/*
 * Copyright (c) 2018, 2019, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * The Universal Permissive License (UPL), Version 1.0
 *
 * Subject to the condition set forth below, permission is hereby granted to any
 * person obtaining a copy of this software, associated documentation and/or
 * data (collectively the "Software"), free of charge and under any and all
 * copyright rights in the Software, and any and all patent rights owned or
 * freely licensable by each licensor hereunder covering either (i) the
 * unmodified Software as contributed to or provided by such licensor, or (ii)
 * the Larger Works (as defined below), to deal in both
 *
 * (a) the Software, and
 *
 * (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
 * one is included with the Software each a "Larger Work" to which the Software
 * is contributed by such licensors),
 *
 * without restriction, including without limitation the rights to copy, create
 * derivative works of, display, perform, and distribute the Software and make,
 * use, sell, offer for sale, import, export, have made, and have sold the
 * Software and the Larger Work(s), and to sublicense the foregoing rights on
 * either these or other terms.
 *
 * This license is subject to the following condition:
 *
 * The above copyright notice and either this complete permission notice or at a
 * minimum a reference to the UPL must be included in all copies or substantial
 * portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
package org.graalvm.nativeimage;

import org.graalvm.nativeimage.c.type.CCharPointer;
import org.graalvm.word.UnsignedWord;

Low-level handler for log messages of native images. Implement this interface to create a custom log handler, i.e., redirect log messages. The custom log handler must be installed in the ImageSingletons, using this interface as the key, at Feature.duringSetup() time: 
 class LogHandlerFeature implements Feature { @Override public void duringSetup(DuringSetupAccess access) { ImageSingletons.add(LogHandler.class, new CustomLogHandler()); } } 
 If no custom log handler is installed, a default is installed Feature.beforeAnalysis() before the static analysis. The default handler prints log messages to the standard output. Installing a custom log handler at a later time, after the default one has been installed, results in an error. 

The methods defined in this interface are called from places where Java object allocation is not
possible, e.g., during a garbage collection or before the heap is set up. If an implementation of
the interface allocates a Java object or array, an error is reported during image generation.
Since:
19.0/**
 * Low-level handler for log messages of native images. Implement this interface to create a custom
 * log handler, i.e., redirect log messages. The custom log handler must be installed in the
 * {@code ImageSingletons}, using this interface as the key, at {@code Feature.duringSetup()} time:
 *
 * <pre>
 *    class LogHandlerFeature implements Feature {
 *        {@literal @}Override
 *        public void duringSetup(DuringSetupAccess access) {
 *            ImageSingletons.add(LogHandler.class, new CustomLogHandler());
 *        }
 *    }
 * </pre>
 *
 * If no custom log handler is installed, a default is installed
 * {@code Feature.beforeAnalysis() before the static analysis}. The default handler prints log
 * messages to the standard output. Installing a custom log handler at a later time, after the
 * default one has been installed, results in an error.
 * <p>
 * The methods defined in this interface are called from places where Java object allocation is not
 * possible, e.g., during a garbage collection or before the heap is set up. If an implementation of
 * the interface allocates a Java object or array, an error is reported during image generation.
 *
 * @since 19.0
 */
public interface LogHandler {

    
Write raw bytes to the log.

The methods defined in this interface are called from places where Java object allocation is
not possible, e.g., during a garbage collection or before the heap is set up. If an
implementation of the interface allocates a Java object or array, an error is reported during
image generation.
Since:
19.0/**
     * Write raw bytes to the log.
     * <p>
     * The methods defined in this interface are called from places where Java object allocation is
     * not possible, e.g., during a garbage collection or before the heap is set up. If an
     * implementation of the interface allocates a Java object or array, an error is reported during
     * image generation.
     *
     * @since 19.0
     */
    void log(CCharPointer bytes, UnsignedWord length);

    
Flush the log to its destination.

The methods defined in this interface are called from places where Java object allocation is
not possible, e.g., during a garbage collection or before the heap is set up. If an
implementation of the interface allocates a Java object or array, an error is reported during
image generation.
Since:
19.0/**
     * Flush the log to its destination.
     * <p>
     * The methods defined in this interface are called from places where Java object allocation is
     * not possible, e.g., during a garbage collection or before the heap is set up. If an
     * implementation of the interface allocates a Java object or array, an error is reported during
     * image generation.
     *
     * @since 19.0
     */
    void flush();

    
Exit the VM because a fatal, non-recoverable error situation has been detected. The
implementation of this method must not return, and it must not throw a Java exception. A
valid implementation is, e.g., to ask the OS to kill the process.

The methods defined in this interface are called from places where Java object allocation is
not possible, e.g., during a garbage collection or before the heap is set up. If an
implementation of the interface allocates a Java object or array, an error is reported during
image generation.
Since:
19.0/**
     * Exit the VM because a fatal, non-recoverable error situation has been detected. The
     * implementation of this method must not return, and it must not throw a Java exception. A
     * valid implementation is, e.g., to ask the OS to kill the process.
     * <p>
     * The methods defined in this interface are called from places where Java object allocation is
     * not possible, e.g., during a garbage collection or before the heap is set up. If an
     * implementation of the interface allocates a Java object or array, an error is reported during
     * image generation.
     *
     * @since 19.0
     */
    void fatalError();
}