RESTRICT AUTOMERGE Close TextClassifier native resources.

Bug: 122904322
Test: atest android.view.textclassifier.TextClassificationManagerTest
Test: (MANUAL)
      1. Start an app with a TextView
      2. Select the text to trigger the text selection toolbar and TextClassifier
      3. Close the app's activity by repeatedly clicking back on the nav bar
      4. Start a Profiler for the app and observe for memory growth
      5. Repeat 1 - 3 several times and observe.
         If the bug still exists, memory should grow at about 4 - 5MB.
	 If the bug is fixed, Memory should remain about the same across activity restarts.

Change-Id: Id9a60dea85cf3949de030042537287ddb29842a2

2 files changed, 39 insertions, 12 deletions

diff --git a/core/java/android/view/textclassifier/TextClassifierImpl.java b/core/java/android/view/textclassifier/TextClassifierImpl.java
index 6e5751abbc40..9aa59c1ffc1e 100644
--- a/core/java/android/view/textclassifier/TextClassifierImpl.java
+++ b/core/java/android/view/textclassifier/TextClassifierImpl.java
@@ -64,6 +64,9 @@ import java.util.concurrent.TimeUnit;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
+//TODO: use java.lang.ref.Cleaner once Android supports Java 9
+import sun.misc.Cleaner;
+
 /**
  * Default implementation of the {@link TextClassifier} interface.
  *
@@ -92,6 +95,8 @@ public final class TextClassifierImpl implements TextClassifier {
     private ModelFile mModel;
     @GuardedBy("mLock") // Do not access outside this lock.
     private TextClassifierImplNative mNative;
+    @GuardedBy("mLock")
+    private Cleaner mNativeCleaner;
 
     private final Object mLoggerLock = new Object();
     @GuardedBy("mLoggerLock") // Do not access outside this lock.
@@ -304,12 +309,12 @@ public final class TextClassifierImpl implements TextClassifier {
             if (bestModel == null) {
                 throw new FileNotFoundException("No model for " + localeList.toLanguageTags());
             }
-            if (mNative == null || !Objects.equals(mModel, bestModel)) {
+            if (mNative == null || mNative.isClosed() || !Objects.equals(mModel, bestModel)) {
                 Log.d(DEFAULT_LOG_TAG, "Loading " + bestModel);
-                destroyNativeIfExistsLocked();
                 final ParcelFileDescriptor fd = ParcelFileDescriptor.open(
                         new File(bestModel.getPath()), ParcelFileDescriptor.MODE_READ_ONLY);
                 mNative = new TextClassifierImplNative(fd.getFd());
+                mNativeCleaner = Cleaner.create(this, new NativeCloser(mNative));
                 closeAndLogError(fd);
                 mModel = bestModel;
             }
@@ -324,14 +329,6 @@ public final class TextClassifierImpl implements TextClassifier {
         }
     }
 
-    @GuardedBy("mLock") // Do not call outside this lock.
-    private void destroyNativeIfExistsLocked() {
-        if (mNative != null) {
-            mNative.close();
-            mNative = null;
-        }
-    }
-
     private static String concatenateLocales(@Nullable LocaleList locales) {
         return (locales == null) ? "" : locales.toLanguageTags();
     }
@@ -822,4 +819,21 @@ public final class TextClassifierImpl implements TextClassifier {
                     parsedTime.hashCode());
         }
     }
+
+    /**
+     * Code to close a TextClassifierImplNative. Must not reference the TextClassifierImpl.
+     */
+    private static final class NativeCloser implements Runnable {
+
+        private final TextClassifierImplNative mNative;
+
+        NativeCloser(TextClassifierImplNative nativeImpl) {
+            mNative = Preconditions.checkNotNull(nativeImpl);
+        }
+
+        @Override
+        public void run() {
+            mNative.close();
+        }
+    }
 }
diff --git a/core/java/android/view/textclassifier/TextClassifierImplNative.java b/core/java/android/view/textclassifier/TextClassifierImplNative.java
index 3d4c8f2863ea..e8f60223d1ed 100644
--- a/core/java/android/view/textclassifier/TextClassifierImplNative.java
+++ b/core/java/android/view/textclassifier/TextClassifierImplNative.java
@@ -28,7 +28,8 @@ final class TextClassifierImplNative {
         System.loadLibrary("textclassifier");
     }
 
-    private final long mModelPtr;
+    private final Object mCloseLock = new Object();
+    private long mModelPtr;
 
     /**
      * Creates a new instance of TextClassifierImplNative, using the provided model image, given as
@@ -102,7 +103,19 @@ final class TextClassifierImplNative {
 
     /** Frees up the allocated memory. */
     public void close() {
-        nativeClose(mModelPtr);
+        synchronized (mCloseLock) {
+            if (!isClosed()) {
+                nativeClose(mModelPtr);
+                mModelPtr = 0;
+            }
+        }
+    }
+
+    /**
+     * Returns true if this object is closed, returns false otherwise.
+     */
+    public boolean isClosed() {
+        return mModelPtr == 0L;
     }
 
     /** Returns a comma separated list of locales supported by the model as BCP 47 tags. */