From a2fe5517bcd966c22827150287f55d683d493573 Mon Sep 17 00:00:00 2001
From: Tianjie Xu <xunchang@google.com>
Date: Thu, 2 Jun 2016 12:38:17 -0700
Subject: Change unit of I/O statistics to MiB

I/O in bytes are too large and it may cause overflow. Moreover, data with
large numbers are grouped in the same bucket of the histogram. This adds
difficulty to the analysis. Changing unit of I/O to MiB so that we can
have a better data distribution.

Bug: 28658632
Change-Id: Id9913d71e62b36ce5d5d2e57676953f4dbd0c7c9
---
 core/java/android/os/RecoverySystem.java | 42 ++++++++++++++++++++++----------
 1 file changed, 29 insertions(+), 13 deletions(-)

(limited to 'core/java/android/os/RecoverySystem.java')

diff --git a/core/java/android/os/RecoverySystem.java b/core/java/android/os/RecoverySystem.java
index 4abbf0efc81d..6c21398e280b 100644
--- a/core/java/android/os/RecoverySystem.java
+++ b/core/java/android/os/RecoverySystem.java
@@ -687,12 +687,13 @@ public class RecoverySystem {
         }
     }
 
-    // Read last_install; then report time for update and I/O to tron.
+    // Read last_install; then report time (in seconds) and I/O (in MiB) for
+    // this update to tron.
     // Only report on the reboots immediately after an OTA update.
     private static void parseLastInstallLog(Context context) {
         try (BufferedReader in = new BufferedReader(new FileReader(LAST_INSTALL_FILE))) {
             String line = null;
-            int bytesWritten = -1, bytesStashed = -1;
+            int bytesWrittenInMiB = -1, bytesStashedInMiB = -1;
             int timeTotal = -1;
             while ((line = in.readLine()) != null) {
                 // Here is an example of lines in last_install:
@@ -705,20 +706,35 @@ public class RecoverySystem {
                     continue;
                 }
                 String numString = line.substring(numIndex + 1).trim();
-                int parsedNum;
+                long parsedNum;
                 try {
-                    parsedNum = Integer.parseInt(numString);
+                    parsedNum = Long.parseLong(numString);
                 } catch (NumberFormatException ignored) {
                     Log.e(TAG, "Failed to parse numbers in " + line);
                     continue;
                 }
 
+                final int MiB = 1024 * 1024;
+                int scaled;
+                try {
+                    if (line.startsWith("bytes")) {
+                        scaled = Math.toIntExact(parsedNum / MiB);
+                    } else {
+                        scaled = Math.toIntExact(parsedNum);
+                    }
+                } catch (ArithmeticException ignored) {
+                    Log.e(TAG, "Number overflows in " + line);
+                    continue;
+                }
+
                 if (line.startsWith("time")) {
-                    timeTotal = parsedNum;
+                    timeTotal = scaled;
                 } else if (line.startsWith("bytes_written")) {
-                    bytesWritten = (bytesWritten == -1) ? parsedNum : bytesWritten + parsedNum;
+                    bytesWrittenInMiB = (bytesWrittenInMiB == -1) ? scaled :
+                            bytesWrittenInMiB + scaled;
                 } else if (line.startsWith("bytes_stashed")) {
-                    bytesStashed = (bytesStashed == -1) ? parsedNum : bytesStashed + parsedNum;
+                    bytesStashedInMiB = (bytesStashedInMiB == -1) ? scaled :
+                            bytesStashedInMiB + scaled;
                 }
             }
 
@@ -726,15 +742,15 @@ public class RecoverySystem {
             if (timeTotal != -1) {
                 MetricsLogger.histogram(context, "ota_time_total", timeTotal);
             }
-            if (bytesWritten != -1) {
-                MetricsLogger.histogram(context, "ota_bytes_written", bytesWritten);
+            if (bytesWrittenInMiB != -1) {
+                MetricsLogger.histogram(context, "ota_written_in_MiBs", bytesWrittenInMiB);
             }
-            if (bytesStashed != -1) {
-                MetricsLogger.histogram(context, "ota_bytes_stashed", bytesStashed);
+            if (bytesStashedInMiB != -1) {
+                MetricsLogger.histogram(context, "ota_stashed_in_MiBs", bytesStashedInMiB);
             }
 
-        } catch (IOException ignored) {
-            Log.e(TAG, "Failed to read lines in last_install", ignored);
+        } catch (IOException e) {
+            Log.e(TAG, "Failed to read lines in last_install", e);
         }
     }
 
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