +=
-            uid.io[FOREGROUND].write_bytes -
+        int64_t fg_wr_delta = uid.io[FOREGROUND].write_bytes -
             last_uid_io_stats[uid.uid].io[FOREGROUND].write_bytes;
+        int64_t bg_wr_delta = uid.io[BACKGROUND].write_bytes -
+            last_uid_io_stats[uid.uid].io[BACKGROUND].write_bytes;
+
+        usage.bytes[READ][FOREGROUND][charger_stat] +=
+            (fg_rd_delta < 0) ? uid.io[FOREGROUND].read_bytes : fg_rd_delta;
+        usage.bytes[READ][BACKGROUND][charger_stat] +=
+            (bg_rd_delta < 0) ? uid.io[BACKGROUND].read_bytes : bg_rd_delta;
+        usage.bytes[WRITE][FOREGROUND][charger_stat] +=
+            (fg_wr_delta < 0) ? uid.io[FOREGROUND].write_bytes : fg_wr_delta;
         usage.bytes[WRITE][BACKGROUND][charger_stat] +=
-            uid.io[BACKGROUND].write_bytes -
-            last_uid_io_stats[uid.uid].io[BACKGROUND].write_bytes;;
+            (bg_wr_delta < 0) ? uid.io[BACKGROUND].write_bytes : bg_wr_delta;
     }
 
     last_uid_io_stats = uid_io_stats;