* Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.

import static org.graalvm.compiler.hotspot.HotSpotGraalOptionValues.GRAAL_OPTION_PROPERTY_PREFIX;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.OutputStream;

import java.util.List;

import org.graalvm.compiler.core.common.SuppressFBWarnings;

import org.graalvm.compiler.options.OptionKey;

import org.graalvm.compiler.options.OptionValues;

import org.graalvm.compiler.serviceprovider.GraalServices;

import jdk.vm.ci.hotspot.HotSpotJVMCIRuntime;

        public static final LogStreamOptionKey LogFile = new LogStreamOptionKey();

    /**

     * An option for a configurable file name that can also open a {@link PrintStream} on the file.

     * If no value is given for the option, the stream will output to HotSpot's

     * {@link HotSpotJVMCIRuntime#getLogStream() log} stream

     */

    private static class LogStreamOptionKey extends OptionKey<String> {

        LogStreamOptionKey() {

            super(null);

        }

        /**

         * @return {@code nameTemplate} with all instances of %p replaced by

         *         {@link GraalServices#getExecutionID()} and %t by

         *         {@link System#currentTimeMillis()}

         */

        private static String makeFilename(String nameTemplate) {

            String name = nameTemplate;

            if (name.contains("%p")) {

                name = name.replaceAll("%p", GraalServices.getExecutionID());

            }

            if (name.contains("%t")) {

                name = name.replaceAll("%t", String.valueOf(System.currentTimeMillis()));

            }

            return name;

        }

        /**

         * An output stream that redirects to {@link HotSpotJVMCIRuntime#getLogStream()}. The

         * {@link HotSpotJVMCIRuntime#getLogStream()} value is only accessed the first time an IO

         * operation is performed on the stream. This is required to break a deadlock in early JVMCI

         * initialization.

         */

        static class DelayedOutputStream extends OutputStream {

            private volatile OutputStream lazy;

            private OutputStream lazy() {

                if (lazy == null) {

                    synchronized (this) {

                        if (lazy == null) {

                            lazy = HotSpotJVMCIRuntime.runtime().getLogStream();

                            PrintStream ps = new PrintStream(lazy);

                            ps.printf("[Use -D%sLogFile=<path> to redirect Graal log output to a file.]%n", GRAAL_OPTION_PROPERTY_PREFIX);

                        }

                    }

                }

                return lazy;

            }

            @Override

            public void write(byte[] b, int off, int len) throws IOException {

                lazy().write(b, off, len);

            }

            @Override

            public void write(int b) throws IOException {

                lazy().write(b);

            }

            @Override

            public void flush() throws IOException {

                lazy().flush();

            }

            @Override

            public void close() throws IOException {

                lazy().close();

            }

        }

        /**

         * Gets the print stream configured by this option. If no file is configured, the print

         * stream will output to HotSpot's {@link HotSpotJVMCIRuntime#getLogStream() log} stream.

         */

        @SuppressFBWarnings(value = "DLS_DEAD_LOCAL_STORE", justification = "false positive on dead store to `ps`")

        public PrintStream getStream(OptionValues options) {

            String nameTemplate = getValue(options);

            if (nameTemplate != null) {

                String name = makeFilename(nameTemplate);

                try {

                    final boolean enableAutoflush = true;

                    PrintStream ps = new PrintStream(new FileOutputStream(name), enableAutoflush);

                    /*

                     * Add the JVM and Java arguments to the log file to help identity it.

                     */

                    List<String> inputArguments = GraalServices.getInputArguments();

                    if (inputArguments != null) {

                        ps.println("VM Arguments: " + String.join(" ", inputArguments));

                    }

                    String cmd = System.getProperty("sun.java.command");

                    if (cmd != null) {

                        ps.println("sun.java.command=" + cmd);

                    }

                    return ps;

                } catch (FileNotFoundException e) {

                    throw new RuntimeException("couldn't open file: " + name, e);

                }

            } else {

                return new PrintStream(new DelayedOutputStream());

            }

        }

    }