tillrohrmann commented on a change in pull request #11160: [FLINK-15094] Use
Unsafe to instantiate and construct DirectByteBuffer
URL: https://github.com/apache/flink/pull/11160#discussion_r383185284
##########
File path:
flink-core/src/main/java/org/apache/flink/core/memory/MemoryUtils.java
##########
@@ -60,32 +63,31 @@
}
}
- /** Should not be instantiated. */
- private MemoryUtils() {}
-
- private static Constructor<? extends ByteBuffer>
getDirectBufferPrivateConstructor() {
+ private static long
getClassFieldOffset(@SuppressWarnings("SameParameterValue") Class<?> cl, String
fieldName) {
+ final String errorMessage = "Could not get field '" + fieldName
+ "' offset in class '" + cl + "' for unsafe operations";
try {
- Constructor<? extends ByteBuffer> constructor =
-
ByteBuffer.allocateDirect(1).getClass().getDeclaredConstructor(long.class,
int.class);
- constructor.setAccessible(true);
- return constructor;
- } catch (NoSuchMethodException e) {
- throw new Error(
- "The private constructor
java.nio.DirectByteBuffer.<init>(long, int) is not available.",
- e);
+ return
UNSAFE.objectFieldOffset(cl.getDeclaredField(fieldName));
} catch (SecurityException e) {
- throw new Error(
- "The private constructor
java.nio.DirectByteBuffer.<init>(long, int) is not available, " +
- "permission denied by security manager",
- e);
+ throw new Error(errorMessage + ", permission denied by
security manager.", e);
+ } catch (NoSuchFieldException e) {
+ throw new Error(errorMessage, e);
} catch (Throwable t) {
- throw new Error(
- "Unclassified error while trying to access
private constructor " +
- "java.nio.DirectByteBuffer.<init>(long,
int).",
- t);
+ throw new Error(errorMessage + ", unclassified error",
t);
+ }
+ }
+
+ private static Class<?>
getClassByName(@SuppressWarnings("SameParameterValue") String className) {
+ //noinspection OverlyBroadCatchBlock
+ try {
+ return Class.forName(className);
+ } catch (Throwable e) {
+ throw new Error("Could not find class '" + className +
"' for unsafe operations.", e);
}
}
+ /** Should not be instantiated. */
+ private MemoryUtils() {}
Review comment:
I would put the constructor at the beginning or the end but not somewhere in
the middle.
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