54 lines
2.3 KiB
Java
54 lines
2.3 KiB
Java
|
/*
|
||
|
|
* Copyright (C) 2022 The Android Open Source Project
|
||
|
|
*
|
||
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
||
|
|
* you may not use this file except in compliance with the License.
|
||
|
|
* You may obtain a copy of the License at
|
||
|
|
*
|
||
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
||
|
|
*
|
||
|
|
* Unless required by applicable law or agreed to in writing, software
|
||
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
||
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||
|
|
* See the License for the specific language governing permissions and
|
||
|
|
* limitations under the License.
|
||
|
|
*/
|
||
|
|
|
||
|
|
package android.system;
|
||
|
|
|
||
|
|
import java.lang.ref.Cleaner;
|
||
|
|
import jdk.internal.ref.CleanerFactory;
|
||
|
|
import libcore.util.NonNull;
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Java.lang.ref.Cleaner encourages each library to create a Cleaner, with an associated
|
||
|
|
* thread, to process Cleaner Runnables for that library's registered cleaning actions.
|
||
|
|
* This approach isolates cleaning actions from different libraries from each other; a slow cleaning
|
||
|
|
* action in one library will only minimally affect cleaning actions in another.
|
||
|
|
*
|
||
|
|
* However, this comes at the cost of introducing one Cleaner thread per library that uses
|
||
|
|
* Cleaners. This could introduce dozens of additional threads per process, which is often
|
||
|
|
* not an acceptable cost, especially on memory-limited devices.
|
||
|
|
*
|
||
|
|
* SystemCleaner instead provides access to a shared Cleaner, shared across the entire process.
|
||
|
|
* It is greatly preferred when all cleaning actions registered by a client are known to
|
||
|
|
* complete quickly, without explicit I/O, interprocess communication, or network access.
|
||
|
|
* Registering a non-terminating or excessively slow cleaning action with the shared cleaner
|
||
|
|
* may cause the process to perform very badly, hang, or be killed.
|
||
|
|
*/
|
||
|
|
public final class SystemCleaner {
|
||
|
|
|
||
|
|
private SystemCleaner() {}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Return a single Cleaner that's shared across the entire process. Thread-safe.
|
||
|
|
* Unlike normal Cleaners, uncaught exceptions during cleaning will throw an uncaught
|
||
|
|
* exception from the daemon running the cleaning action. This will normally cause the
|
||
|
|
* process to crash, and thus cause the problem to be reported.
|
||
|
|
*/
|
||
|
|
@NonNull public static Cleaner cleaner() {
|
||
|
|
return CleanerFactory.cleaner();
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|