diff options
Diffstat (limited to 'synapse/storage/_base.py')
| -rw-r--r-- | synapse/storage/_base.py | 68 |
1 files changed, 59 insertions, 9 deletions
diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py index e01c61d08d..a2da3dd1b1 100644 --- a/synapse/storage/_base.py +++ b/synapse/storage/_base.py @@ -31,7 +31,9 @@ import functools import simplejson as json import sys import time +import threading +DEBUG_CACHES = False logger = logging.getLogger(__name__) @@ -68,9 +70,20 @@ class Cache(object): self.name = name self.keylen = keylen - + self.sequence = 0 + self.thread = None caches_by_name[name] = self.cache + def check_thread(self): + expected_thread = self.thread + if expected_thread is None: + self.thread = threading.current_thread() + else: + if expected_thread is not threading.current_thread(): + raise ValueError( + "Cache objects can only be accessed from the main thread" + ) + def get(self, *keyargs): if len(keyargs) != self.keylen: raise ValueError("Expected a key to have %d items", self.keylen) @@ -82,6 +95,13 @@ class Cache(object): cache_counter.inc_misses(self.name) raise KeyError() + def update(self, sequence, *args): + 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) + self.prefill(*args) + def prefill(self, *args): # because I can't *keyargs, value keyargs = args[:-1] value = args[-1] @@ -96,9 +116,12 @@ class Cache(object): self.cache[keyargs] = value def invalidate(self, *keyargs): + self.check_thread() if len(keyargs) != self.keylen: raise ValueError("Expected a key to have %d items", self.keylen) - + # Increment the sequence number so that any SELECT statements that + # raced with the INSERT don't update the cache (SYN-369) + self.sequence += 1 self.cache.pop(keyargs, None) @@ -128,11 +151,26 @@ def cached(max_entries=1000, num_args=1, lru=False): @defer.inlineCallbacks def wrapped(self, *keyargs): try: - defer.returnValue(cache.get(*keyargs)) + cached_result = cache.get(*keyargs) + if DEBUG_CACHES: + actual_result = yield orig(self, *keyargs) + if actual_result != cached_result: + logger.error( + "Stale cache entry %s%r: cached: %r, actual %r", + orig.__name__, keyargs, + cached_result, actual_result, + ) + raise ValueError("Stale cache entry") + defer.returnValue(cached_result) except KeyError: + # Get the sequence number of the cache before reading from the + # database so that we can tell if the cache is invalidated + # while the SELECT is executing (SYN-369) + sequence = cache.sequence + ret = yield orig(self, *keyargs) - cache.prefill(*keyargs + (ret,)) + cache.update(sequence, *keyargs + (ret,)) defer.returnValue(ret) @@ -147,12 +185,20 @@ class LoggingTransaction(object): """An object that almost-transparently proxies for the 'txn' object passed to the constructor. Adds logging and metrics to the .execute() method.""" - __slots__ = ["txn", "name", "database_engine"] + __slots__ = ["txn", "name", "database_engine", "after_callbacks"] - def __init__(self, txn, name, database_engine): + def __init__(self, txn, name, database_engine, after_callbacks): object.__setattr__(self, "txn", txn) object.__setattr__(self, "name", name) object.__setattr__(self, "database_engine", database_engine) + object.__setattr__(self, "after_callbacks", after_callbacks) + + def call_after(self, callback, *args): + """Call the given callback on the main twisted thread after the + transaction has finished. Used to invalidate the caches on the + correct thread. + """ + self.after_callbacks.append((callback, args)) def __getattr__(self, name): return getattr(self.txn, name) @@ -294,6 +340,8 @@ class SQLBaseStore(object): start_time = time.time() * 1000 + after_callbacks = [] + def inner_func(conn, *args, **kwargs): with LoggingContext("runInteraction") as context: if self.database_engine.is_connection_closed(conn): @@ -318,10 +366,10 @@ class SQLBaseStore(object): while True: try: txn = conn.cursor() - return func( - LoggingTransaction(txn, name, self.database_engine), - *args, **kwargs + txn = LoggingTransaction( + txn, name, self.database_engine, after_callbacks ) + return func(txn, *args, **kwargs) except self.database_engine.module.OperationalError as e: # This can happen if the database disappears mid # transaction. @@ -370,6 +418,8 @@ class SQLBaseStore(object): result = yield self._db_pool.runWithConnection( inner_func, *args, **kwargs ) + for after_callback, after_args in after_callbacks: + after_callback(*after_args) defer.returnValue(result) def cursor_to_dict(self, cursor): |