Fire "dreaming started" and "dreaming stopped" broadcasts.

Dream manager now fires broadcast intents when entering + exiting
dreamland (except when testing).

Power manager can now listen for dreams ending, using polling only
as a backstop.

Also:
 - Bullet-proof dream-manager/dream against known failure modes
 - Add new read/write dream permissions
 - Refactor dream-manager to delegate work + state management into
   a new DreamController class, via a handler

Bug:6999949
Bug:7152024
Change-Id: I986bb7812209d8c95ae1d660a5eee5998a7b08b1
diff --git a/services/java/com/android/server/DreamManagerService.java b/services/java/com/android/server/DreamManagerService.java
new file mode 100644
index 0000000..b02ea7f
--- /dev/null
+++ b/services/java/com/android/server/DreamManagerService.java
@@ -0,0 +1,387 @@
+/*
+ * Copyright (C) 2012 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 com.android.server;
+
+import static android.provider.Settings.Secure.SCREENSAVER_COMPONENTS;
+import static android.provider.Settings.Secure.SCREENSAVER_DEFAULT_COMPONENT;
+
+import android.app.ActivityManagerNative;
+import android.content.BroadcastReceiver;
+import android.content.ComponentName;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.content.ServiceConnection;
+import android.content.pm.PackageManager;
+import android.os.Binder;
+import android.os.Bundle;
+import android.os.Handler;
+import android.os.IBinder;
+import android.os.Message;
+import android.os.RemoteException;
+import android.os.UserHandle;
+import android.provider.Settings;
+import android.service.dreams.Dream;
+import android.service.dreams.IDreamManager;
+import android.util.Slog;
+import android.util.SparseArray;
+
+import java.io.FileDescriptor;
+import java.io.PrintWriter;
+
+/**
+ * Service api for managing dreams.
+ *
+ * @hide
+ */
+public final class DreamManagerService
+        extends IDreamManager.Stub
+        implements ServiceConnection {
+    private static final boolean DEBUG = true;
+    private static final String TAG = DreamManagerService.class.getSimpleName();
+
+    private static final Intent mDreamingStartedIntent = new Intent(Dream.ACTION_DREAMING_STARTED)
+            .addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
+    private static final Intent mDreamingStoppedIntent = new Intent(Dream.ACTION_DREAMING_STOPPED)
+            .addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
+
+    private final Object mLock = new Object();
+    private final DreamController mController;
+    private final DreamControllerHandler mHandler;
+    private final Context mContext;
+
+    private final CurrentUserManager mCurrentUserManager = new CurrentUserManager();
+
+    private final DeathRecipient mAwakenOnBinderDeath = new DeathRecipient() {
+        @Override
+        public void binderDied() {
+            if (DEBUG) Slog.v(TAG, "binderDied()");
+            awaken();
+        }
+    };
+
+    private final DreamController.Listener mControllerListener = new DreamController.Listener() {
+        @Override
+        public void onDreamStopped(boolean wasTest) {
+            synchronized(mLock) {
+                setDreamingLocked(false, wasTest);
+            }
+        }};
+
+    private boolean mIsDreaming;
+
+    public DreamManagerService(Context context) {
+        if (DEBUG) Slog.v(TAG, "DreamManagerService startup");
+        mContext = context;
+        mController = new DreamController(context, mAwakenOnBinderDeath, this, mControllerListener);
+        mHandler = new DreamControllerHandler(mController);
+        mController.setHandler(mHandler);
+    }
+
+    public void systemReady() {
+        mCurrentUserManager.init(mContext);
+
+        if (DEBUG) Slog.v(TAG, "Ready to dream!");
+    }
+
+    @Override
+    protected void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
+        mContext.enforceCallingOrSelfPermission(android.Manifest.permission.DUMP, TAG);
+
+        pw.println("Dreamland:");
+        mController.dump(pw);
+        mCurrentUserManager.dump(pw);
+    }
+
+    // begin IDreamManager api
+    @Override
+    public ComponentName[] getDreamComponents() {
+        checkPermission(android.Manifest.permission.READ_DREAM_STATE);
+        int userId = UserHandle.getCallingUserId();
+
+        final long ident = Binder.clearCallingIdentity();
+        try {
+            return getDreamComponentsForUser(userId);
+        } finally {
+            Binder.restoreCallingIdentity(ident);
+        }
+    }
+
+    @Override
+    public void setDreamComponents(ComponentName[] componentNames) {
+        checkPermission(android.Manifest.permission.WRITE_DREAM_STATE);
+        int userId = UserHandle.getCallingUserId();
+
+        final long ident = Binder.clearCallingIdentity();
+        try {
+            Settings.Secure.putStringForUser(mContext.getContentResolver(),
+                    SCREENSAVER_COMPONENTS,
+                    componentsToString(componentNames),
+                    userId);
+        } finally {
+            Binder.restoreCallingIdentity(ident);
+        }
+    }
+
+    @Override
+    public ComponentName getDefaultDreamComponent() {
+        checkPermission(android.Manifest.permission.READ_DREAM_STATE);
+        int userId = UserHandle.getCallingUserId();
+
+        final long ident = Binder.clearCallingIdentity();
+        try {
+            String name = Settings.Secure.getStringForUser(mContext.getContentResolver(),
+                    SCREENSAVER_DEFAULT_COMPONENT,
+                    userId);
+            return name == null ? null : ComponentName.unflattenFromString(name);
+        } finally {
+            Binder.restoreCallingIdentity(ident);
+        }
+
+    }
+
+    @Override
+    public boolean isDreaming() {
+        checkPermission(android.Manifest.permission.READ_DREAM_STATE);
+
+        return mIsDreaming;
+    }
+
+    @Override
+    public void dream() {
+        checkPermission(android.Manifest.permission.WRITE_DREAM_STATE);
+
+        final long ident = Binder.clearCallingIdentity();
+        try {
+            if (DEBUG) Slog.v(TAG, "Dream now");
+            ComponentName[] dreams = getDreamComponentsForUser(mCurrentUserManager.getCurrentUserId());
+            ComponentName firstDream = dreams != null && dreams.length > 0 ? dreams[0] : null;
+            if (firstDream != null) {
+                mHandler.requestStart(firstDream, false /*isTest*/);
+                synchronized (mLock) {
+                    setDreamingLocked(true, false /*isTest*/);
+                }
+            }
+        } finally {
+            Binder.restoreCallingIdentity(ident);
+        }
+    }
+
+    @Override
+    public void testDream(ComponentName dream) {
+        checkPermission(android.Manifest.permission.WRITE_DREAM_STATE);
+
+        final long ident = Binder.clearCallingIdentity();
+        try {
+            if (DEBUG) Slog.v(TAG, "Test dream name=" + dream);
+            if (dream != null) {
+                mHandler.requestStart(dream, true /*isTest*/);
+                synchronized (mLock) {
+                    setDreamingLocked(true, true /*isTest*/);
+                }
+            }
+        } finally {
+            Binder.restoreCallingIdentity(ident);
+        }
+
+    }
+
+    @Override
+    public void awaken() {
+        checkPermission(android.Manifest.permission.WRITE_DREAM_STATE);
+
+        final long ident = Binder.clearCallingIdentity();
+        try {
+            if (DEBUG) Slog.v(TAG, "Wake up");
+            mHandler.requestStop();
+        } finally {
+            Binder.restoreCallingIdentity(ident);
+        }
+    }
+
+    @Override
+    public void awakenSelf(IBinder token) {
+        // requires no permission, called by Dream from an arbitrary process
+
+        final long ident = Binder.clearCallingIdentity();
+        try {
+            if (DEBUG) Slog.v(TAG, "Wake up from dream: " + token);
+            if (token != null) {
+                mHandler.requestStopSelf(token);
+            }
+        } finally {
+            Binder.restoreCallingIdentity(ident);
+        }
+    }
+    // end IDreamManager api
+
+    // begin ServiceConnection
+    @Override
+    public void onServiceConnected(ComponentName name, IBinder dream) {
+        if (DEBUG) Slog.v(TAG, "Service connected: " + name + " binder=" +
+                dream + " thread=" + Thread.currentThread().getId());
+        mHandler.requestAttach(name, dream);
+    }
+
+    @Override
+    public void onServiceDisconnected(ComponentName name) {
+        if (DEBUG) Slog.v(TAG, "Service disconnected: " + name);
+        // Only happens in exceptional circumstances, awaken just to be safe
+        awaken();
+    }
+    // end ServiceConnection
+
+    private void checkPermission(String permission) {
+        if (PackageManager.PERMISSION_GRANTED != mContext.checkCallingOrSelfPermission(permission)) {
+            throw new SecurityException("Access denied to process: " + Binder.getCallingPid()
+                    + ", must have permission " + permission);
+        }
+    }
+
+    private void setDreamingLocked(boolean isDreaming, boolean isTest) {
+        boolean wasDreaming = mIsDreaming;
+        if (!isTest) {
+            if (!wasDreaming && isDreaming) {
+                if (DEBUG) Slog.v(TAG, "Firing ACTION_DREAMING_STARTED");
+                mContext.sendBroadcast(mDreamingStartedIntent);
+            } else if (wasDreaming && !isDreaming) {
+                if (DEBUG) Slog.v(TAG, "Firing ACTION_DREAMING_STOPPED");
+                mContext.sendBroadcast(mDreamingStoppedIntent);
+            }
+        }
+        mIsDreaming = isDreaming;
+    }
+
+    private ComponentName[] getDreamComponentsForUser(int userId) {
+        String names = Settings.Secure.getStringForUser(mContext.getContentResolver(),
+                SCREENSAVER_COMPONENTS,
+                userId);
+        return names == null ? null : componentsFromString(names);
+    }
+
+    private static String componentsToString(ComponentName[] componentNames) {
+        StringBuilder names = new StringBuilder();
+        if (componentNames != null) {
+            for (ComponentName componentName : componentNames) {
+                if (names.length() > 0) {
+                    names.append(',');
+                }
+                names.append(componentName.flattenToString());
+            }
+        }
+        return names.toString();
+    }
+
+    private static ComponentName[] componentsFromString(String names) {
+        String[] namesArray = names.split(",");
+        ComponentName[] componentNames = new ComponentName[namesArray.length];
+        for (int i = 0; i < namesArray.length; i++) {
+            componentNames[i] = ComponentName.unflattenFromString(namesArray[i]);
+        }
+        return componentNames;
+    }
+
+    /**
+     * Keeps track of the current user, since dream() uses the current user's configuration.
+     */
+    private static class CurrentUserManager {
+        private final Object mLock = new Object();
+        private int mCurrentUserId;
+
+        public void init(Context context) {
+            IntentFilter filter = new IntentFilter();
+            filter.addAction(Intent.ACTION_USER_SWITCHED);
+            context.registerReceiver(new BroadcastReceiver() {
+                @Override
+                public void onReceive(Context context, Intent intent) {
+                    String action = intent.getAction();
+                    if (Intent.ACTION_USER_SWITCHED.equals(action)) {
+                        synchronized(mLock) {
+                            mCurrentUserId = intent.getIntExtra(Intent.EXTRA_USER_HANDLE, 0);
+                            if (DEBUG) Slog.v(TAG, "userId " + mCurrentUserId + " is in the house");
+                        }
+                    }
+                }}, filter);
+            try {
+                synchronized (mLock) {
+                    mCurrentUserId = ActivityManagerNative.getDefault().getCurrentUser().id;
+                }
+            } catch (RemoteException e) {
+                Slog.w(TAG, "Couldn't get current user ID; guessing it's 0", e);
+            }
+        }
+
+        public void dump(PrintWriter pw) {
+            pw.print("  user="); pw.println(getCurrentUserId());
+        }
+
+        public int getCurrentUserId() {
+            synchronized(mLock) {
+                return mCurrentUserId;
+            }
+        }
+    }
+
+    /**
+     * Handler for asynchronous operations performed by the dream manager.
+     *
+     * Ensures operations to {@link DreamController} are single-threaded.
+     */
+    private static final class DreamControllerHandler extends Handler {
+        private final DreamController mController;
+        private final Runnable mStopRunnable = new Runnable() {
+            @Override
+            public void run() {
+                mController.stop();
+            }};
+
+        public DreamControllerHandler(DreamController controller) {
+            super(true /*async*/);
+            mController = controller;
+        }
+
+        public void requestStart(final ComponentName name, final boolean isTest) {
+            post(new Runnable(){
+                @Override
+                public void run() {
+                    mController.start(name, isTest);
+                }});
+        }
+
+        public void requestAttach(final ComponentName name, final IBinder dream) {
+            post(new Runnable(){
+                @Override
+                public void run() {
+                    mController.attach(name, dream);
+                }});
+        }
+
+        public void requestStopSelf(final IBinder token) {
+            post(new Runnable(){
+                @Override
+                public void run() {
+                    mController.stopSelf(token);
+                }});
+        }
+
+        public void requestStop() {
+            post(mStopRunnable);
+        }
+
+    }
+
+}