android activity 管理器AMS----概述

private void startBootstrapServices() {
        // Wait for installd to finish starting up so that it has a chance to
        // create critical directories such as /data/user with the appropriate
        // permissions.  We need this to complete before we initialize other services.
        mInstaller = mSystemServiceManager.startService(Installer.class);

        // Activity manager runs the show.
        mActivityManagerService = mSystemServiceManager.startService(
                ActivityManagerService.Lifecycle.class).getService();
        mActivityManagerService.setSystemServiceManager(mSystemServiceManager);

        // Power manager needs to be started early because other services need it.
        // Native daemons may be watching for it to be registered so it must be ready
        // to handle incoming binder calls immediately (including being able to verify
        // the permissions for those calls).
        mPowerManagerService = mSystemServiceManager.startService(PowerManagerService.class);

        // Now that the power manager has been started, let the activity manager
        // initialize power management features.
        mActivityManagerService.initPowerManagement();

        // Display manager is needed to provide display metrics before package manager
        // starts up.
        mDisplayManagerService = mSystemServiceManager.startService(DisplayManagerService.class);

        // We need the default display before we can initialize the package manager.
        mSystemServiceManager.startBootPhase(SystemService.PHASE_WAIT_FOR_DEFAULT_DISPLAY);

        // Only run "core" apps if we‘re encrypting the device.
        String cryptState = SystemProperties.get("vold.decrypt");
        if (ENCRYPTING_STATE.equals(cryptState)) {
            Slog.w(TAG, "Detected encryption in progress - only parsing core apps");
            mOnlyCore = true;
        } else if (ENCRYPTED_STATE.equals(cryptState)) {
            Slog.w(TAG, "Device encrypted - only parsing core apps");
            mOnlyCore = true;
        }

        // Start the package manager.
        Slog.i(TAG, "Package Manager");
        mPackageManagerService = PackageManagerService.main(mSystemContext, mInstaller,
                mFactoryTestMode != FactoryTest.FACTORY_TEST_OFF, mOnlyCore);
        mFirstBoot = mPackageManagerService.isFirstBoot();
        mPackageManager = mSystemContext.getPackageManager();

        Slog.i(TAG, "User Service");
        ServiceManager.addService(Context.USER_SERVICE, UserManagerService.getInstance());

        // Initialize attribute cache used to cache resources from packages.
        AttributeCache.init(mSystemContext);

        // Set up the Application instance for the system process and get started.
        mActivityManagerService.setSystemProcess();
    }

public ActivityManagerService(Context systemContext) {
        mContext = systemContext;
        mFactoryTest = FactoryTest.getMode();
        mSystemThread = ActivityThread.currentActivityThread();

        Slog.i(TAG, "Memory class: " + ActivityManager.staticGetMemoryClass());

        mHandlerThread = new ServiceThread(TAG,
                android.os.Process.THREAD_PRIORITY_FOREGROUND, false /*allowIo*/);
        mHandlerThread.start();
        mHandler = new MainHandler(mHandlerThread.getLooper());

        mFgBroadcastQueue = new BroadcastQueue(this, mHandler,
                "foreground", BROADCAST_FG_TIMEOUT, false);
        mBgBroadcastQueue = new BroadcastQueue(this, mHandler,
                "background", BROADCAST_BG_TIMEOUT, true);
        mBroadcastQueues[0] = mFgBroadcastQueue;
        mBroadcastQueues[1] = mBgBroadcastQueue;

        mServices = new ActiveServices(this);
        mProviderMap = new ProviderMap(this);

        // TODO: Move creation of battery stats service outside of activity manager service.
        File dataDir = Environment.getDataDirectory();
        File systemDir = new File(dataDir, "system");
        systemDir.mkdirs();
        mBatteryStatsService = new BatteryStatsService(systemDir, mHandler);
        mBatteryStatsService.getActiveStatistics().readLocked();
        mBatteryStatsService.getActiveStatistics().writeAsyncLocked();
        mOnBattery = DEBUG_POWER ? true
                : mBatteryStatsService.getActiveStatistics().getIsOnBattery();
        mBatteryStatsService.getActiveStatistics().setCallback(this);

        mProcessStats = new ProcessStatsService(this, new File(systemDir, "procstats"));

        mAppOpsService = new AppOpsService(new File(systemDir, "appops.xml"), mHandler);

        mGrantFile = new AtomicFile(new File(systemDir, "urigrants.xml"));

        // User 0 is the first and only user that runs at boot.
        mStartedUsers.put(0, new UserStartedState(new UserHandle(0), true));
        mUserLru.add(Integer.valueOf(0));
        updateStartedUserArrayLocked();

        GL_ES_VERSION = SystemProperties.getInt("ro.opengles.version",
            ConfigurationInfo.GL_ES_VERSION_UNDEFINED);

        mConfiguration.setToDefaults();
        mConfiguration.setLocale(Locale.getDefault());

        mConfigurationSeq = mConfiguration.seq = 1;
        mProcessCpuTracker.init();

        mCompatModePackages = new CompatModePackages(this, systemDir, mHandler);
        mIntentFirewall = new IntentFirewall(new IntentFirewallInterface(), mHandler);
        mStackSupervisor = new ActivityStackSupervisor(this);
        mTaskPersister = new TaskPersister(systemDir, mStackSupervisor);

        mProcessCpuThread = new Thread("CpuTracker") {
            @Override
            public void run() {
                while (true) {
                    try {
                        try {
                            synchronized(this) {
                                final long now = SystemClock.uptimeMillis();
                                long nextCpuDelay = (mLastCpuTime.get()+MONITOR_CPU_MAX_TIME)-now;
                                long nextWriteDelay = (mLastWriteTime+BATTERY_STATS_TIME)-now;
                                //Slog.i(TAG, "Cpu delay=" + nextCpuDelay
                                //        + ", write delay=" + nextWriteDelay);
                                if (nextWriteDelay < nextCpuDelay) {
                                    nextCpuDelay = nextWriteDelay;
                                }
                                if (nextCpuDelay > 0) {
                                    mProcessCpuMutexFree.set(true);
                                    this.wait(nextCpuDelay);
                                }
                            }
                        } catch (InterruptedException e) {
                        }
                        updateCpuStatsNow();
                    } catch (Exception e) {
                        Slog.e(TAG, "Unexpected exception collecting process stats", e);
                    }
                }
            }
        };

        mLockToAppRequest = new LockToAppRequestDialog(mContext, this);

        Watchdog.getInstance().addMonitor(this);
        Watchdog.getInstance().addThread(mHandler);
    }