DO NOT MERGE: QNS: less agressive roaming

When connected, QNS no longer triggers network switching if the
current network didn't show up in the scan results.

While there, fixed a QNS unit test failure.

Bug: 31707128
Test: Wifi Unit Tests
Change-Id: I24a16828fb60af4015a4faf4e00c356898729173

1 files changed, 17 insertions, 0 deletions

diff --git a/service/java/com/android/server/wifi/WifiQualifiedNetworkSelector.java b/service/java/com/android/server/wifi/WifiQualifiedNetworkSelector.java
index e916c8c4a..1ddf6ebcb 100644
--- a/service/java/com/android/server/wifi/WifiQualifiedNetworkSelector.java
+++ b/service/java/com/android/server/wifi/WifiQualifiedNetworkSelector.java
@@ -652,6 +652,7 @@ public class WifiQualifiedNetworkSelector {
         StringBuffer noValidSsid = new StringBuffer();
         StringBuffer scoreHistory =  new StringBuffer();
         ArrayList<NetworkKey> unscoredNetworks = new ArrayList<NetworkKey>();
+        boolean scanResultsHaveCurrentBssid = false;
 
         //iterate all scan results and find the best candidate with the highest score
         for (ScanDetail scanDetail : mScanDetails) {
@@ -665,6 +666,12 @@ public class WifiQualifiedNetworkSelector {
                 continue;
             }
 
+            //check if the scan results contain the current connected
+            //BSSID.
+            if (scanResult.BSSID.equals(mCurrentBssid)) {
+                scanResultsHaveCurrentBssid = true;
+            }
+
             final String scanId = toScanId(scanResult);
             //check whether this BSSID is blocked or not
             if (mWifiConfigManager.isBssidBlacklisted(scanResult.BSSID)
@@ -819,6 +826,16 @@ public class WifiQualifiedNetworkSelector {
             localLog(scoreHistory.toString());
         }
 
+        //QNS listens to all single scan results. Some scan requests may not include
+        //the channel of the currently connected network, so the currently connected network
+        //won't show up in the scan results. We don't act on these scan results to avoid
+        //aggressive network switching which might trigger disconnection.
+        if (isConnected && !scanResultsHaveCurrentBssid) {
+            localLog("Current connected BSSID " + mCurrentBssid + " is not in the scan results."
+                    + " Skip network selection.");
+            return null;
+        }
+
         //we need traverse the whole user preference to choose the one user like most now
         if (scanResultCandidate != null) {
             WifiConfiguration tempConfig = networkCandidate;