externalsort.py 文件源码

def items(self, maxfiles=128):
        """Returns a sorted list or iterator of the items in the pool.

        :param maxfiles: maximum number of files to open at once.
        """

        if maxfiles < 2:
            raise ValueError("maxfiles=%s must be >= 2" % maxfiles)

        if not self.runs:
            # We never wrote a run to disk, so just sort the queue in memory
            # and return that
            return sorted(self.current)
        # Write a new run with the leftover items in the queue
        self.save()

        # If we have more runs than allowed open files, merge some of the runs
        if maxfiles < len(self.runs):
            self.reduce_to(maxfiles, maxfiles)

        # Take all the runs off the run list and merge them
        runs = self.runs
        self.runs = []  # Minor detail, makes this object reusable
        return self._merge_runs(runs)