// Copyright 2013 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
package org.chromium.base;
import android.app.Activity;
import android.content.ComponentCallbacks2;
import org.jni_zero.CalledByNative;
import org.jni_zero.NativeMethods;
import org.chromium.base.library_loader.LibraryLoader;
import org.chromium.base.memory.MemoryPressureCallback;
/**
* This class is Java equivalent of base::MemoryPressureListener: it distributes pressure
* signals to callbacks.
*
* The class also serves as an entry point to the native side - once native code is ready,
* it adds native callback.
*
* notifyMemoryPressure() is called exclusively by MemoryPressureMonitor, which
* monitors and throttles pressure signals.
*
* NOTE: this class should only be used on UiThread as defined by ThreadUtils (which is
* Android main thread for Chrome, but can be some other thread for WebView).
*/
public class MemoryPressureListener {
/**
* Sending an intent with this action to Chrome will cause it to issue a call to onLowMemory
* thus simulating a low memory situations.
*/
private static final String ACTION_LOW_MEMORY = "org.chromium.base.ACTION_LOW_MEMORY";
/**
* Sending an intent with this action to Chrome will cause it to issue a call to onTrimMemory
* thus simulating a low memory situations.
*/
private static final String ACTION_TRIM_MEMORY = "org.chromium.base.ACTION_TRIM_MEMORY";
/**
* Sending an intent with this action to Chrome will cause it to issue a call to onTrimMemory
* with notification level TRIM_MEMORY_RUNNING_CRITICAL thus simulating a low memory situation
*/
private static final String ACTION_TRIM_MEMORY_RUNNING_CRITICAL =
"org.chromium.base.ACTION_TRIM_MEMORY_RUNNING_CRITICAL";
/**
* Sending an intent with this action to Chrome will cause it to issue a call to onTrimMemory
* with notification level TRIM_MEMORY_MODERATE thus simulating a low memory situation
*/
private static final String ACTION_TRIM_MEMORY_MODERATE =
"org.chromium.base.ACTION_TRIM_MEMORY_MODERATE";
private static ObserverList<MemoryPressureCallback> sCallbacks;
/** Called by the native side to add native callback. */
@CalledByNative
private static void addNativeCallback() {
ThreadUtils.assertOnUiThread();
addCallback((pressure) -> MemoryPressureListenerJni.get().onMemoryPressure(pressure));
}
/**
* Adds a memory pressure callback.
* Callback is only added once, regardless of the number of addCallback() calls.
* This method should be called only on ThreadUtils.UiThread.
*/
public static void addCallback(MemoryPressureCallback callback) {
ThreadUtils.assertOnUiThread();
if (sCallbacks == null) sCallbacks = new ObserverList<>();
sCallbacks.addObserver(callback);
}
/**
* Removes previously added memory pressure callback.
* This method should be called only on ThreadUtils.UiThread.
*/
public static void removeCallback(MemoryPressureCallback callback) {
ThreadUtils.assertOnUiThread();
if (sCallbacks == null) return;
sCallbacks.removeObserver(callback);
}
/**
* Distributes |pressure| to all callbacks.
* This method should be called only on ThreadUtils.UiThread.
*
* This includes sending the notification to the native side, provided that addNativeCallback()
* has been called. It does not trigger all the clients listening directly to
* ComponentCallbacks2 notifications.
*/
public static void notifyMemoryPressure(@MemoryPressureLevel int pressure) {
ThreadUtils.assertOnUiThread();
if (sCallbacks == null) return;
for (MemoryPressureCallback callback : sCallbacks) {
callback.onPressure(pressure);
}
}
public static void onPreFreeze() {
// We only need the library to be loaded, not the whole browser
// to be initialized because the native side would have no tasks
// to run in this case (they are registered at various points by
// callers elsewhere).
if (!LibraryLoader.getInstance().isInitialized()) return;
MemoryPressureListenerJni.get().onPreFreeze();
}
public static boolean isTrimMemoryBackgroundCritical() {
if (!LibraryLoader.getInstance().isInitialized()) return false;
return MemoryPressureListenerJni.get().isTrimMemoryBackgroundCritical();
}
/**
* Used by applications to simulate a memory pressure signal. By throwing certain intent
* actions.
*/
public static boolean handleDebugIntent(Activity activity, String action) {
ThreadUtils.assertOnUiThread();
if (ACTION_LOW_MEMORY.equals(action)) {
simulateLowMemoryPressureSignal(activity);
} else if (ACTION_TRIM_MEMORY.equals(action)) {
simulateTrimMemoryPressureSignal(activity, ComponentCallbacks2.TRIM_MEMORY_COMPLETE);
} else if (ACTION_TRIM_MEMORY_RUNNING_CRITICAL.equals(action)) {
simulateTrimMemoryPressureSignal(
activity, ComponentCallbacks2.TRIM_MEMORY_RUNNING_CRITICAL);
} else if (ACTION_TRIM_MEMORY_MODERATE.equals(action)) {
simulateTrimMemoryPressureSignal(activity, ComponentCallbacks2.TRIM_MEMORY_MODERATE);
} else {
return false;
}
return true;
}
private static void simulateLowMemoryPressureSignal(Activity activity) {
// The Application and the Activity each have a list of callbacks they notify when this
// method is called. Notifying these will simulate the event at the App/Activity level
// as well as trigger the listener bound from native in this process.
activity.getApplication().onLowMemory();
activity.onLowMemory();
}
private static void simulateTrimMemoryPressureSignal(Activity activity, int level) {
// The Application and the Activity each have a list of callbacks they notify when this
// method is called. Notifying these will simulate the event at the App/Activity level
// as well as trigger the listener bound from native in this process.
activity.getApplication().onTrimMemory(level);
activity.onTrimMemory(level);
}
@NativeMethods
interface Natives {
void onMemoryPressure(@MemoryPressureLevel int pressure);
void onPreFreeze();
boolean isTrimMemoryBackgroundCritical();
}
}
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