88 lines
2.7 KiB
Java
88 lines
2.7 KiB
Java
/**
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* Copyright 2004-present, Facebook, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.facebook.jni;
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import com.facebook.jni.annotations.DoNotStrip;
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import com.facebook.soloader.SoLoader;
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/**
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* This object holds a native C++ member for hybrid Java/C++ objects.
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*
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* <p>NB: THREAD SAFETY
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*
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* <p>{@link #resetNative} deletes the corresponding native object synchronously on whatever thread
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* the method is called on. Otherwise, deletion will occur on the {@link DestructorThread} thread.
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*/
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@DoNotStrip
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public class HybridData {
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static {
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SoLoader.loadLibrary("sonarfb");
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}
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@DoNotStrip private Destructor mDestructor = new Destructor(this);
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/**
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* To explicitly delete the instance, call resetNative(). If the C++ instance is referenced after
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* this is called, a NullPointerException will be thrown. resetNative() may be called multiple
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* times safely. Because the {@link DestructorThread} also calls resetNative, the instance will
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* not leak if this is not called, but timing of deletion and the thread the C++ dtor is called on
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* will be at the whim of the Java GC. If you want to control the thread and timing of the
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* destructor, you should call resetNative() explicitly.
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*/
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public synchronized void resetNative() {
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mDestructor.destruct();
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}
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/**
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* N.B. Thread safety. If you call isValid from a different thread than {@link #resetNative()}
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* then be sure to do so while synchronizing on the hybrid. For example:
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*
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* <pre><code>
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* synchronized(hybrid) {
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* if (hybrid.isValid) {
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* // Do stuff.
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* }
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* }
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* </code></pre>
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*/
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public boolean isValid() {
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return mDestructor.mNativePointer != 0;
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}
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public static class Destructor extends DestructorThread.Destructor {
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// Private C++ instance
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@DoNotStrip private long mNativePointer;
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Destructor(Object referent) {
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super(referent);
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}
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@Override
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void destruct() {
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// When invoked from the DestructorThread instead of resetNative,
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// the DestructorThread has exclusive ownership of the HybridData
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// so synchronization is not necessary.
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deleteNative(mNativePointer);
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mNativePointer = 0;
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}
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static native void deleteNative(long pointer);
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}
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}
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