path: root/src/carquinyol/datastore.py

# Copyright (C) 2008, One Laptop Per Child
# Based on code Copyright (C) 2007, ObjectRealms, LLC
#
# 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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

import logging
import uuid
import time
import os
import sys
import traceback

from decorator import decorator
import dbus
import dbus.service
import gobject

from sugar import mime

from carquinyol import layoutmanager
from carquinyol import migration
from carquinyol.layoutmanager import MAX_QUERY_LIMIT
from carquinyol.metadatastore import MetadataStore
from carquinyol.indexstore import IndexStore
from carquinyol.filestore import FileStore
from carquinyol.optimizer import Optimizer

# the name used by the logger
DS_LOG_CHANNEL = 'org.laptop.sugar.DataStore'

DS_SERVICE = "org.laptop.sugar.DataStore"
DS_DBUS_INTERFACE = "org.laptop.sugar.DataStore"
DS_OBJECT_PATH = "/org/laptop/sugar/DataStore"

logger = logging.getLogger(DS_LOG_CHANNEL)


@decorator
def queue_if_frozen(method, self, *args, **kwargs):
    """Decorator to add method invocations to self.queue if self.frozen is set.

    Should only be used to wrap methods that have no return value.
    """
    if self.frozen:
        self.queue.append(lambda: method(self, *args, **kwargs))
    else:
        return method(self, *args, **kwargs)


class DataStore(dbus.service.Object):
    """D-Bus API and logic for connecting all the other components.
    """

    def __init__(self, **options):
        self.frozen = False
        self.queue = []
        bus_name = dbus.service.BusName(DS_SERVICE,
                                        bus=dbus.SessionBus(),
                                        replace_existing=False,
                                        allow_replacement=False)
        dbus.service.Object.__init__(self, bus_name, DS_OBJECT_PATH)

        migrated = self._migrate()

        self._metadata_store = MetadataStore()
        self._file_store = FileStore()
        self._optimizer = Optimizer(self._file_store, self._metadata_store)
        self._index_store = IndexStore()

        if migrated:
            self._rebuild_index()
            return

        try:
            self._index_store.open_index()
        except Exception:
            logging.exception('Failed to open index, will rebuild')
            self._rebuild_index()
            return

        if not layoutmanager.get_instance().index_updated:
            logging.debug('Index is not up-to-date, will update')
            self._update_index()

    def _migrate(self):
        """Check version of data store on disk and migrate if necessary.

        Returns True if migration was done and an index rebuild is required,
        False otherwise.
        """
        layout_manager = layoutmanager.get_instance()
        old_version = layout_manager.get_version()
        if old_version == layoutmanager.CURRENT_LAYOUT_VERSION:
            return False

        if old_version == 0:
            migration.migrate_from_0()

        layout_manager.set_version(layoutmanager.CURRENT_LAYOUT_VERSION)
        return True

    def _rebuild_index(self):
        """Remove and recreate index."""
        layoutmanager.get_instance().index_updated = False
        self._index_store.close_index()
        self._index_store.remove_index()
        self._index_store.open_index()
        self._update_index()

    def _update_index(self):
        """Find entries that are not yet in the index and add them."""
        uids = layoutmanager.get_instance().find_all()
        logging.debug('Going to update the index with object_ids %r',
            uids)
        gobject.idle_add(lambda: self.__update_index_cb(uids),
                            priority=gobject.PRIORITY_LOW)

    def __update_index_cb(self, uids):
        if uids:
            uid = uids.pop()

            logging.debug('Updating entry %r in index. %d to go.', uid,
                len(uids))

            if not self._index_store.contains(uid):
                try:
                    props = self._metadata_store.retrieve(uid)
                    self._index_store.store(uid, props)
                except Exception:
                    logging.exception('Error processing %r', uid)

        if not uids:
            logging.debug('Finished updating index.')
            layoutmanager.get_instance().index_updated = True
            return False
        else:
            return True

    def _create_completion_cb(self, async_cb, async_err_cb, uid, exc=None):
        logger.debug('_create_completion_cb(%r, %r, %r, %r)', async_cb,
            async_err_cb, uid, exc)
        if exc is not None:
            async_err_cb(exc)
            return

        self.Created(uid)
        self._optimizer.optimize(uid)
        logger.debug('created %s', uid)
        async_cb(uid)

    @dbus.service.method(DS_DBUS_INTERFACE,
                         in_signature='a{sv}sb',
                         out_signature='s',
                         async_callbacks=('async_cb', 'async_err_cb'),
                         byte_arrays=True)
    @queue_if_frozen
    def create(self, props, file_path, transfer_ownership,
               async_cb, async_err_cb):
        uid = str(uuid.uuid4())
        logging.debug('datastore.create %r', uid)

        if not props.get('timestamp', ''):
            props['timestamp'] = int(time.time())

        self._metadata_store.store(uid, props)
        self._index_store.store(uid, props)
        self._file_store.store(uid, file_path, transfer_ownership,
                lambda *args: self._create_completion_cb(async_cb,
                                                         async_err_cb,
                                                         uid,
                                                         *args))

    @dbus.service.signal(DS_DBUS_INTERFACE, signature="s")
    def Created(self, uid):
        pass

    def _update_completion_cb(self, async_cb, async_err_cb, uid, exc=None):
        logger.debug('_update_completion_cb() called with %r / %r, exc %r',
            async_cb, async_err_cb, exc)
        if exc is not None:
            async_err_cb(exc)
            return

        self.Updated(uid)
        self._optimizer.optimize(uid)
        logger.debug('updated %s', uid)
        async_cb()

    @dbus.service.method(DS_DBUS_INTERFACE,
             in_signature='sa{sv}sb',
             out_signature='',
             async_callbacks=('async_cb', 'async_err_cb'),
             byte_arrays=True)
    @queue_if_frozen
    def update(self, uid, props, file_path, transfer_ownership,
               async_cb, async_err_cb):
        logging.debug('datastore.update %r', uid)

        if not props.get('timestamp', ''):
            props['timestamp'] = int(time.time())

        self._metadata_store.store(uid, props)
        self._index_store.store(uid, props)

        if os.path.exists(self._file_store.get_file_path(uid)) and \
                (not file_path or os.path.exists(file_path)):
            self._optimizer.remove(uid)
        self._file_store.store(uid, file_path, transfer_ownership,
                lambda *args: self._update_completion_cb(async_cb,
                                                         async_err_cb,
                                                         uid,
                                                         *args))

    @dbus.service.signal(DS_DBUS_INTERFACE, signature="s")
    def Updated(self, uid):
        pass

    @dbus.service.method(DS_DBUS_INTERFACE,
        in_signature='a{sv}as', out_signature='aa{sv}u',
        async_callbacks=('async_cb', 'async_err_cb'))
    @queue_if_frozen
    def find(self, query, properties, async_cb, async_err_cb):
        self._sync_to_dbus_async(self._find, query, properties,
            async_cb=async_cb, async_err_cb=async_err_cb)

    def _find(self, query, properties):
        logging.debug('datastore.find %r', query)
        t = time.time()

        if layoutmanager.get_instance().index_updated:
            try:
                uids, count = self._index_store.find(query)
            except Exception:
                logging.exception('Failed to query index, will rebuild')
                self._rebuild_index()

        if not layoutmanager.get_instance().index_updated:
            logging.warning('Index updating, returning all entries')
            return self._find_all(query, properties)

        entries = []
        for uid in uids:
            entry_path = layoutmanager.get_instance().get_entry_path(uid)
            if not os.path.exists(entry_path):
                logging.warning(
                    'Inconsistency detected, returning all entries')
                self._rebuild_index()
                return self._find_all(query, properties)

            metadata = self._metadata_store.retrieve(uid, properties)
            entries.append(metadata)

        logger.debug('find(): %r', time.time() - t)

        return entries, count

    def _find_all(self, query, properties):
        uids = layoutmanager.get_instance().find_all()
        count = len(uids)

        offset = query.get('offset', 0)
        limit = query.get('limit', MAX_QUERY_LIMIT)
        uids = uids[offset:offset + limit]

        entries = []
        for uid in uids:
            metadata = self._metadata_store.retrieve(uid, properties)
            entries.append(metadata)

        return entries, count

    @dbus.service.method(DS_DBUS_INTERFACE,
        in_signature='s', out_signature='s',
        sender_keyword='sender',
        async_callbacks=('async_cb', 'async_err_cb'))
    @queue_if_frozen
    def get_filename(self, uid, async_cb, async_err_cb, sender=None):
        self._sync_to_dbus_async(self._get_filename, uid, sender,
            async_cb=async_cb, async_err_cb=async_err_cb)

    def _get_filename(self, uid, sender=None):
        logging.debug('datastore.get_filename %r', uid)
        user_id = dbus.Bus().get_unix_user(sender)
        extension = self._get_extension(uid)
        return self._file_store.retrieve(uid, user_id, extension)

    def _get_extension(self, uid):
        mime_type = self._metadata_store.get_property(uid, 'mime_type')
        if mime_type is None or not mime_type:
            return ''
        return mime.get_primary_extension(mime_type)

    @dbus.service.method(DS_DBUS_INTERFACE,
        in_signature='s', out_signature='a{sv}',
        async_callbacks=('async_cb', 'async_err_cb'))
    @queue_if_frozen
    def get_properties(self, uid, async_cb, async_err_cb):
        self._sync_to_dbus_async(self._get_properties, uid,
            async_cb=async_cb, async_err_cb=async_err_cb)

    def _get_properties(self, uid):
        logging.debug('datastore.get_properties %r', uid)
        metadata = self._metadata_store.retrieve(uid)
        return metadata

    @dbus.service.method(DS_DBUS_INTERFACE,
        in_signature='sa{sv}', out_signature='as',
        async_callbacks=('async_cb', 'async_err_cb'))
    @queue_if_frozen
    def get_uniquevaluesfor(self, propertyname, query, async_cb, async_err_cb):
        self._sync_to_dbus_async(self._get_uniquevaluesfor, propertyname,
            query, async_cb=async_cb, async_err_cb=async_err_cb)

    def _get_uniquevaluesfor(self, propertyname, query):
        if propertyname != 'activity':
            raise ValueError('Only ''activity'' is a supported property name')
        if query:
            raise ValueError('The query parameter is not supported')
        if layoutmanager.get_instance().index_updated:
            return self._index_store.get_activities()
        else:
            logging.warning('Index updating, returning an empty list')
            return []

    @dbus.service.method(DS_DBUS_INTERFACE,
        in_signature='s', out_signature='',
        async_callbacks=('async_cb', 'async_err_cb'))
    @queue_if_frozen
    def delete(self, uid, async_cb, async_err_cb):
        self._sync_to_dbus_async(self._delete, uid,
            async_cb=async_cb, async_err_cb=async_err_cb)

    def _delete(self, uid):
        self._optimizer.remove(uid)

        self._index_store.delete(uid)
        self._file_store.delete(uid)
        self._metadata_store.delete(uid)

        entry_path = layoutmanager.get_instance().get_entry_path(uid)
        os.removedirs(entry_path)

        self.Deleted(uid)
        logger.debug('deleted %s', uid)

    @dbus.service.signal(DS_DBUS_INTERFACE, signature="s")
    def Deleted(self, uid):
        pass

    def stop(self):
        """shutdown the service"""
        self._index_store.close_index()
        self.Stopped()

    @dbus.service.signal(DS_DBUS_INTERFACE)
    def Stopped(self):
        pass

    @dbus.service.method(DS_DBUS_INTERFACE,
                         in_signature="sa{sv}",
                         out_signature='s')
    def mount(self, uri, options=None):
        return ''

    @dbus.service.method(DS_DBUS_INTERFACE,
                         in_signature="",
                         out_signature="aa{sv}")
    def mounts(self):
        return [{'id': 1}]

    @dbus.service.method(DS_DBUS_INTERFACE,
                         in_signature="s",
                         out_signature="")
    def unmount(self, mountpoint_id):
        pass

    @dbus.service.signal(DS_DBUS_INTERFACE, signature="a{sv}")
    def Mounted(self, descriptior):
        pass

    @dbus.service.signal(DS_DBUS_INTERFACE, signature="a{sv}")
    def Unmounted(self, descriptor):
        pass

    @dbus.service.method(DS_DBUS_INTERFACE,
        in_signature='', out_signature='',
        async_callbacks=('async_cb', 'async_err_cb'))
    def freeze(self, async_cb, async_err_cb):
        """Close all open files and stop processing requests until thaw.

        Intended for doing online backups.
        """
        logging.info('Starting to freeze.')
        self.frozen = True
        self._index_store.close_index()
        gobject.idle_add(self._freeze_wait_cb, async_cb, async_err_cb,
            priority=gobject.PRIORITY_LOW+100)

    @dbus.service.method(DS_DBUS_INTERFACE,
        in_signature='', out_signature='',
        async_callbacks=('async_cb', 'async_err_cb'))
    def thaw(self, async_cb, async_err_cb):
        """Resume normal operation after freeze.

        A full restart (including migration if required) will be done.
        """
        if not self.frozen:
            raise ValueError('Trying to thaw while we are not frozen.')

        logging.info('Starting to thaw.')

        layoutmanager.get_instance().recheck_index_updated()

        if self._migrate():
            self._rebuild_index()
        else:
            try:
                self._index_store.open_index()
            except Exception:
                logging.exception('Failed to open index, will rebuild')
                self._rebuild_index()
            else:
                if not layoutmanager.get_instance().index_updated:
                    self._update_index()

        self.frozen = False
        gobject.idle_add(self._thaw_work_cb, async_cb, async_err_cb,
            priority=gobject.PRIORITY_LOW)

    def _freeze_wait_cb(self, async_cb, async_err_cb):
        """Stall the freeze() method while asynchronous operations are in
        progress.
        """
        if self._file_store.async_running() or self._optimizer.async_running():
            return True

        logging.info('Fully frozen.')
        async_cb()
        return False

    def _thaw_work_cb(self, async_cb, async_err_cb):
        """Process requests that were queued during freeze."""
        if not layoutmanager.get_instance().index_updated:
            logging.debug('_thaw_work_cb(): Index is not up-to-date, waiting')
            return True

        if not self.queue:
            logging.info('Fully thawed.')
            async_cb()
            return False

        self.queue.pop(0)()
        return True

    def _sync_to_dbus_async(self, method, *args, **kwargs):
        """Wrap a synchronous method in an asynchronous DBus method.

        The DBus callbacks must be passed as keyword arguments async_cb and
        async_err_cb.
        """
        async_cb = kwargs.pop('async_cb')
        async_err_cb = kwargs.pop('async_err_cb')
        try:
            result = method(*args, **kwargs)
        except Exception, exception:
            async_err_cb(exception)
            return

        if isinstance(result, tuple):
            async_cb(*result)
        elif result is None:
            async_cb()
        else:
            async_cb(result)