path: root/src/sugar/datastore/datastore.py

# Copyright (C) 2007, One Laptop Per Child
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2 of the License, or (at your option) any later version.
#
# This library 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
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the
# Free Software Foundation, Inc., 59 Temple Place - Suite 330,
# Boston, MA 02111-1307, USA.

"""
STABLE.
"""

import logging
import time
from datetime import datetime
import os

import gobject

from sugar.datastore import dbus_helpers
from sugar import mime
from sugar import dispatch

# TODO: subclass from dict
class DSMetadata(gobject.GObject):
    __gsignals__ = {
        'updated': (gobject.SIGNAL_RUN_FIRST, gobject.TYPE_NONE,
                    ([]))
    }

    def __init__(self, props=None):
        gobject.GObject.__init__(self)
        if not props:
            self._props = {}
        else:
            self._props = props

        default_keys = ['bundle_id', 'activity_id',
                        'mime_type', 'title_set_by_user']
        for key in default_keys:
            if not self._props.has_key(key):
                self._props[key] = ''

    def __getitem__(self, key):
        return self._props[key]

    def __setitem__(self, key, value):
        if not self._props.has_key(key) or self._props[key] != value:
            self._props[key] = value
            self.emit('updated')

    def __delitem__(self, key):
        del self._props[key]

    def __contains__(self, key):
        return self._props.__contains__(key)

    def has_key(self, key):
        return self._props.has_key(key)

    def keys(self):
        return self._props.keys()

    def items(self) :
        return self._props.items()

    def get_dictionary(self):
        return self._props

    def copy(self):
        return DSMetadata(self._props.copy())

    def get(self, key, default=None):
        return self._props.get(key, default)

    def update(self, d) :
        for (k,v) in d.items() :
          self[k] = v


class DSObject(object):
    def __init__(self, tree_id, version_id, metadata=None, file_path=None):
        self.tree_id = tree_id
        self.version_id = version_id
        self._metadata = metadata
        self._file_path = file_path
        self._destroyed = False
        self._owns_file = False

    def get_metadata(self):
        if self._metadata is None and self.tree_id is not None:
            metadata = DSMetadata(get_properties((self.tree_id, self.version_id)))
            self._metadata = metadata
        return self._metadata

    def set_metadata(self, metadata):
        if self._metadata != metadata:
            self._metadata = metadata

    metadata = property(get_metadata, set_metadata)

    def get_file_path(self, fetch=True):
        if fetch and self._file_path is None and self.tree_id is not None:
            self.set_file_path(dbus_helpers.get_data(self.tree_id, self.version_id))
            self._owns_file = True
        return self._file_path

    def set_file_path(self, file_path):
        if self._file_path != file_path:
            if self._file_path and self._owns_file:
                if os.path.isfile(self._file_path):
                    os.remove(self._file_path)
                self._owns_file = False
            self._file_path = file_path

    file_path = property(get_file_path, set_file_path)

    def get_object_id(self) :
        if self.tree_id is None and self.version_id is None :
            return None

        return (self.tree_id, self.version_id)

    def set_object_id(self, object_id) :
        self.tree_id, self.version_id = object_id or (None, None)

    object_id = property(get_object_id, set_object_id)

    def destroy(self):
        if self._destroyed:
            logging.warning('This DSObject has already been destroyed!.')
            return
        self._destroyed = True
        if self._file_path and self._owns_file:
            if os.path.isfile(self._file_path):
                os.remove(self._file_path)
            self._owns_file = False
        self._file_path = None

    def __del__(self):
        if not self._destroyed:
            logging.warning('DSObject was deleted without cleaning up first. ' \
                            'Call DSObject.destroy() before disposing it.')
            self.destroy()

    def copy(self):
        return DSObject(None, self._metadata.copy(), self._file_path)


def get(object_id):
    logging.debug('datastore.get %r' % (object_id,))
    tree_id, version_id = object_id
    metadata = dbus_helpers.find({'tree_id': tree_id,
        'version_id': version_id}, {})[0]

    ds_object = DSObject(tree_id, version_id, DSMetadata(metadata), None)
    # TODO: register the object for updates
    return ds_object

def create():
    metadata = DSMetadata()
    return DSObject(tree_id=None, version_id=None, metadata=metadata, file_path=None)

def write(ds_object, transfer_ownership=False,
          reply_handler=None, error_handler=None, timeout=-1):
    logging.debug('datastore.write')

    metadata = ds_object.metadata.get_dictionary()

    file_path = ds_object.get_file_path(fetch=False)
    if file_path is None:
        file_path = ''

    ds_object.object_id = dbus_helpers.save(ds_object.tree_id,
        ds_object.version_id, metadata, file_path, transfer_ownership,
        reply_handler=reply_handler, error_handler=error_handler,
        timeout=timeout)

    ds_object.metadata['tree_id'] = ds_object.tree_id
    ds_object.metadata['version_id'] = ds_object.version_id
    # TODO: register the object for updates
    logging.debug('Written object %r to the datastore.', ds_object.object_id)

def write_metadata(ds_object) :
    dbus_helpers.change_metadata(ds_object.tree_id, ds_object.version_id,
        ds_object.metadata.get_dictionary())

def delete(object_id):
    logging.debug('datastore.delete %r', object_id)
    tree_id, version_id = object_id
    dbus_helpers.delete(tree_id, version_id)

def get_metadata(object_id, metadata_names=[]) :
    tree_id, version_id = object_id
    res = find({'tree_id': tree_id, 'version_id': version_id})
    return (res and res[0]) or None

def find(query, options={}, sorting=None, limit=None, offset=None, properties=None,
         reply_handler=None, error_handler=None):

    query = query.copy()
    options = options.copy()
    querystring = query.pop('query', '')

    if properties:
        options['metadata'] = properties

    if sorting:
        options['sort'] = sorting
    if limit:
        options['limit'] = limit
    if offset:
        options['offset'] = offset

    if reply_handler and error_handler :
        w_reply_handler = (lambda entries, total_count:
            reply_handler(_metadata_to_dsobjects(entries), total_count))

        if querystring :
            return dbus_helpers.textsearch(querystring, query, options,
                w_reply_handler, error_handler)
        else :
            return dbus_helpers.find(query, options,
                w_reply_handler, error_handler)


    if querystring :
        entries, total_count = dbus_helpers.textsearch(querystring, query, options)
    else :
        entries, total_count = dbus_helpers.find(query, options)

    return _metadata_to_dsobjects(entries), total_count

def _metadata_to_dsobjects(entries) :
  return [DSObject(metadata['tree_id'], metadata['version_id'],
      DSMetadata(metadata), None)
      for metadata in entries]

def copy(jobject, mount_point):

    new_jobject = jobject.copy()
    new_jobject.metadata['mountpoint'] = mount_point

    if jobject.metadata.has_key('title'):
        filename = jobject.metadata['title']

        if jobject.metadata.has_key('mime_type'):
            mime_type = jobject.metadata['mime_type']
            extension = mime.get_primary_extension(mime_type)
            if extension:
                filename += '.' + extension

        new_jobject.metadata['suggested_filename'] = filename

    # this will cause the file be retrieved from the DS
    new_jobject.file_path = jobject.file_path

    write(new_jobject)

def complete_indexing():
    return dbus_helpers.check_ready()

def get_unique_values(key):
    return dbus_helpers.find_unique_values({}, key)


class DatastoreListener(object):

    _sig_names = ['saved', 'changedMetadata', 'deleted', 'ready', 'stopped']

    def __init__(self):
        self._datastore = dbus_helpers._get_data_store()
        self._signal_handlers = [
            self._datastore.connect_to_signal(sig_name[0].upper()+sig_name[1:],
                getattr(self, "_datastore_%s_cb" % (sig_name,)))
            for sig_name in self._sig_names]
        for sig_name in self._sig_names :
            setattr(self, sig_name, dispatch.Signal())

    def __del__(self) :
        try :
            for handler in self._signal_handlers :
                handler.remove()
        except :
            # ignore errors during garbage collection - the signal handlers might
            # have already been collected
            pass

    def _datastore_saved_cb(self, tree_id, version_id):
        metadata = get_metadata((tree_id, version_id))
        self.saved.send(self, metadata=metadata)

    def _datastore_changedMetadata_cb(self, tree_id, version_id):
        metadata = get_metadata((tree_id, version_id))
        self.changedMetadata.send(self, metadata=metadata)

    def _datastore_deleted_cb(self, tree_id, version_id):
        self.deleted.send(self, object_id=(tree_id, version_id))

    def _datastore_ready_cb(self):
        self.ready.send(self)

    def _datastore_stopped_cb(self):
        self.stopped.send(self)


_datastore_listener = None
def get_datastore_listener() :
    global _datastore_listener

    if not _datastore_listener :
        _datastore_listener = DatastoreListener()

    return _datastore_listener