code: public Path getLocalPathToRead(String pathStr, 
        Configuration conf) throws IOException {
      AllocatorPerContext context = obtainContext(contextCfgItemName);
      return context.getLocalPathToRead(pathStr, conf);
    }
docs: Get a path from the local FS for reading. We search through all the
  configured dirs for the file's existence and return the complete
  path to the file when we find one
  @param pathStr the requested file (this will be searched)
  @param conf the Configuration object
  @return the complete path to the file on a local disk
  @throws IOException