code: func (dm *DRWMutex) RLock(id, source string) {
  
  	isReadLock := true
  	dm.lockBlocking(drwMutexInfinite, id, source, isReadLock)
  }
docs: // RLock holds a read lock on dm.
  //
  // If one or more read locks are already in use, it will grant another lock.
  // Otherwise the calling go routine blocks until the mutex is available.