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Commit ce78a5f2 authored by Sundeep Ghuman's avatar Sundeep Ghuman
Browse files

Average scan results for AccessPoints. 

This reduces jitter in the WifiTracker and is modeled after a prior
broken implementation which attempted to half-life the rssi each time
AccessPoint.update(ScanResult) is called.

Bug: 34774783
Test: runtest --path
frameworks/base/packages/SettingsLib/tests/integ/src/com/android/settingslib/wifi/AccessPointTest.java

Change-Id: Iab3f9914af40f2fd56e8ae7b45dcbd62176c8a67
parent b9647ebb

packages/SettingsLib/src/com/android/settingslib/wifi/AccessPoint.java

+8 −3
Original line number Diff line number Diff line
@@ -394,8 +394,9 @@ public class AccessPoint implements Comparable<AccessPoint> { 
     *

     * <p>If the given connection is active, the existing value of {@link #mRssi} will be returned.

     * If the given AccessPoint is not active, a value will be calculated from previous scan

     * results, returning the best RSSI for all matching AccessPoints. If the access point is not

     * connected and there are no scan results, the rssi will be set to {@link #UNREACHABLE_RSSI}.

     * results, returning the best RSSI for all matching AccessPoints averaged with the previous

     * value. If the access point is not connected and there are no scan results, the rssi will be

     * set to {@link #UNREACHABLE_RSSI}.

     *

     * <p>Old scan results will be evicted from the cache when this method is invoked.

     */
@@ -413,8 +414,12 @@ public class AccessPoint implements Comparable<AccessPoint> { 
            }

        }



        if (rssi != UNREACHABLE_RSSI && mRssi != UNREACHABLE_RSSI) {

            mRssi = (mRssi + rssi) / 2; // half-life previous value

        } else {

            mRssi = rssi;

        }

    }



    /**

     * Updates {@link #mSeen} based on the scan result cache.

packages/SettingsLib/tests/integ/src/com/android/settingslib/wifi/AccessPointTest.java

+21 −0
Original line number Diff line number Diff line
@@ -195,6 +195,26 @@ public class AccessPointTest { 
        assertThat(ap.getRssi()).isEqualTo(newRssi);

    }



    @Test

    public void testUpdateWithScanResultShouldAverageRssi() {

        String ssid = "ssid";

        int originalRssi = -65;

        int newRssi = -80;

        int expectedRssi = (originalRssi + newRssi) / 2;

        AccessPoint ap =

                new TestAccessPointBuilder(mContext).setSsid(ssid).setRssi(originalRssi).build();



        ScanResult scanResult = new ScanResult();

        scanResult.SSID = ssid;

        scanResult.level = newRssi;

        scanResult.BSSID = "bssid";

        scanResult.timestamp = SystemClock.elapsedRealtime() * 1000;

        scanResult.capabilities = "";

        assertThat(ap.update(scanResult)).isTrue();



        assertThat(ap.getRssi()).isEqualTo(expectedRssi);

    }



    private AccessPoint createAccessPointWithScanResultCache() {

        Bundle bundle = new Bundle();

        ArrayList<ScanResult> scanResults = new ArrayList<>();
@@ -203,6 +223,7 @@ public class AccessPointTest { 
            scanResult.level = i;

            scanResult.BSSID = "bssid-" + i;

            scanResult.timestamp = SystemClock.elapsedRealtime() * 1000;

            scanResult.capabilities = "";

            scanResults.add(scanResult);

        }

packages/SettingsLib/tests/integ/src/com/android/settingslib/wifi/TestAccessPointBuilder.java

+8 −2
Original line number Diff line number Diff line
@@ -73,9 +73,15 @@ public class TestAccessPointBuilder { 
        return this;

    }



    public TestAccessPointBuilder setRssi(int rssi) {

        mRssi = rssi;

        return this;

    }



    /**

    * Set the signal level.

    * Side effect: if this AccessPoint was previously unreachable,

    * Set the rssi based upon the desired signal level.

     *

    * <p>Side effect: if this AccessPoint was previously unreachable,

    * setting the level will also make it reachable.

    */

    public TestAccessPointBuilder setLevel(int level) {