From bbfe4e996c9b9729f19d5b104dc6abfe120531b4 Mon Sep 17 00:00:00 2001 From: Erik Johnston Date: Wed, 17 May 2017 14:31:23 +0100 Subject: Make get_state_groups_from_groups faster. Most of the time was spent copying a dict to filter out sentinel values that indicated that keys did not exist in the dict. The sentinel values were added to ensure that we cached the non-existence of keys. By updating DictionaryCache to keep track of which keys were known to not exist itself we can remove a dictionary copy. --- synapse/storage/state.py | 40 +++++++---------------- synapse/util/caches/dictionary_cache.py | 57 ++++++++++++++++++++++++++------- tests/util/test_dict_cache.py | 2 +- 3 files changed, 58 insertions(+), 41 deletions(-) diff --git a/synapse/storage/state.py b/synapse/storage/state.py index 85acf2ad1e..a7c3d401d4 100644 --- a/synapse/storage/state.py +++ b/synapse/storage/state.py @@ -563,20 +563,22 @@ class StateStore(SQLBaseStore): where a `state_key` of `None` matches all state_keys for the `type`. """ - is_all, state_dict_ids = self._state_group_cache.get(group) + is_all, known_absent, state_dict_ids = self._state_group_cache.get(group) type_to_key = {} missing_types = set() + for typ, state_key in types: + key = (typ, state_key) if state_key is None: type_to_key[typ] = None - missing_types.add((typ, state_key)) + missing_types.add(key) else: if type_to_key.get(typ, object()) is not None: type_to_key.setdefault(typ, set()).add(state_key) - if (typ, state_key) not in state_dict_ids: - missing_types.add((typ, state_key)) + if key not in state_dict_ids and key not in known_absent: + missing_types.add(key) sentinel = object() @@ -590,7 +592,7 @@ class StateStore(SQLBaseStore): return True return False - got_all = not (missing_types or types is None) + got_all = is_all or not missing_types return { k: v for k, v in state_dict_ids.iteritems() @@ -607,7 +609,7 @@ class StateStore(SQLBaseStore): Args: group: The state group to lookup """ - is_all, state_dict_ids = self._state_group_cache.get(group) + is_all, _, state_dict_ids = self._state_group_cache.get(group) return state_dict_ids, is_all @@ -624,7 +626,7 @@ class StateStore(SQLBaseStore): missing_groups = [] if types is not None: for group in set(groups): - state_dict_ids, missing_types, got_all = self._get_some_state_from_cache( + state_dict_ids, _, got_all = self._get_some_state_from_cache( group, types ) results[group] = state_dict_ids @@ -653,19 +655,7 @@ class StateStore(SQLBaseStore): # Now we want to update the cache with all the things we fetched # from the database. for group, group_state_dict in group_to_state_dict.iteritems(): - if types: - # We delibrately put key -> None mappings into the cache to - # cache absence of the key, on the assumption that if we've - # explicitly asked for some types then we will probably ask - # for them again. - state_dict = { - (intern_string(etype), intern_string(state_key)): None - for (etype, state_key) in types - } - state_dict.update(results[group]) - results[group] = state_dict - else: - state_dict = results[group] + state_dict = results[group] state_dict.update( ((intern_string(k[0]), intern_string(k[1])), to_ascii(v)) @@ -677,17 +667,9 @@ class StateStore(SQLBaseStore): key=group, value=state_dict, full=(types is None), + known_absent=types, ) - # Remove all the entries with None values. The None values were just - # used for bookkeeping in the cache. - for group, state_dict in results.iteritems(): - results[group] = { - key: event_id - for key, event_id in state_dict.iteritems() - if event_id - } - defer.returnValue(results) def get_next_state_group(self): diff --git a/synapse/util/caches/dictionary_cache.py b/synapse/util/caches/dictionary_cache.py index cb6933c61c..d4105822b3 100644 --- a/synapse/util/caches/dictionary_cache.py +++ b/synapse/util/caches/dictionary_cache.py @@ -23,7 +23,17 @@ import logging logger = logging.getLogger(__name__) -class DictionaryEntry(namedtuple("DictionaryEntry", ("full", "value"))): +class DictionaryEntry(namedtuple("DictionaryEntry", ("full", "known_absent", "value"))): + """Returned when getting an entry from the cache + + Attributes: + full (bool): Whether the cache has the full or dict or just some keys. + If not full then not all requested keys will necessarily be present + in `value` + known_absent (set): Keys that were looked up in the dict and were not + there. + value (dict): The full or partial dict value + """ def __len__(self): return len(self.value) @@ -58,21 +68,31 @@ class DictionaryCache(object): ) def get(self, key, dict_keys=None): + """Fetch an entry out of the cache + + Args: + key + dict_key(list): If given a set of keys then return only those keys + that exist in the cache. + + Returns: + DictionaryEntry + """ entry = self.cache.get(key, self.sentinel) if entry is not self.sentinel: self.metrics.inc_hits() if dict_keys is None: - return DictionaryEntry(entry.full, dict(entry.value)) + return DictionaryEntry(entry.full, entry.known_absent, dict(entry.value)) else: - return DictionaryEntry(entry.full, { + return DictionaryEntry(entry.full, entry.known_absent, { k: entry.value[k] for k in dict_keys if k in entry.value }) self.metrics.inc_misses() - return DictionaryEntry(False, {}) + return DictionaryEntry(False, set(), {}) def invalidate(self, key): self.check_thread() @@ -87,19 +107,34 @@ class DictionaryCache(object): self.sequence += 1 self.cache.clear() - def update(self, sequence, key, value, full=False): + def update(self, sequence, key, value, full=False, known_absent=None): + """Updates the entry in the cache + + Args: + sequence + key + value (dict): The value to update the cache with. + full (bool): Whether the given value is the full dict, or just a + partial subset there of. If not full then any existing entries + for the key will be updated. + known_absent (set): Set of keys that we know don't exist in the full + dict. + """ self.check_thread() if self.sequence == sequence: # Only update the cache if the caches sequence number matches the # number that the cache had before the SELECT was started (SYN-369) + if known_absent is None: + known_absent = set() if full: - self._insert(key, value) + self._insert(key, value, known_absent) else: - self._update_or_insert(key, value) + self._update_or_insert(key, value, known_absent) - def _update_or_insert(self, key, value): - entry = self.cache.setdefault(key, DictionaryEntry(False, {})) + def _update_or_insert(self, key, value, known_absent): + entry = self.cache.setdefault(key, DictionaryEntry(False, set(), {})) entry.value.update(value) + entry.known_absent.update(known_absent) - def _insert(self, key, value): - self.cache[key] = DictionaryEntry(True, value) + def _insert(self, key, value, known_absent): + self.cache[key] = DictionaryEntry(True, known_absent, value) diff --git a/tests/util/test_dict_cache.py b/tests/util/test_dict_cache.py index 272b71034a..bc92f85fa6 100644 --- a/tests/util/test_dict_cache.py +++ b/tests/util/test_dict_cache.py @@ -28,7 +28,7 @@ class DictCacheTestCase(unittest.TestCase): key = "test_simple_cache_hit_full" v = self.cache.get(key) - self.assertEqual((False, {}), v) + self.assertEqual((False, set(), {}), v) seq = self.cache.sequence test_value = {"test": "test_simple_cache_hit_full"} -- cgit 1.4.1