WifiScanningService: Support multiple scanner impls for single scan

Create a new helper class to track single scan across multiple impls:
a) Pass the scan request to all of the available impls.
Note: We don't attempt to split the original request based on the impl
capability. This would make the implementation lot more complicated.
The lower layers (wificond/driver) should be able to ignore channels/bands
in the original request that cannot be handled by the corresponding iface.
b) Wait till results are reported from all of the impls.
c) Consolidate the results and pass it to external clients.

As long as at-least 1 of the impls scan succeeded, failures from other
impl's are ignored (since some scan results will be available).

Bug: 140111024
Test: atest com.android.server.wifi.scanner
Change-Id: Ib0aa86a28b9a4576cdee10cffcef1c2af2fb7ecd

1 files changed, 138 insertions, 37 deletions

diff --git a/service/java/com/android/server/wifi/scanner/WifiScanningServiceImpl.java b/service/java/com/android/server/wifi/scanner/WifiScanningServiceImpl.java
index 4f0b4825b..715fb113c 100644
--- a/service/java/com/android/server/wifi/scanner/WifiScanningServiceImpl.java
+++ b/service/java/com/android/server/wifi/scanner/WifiScanningServiceImpl.java
@@ -583,9 +583,14 @@ public class WifiScanningServiceImpl extends IWifiScanner.Stub {
         // Scan results cached from the last full single scan request.
         private final List<ScanResult> mCachedScanResults = new ArrayList<>();
 
+        // Tracks scan requests across multiple scanner impls.
+        private final ScannerImplsTracker mScannerImplsTracker;
+
         WifiSingleScanStateMachine(Looper looper) {
             super("WifiSingleScanStateMachine", looper);
 
+            mScannerImplsTracker = new ScannerImplsTracker();
+
             setLogRecSize(128);
             setLogOnlyTransitions(false);
 
@@ -599,53 +604,150 @@ public class WifiScanningServiceImpl extends IWifiScanner.Stub {
             setInitialState(mDefaultState);
         }
 
-        private final class ScanEventHandler implements WifiNative.ScanEventHandler {
-            private final String mImplIfaceName;
-            ScanEventHandler(@NonNull String implIfaceName) {
-                mImplIfaceName = implIfaceName;
+        /**
+         * Tracks a single scan request across all the available scanner impls.
+         *
+         * a) Initiates the scan using the same ScanSettings across all the available impls.
+         * b) Waits for all the impls to report the status of the scan request (success or failure).
+         * c) Calculates a consolidated scan status and sends the results if successful.
+         * Note: If there are failures on some of the scanner impls, we ignore them since we will
+         * get some scan results from the other successful impls. We don't declare total scan
+         * failures, unless all the scanner impls fail.
+         */
+        private final class ScannerImplsTracker {
+            private final class ScanEventHandler implements WifiNative.ScanEventHandler {
+                private final String mImplIfaceName;
+                ScanEventHandler(@NonNull String implIfaceName) {
+                    mImplIfaceName = implIfaceName;
+                }
+
+                /**
+                 * Called to indicate a change in state for the current scan.
+                 * Will dispatch a corresponding event to the state machine
+                 */
+                @Override
+                public void onScanStatus(int event) {
+                    if (DBG) localLog("onScanStatus event received, event=" + event);
+                    switch (event) {
+                        case WifiNative.WIFI_SCAN_RESULTS_AVAILABLE:
+                        case WifiNative.WIFI_SCAN_THRESHOLD_NUM_SCANS:
+                        case WifiNative.WIFI_SCAN_THRESHOLD_PERCENT:
+                            reportScanStatusForImpl(mImplIfaceName, STATUS_SUCCEEDED);
+                            break;
+                        case WifiNative.WIFI_SCAN_FAILED:
+                            reportScanStatusForImpl(mImplIfaceName, STATUS_FAILED);
+                            break;
+                        default:
+                            Log.e(TAG, "Unknown scan status event: " + event);
+                            break;
+                    }
+                }
+
+                /**
+                 * Called for each full scan result if requested
+                 */
+                @Override
+                public void onFullScanResult(ScanResult fullScanResult, int bucketsScanned) {
+                    if (DBG) localLog("onFullScanResult received");
+                    reportFullScanResultForImpl(mImplIfaceName, fullScanResult, bucketsScanned);
+                }
+
+                @Override
+                public void onScanPaused(ScanData[] scanData) {
+                    // should not happen for single scan
+                    Log.e(TAG, "Got scan paused for single scan");
+                }
+
+                @Override
+                public void onScanRestarted() {
+                    // should not happen for single scan
+                    Log.e(TAG, "Got scan restarted for single scan");
+                }
             }
 
+            private static final int STATUS_PENDING = 0;
+            private static final int STATUS_SUCCEEDED = 1;
+            private static final int STATUS_FAILED = 2;
+
+            // Tracks scan status per impl.
+            Map<String, Integer> mStatusPerImpl = new ArrayMap<>();
+
             /**
-             * Called to indicate a change in state for the current scan.
-             * Will dispatch a coresponding event to the state machine
+             * Triggers a new scan on all the available scanner impls.
+             * @return true if the scan succeeded on any of the impl, false otherwise.
              */
-            @Override
-            public void onScanStatus(int event) {
-                if (DBG) localLog("onScanStatus event received, event=" + event);
-                switch (event) {
-                    case WifiNative.WIFI_SCAN_RESULTS_AVAILABLE:
-                    case WifiNative.WIFI_SCAN_THRESHOLD_NUM_SCANS:
-                    case WifiNative.WIFI_SCAN_THRESHOLD_PERCENT:
-                        sendMessage(CMD_SCAN_RESULTS_AVAILABLE);
-                        break;
-                    case WifiNative.WIFI_SCAN_FAILED:
-                        sendMessage(CMD_SCAN_FAILED);
-                        break;
-                    default:
-                        Log.e(TAG, "Unknown scan status event: " + event);
-                        break;
+            public boolean startSingleScan(WifiNative.ScanSettings scanSettings) {
+                mStatusPerImpl.clear();
+                boolean anySuccess = false;
+                for (Map.Entry<String, WifiScannerImpl> entry : mScannerImpls.entrySet()) {
+                    String ifaceName = entry.getKey();
+                    WifiScannerImpl impl = entry.getValue();
+                    boolean success = impl.startSingleScan(
+                            scanSettings, new ScanEventHandler(ifaceName));
+                    if (!success) {
+                        Log.e(TAG, "Failed to start single scan on " + ifaceName);
+                        continue;
+                    }
+                    mStatusPerImpl.put(ifaceName, STATUS_PENDING);
+                    anySuccess = true;
                 }
+                return anySuccess;
             }
 
             /**
-             * Called for each full scan result if requested
+             * Returns the latest scan results from all the available scanner impls.
+             * @return Consolidated list of scan results from all the impl.
              */
-            @Override
-            public void onFullScanResult(ScanResult fullScanResult, int bucketsScanned) {
-                if (DBG) localLog("onFullScanResult received");
-                sendMessage(CMD_FULL_SCAN_RESULTS, 0, bucketsScanned, fullScanResult);
+            public ScanData getLatestSingleScanResults() {
+                ScanData consolidatedScanData = null;
+                for (WifiScannerImpl impl : mScannerImpls.values()) {
+                    ScanData scanData = impl.getLatestSingleScanResults();
+                    if (consolidatedScanData == null) {
+                        consolidatedScanData = new ScanData(scanData);
+                    } else {
+                        consolidatedScanData.addResults(scanData.getResults());
+                    }
+                }
+                return consolidatedScanData;
             }
 
-            @Override
-            public void onScanPaused(ScanData[] scanData) {
-                // should not happen for single scan
-                Log.e(TAG, "Got scan paused for single scan");
+            private void reportFullScanResultForImpl(@NonNull String implIfaceName,
+                    ScanResult fullScanResult, int bucketsScanned) {
+                Integer status = mStatusPerImpl.get(implIfaceName);
+                if (status != null && status == STATUS_PENDING) {
+                    sendMessage(CMD_FULL_SCAN_RESULTS, 0, bucketsScanned, fullScanResult);
+                }
             }
 
-            @Override
-            public void onScanRestarted() {
-                // should not happen for single scan
-                Log.e(TAG, "Got scan restarted for single scan");
+            private int getConsolidatedStatus() {
+                boolean anyPending = mStatusPerImpl.values().stream()
+                        .anyMatch(status -> status == STATUS_PENDING);
+                // at-least one impl status is still pending.
+                if (anyPending) return STATUS_PENDING;
+
+                boolean anySuccess = mStatusPerImpl.values().stream()
+                        .anyMatch(status -> status == STATUS_SUCCEEDED);
+                // one success is good enough to declare consolidated success.
+                if (anySuccess) {
+                    return STATUS_SUCCEEDED;
+                } else {
+                    // all failed.
+                    return STATUS_FAILED;
+                }
+            }
+
+            private void reportScanStatusForImpl(@NonNull String implIfaceName, int newStatus) {
+                Integer currentStatus = mStatusPerImpl.get(implIfaceName);
+                if (currentStatus != null && currentStatus == STATUS_PENDING) {
+                    mStatusPerImpl.put(implIfaceName, newStatus);
+                }
+                // Now check if all the scanner impls scan status is available.
+                int consolidatedStatus = getConsolidatedStatus();
+                if (consolidatedStatus == STATUS_SUCCEEDED) {
+                    sendMessage(CMD_SCAN_RESULTS_AVAILABLE);
+                } else if (consolidatedStatus == STATUS_FAILED) {
+                    sendMessage(CMD_SCAN_FAILED);
+                }
             }
         }
 
@@ -841,7 +943,7 @@ public class WifiScanningServiceImpl extends IWifiScanner.Stub {
                         mWifiMetrics.incrementScanReturnEntry(
                                 WifiMetricsProto.WifiLog.SCAN_SUCCESS,
                                 mActiveScans.size());
-                        reportScanResults(getAnyImpl().getLatestSingleScanResults());
+                        reportScanResults(mScannerImplsTracker.getLatestSingleScanResults());
                         mActiveScans.clear();
                         transitionTo(mIdleState);
                         return HANDLED;
@@ -1049,8 +1151,7 @@ public class WifiScanningServiceImpl extends IWifiScanner.Stub {
             channels.fillBucketSettings(bucketSettings, Integer.MAX_VALUE);
 
             settings.buckets = new WifiNative.BucketSettings[] {bucketSettings};
-            if (getAnyImpl().startSingleScan(settings,
-                    new ScanEventHandler(getAnyImpl().getIfaceName()))) {
+            if (mScannerImplsTracker.startSingleScan(settings)) {
                 // store the active scan settings
                 mActiveScanSettings = settings;
                 // swap pending and active scan requests