Cancel any in-progress scans when media ejected.

Bug: 117909601
Test: atest MediaProviderTests
Change-Id: I7bed0a6672f7c0b4a88dfb590d10b598997ad08d

src/com/android/providers/media/IdleService.java

@@ -24,6 +24,7 @@
 import android.content.ContentProviderClient;
 import android.content.Context;
 import android.os.CancellationSignal;
+import android.os.OperationCanceledException;
 import android.provider.MediaStore;
 
 import java.util.concurrent.TimeUnit;
@@ -40,6 +41,7 @@ public boolean onStartJob(JobParameters params) {
             try (ContentProviderClient cpc = getContentResolver()
                     .acquireContentProviderClient(MediaStore.AUTHORITY)) {
                 ((MediaProvider) cpc.getLocalContentProvider()).onIdleMaintenance(mSignal);
+            } catch (OperationCanceledException ignored) {
             }
             jobFinished(params, false);
         }).start();

src/com/android/providers/media/MediaProvider.java

@@ -148,7 +148,6 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
-import java.util.Iterator;
 import java.util.List;
 import java.util.Locale;
 import java.util.Objects;
@@ -6022,6 +6021,9 @@ public void detachVolume(String volume) {
                     "Deleting the internal volume is not allowed");
         }
 
+        // Signal any scanning to shut down
+        MediaScanner.instance(getContext()).onDetachVolume(volume);
+
         synchronized (mDatabases) {
             DatabaseHelper database = mDatabases.get(volume);
             if (database == null) return;

src/com/android/providers/media/scan/LegacyMediaScanner.java

@@ -66,4 +66,9 @@ public Uri scanFile(File file) {
             Trace.traceEnd(Trace.TRACE_TAG_DATABASE);
         }
     }
+
+    @Override
+    public void onDetachVolume(String volumeName) {
+        // Ignored
+    }
 }

src/com/android/providers/media/scan/MediaScanner.java

@@ -27,6 +27,7 @@ public interface MediaScanner {
     public Context getContext();
     public void scanDirectory(File file);
     public Uri scanFile(File file);
+    public void onDetachVolume(String volumeName);
 
     public static MediaScanner instance(Context context) {
         if (MediaProvider.ENABLE_MODERN_SCANNER) {

src/com/android/providers/media/scan/ModernMediaScanner.java

@@ -52,8 +52,10 @@
 import android.media.MediaMetadataRetriever;
 import android.net.Uri;
 import android.os.Build;
+import android.os.CancellationSignal;
 import android.os.Environment;
 import android.os.FileUtils;
+import android.os.OperationCanceledException;
 import android.os.RemoteException;
 import android.os.Trace;
 import android.provider.MediaStore;
@@ -68,6 +70,7 @@
 import android.util.Log;
 import android.util.LongArray;
 
+import com.android.internal.annotations.GuardedBy;
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.providers.media.util.XmpInterface;
 
@@ -111,8 +114,6 @@ public class ModernMediaScanner implements MediaScanner {
 
     // TODO: deprecate playlist editing
     // TODO: deprecate PARENT column, since callers can't see directories
-    // TODO: replace PRIMARY/SECONDARY_DIRECTORY with PATH
-    // TODO: get real size column wired up for openable columns
 
     private static final SimpleDateFormat sDateFormat;
 
@@ -131,6 +132,13 @@ public class ModernMediaScanner implements MediaScanner {
     private final Context mContext;
     private final ContentResolver mResolver;
 
+    /**
+     * Map from volume name to signals that can be used to cancel any active
+     * scan operations on those volumes.
+     */
+    @GuardedBy("mSignals")
+    private final ArrayMap<String, CancellationSignal> mSignals = new ArrayMap<>();
+
     public ModernMediaScanner(Context context) {
         mContext = context;
         mResolver = context.getContentResolver();
@@ -145,6 +153,7 @@ public Context getContext() {
     public void scanDirectory(File file) {
         try (Scan scan = new Scan(file)) {
             scan.run();
+        } catch (OperationCanceledException ignored) {
         }
     }
 
@@ -153,6 +162,29 @@ public Uri scanFile(File file) {
         try (Scan scan = new Scan(file)) {
             scan.run();
             return scan.mFirstResult;
+        } catch (OperationCanceledException ignored) {
+            return null;
+        }
+    }
+
+    @Override
+    public void onDetachVolume(String volumeName) {
+        synchronized (mSignals) {
+            final CancellationSignal signal = mSignals.remove(volumeName);
+            if (signal != null) {
+                signal.cancel();
+            }
+        }
+    }
+
+    private CancellationSignal getOrCreateSignal(String volumeName) {
+        synchronized (mSignals) {
+            CancellationSignal signal = mSignals.get(volumeName);
+            if (signal == null) {
+                signal = new CancellationSignal();
+                mSignals.put(volumeName, signal);
+            }
+            return signal;
         }
     }
 
@@ -165,6 +197,7 @@ private class Scan implements Runnable, FileVisitor<Path>, AutoCloseable {
         private final File mRoot;
         private final String mVolumeName;
         private final Uri mFilesUri;
+        private final CancellationSignal mSignal;
 
         private final ArrayList<ContentProviderOperation> mPending = new ArrayList<>();
         private LongArray mScannedIds = new LongArray();
@@ -176,6 +209,7 @@ public Scan(File root) {
             mRoot = root;
             mVolumeName = MediaStore.getVolumeName(root);
             mFilesUri = MediaStore.setIncludePending(MediaStore.Files.getContentUri(mVolumeName));
+            mSignal = getOrCreateSignal(mVolumeName);
         }
 
         @Override
@@ -198,13 +232,15 @@ public void run() {
             final long[] scannedIds = mScannedIds.toArray();
             Arrays.sort(scannedIds);
 
+            mSignal.throwIfCanceled();
+
             // Second, clean up any deleted or hidden files, which are all items
             // under requested location that weren't scanned above
             Trace.traceBegin(Trace.TRACE_TAG_DATABASE, "clean");
             try (Cursor c = mResolver.query(mFilesUri,
                     new String[] { FileColumns._ID }, FileColumns.DATA + " LIKE ? ESCAPE '\\'",
                     new String[] { escapeForLike(mRoot.getAbsolutePath()) + '%' },
-                    FileColumns._ID + " DESC")) {
+                    FileColumns._ID + " DESC", mSignal)) {
                 while (c.moveToNext()) {
                     final long id = c.getLong(0);
                     if (Arrays.binarySearch(scannedIds, id) < 0) {
@@ -221,6 +257,8 @@ public void run() {
                 Trace.traceEnd(Trace.TRACE_TAG_DATABASE);
             }
 
+            mSignal.throwIfCanceled();
+
             // Third, resolve any playlists that we scanned
             for (int i = 0; i < mPlaylistIds.size(); i++) {
                 final Uri uri = MediaStore.Files.getContentUri(mVolumeName, mPlaylistIds.get(i));
@@ -245,6 +283,9 @@ public void close() {
         @Override
         public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs)
                 throws IOException {
+            // Possibly bail before digging into each directory
+            mSignal.throwIfCanceled();
+
             if (isDirectoryHidden(dir.toFile())) {
                 return FileVisitResult.SKIP_SUBTREE;
             }

tests/src/com/android/providers/media/scan/ModernMediaScannerTest.java

@@ -39,6 +39,9 @@
 import android.provider.MediaStore.Files.FileColumns;
 import android.provider.MediaStore.MediaColumns;
 
+import androidx.test.InstrumentationRegistry;
+import androidx.test.runner.AndroidJUnit4;
+
 import com.android.internal.os.BackgroundThread;
 import com.android.providers.media.MediaProvider;
 import com.android.providers.media.scan.MediaScannerTest.IsolatedContext;
@@ -55,9 +58,6 @@
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
 
-import androidx.test.InstrumentationRegistry;
-import androidx.test.runner.AndroidJUnit4;
-
 @RunWith(AndroidJUnit4.class)
 public class ModernMediaScannerTest {
     // TODO: scan directory-vs-files and confirm identical results