[ot][spam][crazy] log 2: append-only random writes

[Undiscussed Horrific Abuse, One Victim of Many]

last stable version was at
https://lists.cpunks.org/pipermail/cypherpunks/2022-July/102291.html

# member variables draft. i think this is all the information that
# was being replaced by leaf and index iteration.
# - leaf count can be updated by summing children when graph is
#   changed.
#  - height is simply maximum child height + 1, can also update
#    when graph is changed
#  - parents is for adding dropped nodes to when branches are made
#    more shallow. it can be prefix-compared against to find a
#    shared ancestor when unifying neighboring entries. the only
#    other update I'm thinking of is when a new flush adds a shared
#    parent to every node.
#       it may be simpler or clearer to retain parent references,
#       and walk up them to the root to form parents lists when
#       they are needed; unsure
class Data:
    def __init__(self, offset, data, end = None, height = 0, _parents
= [], leaves = 1, parent = None):
        self.start = offset
        self.data = data
        if end is None:
            self.end = self.start + len(self.data)
        self.height = 0
        self.parent = parent
        self._parents = _parents
        self.leaves = 1
class Flush:
    def __init__(self, parent = None):
        self.parent = parent
        if self.parent is not None:
            self.index = [self.parent]
            # this should expand self.parent if it's too deep, and
shallow it if there is only one child
            # we don't want to expand the index past the max depth
        else:
            self.index = []
    def write(self, offset, data):
        # 1. trim index to left and right of data
                # when trimming, can make the trimmed nodes shallower
if parts are removed. removed parents can be added to .parents
                # if trimming makes a branch shallower at its leaves,
it may become mergeable with its other neighbor
        # 2. remove items in between and replace with data
        # 3. merge data