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Commit 318a9308 authored by Ajay Panicker's avatar Ajay Panicker
Browse files

Switch GATT scan timekeeping to use a different clock 

System.currentTimeMillis() could cause a scan to have a negative scan
time if the system time changed during a scan. Switch to
SystemClock.elapsedRealtime which is guaranteed to be monotonic.

Test: Start a scan and change system time
Bug: 62057540
Change-Id: Ie4d88df96c0a133955f46c355660756e587d29c5
parent 2df98dca

src/com/android/bluetooth/gatt/AppScanStats.java

+10 −8
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ import android.bluetooth.le.ScanSettings; 
import android.os.Binder;

import android.os.WorkSource;

import android.os.ServiceManager;

import android.os.SystemClock;

import android.os.RemoteException;

import com.android.internal.app.IBatteryStats;

import java.text.DateFormat;
@@ -117,7 +118,7 @@ import com.android.bluetooth.btservice.BluetoothProto; 


        this.scansStarted++;

        isScanning = true;

        startTime = System.currentTimeMillis();

        startTime = SystemClock.elapsedRealtime();



        LastScan scan = new LastScan(startTime, 0, false, false, filtered);

        if (settings != null) {
@@ -146,7 +147,7 @@ import com.android.bluetooth.btservice.BluetoothProto; 


        this.scansStopped++;

        isScanning = false;

        stopTime = System.currentTimeMillis();

        stopTime = SystemClock.elapsedRealtime();

        long scanDuration = stopTime - startTime;



        minScanTime = Math.min(scanDuration, minScanTime);
@@ -189,8 +190,8 @@ import com.android.bluetooth.btservice.BluetoothProto; 
            return false;

        }



        return (System.currentTimeMillis() - lastScans.get(0).timestamp) <

            EXCESSIVE_SCANNING_PERIOD_MS;

        return (SystemClock.elapsedRealtime() - lastScans.get(0).timestamp)

                < EXCESSIVE_SCANNING_PERIOD_MS;

    }



    synchronized boolean isScanningTooLong() {
@@ -198,7 +199,7 @@ import com.android.bluetooth.btservice.BluetoothProto; 
            return false;

        }



        return (System.currentTimeMillis() - startTime) > SCAN_TIMEOUT_MS;

        return (SystemClock.elapsedRealtime() - startTime) > SCAN_TIMEOUT_MS;

    }



    // This function truncates the app name for privacy reasons. Apps with
@@ -222,7 +223,7 @@ import com.android.bluetooth.btservice.BluetoothProto; 
    }



    synchronized void dumpToString(StringBuilder sb) {

        long currTime = System.currentTimeMillis();

        long currTime = SystemClock.elapsedRealtime();

        long maxScan = maxScanTime;

        long minScan = minScanTime;

        long scanDuration = 0;
@@ -273,7 +274,8 @@ import com.android.bluetooth.btservice.BluetoothProto; 


            for (int i = 0; i < lastScansSize; i++) {

                LastScan scan = lastScans.get(i);

                Date timestamp = new Date(scan.timestamp);

                Date timestamp = new Date(System.currentTimeMillis() - SystemClock.elapsedRealtime()

                        + scan.timestamp);

                sb.append("    " + dateFormat.format(timestamp) + " - ");

                sb.append(scan.duration + "ms ");

                if (scan.opportunistic) sb.append("Opp ");
@@ -305,7 +307,7 @@ import com.android.bluetooth.btservice.BluetoothProto; 
            Iterator<ContextMap.Connection> ii = connections.iterator();

            while(ii.hasNext()) {

                ContextMap.Connection connection = ii.next();

                long connectionTime = System.currentTimeMillis() - connection.startTime;

                long connectionTime = SystemClock.elapsedRealtime() - connection.startTime;

                sb.append("    " + connection.connId + ": " +

                          connection.address + " " + connectionTime + "ms\n");

            }