Does this class cause problems in multithreading?

[flat kayak]

public abstract class ObjectCache<T> {
  protected volatile T object;

  protected int expireAt = 0;

  private final ReentrantLock mutex = new ReentrantLock(true);

  public abstract T create();

  protected abstract int getExpireSeconds();

  public T get()
  {
    if(mutex.isLocked() && this.object != null)
    {
      return this.object;
    }

    mutex.lock();
    try
    {
      int unixTimestamp = (int) (System.currentTimeMillis() / 1000L);
      if(expireAt < unixTimestamp)
      {
        this.expireAt = (int) unixTimestamp + getExpireSeconds();
        this.object = create();
      }
    }
    finally
    {
      mutex.unlock();
    }
    return this.object;
  }
}

Does this class cause multithreading problems?

[worn field]

Detected code, here are some useful tools:

Formatted code

public abstract class ObjectCache<T> {
  protected volatile T object;
  protected int expireAt = 0;
  private final ReentrantLock mutex = new ReentrantLock(true);
  public abstract T create();
  protected abstract int getExpireSeconds();
  public T get() {
    if (mutex.isLocked() && this .object != null ) {
      return this .object;
    }
    mutex.lock();
    try {
      int unixTimestamp = (int ) (System.currentTimeMillis() / 1000L);
      if (expireAt < unixTimestamp) {
        this .expireAt = (int ) unixTimestamp + getExpireSeconds();
        this .object = create();
      }
    } finally {
      mutex.unlock();
    }
    return this .object;
  }
}

<@&987246399047479336> please have a look, thanks.

[worn field]

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w ReentrantLock();

public T getObject() {
if (object == null || System.currentTimeMillis() >= expireAt) {
mutex.lock();
try {
if (object == null || System.currentTimeMillis() >= expireAt) {
object = createObject();
expireAt = calculateExpireAt();
}
} finally {
mutex.unlock();
}
}
return object;
}

protected abstract T createObject();

protected abstract int calculateExpireAt();
}