Merging Managed and Important connection.

content/public/android/java/src/org/chromium/content/browser/ManagedChildProcessConnection.java

-// Copyright 2013 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-package org.chromium.content.browser;
-
-import android.content.Context;
-import android.os.Bundle;
-
-import org.chromium.base.Log;
-import org.chromium.base.VisibleForTesting;
-import org.chromium.base.process_launcher.ChildProcessCreationParams;
-
-/**
- * ManagedChildProcessConnection is a connection to a child service that can hold several bindings
- * to the service so it can be more or less agressively protected against OOM.
- * Accessed from the launcher thread. (but for isOomProtectedOrWasWhenDied()).
- */
-public class ManagedChildProcessConnection extends BaseChildProcessConnection {
-    private static final String TAG = "ManChildProcessConn";
-
-    public static final Factory FACTORY = new BaseChildProcessConnection.Factory() {
-        @Override
-        public BaseChildProcessConnection create(Context context, DeathCallback deathCallback,
-                String serviceClassName, Bundle childProcessCommonParameters,
-                ChildProcessCreationParams creationParams) {
-            assert LauncherThread.runningOnLauncherThread();
-            return new ManagedChildProcessConnection(context, deathCallback, serviceClassName,
-                    childProcessCommonParameters, creationParams);
-        }
-    };
-
-    // Initial binding protects the newly spawned process from being killed before it is put to use,
-    // it is maintained between calls to start() and removeInitialBinding().
-    private final ChildServiceConnection mInitialBinding;
-
-    // Strong binding will make the service priority equal to the priority of the activity. We want
-    // the OS to be able to kill background renderers as it kills other background apps, so strong
-    // bindings are maintained only for services that are active at the moment (between
-    // addStrongBinding() and removeStrongBinding()).
-    private final ChildServiceConnection mStrongBinding;
-
-    // Low priority binding maintained in the entire lifetime of the connection, i.e. between calls
-    // to start() and stop().
-    private final ChildServiceConnection mWaivedBinding;
-
-    // Incremented on addStrongBinding(), decremented on removeStrongBinding().
-    private int mStrongBindingCount;
-
-    // Moderate binding will make the service priority equal to the priority of a visible process
-    // while the app is in the foreground. It will stay bound only while the app is in the
-    // foreground to protect a background process from the system out-of-memory killer.
-    private final ChildServiceConnection mModerateBinding;
-
-    // Indicates whether the connection is OOM protected (if the connection is unbound, it contains
-    // the state at time of unbinding).
-    private boolean mOomProtected;
-
-    // Set to true once unbind() was called.
-    private boolean mUnbound;
-
-    @VisibleForTesting
-    ManagedChildProcessConnection(Context context, DeathCallback deathCallback,
-            String serviceClassName, Bundle childProcessCommonParameters,
-            ChildProcessCreationParams creationParams) {
-        super(context, deathCallback, serviceClassName, childProcessCommonParameters,
-                creationParams);
-
-        int initialFlags = Context.BIND_AUTO_CREATE;
-        int extraBindFlags = shouldBindAsExportedService() ? Context.BIND_EXTERNAL_SERVICE : 0;
-        mInitialBinding = createServiceConnection(initialFlags | extraBindFlags);
-        mStrongBinding = createServiceConnection(
-                Context.BIND_AUTO_CREATE | Context.BIND_IMPORTANT | extraBindFlags);
-        mWaivedBinding = createServiceConnection(
-                Context.BIND_AUTO_CREATE | Context.BIND_WAIVE_PRIORITY | extraBindFlags);
-        mModerateBinding = createServiceConnection(Context.BIND_AUTO_CREATE | extraBindFlags);
-    }
-
-    @Override
-    protected boolean bind() {
-        assert LauncherThread.runningOnLauncherThread();
-        assert !mUnbound;
-        if (!mInitialBinding.bind()) {
-            return false;
-        }
-        updateOomProtectedState();
-        mWaivedBinding.bind();
-        return true;
-    }
-
-    @Override
-    public void unbind() {
-        assert LauncherThread.runningOnLauncherThread();
-        mUnbound = true;
-        mInitialBinding.unbind();
-        mStrongBinding.unbind();
-        // Note that we don't update the OOM state here as to preserve the last OOM state.
-        mWaivedBinding.unbind();
-        mModerateBinding.unbind();
-        mStrongBindingCount = 0;
-    }
-
-    public boolean isInitialBindingBound() {
-        assert LauncherThread.runningOnLauncherThread();
-        return mInitialBinding.isBound();
-    }
-
-    public boolean isStrongBindingBound() {
-        assert LauncherThread.runningOnLauncherThread();
-        return mStrongBinding.isBound();
-    }
-
-    public void addInitialBinding() {
-        assert LauncherThread.runningOnLauncherThread();
-        mInitialBinding.bind();
-        updateOomProtectedState();
-    }
-
-    public void removeInitialBinding() {
-        assert LauncherThread.runningOnLauncherThread();
-        mInitialBinding.unbind();
-        updateOomProtectedState();
-    }
-
-    /**
-     * @return true if the connection is bound and OOM protected or was OOM protected when unbound.
-     */
-    public boolean isOomProtectedOrWasWhenDied() {
-        // WARNING: this method can be called from a thread other than the launcher thread.
-        // Note that it returns the current OOM protected state and is racy. This not really
-        // preventable without changing the caller's API, short of blocking.
-        return mOomProtected;
-    }
-
-    public void dropOomBindings() {
-        assert LauncherThread.runningOnLauncherThread();
-        mInitialBinding.unbind();
-
-        mStrongBindingCount = 0;
-        mStrongBinding.unbind();
-        updateOomProtectedState();
-
-        mModerateBinding.unbind();
-    }
-
-    public void addStrongBinding() {
-        assert LauncherThread.runningOnLauncherThread();
-        if (!isConnected()) {
-            Log.w(TAG, "The connection is not bound for %d", getPid());
-            return;
-        }
-        if (mStrongBindingCount == 0) {
-            mStrongBinding.bind();
-            updateOomProtectedState();
-        }
-        mStrongBindingCount++;
-    }
-
-    public void removeStrongBinding() {
-        assert LauncherThread.runningOnLauncherThread();
-        if (!isConnected()) {
-            Log.w(TAG, "The connection is not bound for %d", getPid());
-            return;
-        }
-        assert mStrongBindingCount > 0;
-        mStrongBindingCount--;
-        if (mStrongBindingCount == 0) {
-            mStrongBinding.unbind();
-            updateOomProtectedState();
-        }
-        updateOomProtectedState();
-    }
-
-    public boolean isModerateBindingBound() {
-        assert LauncherThread.runningOnLauncherThread();
-        return mModerateBinding.isBound();
-    }
-
-    public void addModerateBinding() {
-        assert LauncherThread.runningOnLauncherThread();
-        if (!isConnected()) {
-            Log.w(TAG, "The connection is not bound for %d", getPid());
-            return;
-        }
-        mModerateBinding.bind();
-    }
-
-    public void removeModerateBinding() {
-        assert LauncherThread.runningOnLauncherThread();
-        if (!isConnected()) {
-            Log.w(TAG, "The connection is not bound for %d", getPid());
-            return;
-        }
-        mModerateBinding.unbind();
-    }
-
-    // Should be called every time the mInitialBinding or mStrongBinding are bound/unbound.
-    private void updateOomProtectedState() {
-        if (!mUnbound) {
-            mOomProtected = mInitialBinding.isBound() || mStrongBinding.isBound();
-        }
-    }
-}