인프런 커뮤니티 질문&답변

https://www.inflearn.com/questions/347336

해당 질문 글에서 ConcurrentHashMap 을 사용하더라도 예제에 발생하는 동시성 이슈를 막을 수 없다고 하셔서

저도 궁금해서 ConcurrentHashMap 을 사용한 LogTrace를 만들어서 테스트를 몇 번 돌려봤는데

정상적으로 처리되는거 같은데 또 다른 이슈가 있는건가요??

package hello.advanced.trace.logtrace;

import java.util.concurrent.ConcurrentHashMap;

import hello.advanced.trace.TraceId;
import hello.advanced.trace.TraceStatus;
import lombok.extern.slf4j.Slf4j;

@Slf4j
public class MapLogTrace implements LogTrace {

	private static final String START_PREFIX = "-->";
	private static final String COMPLETE_PREFIX = "<--";
	private static final String EX_PREFIX = "<X-";

	private ConcurrentHashMap<Thread, TraceId> map = new ConcurrentHashMap<>();

	@Override
	public TraceStatus begin(String message) {
		syncTraceId();
		Long startTimeMs = getCurrentTimeMillis();
		TraceId traceId = map.get(Thread.currentThread());
		log.info("[{}] {}{}", traceId.getId(), addSpace(START_PREFIX, traceId.getLevel()), message);
		return new TraceStatus(traceId, startTimeMs, message);
	}

	private void syncTraceId() {
		Thread thread = Thread.currentThread();
		TraceId traceId = map.get(thread);
		if (traceId == null) {
			map.put(thread, new TraceId());
		} else {
			map.put(thread, traceId.createNextId());
		}
	}

	@Override
	public void end(TraceStatus status) {
		complete(status, null);
	}

	@Override
	public void exception(TraceStatus status, Exception ex) {
		complete(status, ex);
	}

	private void complete(TraceStatus status, Exception ex) {
		Long stopTimeMs = getCurrentTimeMillis();
		long resultTimeMs = stopTimeMs - status.getStartTimeMs();
		TraceId traceId = status.getTraceId();
		if (ex == null) {
			log.info("[{}] {}{} time={}ms", traceId.getId(), addSpace(COMPLETE_PREFIX, traceId.getLevel()),
				status.getMessage(), resultTimeMs);
		} else {
			log.info("[{}] {}{} time={}ms ex={}", traceId.getId(), addSpace(EX_PREFIX, traceId.getLevel()),
				status.getMessage(), resultTimeMs, ex.toString());
		}

		releaseTraceId();
	}

	private void releaseTraceId() {
		Thread thread = Thread.currentThread();
		TraceId traceId = map.get(thread);
		if (traceId.isFirstLevel()) {
			map.remove(thread);
		} else {
			map.put(thread, traceId.createPreviousId());
		}
	}

	private String addSpace(String prefix, int level) {
		StringBuilder sb = new StringBuilder();
		for (int i = 0; i < level; i++) {
			sb.append((i == level - 1) ? "|" + prefix : "|   ");
		}
		return sb.toString();
	}

	private Long getCurrentTimeMillis() {
		return System.currentTimeMillis();
	}

}