[GitHub] nifi pull request #1586: NIFI-3586: Fix for retrieving ProcessID for NiFi un...

[trkurc <gi...@git.apache.org>]

Github user trkurc commented on a diff in the pull request:

    https://github.com/apache/nifi/pull/1586#discussion_r109320687
  
    --- Diff: nifi-bootstrap/src/main/java/org/apache/nifi/bootstrap/util/OSUtil.java ---
    @@ -0,0 +1,81 @@
    +/*
    + * Licensed to the Apache Software Foundation (ASF) under one or more
    + * contributor license agreements.  See the NOTICE file distributed with
    + * this work for additional information regarding copyright ownership.
    + * The ASF licenses this file to You under the Apache License, Version 2.0
    + * (the "License"); you may not use this file except in compliance with
    + * the License.  You may obtain a copy of the License at
    + *
    + *     http://www.apache.org/licenses/LICENSE-2.0
    + *
    + * Unless required by applicable law or agreed to in writing, software
    + * distributed under the License is distributed on an "AS IS" BASIS,
    + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    + * See the License for the specific language governing permissions and
    + * limitations under the License.
    + */
    +
    +package org.apache.nifi.bootstrap.util;
    +
    +import java.lang.reflect.Field;
    +
    +import org.slf4j.Logger;
    +import com.sun.jna.Pointer;
    +import com.sun.jna.platform.win32.Kernel32;
    +import com.sun.jna.platform.win32.WinNT;
    +
    +/**
    + * OS specific utilities with generic method interfaces
    + */
    +public final class OSUtil {
    +
    +    private static Long getUnicesPid(final Process process, final Logger logger) {
    +        try {
    +            final Class<?> procClass = process.getClass();
    +            final Field pidField = procClass.getDeclaredField("pid");
    +            pidField.setAccessible(true);
    +            final Object pidObject = pidField.get(process);
    +
    +            logger.debug("PID Object = {}", pidObject);
    +
    +            if (pidObject instanceof Number) {
    +                return ((Number) pidObject).longValue();
    +            }
    +            return null;
    +        } catch (final IllegalAccessException | NoSuchFieldException nsfe) {
    +            logger.debug("Could not find PID for child process due to {}", nsfe);
    +            return null;
    +        }
    +    }
    +
    +    private static Long getWindowsProcessId(final Process process, final Logger logger) {
    +        /* determine the pid on windows plattforms */
    +        try {
    +            Field f = process.getClass().getDeclaredField("handle");
    +            f.setAccessible(true);
    +            long handl = f.getLong(process);
    +
    +            Kernel32 kernel = Kernel32.INSTANCE;
    +            WinNT.HANDLE handle = new WinNT.HANDLE();
    +            handle.setPointer(Pointer.createConstant(handl));
    +            int ret = kernel.GetProcessId(handle);
    +            logger.debug("Detected pid: {}", ret);
    +            return Long.valueOf(ret);
    +        } catch (final IllegalAccessException | NoSuchFieldException nsfe) {
    +            logger.debug("Could not find PID for child process due to {}", nsfe);
    +        }
    +        return null;
    +    }
    +
    +    public static Long getProcessId(final Process process, final Logger logger) {
    --- End diff --
    
    I know it wasn't there before when this was a private method before, but I'd LOVE to see a javadoc comment to describe the contract for this method. I think returning null is a bit counter-intuitive


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