code: void flush() {
  		internalLock.writeLock().lock();
  		flushLock.lock();
  		try {
  			if (isNew || modifiedBy.size() > 0) {
  				VanillaDb.logMgr().flush(lastLsn);
  				contents.write(blk);
  				modifiedBy.clear();
  				isNew = false;
  			}
  		} finally {
  			flushLock.unlock();
  			internalLock.writeLock().unlock();
  		}
  	}
docs: Writes the page to its disk block if the page is dirty. The method
  ensures that the corresponding log record has been written to disk prior
  to writing the page to disk.