lbry-sdk/lbry/wallet/server/db/elasticsearch/search.py
2021-07-22 16:25:55 -03:00

639 lines
29 KiB
Python

import asyncio
import struct
from binascii import unhexlify
from collections import Counter, deque
from decimal import Decimal
from operator import itemgetter
from typing import Optional, List, Iterable, Union
from elasticsearch import AsyncElasticsearch, NotFoundError, ConnectionError
from elasticsearch.helpers import async_streaming_bulk
from lbry.crypto.base58 import Base58
from lbry.error import ResolveCensoredError, claim_id as parse_claim_id
from lbry.schema.result import Outputs, Censor
from lbry.schema.tags import clean_tags
from lbry.schema.url import URL, normalize_name
from lbry.utils import LRUCache
from lbry.wallet.server.db.common import CLAIM_TYPES, STREAM_TYPES
from lbry.wallet.server.db.elasticsearch.constants import INDEX_DEFAULT_SETTINGS, REPLACEMENTS, FIELDS, TEXT_FIELDS, \
RANGE_FIELDS, ALL_FIELDS
from lbry.wallet.server.util import class_logger
class ChannelResolution(str):
@classmethod
def lookup_error(cls, url):
return LookupError(f'Could not find channel in "{url}".')
class StreamResolution(str):
@classmethod
def lookup_error(cls, url):
return LookupError(f'Could not find claim at "{url}".')
class IndexVersionMismatch(Exception):
def __init__(self, got_version, expected_version):
self.got_version = got_version
self.expected_version = expected_version
class SearchIndex:
VERSION = 1
def __init__(self, index_prefix: str, search_timeout=3.0, elastic_host='localhost', elastic_port=9200):
self.search_timeout = search_timeout
self.sync_timeout = 600 # wont hit that 99% of the time, but can hit on a fresh import
self.search_client: Optional[AsyncElasticsearch] = None
self.sync_client: Optional[AsyncElasticsearch] = None
self.index = index_prefix + 'claims'
self.logger = class_logger(__name__, self.__class__.__name__)
self.claim_cache = LRUCache(2 ** 15)
self.short_id_cache = LRUCache(2 ** 17)
self.search_cache = LRUCache(2 ** 17)
self.resolution_cache = LRUCache(2 ** 17)
self._elastic_host = elastic_host
self._elastic_port = elastic_port
async def get_index_version(self) -> int:
try:
template = await self.sync_client.indices.get_template(self.index)
return template[self.index]['version']
except NotFoundError:
return 0
async def set_index_version(self, version):
await self.sync_client.indices.put_template(
self.index, body={'version': version, 'index_patterns': ['ignored']}, ignore=400
)
async def start(self) -> bool:
if self.sync_client:
return False
hosts = [{'host': self._elastic_host, 'port': self._elastic_port}]
self.sync_client = AsyncElasticsearch(hosts, timeout=self.sync_timeout)
self.search_client = AsyncElasticsearch(hosts, timeout=self.search_timeout)
while True:
try:
await self.sync_client.cluster.health(wait_for_status='yellow')
break
except ConnectionError:
self.logger.warning("Failed to connect to Elasticsearch. Waiting for it!")
await asyncio.sleep(1)
res = await self.sync_client.indices.create(self.index, INDEX_DEFAULT_SETTINGS, ignore=400)
acked = res.get('acknowledged', False)
if acked:
await self.set_index_version(self.VERSION)
return acked
index_version = await self.get_index_version()
if index_version != self.VERSION:
self.logger.error("es search index has an incompatible version: %s vs %s", index_version, self.VERSION)
raise IndexVersionMismatch(index_version, self.VERSION)
return acked
def stop(self):
clients = [self.sync_client, self.search_client]
self.sync_client, self.search_client = None, None
return asyncio.ensure_future(asyncio.gather(*(client.close() for client in clients)))
def delete_index(self):
return self.sync_client.indices.delete(self.index, ignore_unavailable=True)
async def _consume_claim_producer(self, claim_producer):
count = 0
for op, doc in claim_producer:
if op == 'delete':
yield {'_index': self.index, '_op_type': 'delete', '_id': doc}
else:
yield extract_doc(doc, self.index)
count += 1
if count % 100 == 0:
self.logger.info("Indexing in progress, %d claims.", count)
self.logger.info("Indexing done for %d claims.", count)
async def claim_consumer(self, claim_producer):
touched = set()
async for ok, item in async_streaming_bulk(self.sync_client, self._consume_claim_producer(claim_producer),
raise_on_error=False):
if not ok:
self.logger.warning("indexing failed for an item: %s", item)
else:
item = item.popitem()[1]
touched.add(item['_id'])
await self.sync_client.indices.refresh(self.index)
self.logger.info("Indexing done.")
def update_filter_query(self, censor_type, blockdict, channels=False):
blockdict = {key[::-1].hex(): value[::-1].hex() for key, value in blockdict.items()}
if channels:
update = expand_query(channel_id__in=list(blockdict.keys()), censor_type=f"<{censor_type}")
else:
update = expand_query(claim_id__in=list(blockdict.keys()), censor_type=f"<{censor_type}")
key = 'channel_id' if channels else 'claim_id'
update['script'] = {
"source": f"ctx._source.censor_type={censor_type}; ctx._source.censoring_channel_id=params[ctx._source.{key}]",
"lang": "painless",
"params": blockdict
}
return update
async def apply_filters(self, blocked_streams, blocked_channels, filtered_streams, filtered_channels):
if filtered_streams:
await self.sync_client.update_by_query(
self.index, body=self.update_filter_query(Censor.SEARCH, filtered_streams), slices=4)
await self.sync_client.indices.refresh(self.index)
if filtered_channels:
await self.sync_client.update_by_query(
self.index, body=self.update_filter_query(Censor.SEARCH, filtered_channels), slices=4)
await self.sync_client.indices.refresh(self.index)
await self.sync_client.update_by_query(
self.index, body=self.update_filter_query(Censor.SEARCH, filtered_channels, True), slices=4)
await self.sync_client.indices.refresh(self.index)
if blocked_streams:
await self.sync_client.update_by_query(
self.index, body=self.update_filter_query(Censor.RESOLVE, blocked_streams), slices=4)
await self.sync_client.indices.refresh(self.index)
if blocked_channels:
await self.sync_client.update_by_query(
self.index, body=self.update_filter_query(Censor.RESOLVE, blocked_channels), slices=4)
await self.sync_client.indices.refresh(self.index)
await self.sync_client.update_by_query(
self.index, body=self.update_filter_query(Censor.RESOLVE, blocked_channels, True), slices=4)
await self.sync_client.indices.refresh(self.index)
self.clear_caches()
def clear_caches(self):
self.search_cache.clear()
self.short_id_cache.clear()
self.claim_cache.clear()
self.resolution_cache.clear()
async def session_query(self, query_name, kwargs):
offset, total = kwargs.get('offset', 0) if isinstance(kwargs, dict) else 0, 0
total_referenced = []
if query_name == 'resolve':
total_referenced, response, censor = await self.resolve(*kwargs)
else:
cache_item = ResultCacheItem.from_cache(str(kwargs), self.search_cache)
if cache_item.result is not None:
return cache_item.result
async with cache_item.lock:
if cache_item.result:
return cache_item.result
censor = Censor(Censor.SEARCH)
if kwargs.get('no_totals'):
response, offset, total = await self.search(**kwargs, censor_type=Censor.NOT_CENSORED)
else:
response, offset, total = await self.search(**kwargs)
censor.apply(response)
total_referenced.extend(response)
if censor.censored:
response, _, _ = await self.search(**kwargs, censor_type=Censor.NOT_CENSORED)
total_referenced.extend(response)
result = Outputs.to_base64(
response, await self._get_referenced_rows(total_referenced), offset, total, censor
)
cache_item.result = result
return result
return Outputs.to_base64(response, await self._get_referenced_rows(total_referenced), offset, total, censor)
async def resolve(self, *urls):
censor = Censor(Censor.RESOLVE)
results = [await self.resolve_url(url) for url in urls]
# just heat the cache
await self.populate_claim_cache(*filter(lambda x: isinstance(x, str), results))
results = [self._get_from_cache_or_error(url, result) for url, result in zip(urls, results)]
censored = [
result if not isinstance(result, dict) or not censor.censor(result)
else ResolveCensoredError(url, result['censoring_channel_id'])
for url, result in zip(urls, results)
]
return results, censored, censor
def _get_from_cache_or_error(self, url: str, resolution: Union[LookupError, StreamResolution, ChannelResolution]):
cached = self.claim_cache.get(resolution)
return cached or (resolution if isinstance(resolution, LookupError) else resolution.lookup_error(url))
async def get_many(self, *claim_ids):
await self.populate_claim_cache(*claim_ids)
return filter(None, map(self.claim_cache.get, claim_ids))
async def populate_claim_cache(self, *claim_ids):
missing = [claim_id for claim_id in claim_ids if self.claim_cache.get(claim_id) is None]
if missing:
results = await self.search_client.mget(
index=self.index, body={"ids": missing}
)
for result in expand_result(filter(lambda doc: doc['found'], results["docs"])):
self.claim_cache.set(result['claim_id'], result)
async def full_id_from_short_id(self, name, short_id, channel_id=None):
key = '#'.join((channel_id or '', name, short_id))
if key not in self.short_id_cache:
query = {'name': name, 'claim_id': short_id}
if channel_id:
query['channel_id'] = channel_id
query['order_by'] = ['^channel_join']
query['signature_valid'] = True
else:
query['order_by'] = '^creation_height'
result, _, _ = await self.search(**query, limit=1)
if len(result) == 1:
result = result[0]['claim_id']
self.short_id_cache[key] = result
return self.short_id_cache.get(key, None)
async def search(self, **kwargs):
if 'channel' in kwargs:
kwargs['channel_id'] = await self.resolve_url(kwargs.pop('channel'))
if not kwargs['channel_id'] or not isinstance(kwargs['channel_id'], str):
return [], 0, 0
try:
return await self.search_ahead(**kwargs)
except NotFoundError:
return [], 0, 0
return expand_result(result['hits']), 0, result.get('total', {}).get('value', 0)
async def search_ahead(self, **kwargs):
# 'limit_claims_per_channel' case. Fetch 1000 results, reorder, slice, inflate and return
per_channel_per_page = kwargs.pop('limit_claims_per_channel', 0) or 0
remove_duplicates = kwargs.pop('remove_duplicates', False)
page_size = kwargs.pop('limit', 10)
offset = kwargs.pop('offset', 0)
kwargs['limit'] = 1000
cache_item = ResultCacheItem.from_cache(f"ahead{per_channel_per_page}{kwargs}", self.search_cache)
if cache_item.result is not None:
reordered_hits = cache_item.result
else:
async with cache_item.lock:
if cache_item.result:
reordered_hits = cache_item.result
else:
query = expand_query(**kwargs)
search_hits = deque((await self.search_client.search(
query, index=self.index, track_total_hits=False,
_source_includes=['_id', 'channel_id', 'reposted_claim_id', 'creation_height']
))['hits']['hits'])
if remove_duplicates:
search_hits = self.__remove_duplicates(search_hits)
if per_channel_per_page > 0:
reordered_hits = self.__search_ahead(search_hits, page_size, per_channel_per_page)
else:
reordered_hits = [(hit['_id'], hit['_source']['channel_id']) for hit in search_hits]
cache_item.result = reordered_hits
result = list(await self.get_many(*(claim_id for claim_id, _ in reordered_hits[offset:(offset + page_size)])))
return result, 0, len(reordered_hits)
def __remove_duplicates(self, search_hits: deque) -> deque:
known_ids = {} # claim_id -> (creation_height, hit_id), where hit_id is either reposted claim id or original
dropped = set()
for hit in search_hits:
hit_height, hit_id = hit['_source']['creation_height'], hit['_source']['reposted_claim_id'] or hit['_id']
if hit_id not in known_ids:
known_ids[hit_id] = (hit_height, hit['_id'])
else:
previous_height, previous_id = known_ids[hit_id]
if hit_height < previous_height:
known_ids[hit_id] = (hit_height, hit['_id'])
dropped.add(previous_id)
else:
dropped.add(hit['_id'])
return deque(hit for hit in search_hits if hit['_id'] not in dropped)
def __search_ahead(self, search_hits: list, page_size: int, per_channel_per_page: int):
reordered_hits = []
channel_counters = Counter()
next_page_hits_maybe_check_later = deque()
while search_hits or next_page_hits_maybe_check_later:
if reordered_hits and len(reordered_hits) % page_size == 0:
channel_counters.clear()
elif not reordered_hits:
pass
else:
break # means last page was incomplete and we are left with bad replacements
for _ in range(len(next_page_hits_maybe_check_later)):
claim_id, channel_id = next_page_hits_maybe_check_later.popleft()
if per_channel_per_page > 0 and channel_counters[channel_id] < per_channel_per_page:
reordered_hits.append((claim_id, channel_id))
channel_counters[channel_id] += 1
else:
next_page_hits_maybe_check_later.append((claim_id, channel_id))
while search_hits:
hit = search_hits.popleft()
hit_id, hit_channel_id = hit['_id'], hit['_source']['channel_id']
if hit_channel_id is None or per_channel_per_page <= 0:
reordered_hits.append((hit_id, hit_channel_id))
elif channel_counters[hit_channel_id] < per_channel_per_page:
reordered_hits.append((hit_id, hit_channel_id))
channel_counters[hit_channel_id] += 1
if len(reordered_hits) % page_size == 0:
break
else:
next_page_hits_maybe_check_later.append((hit_id, hit_channel_id))
return reordered_hits
async def resolve_url(self, raw_url):
if raw_url not in self.resolution_cache:
self.resolution_cache[raw_url] = await self._resolve_url(raw_url)
return self.resolution_cache[raw_url]
async def _resolve_url(self, raw_url):
try:
url = URL.parse(raw_url)
except ValueError as e:
return e
stream = LookupError(f'Could not find claim at "{raw_url}".')
channel_id = await self.resolve_channel_id(url)
if isinstance(channel_id, LookupError):
return channel_id
stream = (await self.resolve_stream(url, channel_id if isinstance(channel_id, str) else None)) or stream
if url.has_stream:
return StreamResolution(stream)
else:
return ChannelResolution(channel_id)
async def resolve_channel_id(self, url: URL):
if not url.has_channel:
return
if url.channel.is_fullid:
return url.channel.claim_id
if url.channel.is_shortid:
channel_id = await self.full_id_from_short_id(url.channel.name, url.channel.claim_id)
if not channel_id:
return LookupError(f'Could not find channel in "{url}".')
return channel_id
query = url.channel.to_dict()
if set(query) == {'name'}:
query['is_controlling'] = True
else:
query['order_by'] = ['^creation_height']
matches, _, _ = await self.search(**query, limit=1)
if matches:
channel_id = matches[0]['claim_id']
else:
return LookupError(f'Could not find channel in "{url}".')
return channel_id
async def resolve_stream(self, url: URL, channel_id: str = None):
if not url.has_stream:
return None
if url.has_channel and channel_id is None:
return None
query = url.stream.to_dict()
if url.stream.claim_id is not None:
if url.stream.is_fullid:
claim_id = url.stream.claim_id
else:
claim_id = await self.full_id_from_short_id(query['name'], query['claim_id'], channel_id)
return claim_id
if channel_id is not None:
if set(query) == {'name'}:
# temporarily emulate is_controlling for claims in channel
query['order_by'] = ['effective_amount', '^height']
else:
query['order_by'] = ['^channel_join']
query['channel_id'] = channel_id
query['signature_valid'] = True
elif set(query) == {'name'}:
query['is_controlling'] = True
matches, _, _ = await self.search(**query, limit=1)
if matches:
return matches[0]['claim_id']
async def _get_referenced_rows(self, txo_rows: List[dict]):
txo_rows = [row for row in txo_rows if isinstance(row, dict)]
referenced_ids = set(filter(None, map(itemgetter('reposted_claim_id'), txo_rows)))
referenced_ids |= set(filter(None, (row['channel_id'] for row in txo_rows)))
referenced_ids |= set(filter(None, (row['censoring_channel_id'] for row in txo_rows)))
referenced_txos = []
if referenced_ids:
referenced_txos.extend(await self.get_many(*referenced_ids))
referenced_ids = set(filter(None, (row['channel_id'] for row in referenced_txos)))
if referenced_ids:
referenced_txos.extend(await self.get_many(*referenced_ids))
return referenced_txos
def extract_doc(doc, index):
doc['claim_id'] = doc.pop('claim_hash')[::-1].hex()
if doc['reposted_claim_hash'] is not None:
doc['reposted_claim_id'] = doc.pop('reposted_claim_hash')[::-1].hex()
else:
doc['reposted_claim_id'] = None
channel_hash = doc.pop('channel_hash')
doc['channel_id'] = channel_hash[::-1].hex() if channel_hash else channel_hash
doc['censoring_channel_id'] = doc.get('censoring_channel_id')
txo_hash = doc.pop('txo_hash')
doc['tx_id'] = txo_hash[:32][::-1].hex()
doc['tx_nout'] = struct.unpack('<I', txo_hash[32:])[0]
doc['is_controlling'] = bool(doc['is_controlling'])
doc['signature'] = (doc.pop('signature') or b'').hex() or None
doc['signature_digest'] = (doc.pop('signature_digest') or b'').hex() or None
doc['public_key_bytes'] = (doc.pop('public_key_bytes') or b'').hex() or None
doc['public_key_id'] = (doc.pop('public_key_hash') or b'').hex() or None
doc['signature_valid'] = bool(doc['signature_valid'])
doc['claim_type'] = doc.get('claim_type', 0) or 0
doc['stream_type'] = int(doc.get('stream_type', 0) or 0)
doc['has_source'] = bool(doc['has_source'])
doc = {key: value for key, value in doc.items() if key in ALL_FIELDS}
return {'doc': doc, '_id': doc['claim_id'], '_index': index, '_op_type': 'update', 'doc_as_upsert': True}
def expand_query(**kwargs):
if "amount_order" in kwargs:
kwargs["limit"] = 1
kwargs["order_by"] = "effective_amount"
kwargs["offset"] = int(kwargs["amount_order"]) - 1
if 'name' in kwargs:
kwargs['name'] = normalize_name(kwargs.pop('name'))
if kwargs.get('is_controlling') is False:
kwargs.pop('is_controlling')
query = {'must': [], 'must_not': []}
collapse = None
for key, value in kwargs.items():
key = key.replace('claim.', '')
many = key.endswith('__in') or isinstance(value, list)
if many:
key = key.replace('__in', '')
value = list(filter(None, value))
if value is None or isinstance(value, list) and len(value) == 0:
continue
key = REPLACEMENTS.get(key, key)
if key in FIELDS:
partial_id = False
if key == 'claim_type':
if isinstance(value, str):
value = CLAIM_TYPES[value]
else:
value = [CLAIM_TYPES[claim_type] for claim_type in value]
if key == '_id':
if isinstance(value, Iterable):
value = [item[::-1].hex() for item in value]
else:
value = value[::-1].hex()
if not many and key in ('_id', 'claim_id') and len(value) < 20:
partial_id = True
if key == 'public_key_id':
value = Base58.decode(value)[1:21].hex()
if key == 'signature_valid':
continue # handled later
if key in TEXT_FIELDS:
key += '.keyword'
ops = {'<=': 'lte', '>=': 'gte', '<': 'lt', '>': 'gt'}
if partial_id:
query['must'].append({"prefix": {"claim_id": value}})
elif key in RANGE_FIELDS and isinstance(value, str) and value[0] in ops:
operator_length = 2 if value[:2] in ops else 1
operator, value = value[:operator_length], value[operator_length:]
if key == 'fee_amount':
value = str(Decimal(value)*1000)
query['must'].append({"range": {key: {ops[operator]: value}}})
elif many:
query['must'].append({"terms": {key: value}})
else:
if key == 'fee_amount':
value = str(Decimal(value)*1000)
query['must'].append({"term": {key: {"value": value}}})
elif key == 'not_channel_ids':
for channel_id in value:
query['must_not'].append({"term": {'channel_id.keyword': channel_id}})
query['must_not'].append({"term": {'_id': channel_id}})
elif key == 'channel_ids':
query['must'].append({"terms": {'channel_id.keyword': value}})
elif key == 'claim_ids':
query['must'].append({"terms": {'claim_id.keyword': value}})
elif key == 'media_types':
query['must'].append({"terms": {'media_type.keyword': value}})
elif key == 'stream_types':
query['must'].append({"terms": {'stream_type': [STREAM_TYPES[stype] for stype in value]}})
elif key == 'any_languages':
query['must'].append({"terms": {'languages': clean_tags(value)}})
elif key == 'any_languages':
query['must'].append({"terms": {'languages': value}})
elif key == 'all_languages':
query['must'].extend([{"term": {'languages': tag}} for tag in value])
elif key == 'any_tags':
query['must'].append({"terms": {'tags.keyword': clean_tags(value)}})
elif key == 'all_tags':
query['must'].extend([{"term": {'tags.keyword': tag}} for tag in clean_tags(value)])
elif key == 'not_tags':
query['must_not'].extend([{"term": {'tags.keyword': tag}} for tag in clean_tags(value)])
elif key == 'not_claim_id':
query['must_not'].extend([{"term": {'claim_id.keyword': cid}} for cid in value])
elif key == 'limit_claims_per_channel':
collapse = ('channel_id.keyword', value)
if kwargs.get('has_channel_signature'):
query['must'].append({"exists": {"field": "signature_digest"}})
if 'signature_valid' in kwargs:
query['must'].append({"term": {"signature_valid": bool(kwargs["signature_valid"])}})
elif 'signature_valid' in kwargs:
query.setdefault('should', [])
query["minimum_should_match"] = 1
query['should'].append({"bool": {"must_not": {"exists": {"field": "signature_digest"}}}})
query['should'].append({"term": {"signature_valid": bool(kwargs["signature_valid"])}})
if 'has_source' in kwargs:
query.setdefault('should', [])
query["minimum_should_match"] = 1
is_stream_or_repost = {"terms": {"claim_type": [CLAIM_TYPES['stream'], CLAIM_TYPES['repost']]}}
query['should'].append(
{"bool": {"must": [{"match": {"has_source": kwargs['has_source']}}, is_stream_or_repost]}})
query['should'].append({"bool": {"must_not": [is_stream_or_repost]}})
query['should'].append({"bool": {"must": [{"term": {"reposted_claim_type": CLAIM_TYPES['channel']}}]}})
if kwargs.get('text'):
query['must'].append(
{"simple_query_string":
{"query": kwargs["text"], "fields": [
"claim_name^4", "channel_name^8", "title^1", "description^.5", "author^1", "tags^.5"
]}})
query = {
"_source": {"excludes": ["description", "title"]},
'query': {'bool': query},
"sort": [],
}
if "limit" in kwargs:
query["size"] = kwargs["limit"]
if 'offset' in kwargs:
query["from"] = kwargs["offset"]
if 'order_by' in kwargs:
if isinstance(kwargs["order_by"], str):
kwargs["order_by"] = [kwargs["order_by"]]
for value in kwargs['order_by']:
if 'trending_group' in value:
# fixme: trending_mixed is 0 for all records on variable decay, making sort slow.
continue
is_asc = value.startswith('^')
value = value[1:] if is_asc else value
value = REPLACEMENTS.get(value, value)
if value in TEXT_FIELDS:
value += '.keyword'
query['sort'].append({value: "asc" if is_asc else "desc"})
if collapse:
query["collapse"] = {
"field": collapse[0],
"inner_hits": {
"name": collapse[0],
"size": collapse[1],
"sort": query["sort"]
}
}
return query
def expand_result(results):
inner_hits = []
expanded = []
for result in results:
if result.get("inner_hits"):
for _, inner_hit in result["inner_hits"].items():
inner_hits.extend(inner_hit["hits"]["hits"])
continue
result = result['_source']
result['claim_hash'] = unhexlify(result['claim_id'])[::-1]
if result['reposted_claim_id']:
result['reposted_claim_hash'] = unhexlify(result['reposted_claim_id'])[::-1]
else:
result['reposted_claim_hash'] = None
result['channel_hash'] = unhexlify(result['channel_id'])[::-1] if result['channel_id'] else None
result['txo_hash'] = unhexlify(result['tx_id'])[::-1] + struct.pack('<I', result['tx_nout'])
result['tx_hash'] = unhexlify(result['tx_id'])[::-1]
expanded.append(result)
if inner_hits:
return expand_result(inner_hits)
return expanded
class ResultCacheItem:
__slots__ = '_result', 'lock', 'has_result'
def __init__(self):
self.has_result = asyncio.Event()
self.lock = asyncio.Lock()
self._result = None
@property
def result(self) -> str:
return self._result
@result.setter
def result(self, result: str):
self._result = result
if result is not None:
self.has_result.set()
@classmethod
def from_cache(cls, cache_key, cache):
cache_item = cache.get(cache_key)
if cache_item is None:
cache_item = cache[cache_key] = ResultCacheItem()
return cache_item