59d680f4e9
Summary: Upgrades Yoga’s copy of *fbjni* to the latest version. This will enable us - to move from `finalize()` to `PhantomReference` to deallocate native memory, with the potential of making GC more efficient. - to remove the internal dependency to *libfb,* allowing apps without an own dependency to ship less code Reviewed By: passy Differential Revision: D16220924 fbshipit-source-id: e8233fe2b5403946ff51f43cb6def558ded52fda
78 lines
2.3 KiB
Java
78 lines
2.3 KiB
Java
/**
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This source code is licensed under the MIT license found in the LICENSE
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* file in the root directory of this source tree.
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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("fbjni");
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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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protected 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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