Merge "Ensure local settings caches are not stale" into nyc-dev

3 files changed, 383 insertions, 30 deletions

diff --git a/core/java/android/provider/Settings.java b/core/java/android/provider/Settings.java
index 12307c54b7a8..4ca1b977d857 100755
--- a/core/java/android/provider/Settings.java
+++ b/core/java/android/provider/Settings.java
@@ -16,6 +16,7 @@
 
 package android.provider;
 
+import android.annotation.NonNull;
 import android.annotation.SdkConstant;
 import android.annotation.SdkConstant.SdkConstantType;
 import android.annotation.SystemApi;
@@ -50,7 +51,6 @@ import android.os.IBinder;
 import android.os.Process;
 import android.os.RemoteException;
 import android.os.ServiceManager;
-import android.os.SystemProperties;
 import android.os.UserHandle;
 import android.os.Build.VERSION_CODES;
 import android.speech.tts.TextToSpeech;
@@ -61,9 +61,12 @@ import android.util.ArraySet;
 import android.util.LocaleList;
 import android.util.Log;
 
+import android.util.MemoryIntArray;
+import com.android.internal.annotations.GuardedBy;
 import com.android.internal.util.ArrayUtils;
 import com.android.internal.widget.ILockSettings;
 
+import java.io.IOException;
 import java.net.URISyntaxException;
 import java.text.SimpleDateFormat;
 import java.util.HashMap;
@@ -1282,6 +1285,29 @@ public final class Settings {
     public static final String CALL_METHOD_GET_GLOBAL = "GET_global";
 
     /**
+     * @hide - Specifies that the caller of the fast-path call()-based flow tracks
+     * the settings generation in order to cache values locally. If this key is
+     * mapped to a <code>null</code> string extra in the request bundle, the response
+     * bundle will contain the same key mapped to a parcelable extra which would be
+     * an {@link android.util.MemoryIntArray}. The response will also contain an
+     * integer mapped to the {@link #CALL_METHOD_GENERATION_INDEX_KEY} which is the
+     * index in the array clients should use to lookup the generation. For efficiency
+     * the caller should request the generation tracking memory array only if it
+     * doesn't already have it.
+     *
+     * @see #CALL_METHOD_GENERATION_INDEX_KEY
+     */
+    public static final String CALL_METHOD_TRACK_GENERATION_KEY = "_track_generation";
+
+    /**
+     * @hide Key with the location in the {@link android.util.MemoryIntArray} where
+     * to look up the generation id of the backing table.
+     *
+     * @see #CALL_METHOD_TRACK_GENERATION_KEY
+     */
+    public static final String CALL_METHOD_GENERATION_INDEX_KEY = "_generation_index";
+
+    /**
      * @hide - User handle argument extra to the fast-path call()-based requests
      */
     public static final String CALL_METHOD_USER_KEY = "_user";
@@ -1424,9 +1450,42 @@ public final class Settings {
         }
     }
 
+    private static final class GenerationTracker {
+        private final MemoryIntArray mArray;
+        private final int mIndex;
+        private int mCurrentGeneration;
+
+        public GenerationTracker(@NonNull MemoryIntArray array, int index) {
+            mArray = array;
+            mIndex = index;
+            mCurrentGeneration = readCurrentGeneration();
+        }
+
+        public boolean isGenerationChanged() {
+            final int currentGeneration = readCurrentGeneration();
+            if (currentGeneration >= 0) {
+                if (currentGeneration == mCurrentGeneration) {
+                    return false;
+                }
+                mCurrentGeneration = currentGeneration;
+            }
+            return true;
+        }
+
+        private int readCurrentGeneration() {
+            try {
+                return mArray.get(mIndex);
+            } catch (IOException e) {
+                Log.e(TAG, "Error getting current generation", e);
+            }
+            return -1;
+        }
+    }
+
     // Thread-safe.
     private static class NameValueCache {
-        private final String mVersionSystemProperty;
+        private static final boolean DEBUG = false;
+
         private final Uri mUri;
 
         private static final String[] SELECT_VALUE =
@@ -1435,7 +1494,6 @@ public final class Settings {
 
         // Must synchronize on 'this' to access mValues and mValuesVersion.
         private final HashMap<String, String> mValues = new HashMap<String, String>();
-        private long mValuesVersion = 0;
 
         // Initially null; set lazily and held forever.  Synchronized on 'this'.
         private IContentProvider mContentProvider = null;
@@ -1445,9 +1503,10 @@ public final class Settings {
         private final String mCallGetCommand;
         private final String mCallSetCommand;
 
-        public NameValueCache(String versionSystemProperty, Uri uri,
-                String getCommand, String setCommand) {
-            mVersionSystemProperty = versionSystemProperty;
+        @GuardedBy("this")
+        private GenerationTracker mGenerationTracker;
+
+        public NameValueCache(Uri uri, String getCommand, String setCommand) {
             mUri = uri;
             mCallGetCommand = getCommand;
             mCallSetCommand = setCommand;
@@ -1482,22 +1541,18 @@ public final class Settings {
         public String getStringForUser(ContentResolver cr, String name, final int userHandle) {
             final boolean isSelf = (userHandle == UserHandle.myUserId());
             if (isSelf) {
-                long newValuesVersion = SystemProperties.getLong(mVersionSystemProperty, 0);
-
-                // Our own user's settings data uses a client-side cache
                 synchronized (this) {
-                    if (mValuesVersion != newValuesVersion) {
-                        if (LOCAL_LOGV || false) {
-                            Log.v(TAG, "invalidate [" + mUri.getLastPathSegment() + "]: current "
-                                    + newValuesVersion + " != cached " + mValuesVersion);
+                    if (mGenerationTracker != null) {
+                        if (mGenerationTracker.isGenerationChanged()) {
+                            if (DEBUG) {
+                                Log.i(TAG, "Generation changed for type:"
+                                        + mUri.getPath() + " in package:"
+                                        + cr.getPackageName() +" and user:" + userHandle);
+                            }
+                            mValues.clear();
+                        } else if (mValues.containsKey(name)) {
+                            return mValues.get(name);
                         }
-
-                        mValues.clear();
-                        mValuesVersion = newValuesVersion;
-                    }
-
-                    if (mValues.containsKey(name)) {
-                        return mValues.get(name);  // Could be null, that's OK -- negative caching
                     }
                 }
             } else {
@@ -1518,12 +1573,42 @@ public final class Settings {
                         args = new Bundle();
                         args.putInt(CALL_METHOD_USER_KEY, userHandle);
                     }
+                    boolean needsGenerationTracker = false;
+                    synchronized (this) {
+                        if (isSelf && mGenerationTracker == null) {
+                            needsGenerationTracker = true;
+                            if (args == null) {
+                                args = new Bundle();
+                            }
+                            args.putString(CALL_METHOD_TRACK_GENERATION_KEY, null);
+                            if (DEBUG) {
+                                Log.i(TAG, "Requested generation tracker for type: "+ mUri.getPath()
+                                        + " in package:" + cr.getPackageName() +" and user:"
+                                        + userHandle);
+                            }
+                        }
+                    }
                     Bundle b = cp.call(cr.getPackageName(), mCallGetCommand, name, args);
                     if (b != null) {
-                        String value = b.getPairValue();
+                        String value = b.getString(Settings.NameValueTable.VALUE);
                         // Don't update our cache for reads of other users' data
                         if (isSelf) {
                             synchronized (this) {
+                                if (needsGenerationTracker) {
+                                    MemoryIntArray array = b.getParcelable(
+                                            CALL_METHOD_TRACK_GENERATION_KEY);
+                                    final int index = b.getInt(
+                                            CALL_METHOD_GENERATION_INDEX_KEY, -1);
+                                    if (array != null && index >= 0) {
+                                        if (DEBUG) {
+                                            Log.i(TAG, "Received generation tracker for type:"
+                                                    + mUri.getPath() + " in package:"
+                                                    + cr.getPackageName() + " and user:"
+                                                    + userHandle + " with index:" + index);
+                                        }
+                                        mGenerationTracker = new GenerationTracker(array, index);
+                                    }
+                                }
                                 mValues.put(name, value);
                             }
                         } else {
@@ -1592,8 +1677,6 @@ public final class Settings {
      * functions for accessing individual settings entries.
      */
     public static final class System extends NameValueTable {
-        public static final String SYS_PROP_SETTING_VERSION = "sys.settings_system_version";
-
         private static final float DEFAULT_FONT_SCALE = 1.0f;
 
         /** @hide */
@@ -1608,7 +1691,6 @@ public final class Settings {
             Uri.parse("content://" + AUTHORITY + "/system");
 
         private static final NameValueCache sNameValueCache = new NameValueCache(
-                SYS_PROP_SETTING_VERSION,
                 CONTENT_URI,
                 CALL_METHOD_GET_SYSTEM,
                 CALL_METHOD_PUT_SYSTEM);
@@ -3913,8 +3995,6 @@ public final class Settings {
      * APIs for those values, not modified directly by applications.
      */
     public static final class Secure extends NameValueTable {
-        public static final String SYS_PROP_SETTING_VERSION = "sys.settings_secure_version";
-
         /**
          * The content:// style URL for this table
          */
@@ -3923,7 +4003,6 @@ public final class Settings {
 
         // Populated lazily, guarded by class object:
         private static final NameValueCache sNameValueCache = new NameValueCache(
-                SYS_PROP_SETTING_VERSION,
                 CONTENT_URI,
                 CALL_METHOD_GET_SECURE,
                 CALL_METHOD_PUT_SECURE);
@@ -6360,8 +6439,6 @@ public final class Settings {
      * explicitly modify through the system UI or specialized APIs for those values.
      */
     public static final class Global extends NameValueTable {
-        public static final String SYS_PROP_SETTING_VERSION = "sys.settings_global_version";
-
         /**
          * The content:// style URL for global secure settings items.  Not public.
          */
@@ -8412,7 +8489,6 @@ public final class Settings {
 
         // Populated lazily, guarded by class object:
         private static NameValueCache sNameValueCache = new NameValueCache(
-                    SYS_PROP_SETTING_VERSION,
                     CONTENT_URI,
                     CALL_METHOD_GET_GLOBAL,
                     CALL_METHOD_PUT_GLOBAL);
diff --git a/core/java/android/util/MemoryIntArray.aidl b/core/java/android/util/MemoryIntArray.aidl
new file mode 100644
index 000000000000..3b15535b28c2
--- /dev/null
+++ b/core/java/android/util/MemoryIntArray.aidl
@@ -0,0 +1,19 @@
+/**
+ * Copyright (c) 2016, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.util;
+
+parcelable MemoryIntArray;
diff --git a/core/java/android/util/MemoryIntArray.java b/core/java/android/util/MemoryIntArray.java
new file mode 100644
index 000000000000..c3bd963708d7
--- /dev/null
+++ b/core/java/android/util/MemoryIntArray.java
@@ -0,0 +1,258 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.util;
+
+import android.os.Parcel;
+import android.os.ParcelFileDescriptor;
+import android.os.Parcelable;
+import android.os.Process;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.util.UUID;
+
+/**
+ * This class is an array of integers that is backed by shared memory.
+ * It is useful for efficiently sharing state between processes. The
+ * write and read operations are guaranteed to not result in read/
+ * write memory tear, i.e. they are atomic. However, multiple read/
+ * write operations are <strong>not</strong> synchronized between
+ * each other.
+ * <p>
+ * The data structure is designed to have one owner process that can
+ * read/write. There may be multiple client processes that can only read or
+ * read/write depending how the data structure was configured when
+ * instantiated. The owner process is the process that created the array.
+ * The shared memory is pinned (not reclaimed by the system) until the
+ * owning process dies or the data structure is closed. This class
+ * is <strong>not</strong> thread safe. You should not interact with
+ * an instance of this class once it is closed.
+ * </p>
+ *
+ * @hide
+ */
+public final class MemoryIntArray implements Parcelable, Closeable {
+    private static final int MAX_SIZE = 1024;
+
+    private final int mOwnerPid;
+    private final boolean mClientWritable;
+    private final long mMemoryAddr;
+    private ParcelFileDescriptor mFd;
+
+    /**
+     * Creates a new instance.
+     *
+     * @param size The size of the array in terms of integer slots. Cannot be
+     *     more than {@link #getMaxSize()}.
+     * @param clientWritable Whether other processes can write to the array.
+     * @throws IOException If an error occurs while accessing the shared memory.
+     */
+    public MemoryIntArray(int size, boolean clientWritable) throws IOException {
+        if (size > MAX_SIZE) {
+            throw new IllegalArgumentException("Max size is " + MAX_SIZE);
+        }
+        mOwnerPid = Process.myPid();
+        mClientWritable = clientWritable;
+        final String name = UUID.randomUUID().toString();
+        mFd = ParcelFileDescriptor.fromFd(nativeCreate(name, size));
+        mMemoryAddr = nativeOpen(mFd.getFd(), true, clientWritable);
+    }
+
+    private MemoryIntArray(Parcel parcel) throws IOException {
+        mOwnerPid = parcel.readInt();
+        mClientWritable = (parcel.readInt() == 1);
+        mFd = parcel.readParcelable(null);
+        if (mFd == null) {
+            throw new IOException("No backing file descriptor");
+        }
+        final long memoryAddress = parcel.readLong();
+        if (isOwner()) {
+            mMemoryAddr = memoryAddress;
+        } else {
+            mMemoryAddr = nativeOpen(mFd.getFd(), false, mClientWritable);
+        }
+    }
+
+    /**
+     * @return Gets whether this array is mutable.
+     */
+    public boolean isWritable() {
+        enforceNotClosed();
+        return isOwner() || mClientWritable;
+    }
+
+    /**
+     * Gets the value at a given index.
+     *
+     * @param index The index.
+     * @return The value at this index.
+     * @throws IOException If an error occurs while accessing the shared memory.
+     */
+    public int get(int index) throws IOException {
+        enforceNotClosed();
+        enforceValidIndex(index);
+        return nativeGet(mFd.getFd(), mMemoryAddr, index, isOwner());
+    }
+
+    /**
+     * Sets the value at a given index. This method can be called only if
+     * {@link #isWritable()} returns true which means your process is the
+     * owner.
+     *
+     * @param index The index.
+     * @param value The value to set.
+     * @throws IOException If an error occurs while accessing the shared memory.
+     */
+    public void set(int index, int value) throws IOException {
+        enforceNotClosed();
+        enforceWritable();
+        enforceValidIndex(index);
+        nativeSet(mFd.getFd(), mMemoryAddr, index, value, isOwner());
+    }
+
+    /**
+     * Gets the array size.
+     *
+     * @throws IOException If an error occurs while accessing the shared memory.
+     */
+    public int size() throws IOException {
+        enforceNotClosed();
+        return nativeSize(mFd.getFd());
+    }
+
+    /**
+     * Closes the array releasing resources.
+     *
+     * @throws IOException If an error occurs while accessing the shared memory.
+     */
+    @Override
+    public void close() throws IOException {
+        if (!isClosed()) {
+            nativeClose(mFd.getFd(), mMemoryAddr, isOwner());
+            mFd = null;
+        }
+    }
+
+    /**
+     * @return Whether this array is closed and shouldn't be used.
+     */
+    public boolean isClosed() {
+        return mFd == null;
+    }
+
+    @Override
+    protected void finalize() throws Throwable {
+        close();
+        super.finalize();
+    }
+
+    @Override
+    public int describeContents() {
+        return CONTENTS_FILE_DESCRIPTOR;
+    }
+
+    @Override
+    public void writeToParcel(Parcel parcel, int flags) {
+        parcel.writeInt(mOwnerPid);
+        parcel.writeInt(mClientWritable ? 1 : 0);
+        parcel.writeParcelable(mFd, 0);
+        parcel.writeLong(mMemoryAddr);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (obj == null) {
+            return false;
+        }
+        if (this == obj) {
+            return true;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        MemoryIntArray other = (MemoryIntArray) obj;
+        if (mFd == null) {
+            if (other.mFd != null) {
+                return false;
+            }
+        } else if (mFd.getFd() != other.mFd.getFd()) {
+            return false;
+        }
+        return true;
+    }
+
+    @Override
+    public int hashCode() {
+        return mFd != null ? mFd.hashCode() : 1;
+    }
+
+    private boolean isOwner() {
+        return mOwnerPid == Process.myPid();
+    }
+
+    private void enforceNotClosed() {
+        if (isClosed()) {
+            throw new IllegalStateException("cannot interact with a closed instance");
+        }
+    }
+
+    private void enforceValidIndex(int index) throws IOException {
+        final int size = size();
+        if (index < 0 || index > size - 1) {
+            throw new IndexOutOfBoundsException(
+                    index + " not between 0 and " + (size - 1));
+        }
+    }
+
+    private void enforceWritable() {
+        if (!isWritable()) {
+            throw new UnsupportedOperationException("array is not writable");
+        }
+    }
+
+    private native int nativeCreate(String name, int size);
+    private native long nativeOpen(int fd, boolean owner, boolean writable);
+    private native void nativeClose(int fd, long memoryAddr, boolean owner);
+    private native int nativeGet(int fd, long memoryAddr, int index, boolean owner);
+    private native void nativeSet(int fd, long memoryAddr, int index, int value, boolean owner);
+    private native int nativeSize(int fd);
+    private native static int nativeGetMemoryPageSize();
+
+    /**
+     * @return The max array size.
+     */
+    public static int getMaxSize() {
+        return MAX_SIZE;
+    }
+
+    public static final Parcelable.Creator<MemoryIntArray> CREATOR =
+            new Parcelable.Creator<MemoryIntArray>() {
+        @Override
+        public MemoryIntArray createFromParcel(Parcel parcel) {
+            try {
+                return new MemoryIntArray(parcel);
+            } catch (IOException ioe) {
+                throw new RuntimeException(ioe);
+            }
+        }
+
+        @Override
+        public MemoryIntArray[] newArray(int size) {
+            return new MemoryIntArray[size];
+        }
+    };
+}