Pno channel culling: add frequencies to PnoNetworks

timestamped frequencies for each configured network are
obtained from mScanDetailCaches.
These frequencies are then linked to pno networks
to pass down for frequency culling.

Bug: 64312268
Test: compile
Test: turn wifi verbose logging on; connect to TP-LINK_B6C1_5G with
shield box open. Close shield box and wait for wifi to disconnect. Turn
screen off and verify print out with logcat:
WifiConfigManager: retrievePnoNetworkList "TP-LINK_B6C1_5G":[5785]
Change-Id: I716d17a32528b2f78c977b463792f01df6712894

1 files changed, 58 insertions, 2 deletions

diff --git a/service/java/com/android/server/wifi/WifiConfigManager.java b/service/java/com/android/server/wifi/WifiConfigManager.java
index 4b622bf31..1fdabfa07 100644
--- a/service/java/com/android/server/wifi/WifiConfigManager.java
+++ b/service/java/com/android/server/wifi/WifiConfigManager.java
@@ -61,6 +61,7 @@ import java.io.FileDescriptor;
 import java.io.IOException;
 import java.io.PrintWriter;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.BitSet;
 import java.util.Calendar;
 import java.util.Collection;
@@ -212,6 +213,12 @@ public class WifiConfigManager {
      * Maximum age of scan results that can be used for averaging out RSSI value.
      */
     private static final int SCAN_RESULT_MAXIMUM_AGE_MS = 40000;
+
+    /**
+     * Maximum age of frequencies last seen to be included in pno scans. (30 days)
+     */
+    @VisibleForTesting
+    public static final long MAX_PNO_SCAN_FREQUENCY_AGE_MS = (long) 1000 * 3600 * 24 * 30;
     /**
      * General sorting algorithm of all networks for scanning purposes:
      * Place the configurations in descending order of their |numAssociation| values. If networks
@@ -278,6 +285,7 @@ public class WifiConfigManager {
      * Number of channels to scan for during partial scans initiated while connected.
      */
     private final int mMaxNumActiveChannelsForPartialScans;
+
     /**
      * Verbose logging flag. Toggled by developer options.
      */
@@ -374,7 +382,6 @@ public class WifiConfigManager {
                 R.bool.config_wifi_only_link_same_credential_configurations);
         mMaxNumActiveChannelsForPartialScans = mContext.getResources().getInteger(
                 R.integer.config_wifi_framework_associated_partial_scan_max_num_active_channels);
-
         try {
             mSystemUiUid = mContext.getPackageManager().getPackageUidAsUser(SYSUI_PACKAGE_NAME,
                     PackageManager.MATCH_SYSTEM_ONLY, UserHandle.USER_SYSTEM);
@@ -2358,6 +2365,42 @@ public class WifiConfigManager {
     }
 
     /**
+     * Retrieve a set of channels on which AP's for the provided network was seen using the
+     * internal ScanResult's cache {@link #mScanDetailCaches}. This is used to reduced the list
+     * of frequencies for pno scans.
+     *
+     * @param networkId       network ID corresponding to the network.
+     * @param ageInMillis     only consider scan details whose timestamps are earlier than this.
+     * @return Set containing the frequencies on which this network was found, null if the network
+     * was not found or there are no associated scan details in the cache.
+     */
+    private Set<Integer> fetchChannelSetForNetworkForPnoScan(int networkId, long ageInMillis) {
+        WifiConfiguration config = getInternalConfiguredNetwork(networkId);
+        if (config == null) {
+            return null;
+        }
+        ScanDetailCache scanDetailCache = getScanDetailCacheForNetwork(networkId);
+        if (scanDetailCache == null) {
+            return null;
+        }
+        if (mVerboseLoggingEnabled) {
+            Log.v(TAG, new StringBuilder("fetchChannelSetForNetworkForPnoScan ageInMillis ")
+                    .append(ageInMillis)
+                    .append(" for ")
+                    .append(config.configKey())
+                    .append(" bssids " + scanDetailCache.size())
+                    .toString());
+        }
+        Set<Integer> channelSet = new HashSet<>();
+        long nowInMillis = mClock.getWallClockMillis();
+
+        // Add channels for the network to the output.
+        addToChannelSetForNetworkFromScanDetailCache(channelSet, scanDetailCache, nowInMillis,
+                ageInMillis, Integer.MAX_VALUE);
+        return channelSet;
+    }
+
+    /**
      * Retrieves a list of all the saved networks before enabling disconnected/connected PNO.
      *
      * PNO network list sent to the firmware has limited size. If there are a lot of saved
@@ -2384,7 +2427,20 @@ public class WifiConfigManager {
         Collections.sort(networks, sScanListComparator);
         // The most frequently connected network has the highest priority now.
         for (WifiConfiguration config : networks) {
-            pnoList.add(WifiConfigurationUtil.createPnoNetwork(config));
+            WifiScanner.PnoSettings.PnoNetwork pnoNetwork =
+                    WifiConfigurationUtil.createPnoNetwork(config);
+            Set<Integer> channelSet = fetchChannelSetForNetworkForPnoScan(config.networkId,
+                    MAX_PNO_SCAN_FREQUENCY_AGE_MS);
+            if (channelSet != null) {
+                pnoNetwork.frequencies = channelSet.stream()
+                        .mapToInt(Integer::intValue)
+                        .toArray();
+            }
+            pnoList.add(pnoNetwork);
+            if (mVerboseLoggingEnabled) {
+                Log.v(TAG, "retrievePnoNetworkList " + pnoNetwork.ssid + ":"
+                        + Arrays.toString(pnoNetwork.frequencies));
+            }
         }
         return pnoList;
     }