/*
 * 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.dubbo.common.utils;

import java.io.OutputStream;
import java.lang.management.LockInfo;
import java.lang.management.ManagementFactory;
import java.lang.management.MonitorInfo;
import java.lang.management.ThreadInfo;
import java.lang.management.ThreadMXBean;

import org.apache.dubbo.common.constants.CommonConstants;

import static java.lang.Thread.State.BLOCKED;
import static java.lang.Thread.State.TIMED_WAITING;
import static java.lang.Thread.State.WAITING;

public class JVMUtil {
    public static void jstack(OutputStream stream) throws Exception {
        ThreadMXBean threadMxBean = ManagementFactory.getThreadMXBean();
        for (ThreadInfo threadInfo : threadMxBean.dumpAllThreads(true, true)) {
            stream.write(getThreadDumpString(threadInfo).getBytes());
        }
    }

    private static String getThreadDumpString(ThreadInfo threadInfo) {
        StringBuilder sb = new StringBuilder("\"" + threadInfo.getThreadName() + "\"" +
                " Id=" + threadInfo.getThreadId() + " " +
                threadInfo.getThreadState());
        if (threadInfo.getLockName() != null) {
            sb.append(" on " + threadInfo.getLockName());
        }
        if (threadInfo.getLockOwnerName() != null) {
            sb.append(" owned by \"" + threadInfo.getLockOwnerName() +
                    "\" Id=" + threadInfo.getLockOwnerId());
        }
        if (threadInfo.isSuspended()) {
            sb.append(" (suspended)");
        }
        if (threadInfo.isInNative()) {
            sb.append(" (in native)");
        }
        sb.append('\n');
        int i = 0;
        // default is 32, means only print up to 32 lines
        int jstackMaxLine = 32;
        String jstackMaxLineStr = System.getProperty(CommonConstants.DUBBO_JSTACK_MAXLINE);
        if(StringUtils.isNotEmpty(jstackMaxLineStr)) {
            try {
                jstackMaxLine = Integer.parseInt(jstackMaxLineStr);
            }catch (Exception ignore) {}
        }
        StackTraceElement[] stackTrace = threadInfo.getStackTrace();
        MonitorInfo[] lockedMonitors = threadInfo.getLockedMonitors();
        for (; i < stackTrace.length && i < jstackMaxLine; i++) {
            StackTraceElement ste = stackTrace[i];
            sb.append("\tat ").append(ste.toString());
            sb.append('\n');
            if (i == 0 && threadInfo.getLockInfo() != null) {
                Thread.State ts = threadInfo.getThreadState();
                if (BLOCKED.equals(ts)) {
                    sb.append("\t-  blocked on ").append(threadInfo.getLockInfo());
                    sb.append('\n');
                } else if (WAITING.equals(ts) || TIMED_WAITING.equals(ts)) {
                    sb.append("\t-  waiting on ").append(threadInfo.getLockInfo());
                    sb.append('\n');
                }
            }

            for (MonitorInfo mi : lockedMonitors) {
                if (mi.getLockedStackDepth() == i) {
                    sb.append("\t-  locked ").append(mi);
                    sb.append('\n');
                }
            }
        }
        if (i < stackTrace.length) {
            sb.append("\t...");
            sb.append('\n');
        }

        LockInfo[] locks = threadInfo.getLockedSynchronizers();
        if (locks.length > 0) {
            sb.append("\n\tNumber of locked synchronizers = " + locks.length);
            sb.append('\n');
            for (LockInfo li : locks) {
                sb.append("\t- " + li);
                sb.append('\n');
            }
        }
        sb.append('\n');
        return sb.toString();
    }
}
