comparison mercurial/pure/parsers.py @ 44333:50ad851efd9b

nodemap: introduce append-only incremental update of the persistent data

Rewriting the full nodemap for each transaction has a cost we would like to
avoid. We introduce a new way to write persistent nodemap data by adding new
information at the end for file. Any new and updated block as added at the end
of the file. The last block is the new root node.

With this method, some of the block already on disk get "dereferenced" and
become dead data. In later changesets, We'll start tracking the amount of dead
data to eventually re-generate a full nodemap.

Differential Revision: https://phab.mercurial-scm.org/D7886

44323:76a96e3a2bbb

        The nodemap should be valid for the full set of revisions in the
        index."""
        return nodemaputil.persistent_data(self)

    def update_nodemap_data(self, nm_data):
        """provide full blokc of persisted binary data for a nodemap

        The data are expected to come from disk. See `nodemap_data_all` for a
        produceur of such data."""
        if nm_data is not None:
            nodemaputil.parse_data(nm_data)


class InlinedIndexObject(BaseIndexObject):
    def __init__(self, data, inline=0):
        self._data = data

44333:50ad851efd9b

        The nodemap should be valid for the full set of revisions in the
        index."""
        return nodemaputil.persistent_data(self)

    def nodemap_data_incremental(self):
        """Return bytes containing a incremental update to persistent nodemap

        This containst the data for an append-only update of the data provided
        in the last call to `update_nodemap_data`.
        """
        if self._nm_root is None:
            return None
        data = nodemaputil.update_persistent_data(
            self, self._nm_root, self._nm_max_idx, self._nm_rev
        )
        self._nm_root = self._nm_max_idx = self._nm_rev = None
        return data

    def update_nodemap_data(self, nm_data):
        """provide full blokc of persisted binary data for a nodemap

        The data are expected to come from disk. See `nodemap_data_all` for a
        produceur of such data."""
        if nm_data is not None:
            self._nm_root, self._nm_max_idx = nodemaputil.parse_data(nm_data)
            if self._nm_root:
                self._nm_rev = len(self) - 1
            else:
                self._nm_root = self._nm_max_idx = self._nm_rev = None


class InlinedIndexObject(BaseIndexObject):
    def __init__(self, data, inline=0):
        self._data = data