CallbackUtil.java

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 * Copyright (c) 2002-2010 LWJGL Project
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 *   its contributors may be used to endorse or promote products derived
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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package org.lwjgl.opencl;

import java.util.HashMap;
import java.util.Map;

/**
 * Utility class that handles OpenCL API callbacks.
 *
 * @author Spasi
 */
final class CallbackUtil {

	private static final Map<CLContext, Long> contextUserData = new HashMap<CLContext, Long>();

	private CallbackUtil() {}

	/**
	 * Creates a new global reference to the specified Object.
	 *
	 * @param obj the Object
	 *
	 * @return the GlobalRef memory address or 0 if the Object is null.
	 */
	static long createGlobalRef(final Object obj) {
		return obj == null ? 0 : ncreateGlobalRef(obj);
	}

	/**
	 * Creates a new global reference to the specified Object.
	 *
	 * @param obj the Object
	 *
	 * @return the GlobalRef memory address.
	 */
	private static native long ncreateGlobalRef(Object obj);

	/**
	 * Deletes a global reference.
	 *
	 * @param ref the GlobalRef memory address.
	 */
	static native void deleteGlobalRef(long ref);

	/**
	 * Deletes the global reference represented by user_data if an OpenCL error occured.
	 *
	 * @param errcode   the error code
	 * @param user_data the GlobalRef memory address
	 */
	static void checkCallback(final int errcode, final long user_data) {
		if ( errcode != 0x0 && user_data != 0 )
			deleteGlobalRef(user_data);
	}

	/* [ Context callback functionality ]
		This is a little weird, so here's an explanation of what's happening for future reference:
		Before making the clCreateContext call we create a global reference to the CLContextCallback object (using JNI's NewGlobalRef function).
		We pass that global reference to the user_data parameter of clCreateContext. If clCreateContext returns anything but CL_SUCCESS, we
		immediately destroy the global reference to avoid the memory leak. If the new context was created successfully, we associate the context
		with the global reference in the contextUserData HashMap. On a future call to clReleaseContext, we clear that association and destroy the
		global reference (if the reference count is 0).
	*/

	/**
	 * Returns the memory address of the native function we pass to clCreateContext(FromType).
	 *
	 * @return the callback function address
	 */
	static native long getContextCallback();

	/* [ Other callback functionality ]
		The other callbacks are simpler. We create the GlobalRef before passing the callback,
		we delete it when we receive the callback call.
	*/

	/**
	 * Returns the memory address of the native function we pass to clSetMemObjectDestructorCallback.
	 *
	 * @return the callback function address
	 */
	static native long getMemObjectDestructorCallback();

	/**
	 * Returns the memory address of the native function we pass to clBuildProgram.
	 *
	 * @return the callback function address
	 */
	static native long getProgramCallback();

	/**
	 * Returns the memory address of the native function we pass to clEnqueueNativeKernel.
	 *
	 * @return the callback function address
	 */
	static native long getNativeKernelCallback();

	/**
	 * Returns the memory address of the native function we pass to clSetEventCallback.
	 *
	 * @return the callback function address
	 */
	static native long getEventCallback();

	/**
	 * Returns the memory address of the native function we pass to clSetPrintfCallback.
	 *
	 * @return the callback function address
	 */
	static native long getPrintfCallback();

	/**
	 * Returns the memory address of the native function we pass to clCreateContext(FromType),
	 * when <code>APPLEContextLoggingUtil.SYSTEM_LOG_CALLBACK</code> is used.
	 *
	 * @return the callback function address
	 *
	 * @see APPLEContextLoggingUtil#SYSTEM_LOG_CALLBACK
	 */
	static native long getLogMessageToSystemLogAPPLE();

	/**
	 * Returns the memory address of the native function we pass to clCreateContext(FromType),
	 * when <code>APPLEContextLoggingUtil.STD_OUT_CALLBACK</code> is used.
	 *
	 * @return the callback function address
	 *
	 * @see APPLEContextLoggingUtil#STD_OUT_CALLBACK
	 */
	static native long getLogMessageToStdoutAPPLE();

	/**
	 * Returns the memory address of the native function we pass to clCreateContext(FromType),
	 * when <code>APPLEContextLoggingUtil.STD_ERR_CALLBACK</code> is used.
	 *
	 * @return the callback function address
	 *
	 * @see APPLEContextLoggingUtil#STD_ERR_CALLBACK
	 */
	static native long getLogMessageToStderrAPPLE();

}