Merge "Double check the sha1 for ranges during package generation" am: 92d73d3a am: e62b2788

    # Double-check our work.

    self.AssertSequenceGood()

    self.AssertSha1Good()

    self.ComputePatches(prefix)

    self.WriteTransfers(prefix)

                    xf.tgt_name + " (from " + xf.src_name + ")"),

                xf.tgt_ranges, xf.src_ranges))

  def AssertSha1Good(self):

    """Check the SHA-1 of the src & tgt blocks in the transfer list.

    Double check the SHA-1 value to avoid the issue in b/71908713, where

    SparseImage.RangeSha1() messed up with the hash calculation in multi-thread

    environment. That specific problem has been fixed by protecting the

    underlying generator function 'SparseImage._GetRangeData()' with lock.

    """

    for xf in self.transfers:

      tgt_sha1 = self.tgt.RangeSha1(xf.tgt_ranges)

      assert xf.tgt_sha1 == tgt_sha1

      if xf.style == "diff":

        src_sha1 = self.src.RangeSha1(xf.src_ranges)

        assert xf.src_sha1 == src_sha1

  def AssertSequenceGood(self):

    # Simulate the sequences of transfers we will output, and check that:

    # - we never read a block after writing it, and