[MS81] Support remove history before cutoff timestamp

This is needed to ensure corrupted data can be clean up if
the data migration process dones't go well.

Test: NetworkStatsCollectionTest
Bug: 197717846
Change-Id: Ic76ad6f3e96f03791b48988fb2622c9c647ffc7c
(cherry picked from commit 306a00316cac03a0c61f995316c9c5682bec2a19)
Merged-In: Ic76ad6f3e96f03791b48988fb2622c9c647ffc7c

1 files changed, 20 insertions, 0 deletions

diff --git a/framework-t/src/android/net/NetworkStatsCollection.java b/framework-t/src/android/net/NetworkStatsCollection.java
index b59a890a2a..29ea772bc3 100644
--- a/framework-t/src/android/net/NetworkStatsCollection.java
+++ b/framework-t/src/android/net/NetworkStatsCollection.java
@@ -694,6 +694,26 @@ public class NetworkStatsCollection implements FileRotator.Reader, FileRotator.W
         }
     }
 
+    /**
+     * Remove histories which contains or is before the cutoff timestamp.
+     * @hide
+     */
+    public void removeHistoryBefore(long cutoffMillis) {
+        final ArrayList<Key> knownKeys = new ArrayList<>();
+        knownKeys.addAll(mStats.keySet());
+
+        for (Key key : knownKeys) {
+            final NetworkStatsHistory history = mStats.get(key);
+            if (history.getStart() > cutoffMillis) continue;
+
+            history.removeBucketsStartingBefore(cutoffMillis);
+            if (history.size() == 0) {
+                mStats.remove(key);
+            }
+            mDirty = true;
+        }
+    }
+
     private void noteRecordedHistory(long startMillis, long endMillis, long totalBytes) {
         if (startMillis < mStartMillis) mStartMillis = startMillis;
         if (endMillis > mEndMillis) mEndMillis = endMillis;