io.undertow.server.DirectByteBufferDeallocator Maven / Gradle / Ivy
package io.undertow.server;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.nio.ByteBuffer;
import java.security.AccessController;
import java.security.PrivilegedAction;
import io.undertow.UndertowLogger;
import sun.misc.Unsafe;
/**
* {@link DirectByteBufferDeallocator} Utility class used to free direct buffer memory.
*/
public final class DirectByteBufferDeallocator {
private static final boolean SUPPORTED;
private static final Method cleaner;
private static final Method cleanerClean;
private static final Unsafe UNSAFE;
static {
String versionString = System.getProperty("java.specification.version");
if(versionString.startsWith("1.")) {
versionString = versionString.substring(2);
}
int version = Integer.parseInt(versionString);
Method tmpCleaner = null;
Method tmpCleanerClean = null;
boolean supported;
Unsafe tmpUnsafe = null;
if (version < 9) {
try {
tmpCleaner = getAccesibleMethod("java.nio.DirectByteBuffer", "cleaner");
tmpCleanerClean = getAccesibleMethod("sun.misc.Cleaner", "clean");
supported = true;
} catch (Throwable t) {
UndertowLogger.ROOT_LOGGER.directBufferDeallocatorInitializationFailed(t);
supported = false;
}
} else {
try {
tmpUnsafe = getUnsafe();
tmpCleanerClean = getDeclaredMethod(tmpUnsafe, "invokeCleaner", ByteBuffer.class);
supported = true;
} catch (Throwable t) {
UndertowLogger.ROOT_LOGGER.directBufferDeallocatorInitializationFailed(t);
supported = false;
}
}
SUPPORTED = supported;
cleaner = tmpCleaner;
cleanerClean = tmpCleanerClean;
UNSAFE = tmpUnsafe;
}
private DirectByteBufferDeallocator() {
// Utility Class
}
/**
* Attempts to deallocate the underlying direct memory.
* This is a no-op for buffers where {@link ByteBuffer#isDirect()} returns false.
*
* @param buffer to deallocate
*/
public static void free(ByteBuffer buffer) {
if (SUPPORTED && buffer != null && buffer.isDirect()) {
try {
if (UNSAFE != null) {
//use the JDK9 method
cleanerClean.invoke(UNSAFE, buffer);
} else {
Object cleaner = DirectByteBufferDeallocator.cleaner.invoke(buffer);
cleanerClean.invoke(cleaner);
}
} catch (Throwable t) {
UndertowLogger.ROOT_LOGGER.directBufferDeallocationFailed(t);
}
}
}
private static Unsafe getUnsafe() {
if (System.getSecurityManager() != null) {
return AccessController.doPrivileged(new PrivilegedAction() {
public Unsafe run() {
return getUnsafe0();
}
});
}
return getUnsafe0();
}
private static Unsafe getUnsafe0() {
try {
Field theUnsafe = Unsafe.class.getDeclaredField("theUnsafe");
theUnsafe.setAccessible(true);
return (Unsafe) theUnsafe.get(null);
} catch (Throwable t) {
throw new RuntimeException("JDK did not allow accessing unsafe", t);
}
}
private static Method getAccesibleMethod(String className, String methodName) {
if (System.getSecurityManager() != null) {
return AccessController.doPrivileged(new PrivilegedAction() {
@Override
public Method run() {
return getAccesibleMethod0(className, methodName);
}
});
}
return getAccesibleMethod0(className, methodName);
}
private static Method getAccesibleMethod0(String className, String methodName) {
try {
Method method = Class.forName(className).getMethod(methodName);
method.setAccessible(true);
return method;
} catch (Throwable t) {
throw new RuntimeException("JDK did not allow accessing method", t);
}
}
private static Method getDeclaredMethod(Unsafe tmpUnsafe, String methodName, Class... parameterTypes) {
if (System.getSecurityManager() != null) {
return AccessController.doPrivileged(new PrivilegedAction() {
@Override
public Method run() {
return getDeclaredMethod0(tmpUnsafe, methodName, parameterTypes);
}
});
}
return getDeclaredMethod0(tmpUnsafe, methodName, parameterTypes);
}
private static Method getDeclaredMethod0(Unsafe tmpUnsafe, String methodName, Class... parameterTypes) {
try {
Method method = tmpUnsafe.getClass().getDeclaredMethod(methodName, parameterTypes);
method.setAccessible(true);
return method;
} catch (Throwable t) {
throw new RuntimeException("JDK did not allow accessing method", t);
}
}
}