Source code for coherence.backend

# -*- coding: utf-8 -*-

# Licensed under the MIT license
# http://opensource.org/licenses/mit-license.php

import time
from functools import cmp_to_key
from abc import ABCMeta, abstractmethod

# Copyright 2007,, Frank Scholz <coherence@beebits.net>
from lxml import etree

import coherence.extern.louie as louie
from coherence import log
from coherence.extern.simple_plugin import Plugin
from coherence.upnp.core import DIDLLite
from coherence.upnp.core.utils import getPage


[docs]class Backend(log.LogAble, Plugin): """ the base class for all backends if there are any UPnP service actions, that can't be handled by the service classes itself, or need some special adjustments for the backend, they need to be defined here. Like maybe upnp_Browse for the CDS Browse action. """ # list the device classes below, like ['MediaServer','MediaRenderer'] implements = [] logCategory = 'backend'
[docs] def __init__(self, server, **kwargs): """ the init method for a backend, should probably most of the time be overwritten when the init is done, send a signal to its device the device will then setup and announce itself, after that it calls the backends upnp_init method """ self.config = kwargs self.server = server # the UPnP device that's hosting that backend """ do whatever is necessary with the stuff we can extract from the config dict, connect maybe to an external data-source and start up the backend after that's done, tell Coherence about it """ log.LogAble.__init__(self) Plugin.__init__(self) """ this has to be done in the actual backend, maybe it has to wait for an answer from an external data-source first """
# self.init_completed()
[docs] def init_completed(self, *args, **kwargs): """ inform Coherence that this backend is ready for announcement this method just accepts any form of arguments as we don't under which circumstances it is called """ louie.send('Coherence.UPnP.Backend.init_completed', None, backend=self)
[docs] def upnp_init(self): """ this method gets called after the device is fired, here all initializations of service related state variables should happen, as the services aren't available before that point """ pass
[docs]class BackendStore(Backend): """ the base class for all MediaServer backend stores """ __metaclass__ = ABCMeta logCategory = 'backend_store'
[docs] def __init__(self, server, *args, **kwargs): """ the init method for a MediaServer backend, should probably most of the time be overwritten when the init is done, send a signal to its device the device will then setup and announce itself, after that it calls the backends upnp_init method """ Backend.__init__(self, server, *args) self.config = kwargs self.server = server # the UPnP device that's hosting that backend self.update_id = 0 """ do whatever is necessary with the stuff we can extract from the config dict """ """ in case we want so serve something via the MediaServer web backend the BackendItem should pass an URI assembled of urlbase + '/' + id to the DIDLLite.Resource """ self.urlbase = kwargs.get('urlbase', '') if not self.urlbase.endswith('/'): self.urlbase += '/' self.wmc_mapping = {'4': '4', '5': '5', '6': '6', '7': '7', '14': '14', 'F': 'F', '11': '11', '16': '16', 'B': 'B', 'C': 'C', 'D': 'D', '13': '13', '17': '17', '8': '8', '9': '9', '10': '10', '15': '15', 'A': 'A', 'E': 'E'} self.wmc_mapping.update({'4': lambda: self._get_all_items(0), '8': lambda: self._get_all_items(0), 'B': lambda: self._get_all_items(0), }) """ and send out the signal when ready """
# louie.send('Coherence.UPnP.Backend.init_completed', # None, backend=self)
[docs] def release(self): """ if anything needs to be cleaned up upon shutdown of this backend, this is the place for it """ pass
[docs] def _get_all_items(self, id): """ a helper method to get all items as a response to some XBox 360 UPnP Search action probably never be used as the backend will overwrite the wmc_mapping with more appropriate methods """ items = [] item = self.get_by_id(id) if item is not None: containers = [item] while len(containers) > 0: container = containers.pop() if container.mimetype not in ['root', 'directory']: continue for child in container.get_children(0, 0): if child.mimetype in ['root', 'directory']: containers.append(child) else: items.append(child) return items
[docs] @abstractmethod def get_by_id(self, id): """ called by the CDS or the MediaServer web id is the id property of our DIDLLite item if this MediaServer implements containers, that can share their content, like 'all tracks', 'album' and 'album_of_artist' - they all have the same track item as content - then the id may be passed by the CDS like this: 'id@container' or 'id@container@container@container...' therefore a if isinstance(id, basestring): id = id.split('@',1) id = id[0] may be appropriate as the first thing to do when entering this method should return - None when no matching item for that id is found, - a BackendItem, - or a Deferred """ return None
[docs]class BackendItem(log.LogAble): """ the base class for all MediaServer backend items """ logCategory = 'backend_item'
[docs] def __init__(self, *args, **kwargs): """ most of the time we collect the necessary data for an UPnP ContentDirectoryService Container or Object and instantiate it here self.item = DIDLLite.Container(id,parent_id,name,...) or self.item = DIDLLite.MusicTrack(id,parent_id,name,...) To make that a valid UPnP CDS Object it needs one or more DIDLLite.Resource(uri,protocolInfo) self.item.res = [] res = DIDLLite.Resource(url, 'http-get:*:%s:*' % mimetype) url : the urlbase of our backend + '/' + our id res.size = size self.item.res.append(res) """ log.LogAble.__init__(self) self.store = None self.storage_id = None # the basename of a file, the album title, the artists name... # is expected to be unicode self.name = 'my_name' self.item = None self.update_id = 0 # the update id of that item, # when an UPnP ContentDirectoryService Container # this should be incremented on every modification # the filepath of our media file, or alternatively # a FilePath or a ReverseProxyResource object self.location = None self.cover = None # if we have some album art image, let's put
# the filepath or link into here
[docs] def get_children(self, start=0, end=0): """ called by the CDS and the MediaServer web should return - a list of its childs[start:end] - or a Deferred if end == 0, the request is for all childs after start - childs[start:] """ pass
[docs] def get_child_count(self): """ called by the CDS should return - the number of its childs - len(childs) - or a Deferred """
[docs] def get_item(self): """ called by the CDS and the MediaServer web should return - an UPnP ContentDirectoryServer DIDLLite object - or a Deferred """ return self.item
[docs] def get_name(self): """ called by the MediaServer web should return - the name of the item, it is always expected to be in unicode """ return self.name
[docs] def get_path(self): """ called by the MediaServer web should return - the filepath where to find the media file that this item does refer to """ return self.location
[docs] def get_cover(self): """ called by the MediaServer web should return - the filepath where to find the album art file only needed when we have created for that item an albumArtURI property that does point back to us """ return self.cover
def __repr__(self): return "%s[%s]" % (self.__class__.__name__, self.get_name())
[docs]class BackendRssMixin: def __init__(self): pass
[docs] def update_data(self, rss_url, container=None): """ creates a deferred chain to retrieve the rdf file, parse and extract the metadata and reschedule itself """ def fail(f): # TODO fix loggable thing self.info("fail %r", f) self.debug(f.getTraceback()) return f dfr = getPage(rss_url) dfr.addCallback(etree.fromstring) dfr.addErrback(fail) dfr.addCallback(self.parse_data, container) dfr.addErrback(fail) dfr.addBoth(self.queue_update, rss_url, container) return dfr
[docs] def parse_data(self, xml_data, container): """ extract media info and create BackendItems """ pass
[docs] def queue_update(self, error_or_failure, rss_url, container): from twisted.internet import reactor reactor.callLater(self.refresh, self.update_data, rss_url, container)
[docs]class Container(BackendItem): def __init__(self, parent, title): BackendItem.__init__(self) self.parent = parent if self.parent is not None: self.parent_id = self.parent.get_id() else: self.parent_id = -1 self.name = title self.mimetype = 'directory' self.children = [] self.children_ids = {} self.children_by_external_id = {} self.update_id = 0 self.item = None self.sorted = False def childs_sort(x, y): return cmp_to_key(x.name, y.name) self.sorting_method = childs_sort
[docs] def register_child(self, child, external_id=None): id = self.store.append_item(child) child.url = self.store.urlbase + str(id) child.parent = self if external_id is not None: child.external_id = external_id self.children_by_external_id[external_id] = child
[docs] def add_child(self, child, external_id=None, update=True): self.register_child(child, external_id) if self.children is None: self.children = [] self.children.append(child) self.sorted = False if update: self.update_id += 1
[docs] def remove_child(self, child, external_id=None, update=True): self.children.remove(child) self.store.remove_item(child) if update: self.update_id += 1 if external_id is not None: child.external_id = None del self.children_by_external_id[external_id]
[docs] def get_children(self, start=0, end=0): if not self.sorted: self.children = sorted( self.children.sort, key=cmp_to_key(self.sorting_method)) self.sorted = True if end != 0: return self.children[start:end] return self.children[start:]
[docs] def get_child_count(self): if self.children is None: return 0 return len(self.children)
[docs] def get_path(self): return self.store.urlbase + str(self.storage_id)
[docs] def get_item(self): if self.item is None: self.item = DIDLLite.Container(self.storage_id, self.parent_id, self.name) self.item.childCount = len(self.children) return self.item
[docs] def get_name(self): return self.name
[docs] def get_id(self): return self.storage_id
[docs] def get_update_id(self): return self.update_id
[docs]class LazyContainer(Container): logCategory = 'lazyContainer' def __init__(self, parent, title, external_id=None, refresh=0, childrenRetriever=None, **kwargs): Container.__init__(self, parent, title) self.childrenRetrievingNeeded = True self.childrenRetrievingDeferred = None self.childrenRetriever = childrenRetriever self.children_retrieval_campaign_in_progress = False self.childrenRetriever_params = kwargs self.childrenRetriever_params['parent'] = self self.has_pages = ('per_page' in self.childrenRetriever_params) self.external_id = None self.external_id = external_id self.retrieved_children = {} self.last_updated = 0 self.refresh = refresh
[docs] def replace_by(self, item): if self.external_id is not None and item.external_id is not None: return self.external_id == item.external_id return True
[docs] def add_child(self, child, external_id=None, update=True): if self.children_retrieval_campaign_in_progress is True: self.retrieved_children[external_id] = child else: Container.add_child(self, child, external_id=external_id, update=update)
[docs] def update_children(self, new_children, old_children): children_to_be_removed = {} children_to_be_replaced = {} children_to_be_added = {} # Phase 1 # let's classify the item between items to be removed, # to be updated or to be added self.debug("Refresh pass 1:%d %d", len(new_children), len(old_children)) for id, item in list(old_children.items()): children_to_be_removed[id] = item for id, item in list(new_children.items()): if id in old_children: # print(id, "already there") children_to_be_replaced[id] = old_children[id] del children_to_be_removed[id] else: children_to_be_added[id] = new_children[id] # Phase 2 # Now, we remove, update or add the relevant items # to the list of items self.debug("Refresh pass 2: %d %d %d", len(children_to_be_removed), len(children_to_be_replaced), len(children_to_be_added)) # Remove relevant items from Container children for id, item in list(children_to_be_removed.items()): self.remove_child(item, external_id=id, update=False) # Update relevant items from Container children for id, item in list(children_to_be_replaced.items()): old_item = item new_item = new_children[id] replaced = False if hasattr(old_item, 'replace_by'): replaced = old_item.replace_by(new_item) if replaced is False: # print("No replacement possible: # we remove and add the item again") self.remove_child(old_item, external_id=id, update=False) self.add_child(new_item, external_id=id, update=False) # Add relevant items to COntainer children for id, item in list(children_to_be_added.items()): self.add_child(item, external_id=id, update=False) self.update_id += 1
[docs] def start_children_retrieval_campaign(self): self.last_updated = time.time() self.retrieved_children = {} self.children_retrieval_campaign_in_progress = True
[docs] def end_children_retrieval_campaign(self, success=True): self.children_retrieval_campaign_in_progress = False if success is True: self.update_children(self.retrieved_children, self.children_by_external_id) self.update_id += 1 self.last_updated = time.time() self.retrieved_children = {}
[docs] def retrieve_children(self, start=0, page=0): def items_retrieved(result, page, start_offset): if self.childrenRetrievingNeeded is True: new_offset = len(self.retrieved_children) return self.retrieve_children( new_offset, page + 1) # we try the next page return self.retrieved_children self.childrenRetrievingNeeded = False if self.has_pages is True: self.childrenRetriever_params['offset'] = start self.childrenRetriever_params['page'] = page d = self.childrenRetriever(**self.childrenRetriever_params) d.addCallback(items_retrieved, page, start) return d
[docs] def retrieve_all_children(self, start=0, request_count=0): def all_items_retrieved(result): self.end_children_retrieval_campaign(True) return super(LazyContainer, self).get_children( start, request_count) def error_while_retrieving_items(error): self.end_children_retrieval_campaign(False) return super(LazyContainer, self).get_children( start, request_count) self.start_children_retrieval_campaign() if self.childrenRetriever is not None: d = self.retrieve_children(start) if start == 0: d.addCallbacks(all_items_retrieved, error_while_retrieving_items) return d else: self.end_children_retrieval_campaign() return self.children
[docs] def get_children(self, start=0, request_count=0): # Check if an update is needed since last update current_time = time.time() delay_since_last_updated = current_time - self.last_updated period = self.refresh if (period > 0) and (delay_since_last_updated > period): self.info("Last update is older than %d s -> update data", period) self.childrenRetrievingNeeded = True if self.childrenRetrievingNeeded is True: return self.retrieve_all_children(start, request_count) return Container.get_children(self, start, request_count)
ROOT_CONTAINER_ID = 0 SEED_ITEM_ID = 1000
[docs]class AbstractBackendStore(BackendStore): def __init__(self, server, **kwargs): BackendStore.__init__(self, server, **kwargs) self.next_id = SEED_ITEM_ID self.store = {}
[docs] def len(self): return len(self.store)
[docs] def set_root_item(self, item): return self.append_item(item, storage_id=ROOT_CONTAINER_ID)
[docs] def get_root_id(self): return ROOT_CONTAINER_ID
[docs] def get_root_item(self): return self.get_by_id(ROOT_CONTAINER_ID)
[docs] def append_item(self, item, storage_id=None): if storage_id is None: storage_id = self.getnextID() self.store[storage_id] = item item.storage_id = storage_id item.store = self return storage_id
[docs] def remove_item(self, item): del self.store[item.storage_id] item.storage_id = -1 item.store = None
[docs] def get_by_id(self, id): if isinstance(id, str): id = id.split('@', 1) id = id[0].split('.')[0] try: return self.store[int(id)] except (ValueError, KeyError): pass return None
[docs] def getnextID(self): ret = self.next_id self.next_id += 1 return ret
def __repr__(self): return self.__class__.__name__