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/* 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.process;
import android.content.ComponentCallbacks2;
import android.content.res.Configuration;
import android.util.Log;
import androidx.annotation.NonNull;
import org.mozilla.gecko.GeckoAppShell;
public class MemoryController implements ComponentCallbacks2 {
private static final String LOGTAG = "MemoryController";
private long mLastLowMemoryNotificationTime = 0;
// Allowed elapsed time between full GCs while under constant memory pressure
private static final long LOW_MEMORY_ONGOING_RESET_TIME_MS = 10000;
private static final int LOW = 0;
private static final int MODERATE = 1;
private static final int CRITICAL = 2;
private int memoryLevelFromTrim(final int level) {
if (level >= ComponentCallbacks2.TRIM_MEMORY_COMPLETE
|| level == ComponentCallbacks2.TRIM_MEMORY_RUNNING_CRITICAL) {
return CRITICAL;
} else if (level >= ComponentCallbacks2.TRIM_MEMORY_BACKGROUND) {
return MODERATE;
}
return LOW;
}
public void onTrimMemory(final int level) {
Log.i(LOGTAG, "onTrimMemory(" + level + ")");
onMemoryNotification(memoryLevelFromTrim(level));
}
@Override
public void onConfigurationChanged(final @NonNull Configuration newConfig) {}
public void onLowMemory() {
Log.i(LOGTAG, "onLowMemory");
onMemoryNotification(CRITICAL);
}
private void onMemoryNotification(final int level) {
if (level == LOW) {
// The trim level is too low to be actionable
return;
}
// See nsIMemory.idl for descriptions of the various arguments to the "memory-pressure"
// observer.
final String observerArg;
final long currentNotificationTime = System.currentTimeMillis();
if (level == CRITICAL
|| (currentNotificationTime - mLastLowMemoryNotificationTime)
>= LOW_MEMORY_ONGOING_RESET_TIME_MS) {
// We do a full "low-memory" notification for both new and last-ditch onTrimMemory requests.
observerArg = "low-memory";
mLastLowMemoryNotificationTime = currentNotificationTime;
} else {
// If it has been less than ten seconds since the last time we sent a "low-memory"
// notification, we send a "low-memory-ongoing" notification instead.
// This prevents Gecko from re-doing full GC's repeatedly over and over in succession,
// as they are expensive and quickly result in diminishing returns.
observerArg = "low-memory-ongoing";
}
GeckoAppShell.notifyObservers("memory-pressure", observerArg);
}
}
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