The Tor Browser: mobile/android/base/MemoryMonitor.java@6474c204b198 (annotated)

mobile/android/base/MemoryMonitor.java@6474c204b198 (annotated)

mobile/android/base/MemoryMonitor.java

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- Mode: Java; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 package org.mozilla.gecko;
 import org.mozilla.gecko.db.BrowserContract;
 import org.mozilla.gecko.db.BrowserDB;
 import org.mozilla.gecko.favicons.Favicons;
 import org.mozilla.gecko.util.ThreadUtils;
 import android.content.BroadcastReceiver;
 import android.content.ComponentCallbacks2;
 import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.os.Build;
 import android.util.Log;
 /**
   * This is a utility class to keep track of how much memory and disk-space pressure
   * the system is under. It receives input from GeckoActivity via the onLowMemory() and
   * onTrimMemory() functions, and also listens for some system intents related to
   * disk-space notifications. Internally it will track how much memory and disk pressure
   * the system is under, and perform various actions to help alleviate the pressure.
   *
   * Note that since there is no notification for when the system has lots of free memory
   * again, this class also assumes that, over time, the system will free up memory. This
   * assumption is implemented using a timer that slowly lowers the internal memory
   * pressure state if no new low-memory notifications are received.
   *
   * Synchronization note: MemoryMonitor contains an inner class PressureDecrementer. Both
   * of these classes may be accessed from various threads, and have both been designed to
   * be thread-safe. In terms of lock ordering, code holding the PressureDecrementer lock
   * is allowed to pick up the MemoryMonitor lock, but not vice-versa.
   */
 class MemoryMonitor extends BroadcastReceiver {
     private static final String LOGTAG = "GeckoMemoryMonitor";
     private static final String ACTION_MEMORY_DUMP = "org.mozilla.gecko.MEMORY_DUMP";
     private static final String ACTION_FORCE_PRESSURE = "org.mozilla.gecko.FORCE_MEMORY_PRESSURE";
     // Memory pressue levels, keep in sync with those in AndroidJavaWrappers.h
     private static final int MEMORY_PRESSURE_NONE = 0;
     private static final int MEMORY_PRESSURE_CLEANUP = 1;
     private static final int MEMORY_PRESSURE_LOW = 2;
     private static final int MEMORY_PRESSURE_MEDIUM = 3;
     private static final int MEMORY_PRESSURE_HIGH = 4;
     private static MemoryMonitor sInstance = new MemoryMonitor();
     static MemoryMonitor getInstance() {
         return sInstance;
     }
     private final PressureDecrementer mPressureDecrementer;
     private int mMemoryPressure;
     private boolean mStoragePressure;
     private boolean mInited;
     private MemoryMonitor() {
         mPressureDecrementer = new PressureDecrementer();
         mMemoryPressure = MEMORY_PRESSURE_NONE;
         mStoragePressure = false;
     }
     public void init(final Context context) {
         if (mInited) {
             return;
         }
         IntentFilter filter = new IntentFilter();
         filter.addAction(Intent.ACTION_DEVICE_STORAGE_LOW);
         filter.addAction(Intent.ACTION_DEVICE_STORAGE_OK);
         filter.addAction(ACTION_MEMORY_DUMP);
         filter.addAction(ACTION_FORCE_PRESSURE);
         context.getApplicationContext().registerReceiver(this, filter);
         mInited = true;
     }
     public void onLowMemory() {
         Log.d(LOGTAG, "onLowMemory() notification received");
         if (increaseMemoryPressure(MEMORY_PRESSURE_HIGH)) {
             // We need to wait on Gecko here, because if we haven't reduced
             // memory usage enough when we return from this, Android will kill us.
             GeckoAppShell.sendEventToGeckoSync(GeckoEvent.createNoOpEvent());
         }
     }
     public void onTrimMemory(int level) {
         Log.d(LOGTAG, "onTrimMemory() notification received with level " + level);
         if (Build.VERSION.SDK_INT < 14) {
             // this won't even get called pre-ICS
             return;
         }
         if (level >= ComponentCallbacks2.TRIM_MEMORY_COMPLETE) {
             increaseMemoryPressure(MEMORY_PRESSURE_HIGH);
         } else if (level >= ComponentCallbacks2.TRIM_MEMORY_MODERATE) {
             increaseMemoryPressure(MEMORY_PRESSURE_MEDIUM);
         } else if (level >= ComponentCallbacks2.TRIM_MEMORY_UI_HIDDEN) {
             // includes TRIM_MEMORY_BACKGROUND
             increaseMemoryPressure(MEMORY_PRESSURE_CLEANUP);
         } else {
             // levels down here mean gecko is the foreground process so we
             // should be less aggressive with wiping memory as it may impact
             // user experience.
             increaseMemoryPressure(MEMORY_PRESSURE_LOW);
         }
     }
     @Override
     public void onReceive(Context context, Intent intent) {
         if (Intent.ACTION_DEVICE_STORAGE_LOW.equals(intent.getAction())) {
             Log.d(LOGTAG, "Device storage is low");
             mStoragePressure = true;
             ThreadUtils.postToBackgroundThread(new StorageReducer(context));
         } else if (Intent.ACTION_DEVICE_STORAGE_OK.equals(intent.getAction())) {
             Log.d(LOGTAG, "Device storage is ok");
             mStoragePressure = false;
         } else if (ACTION_MEMORY_DUMP.equals(intent.getAction())) {
             String label = intent.getStringExtra("label");
             if (label == null) {
                 label = "default";
             }
             GeckoAppShell.sendEventToGecko(GeckoEvent.createBroadcastEvent("Memory:Dump", label));
         } else if (ACTION_FORCE_PRESSURE.equals(intent.getAction())) {
             increaseMemoryPressure(MEMORY_PRESSURE_HIGH);
         }
     }
     private boolean increaseMemoryPressure(int level) {
         int oldLevel;
         synchronized (this) {
             // bump up our level if we're not already higher
             if (mMemoryPressure > level) {
                 return false;
             }
             oldLevel = mMemoryPressure;
             mMemoryPressure = level;
         }
         // since we don't get notifications for when memory pressure is off,
         // we schedule our own timer to slowly back off the memory pressure level.
         // note that this will reset the time to next decrement if the decrementer
         // is already running, which is the desired behaviour because we just got
         // a new low-mem notification.
         mPressureDecrementer.start();
         if (oldLevel == level) {
             // if we're not going to a higher level we probably don't
             // need to run another round of the same memory reductions
             // we did on the last memory pressure increase.
             return false;
         }
         // TODO hook in memory-reduction stuff for different levels here
         if (level >= MEMORY_PRESSURE_MEDIUM) {
             //Only send medium or higher events because that's all that is used right now
             if (GeckoThread.checkLaunchState(GeckoThread.LaunchState.GeckoRunning)) {
                 GeckoAppShell.dispatchMemoryPressure();
             }
             Favicons.clearMemCache();
         }
         return true;
     }
     private boolean decreaseMemoryPressure() {
         int newLevel;
         synchronized (this) {
             if (mMemoryPressure <= 0) {
                 return false;
             }
             newLevel = --mMemoryPressure;
         }
         Log.d(LOGTAG, "Decreased memory pressure to " + newLevel);
         return true;
     }
     class PressureDecrementer implements Runnable {
         private static final int DECREMENT_DELAY = 5 * 60 * 1000; // 5 minutes
         private boolean mPosted;
         synchronized void start() {
             if (mPosted) {
                 // cancel the old one before scheduling a new one
                 ThreadUtils.getBackgroundHandler().removeCallbacks(this);
             }
             ThreadUtils.getBackgroundHandler().postDelayed(this, DECREMENT_DELAY);
             mPosted = true;
         }
         @Override
         public synchronized void run() {
             if (!decreaseMemoryPressure()) {
                 // done decrementing, bail out
                 mPosted = false;
                 return;
             }
             // need to keep decrementing
             ThreadUtils.getBackgroundHandler().postDelayed(this, DECREMENT_DELAY);
         }
     }
     class StorageReducer implements Runnable {
         private final Context mContext;
         public StorageReducer(final Context context) {
             this.mContext = context;
         }
         @Override
         public void run() {
             // this might get run right on startup, if so wait 10 seconds and try again
             if (!GeckoThread.checkLaunchState(GeckoThread.LaunchState.GeckoRunning)) {
                 ThreadUtils.getBackgroundHandler().postDelayed(this, 10000);
                 return;
             }
             if (!mStoragePressure) {
                 // pressure is off, so we can abort
                 return;
             }
             BrowserDB.expireHistory(mContext.getContentResolver(),
                                     BrowserContract.ExpirePriority.AGGRESSIVE);
             BrowserDB.removeThumbnails(mContext.getContentResolver());
             // TODO: drop or shrink disk caches
         }
     }
 }

The Tor Browser / annotate

mobile/android/base/MemoryMonitor.java@6474c204b198 (annotated)

mobile/android/base/MemoryMonitor.java