/brz/remove-bazaar

# Copyright (C) 2009 Canonical Ltd

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

"""A manager of caches."""

from bzrlib import lru_cache, trace

from bzrlib.plugins.fastimport import helpers

class CacheManager(object):

    def __init__(self, info=None, verbose=False, inventory_cache_size=10):

        """Create a manager of caches.

        :param info: a ConfigObj holding the output from

            the --info processor, or None if no hints are available

        """

        self.verbose = verbose

        # dataref -> data. datref is either :mark or the sha-1.

        # Sticky blobs aren't removed after being referenced.

        self._blobs = {}

        self._sticky_blobs = {}

        # revision-id -> Inventory cache

        # these are large and we probably don't need too many as

        # most parents are recent in history

        self.inventories = lru_cache.LRUCache(inventory_cache_size)

        # import commmit-ids -> revision-id lookup table

        # we need to keep all of these but they are small

        self.revision_ids = {}

        # (path, branch_ref) -> file-ids - as generated.

        # (Use store_file_id/fetch_fileid methods rather than direct access.)

        # Head tracking: last ref, last id per ref & map of commit ids to ref*s*

        self.last_ref = None

        self.last_ids = {}

        self.heads = {}

        # Work out the blobs to make sticky - None means all

        self._blob_ref_counts = {}

        if info is not None:

            try:

                blobs_by_counts = info['Blob reference counts']

                # The parser hands values back as lists, already parsed

                for count, blob_list in blobs_by_counts.items():

                    n = int(count)

                    for b in blob_list:

                        self._blob_ref_counts[b] = n

            except KeyError:

                # info not in file - possible when no blobs used

                pass

    def dump_stats(self, note=trace.note):

        """Dump some statistics about what we cached."""

        # TODO: add in inventory stastistics

        note("Cache statistics:")

        self._show_stats_for(self._sticky_blobs, "sticky blobs", note=note)

        self._show_stats_for(self.revision_ids, "revision-ids", note=note)

        # These aren't interesting so omit from the output, at least for now

        #self._show_stats_for(self._blobs, "other blobs", note=note)

        #self._show_stats_for(self.last_ids, "last-ids", note=note)

        #self._show_stats_for(self.heads, "heads", note=note)

    def _show_stats_for(self, dict, label, note=trace.note, tuple_key=False):

        """Dump statistics about a given dictionary.

        By the key and value need to support len().

        """

        count = len(dict)

        if tuple_key:

            size = sum(map(len, (''.join(k) for k in dict.keys())))

        else:

            size = sum(map(len, dict.keys()))

        size += sum(map(len, dict.values()))

        size = size * 1.0 / 1024

        unit = 'K'

        if size > 1024:

            size = size / 1024

            unit = 'M'

            if size > 1024:

                size = size / 1024

                unit = 'G'

        note("    %-12s: %8.1f %s (%d %s)" % (label, size, unit, count,

            helpers.single_plural(count, "item", "items")))

    def clear_all(self):

        """Free up any memory used by the caches."""

        self._blobs.clear()

        self._sticky_blobs.clear()

        self.revision_ids.clear()

        self.last_ids.clear()

        self.heads.clear()

        self.inventories.clear()

    def store_blob(self, id, data):

        """Store a blob of data."""

        # Note: If we're not reference counting, everything has to be sticky

        if not self._blob_ref_counts or id in self._blob_ref_counts:

            self._sticky_blobs[id] = data

        elif data == '':

            # Empty data is always sticky

            self._sticky_blobs[id] = data

        else:

            self._blobs[id] = data

    def fetch_blob(self, id):

        """Fetch a blob of data."""

        try:

            b = self._sticky_blobs[id]

            if self._blob_ref_counts and b != '':

                self._blob_ref_counts[id] -= 1

                if self._blob_ref_counts[id] == 0:

                    del self._sticky_blobs[id]

            return b

        except KeyError:

            return self._blobs.pop(id)

    def track_heads(self, cmd):

        """Track the repository heads given a CommitCommand.

        :param cmd: the CommitCommand

        :return: the list of parents in terms of commit-ids

        """

        # Get the true set of parents

        if cmd.from_ is not None:

            parents = [cmd.from_]

        else:

            last_id = self.last_ids.get(cmd.ref)

            if last_id is not None:

                parents = [last_id]

            else:

                parents = []

        parents.extend(cmd.merges)

        # Track the heads

        self.track_heads_for_ref(cmd.ref, cmd.id, parents)

        return parents

    def track_heads_for_ref(self, cmd_ref, cmd_id, parents=None):

        if parents is not None:

            for parent in parents:

                if parent in self.heads:

                    del self.heads[parent]

        self.heads.setdefault(cmd_id, set()).add(cmd_ref)

        self.last_ids[cmd_ref] = cmd_id

        self.last_ref = cmd_ref