Merge "ScanRequestProxy: Allow short bursts of scan requests" into pi-dev

2 files changed, 95 insertions, 57 deletions

diff --git a/service/java/com/android/server/wifi/ScanRequestProxy.java b/service/java/com/android/server/wifi/ScanRequestProxy.java
index d4c9b3ef0..b9e48ea56 100644
--- a/service/java/com/android/server/wifi/ScanRequestProxy.java
+++ b/service/java/com/android/server/wifi/ScanRequestProxy.java
@@ -34,6 +34,8 @@ import com.android.server.wifi.util.WifiPermissionsUtil;
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Iterator;
+import java.util.LinkedList;
 import java.util.List;
 
 import javax.annotation.concurrent.NotThreadSafe;
@@ -51,15 +53,21 @@ import javax.annotation.concurrent.NotThreadSafe;
  * c) Will send out the {@link WifiManager#SCAN_RESULTS_AVAILABLE_ACTION} broadcast when new
  * scan results are available.
  * d) Throttle scan requests from non-setting apps:
- *    d.1) For foreground apps, throttle to a max of 1 scan per app every 30 seconds.
- *    d.2) For background apps, throttle to a max of 1 scan from any app every 30 minutes.
+ *  a) Each foreground app can request a max of
+ *   {@link #SCAN_REQUEST_THROTTLE_MAX_IN_TIME_WINDOW_FG_APPS} scan every
+ *   {@link #SCAN_REQUEST_THROTTLE_TIME_WINDOW_FG_APPS_MS}.
+ *  b) Background apps combined can request 1 scan every
+ *   {@link #SCAN_REQUEST_THROTTLE_INTERVAL_BG_APPS_MS}.
  * Note: This class is not thread-safe. It needs to be invoked from WifiStateMachine thread only.
  */
 @NotThreadSafe
 public class ScanRequestProxy {
     private static final String TAG = "WifiScanRequestProxy";
+
+    @VisibleForTesting
+    public static final int SCAN_REQUEST_THROTTLE_TIME_WINDOW_FG_APPS_MS = 120 * 1000;
     @VisibleForTesting
-    public static final int SCAN_REQUEST_THROTTLE_INTERVAL_FG_APPS_MS = 30 * 1000;
+    public static final int SCAN_REQUEST_THROTTLE_MAX_IN_TIME_WINDOW_FG_APPS = 4;
     @VisibleForTesting
     public static final int SCAN_REQUEST_THROTTLE_INTERVAL_BG_APPS_MS = 30 * 60 * 1000;
 
@@ -81,8 +89,8 @@ public class ScanRequestProxy {
     private boolean mIsScanProcessingComplete = true;
     // Timestamps for the last scan requested by any background app.
     private long mLastScanTimestampForBgApps = 0;
-    // Timestamps for the last scan requested by each foreground app.
-    private final ArrayMap<String, Long> mLastScanTimestampsForFgApps = new ArrayMap();
+    // Timestamps for the list of last few scan requests by each foreground app.
+    private final ArrayMap<String, LinkedList<Long>> mLastScanTimestampsForFgApps = new ArrayMap();
     // Scan results cached from the last full single scan request.
     private final List<ScanResult> mLastScanResults = new ArrayList<>();
     // Common scan listener for scan requests.
@@ -223,19 +231,47 @@ public class ScanRequestProxy {
         }
     }
 
+    private void trimPastScanRequestTimesForForegroundApp(
+            List<Long> scanRequestTimestamps, long currentTimeMillis) {
+        Iterator<Long> timestampsIter = scanRequestTimestamps.iterator();
+        while (timestampsIter.hasNext()) {
+            Long scanRequestTimeMillis = timestampsIter.next();
+            if ((currentTimeMillis - scanRequestTimeMillis)
+                    > SCAN_REQUEST_THROTTLE_TIME_WINDOW_FG_APPS_MS) {
+                timestampsIter.remove();
+            } else {
+                // This list is sorted by timestamps, so we can skip any more checks
+                break;
+            }
+        }
+    }
+
+    private LinkedList<Long> getOrCreateScanRequestTimestampsForForegroundApp(String packageName) {
+        LinkedList<Long> scanRequestTimestamps = mLastScanTimestampsForFgApps.get(packageName);
+        if (scanRequestTimestamps == null) {
+            scanRequestTimestamps = new LinkedList<>();
+            mLastScanTimestampsForFgApps.put(packageName, scanRequestTimestamps);
+        }
+        return scanRequestTimestamps;
+    }
+
     /**
      * Checks if the scan request from the app (specified by packageName) needs
      * to be throttled.
+     * The throttle limit allows a max of {@link #SCAN_REQUEST_THROTTLE_MAX_IN_TIME_WINDOW_FG_APPS}
+     * in {@link #SCAN_REQUEST_THROTTLE_TIME_WINDOW_FG_APPS_MS} window.
      */
     private boolean shouldScanRequestBeThrottledForForegroundApp(String packageName) {
-        long lastScanMs = mLastScanTimestampsForFgApps.getOrDefault(packageName, 0L);
-        long elapsedRealtime = mClock.getElapsedSinceBootMillis();
-        if (lastScanMs != 0
-                && (elapsedRealtime - lastScanMs) < SCAN_REQUEST_THROTTLE_INTERVAL_FG_APPS_MS) {
+        LinkedList<Long> scanRequestTimestamps =
+                getOrCreateScanRequestTimestampsForForegroundApp(packageName);
+        long currentTimeMillis = mClock.getElapsedSinceBootMillis();
+        // First evict old entries from the list.
+        trimPastScanRequestTimesForForegroundApp(scanRequestTimestamps, currentTimeMillis);
+        if (scanRequestTimestamps.size() >= SCAN_REQUEST_THROTTLE_MAX_IN_TIME_WINDOW_FG_APPS) {
             return true;
         }
         // Proceed with the scan request and record the time.
-        mLastScanTimestampsForFgApps.put(packageName, elapsedRealtime);
+        scanRequestTimestamps.addLast(currentTimeMillis);
         return false;
     }
 
@@ -275,11 +311,6 @@ public class ScanRequestProxy {
     /**
      * Checks if the scan request from the app (specified by callingUid & packageName) needs
      * to be throttled.
-     *
-     * a) Each foreground app can request 1 scan every
-     * {@link #SCAN_REQUEST_THROTTLE_INTERVAL_FG_APPS_MS}.
-     * b) Background apps combined can request 1 scan every
-     * {@link #SCAN_REQUEST_THROTTLE_INTERVAL_BG_APPS_MS}.
      */
     private boolean shouldScanRequestBeThrottledForApp(int callingUid, String packageName) {
         boolean isThrottled;
diff --git a/tests/wifitests/src/com/android/server/wifi/ScanRequestProxyTest.java b/tests/wifitests/src/com/android/server/wifi/ScanRequestProxyTest.java
index 6a2f72d3a..b42f53648 100644
--- a/tests/wifitests/src/com/android/server/wifi/ScanRequestProxyTest.java
+++ b/tests/wifitests/src/com/android/server/wifi/ScanRequestProxyTest.java
@@ -18,6 +18,9 @@ package com.android.server.wifi;
 
 import static android.app.ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND_SERVICE;
 
+import static com.android.server.wifi.ScanRequestProxy.SCAN_REQUEST_THROTTLE_MAX_IN_TIME_WINDOW_FG_APPS;
+import static com.android.server.wifi.ScanRequestProxy.SCAN_REQUEST_THROTTLE_TIME_WINDOW_FG_APPS_MS;
+
 import static org.junit.Assert.*;
 import static org.mockito.Mockito.*;
 
@@ -459,48 +462,50 @@ public class ScanRequestProxyTest {
     }
 
     /**
-     * Ensure new scan requests from the same app are rejected if it's before
-     * {@link ScanRequestProxy#SCAN_REQUEST_THROTTLE_INTERVAL_FG_APPS_MS}
+     * Ensure new scan requests from the same app are rejected if there are more than
+     * {@link ScanRequestProxy#SCAN_REQUEST_THROTTLE_MAX_IN_TIME_WINDOW_FG_APPS} requests in
+     * {@link ScanRequestProxy#SCAN_REQUEST_THROTTLE_TIME_WINDOW_FG_APPS_MS}
      */
     @Test
-    public void testSuccessiveScanRequestFromSameAppThrottled() {
+    public void testSuccessiveScanRequestFromSameFgAppThrottled() {
         long firstRequestMs = 782;
         when(mClock.getElapsedSinceBootMillis()).thenReturn(firstRequestMs);
-        // Make scan request 1.
-        assertTrue(mScanRequestProxy.startScan(TEST_UID, TEST_PACKAGE_NAME_1));
-        mInOrder.verify(mWifiScanner).startScan(any(), any(), any());
-
-        long secondRequestMs =
-                firstRequestMs + ScanRequestProxy.SCAN_REQUEST_THROTTLE_INTERVAL_FG_APPS_MS - 1;
-        when(mClock.getElapsedSinceBootMillis()).thenReturn(secondRequestMs);
-        // Make scan request 2 from the same package name & ensure that it is throttled.
+        for (int i = 0; i < SCAN_REQUEST_THROTTLE_MAX_IN_TIME_WINDOW_FG_APPS; i++) {
+            when(mClock.getElapsedSinceBootMillis()).thenReturn(firstRequestMs + i);
+            assertTrue(mScanRequestProxy.startScan(TEST_UID, TEST_PACKAGE_NAME_1));
+            mInOrder.verify(mWifiScanner).startScan(any(), any(), any());
+        }
+        // Make next scan request from the same package name & ensure that it is throttled.
         assertFalse(mScanRequestProxy.startScan(TEST_UID, TEST_PACKAGE_NAME_1));
         validateScanResultsFailureBroadcastSent(TEST_PACKAGE_NAME_1);
 
-        verify(mWifiMetrics, times(2)).incrementExternalAppOneshotScanRequestsCount();
+        verify(mWifiMetrics, times(SCAN_REQUEST_THROTTLE_MAX_IN_TIME_WINDOW_FG_APPS + 1))
+                .incrementExternalAppOneshotScanRequestsCount();
         verify(mWifiMetrics).incrementExternalForegroundAppOneshotScanRequestsThrottledCount();
     }
 
     /**
-     * Ensure new scan requests from the same app are not rejected if it's after
-     * {@link ScanRequestProxy#SCAN_REQUEST_THROTTLE_INTERVAL_FG_APPS_MS}
+     * Ensure new scan requests from the same app are rejected if there are more than
+     * {@link ScanRequestProxy#SCAN_REQUEST_THROTTLE_MAX_IN_TIME_WINDOW_FG_APPS} requests after
+     * {@link ScanRequestProxy#SCAN_REQUEST_THROTTLE_TIME_WINDOW_FG_APPS_MS}
      */
     @Test
-    public void testSuccessiveScanRequestFromSameAppNotThrottled() {
+    public void testSuccessiveScanRequestFromSameFgAppNotThrottled() {
         long firstRequestMs = 782;
         when(mClock.getElapsedSinceBootMillis()).thenReturn(firstRequestMs);
-        // Make scan request 1.
-        assertTrue(mScanRequestProxy.startScan(TEST_UID, TEST_PACKAGE_NAME_1));
-        mInOrder.verify(mWifiScanner).startScan(any(), any(), any());
-
-        long secondRequestMs =
-                firstRequestMs + ScanRequestProxy.SCAN_REQUEST_THROTTLE_INTERVAL_FG_APPS_MS + 1;
-        when(mClock.getElapsedSinceBootMillis()).thenReturn(secondRequestMs);
-        // Make scan request 2 from the same package name & ensure that it is not throttled.
+        for (int i = 0; i < SCAN_REQUEST_THROTTLE_MAX_IN_TIME_WINDOW_FG_APPS; i++) {
+            when(mClock.getElapsedSinceBootMillis()).thenReturn(firstRequestMs + i);
+            assertTrue(mScanRequestProxy.startScan(TEST_UID, TEST_PACKAGE_NAME_1));
+            mInOrder.verify(mWifiScanner).startScan(any(), any(), any());
+        }
+        long lastRequestMs = firstRequestMs + SCAN_REQUEST_THROTTLE_TIME_WINDOW_FG_APPS_MS + 1;
+        when(mClock.getElapsedSinceBootMillis()).thenReturn(lastRequestMs);
+        // Make next scan request from the same package name & ensure that it is not throttled.
         assertTrue(mScanRequestProxy.startScan(TEST_UID, TEST_PACKAGE_NAME_1));
         mInOrder.verify(mWifiScanner).startScan(any(), any(), any());
 
-        verify(mWifiMetrics, times(2)).incrementExternalAppOneshotScanRequestsCount();
+        verify(mWifiMetrics, times(SCAN_REQUEST_THROTTLE_MAX_IN_TIME_WINDOW_FG_APPS + 1))
+                .incrementExternalAppOneshotScanRequestsCount();
     }
 
     /**
@@ -513,14 +518,12 @@ public class ScanRequestProxyTest {
 
         long firstRequestMs = 782;
         when(mClock.getElapsedSinceBootMillis()).thenReturn(firstRequestMs);
-        // Make scan request 1.
-        assertTrue(mScanRequestProxy.startScan(TEST_UID, TEST_PACKAGE_NAME_1));
-        mInOrder.verify(mWifiScanner).startScan(any(), any(), any());
-
-        long secondRequestMs =
-                firstRequestMs + ScanRequestProxy.SCAN_REQUEST_THROTTLE_INTERVAL_FG_APPS_MS - 1;
-        when(mClock.getElapsedSinceBootMillis()).thenReturn(secondRequestMs);
-        // Make scan request 2 from the same package name & ensure that it is not throttled.
+        for (int i = 0; i < SCAN_REQUEST_THROTTLE_MAX_IN_TIME_WINDOW_FG_APPS; i++) {
+            when(mClock.getElapsedSinceBootMillis()).thenReturn(firstRequestMs + i);
+            assertTrue(mScanRequestProxy.startScan(TEST_UID, TEST_PACKAGE_NAME_1));
+            mInOrder.verify(mWifiScanner).startScan(any(), any(), any());
+        }
+        // Make next scan request from the same package name & ensure that it is not throttled.
         assertTrue(mScanRequestProxy.startScan(TEST_UID, TEST_PACKAGE_NAME_1));
         mInOrder.verify(mWifiScanner).startScan(any(), any(), any());
     }
@@ -529,23 +532,27 @@ public class ScanRequestProxyTest {
      * Ensure new scan requests from different apps are not throttled.
      */
     @Test
-    public void testSuccessiveScanRequestFromDifferentAppsNotThrottled() {
+    public void testSuccessiveScanRequestFromDifferentFgAppsNotThrottled() {
         long firstRequestMs = 782;
         when(mClock.getElapsedSinceBootMillis()).thenReturn(firstRequestMs);
-        // Make scan request 1.
+        for (int i = 0; i < SCAN_REQUEST_THROTTLE_MAX_IN_TIME_WINDOW_FG_APPS / 2; i++) {
+            when(mClock.getElapsedSinceBootMillis()).thenReturn(firstRequestMs + i);
+            assertTrue(mScanRequestProxy.startScan(TEST_UID, TEST_PACKAGE_NAME_1));
+            mInOrder.verify(mWifiScanner).startScan(any(), any(), any());
+        }
+        for (int i = 0; i < SCAN_REQUEST_THROTTLE_MAX_IN_TIME_WINDOW_FG_APPS / 2; i++) {
+            when(mClock.getElapsedSinceBootMillis()).thenReturn(firstRequestMs + i);
+            assertTrue(mScanRequestProxy.startScan(TEST_UID, TEST_PACKAGE_NAME_2));
+            mInOrder.verify(mWifiScanner).startScan(any(), any(), any());
+        }
+        // Make next scan request from both the package name & ensure that it is not throttled.
         assertTrue(mScanRequestProxy.startScan(TEST_UID, TEST_PACKAGE_NAME_1));
         mInOrder.verify(mWifiScanner).startScan(any(), any(), any());
-
-        // Make scan request 2 from the same package name & ensure that it is throttled.
-        assertFalse(mScanRequestProxy.startScan(TEST_UID, TEST_PACKAGE_NAME_1));
-        validateScanResultsFailureBroadcastSent(TEST_PACKAGE_NAME_1);
-
-        // Make scan request 3 from a different package name & ensure that it is not throttled.
         assertTrue(mScanRequestProxy.startScan(TEST_UID, TEST_PACKAGE_NAME_2));
         mInOrder.verify(mWifiScanner).startScan(any(), any(), any());
 
-        verify(mWifiMetrics, times(3)).incrementExternalAppOneshotScanRequestsCount();
-        verify(mWifiMetrics).incrementExternalForegroundAppOneshotScanRequestsThrottledCount();
+        verify(mWifiMetrics, times(SCAN_REQUEST_THROTTLE_MAX_IN_TIME_WINDOW_FG_APPS + 2))
+                .incrementExternalAppOneshotScanRequestsCount();
     }
 
     /**