Merge "BatteryStats: Stop reading kernel memory stats when unvailable" into oc-dev

import com.android.internal.annotations.VisibleForTesting;

import java.io.BufferedReader;

import java.io.FileNotFoundException;

import java.io.FileReader;

import java.io.IOException;

public class KernelMemoryBandwidthStats {

    private static final String TAG = "KernelMemoryBandwidthStats";

    final protected LongSparseLongArray mBandwidthEntries = new LongSparseLongArray();

    private static final String mSysfsFile = "/sys/kernel/memory_state_time/show_stat";

    private static final boolean DEBUG = false;

    protected final LongSparseLongArray mBandwidthEntries = new LongSparseLongArray();

    private boolean mStatsDoNotExist = false;

    public void updateStats() {

        if (mStatsDoNotExist) {

            // Skip reading.

            return;

        }

        StrictMode.ThreadPolicy policy = StrictMode.allowThreadDiskReads();

        try (BufferedReader reader = new BufferedReader(new FileReader(mSysfsFile))) {

            parseStats(reader);

        } catch (FileNotFoundException e) {

            Slog.w(TAG, "No kernel memory bandwidth stats available");

            mBandwidthEntries.clear();

            mStatsDoNotExist = true;

        } catch (IOException e) {

            Slog.e(TAG, "Failed to read memory bandwidth: " + e.getMessage());

            mBandwidthEntries.clear();