Don't hammer the database for destination retry timings every ~5mins (#10036)

synapse/storage/databases/main/transactions.py

@@ -16,13 +16,15 @@ import logging
 from collections import namedtuple
 from typing import Iterable, List, Optional, Tuple
 
+import attr
 from canonicaljson import encode_canonical_json
 
 from synapse.metrics.background_process_metrics import wrap_as_background_process
-from synapse.storage._base import SQLBaseStore, db_to_json
+from synapse.storage._base import db_to_json
 from synapse.storage.database import DatabasePool, LoggingTransaction
+from synapse.storage.databases.main.cache import CacheInvalidationWorkerStore
 from synapse.types import JsonDict
-from synapse.util.caches.expiringcache import ExpiringCache
+from synapse.util.caches.descriptors import cached
 
 db_binary_type = memoryview
 
@@ -38,10 +40,23 @@ _UpdateTransactionRow = namedtuple(
     "_TransactionRow", ("response_code", "response_json")
 )
 
-SENTINEL = object()
+
+@attr.s(slots=True, frozen=True, auto_attribs=True)
+class DestinationRetryTimings:
+    """The current destination retry timing info for a remote server."""
+
+    # The first time we tried and failed to reach the remote server, in ms.
+    failure_ts: int
+
+    # The last time we tried and failed to reach the remote server, in ms.
+    retry_last_ts: int
+
+    # How long since the last time we tried to reach the remote server before
+    # trying again, in ms.
+    retry_interval: int
 
 
-class TransactionWorkerStore(SQLBaseStore):
+class TransactionWorkerStore(CacheInvalidationWorkerStore):
     def __init__(self, database: DatabasePool, db_conn, hs):
         super().__init__(database, db_conn, hs)
 
@@ -60,19 +75,6 @@ class TransactionWorkerStore(SQLBaseStore):
             "_cleanup_transactions", _cleanup_transactions_txn
         )
 
-
-class TransactionStore(TransactionWorkerStore):
-    """A collection of queries for handling PDUs."""
-
-    def __init__(self, database: DatabasePool, db_conn, hs):
-        super().__init__(database, db_conn, hs)
-
-        self._destination_retry_cache = ExpiringCache(
-            cache_name="get_destination_retry_timings",
-            clock=self._clock,
-            expiry_ms=5 * 60 * 1000,
-        )
-
     async def get_received_txn_response(
         self, transaction_id: str, origin: str
     ) -> Optional[Tuple[int, JsonDict]]:
@@ -145,7 +147,11 @@ class TransactionStore(TransactionWorkerStore):
             desc="set_received_txn_response",
         )
 
-    async def get_destination_retry_timings(self, destination):
+    @cached(max_entries=10000)
+    async def get_destination_retry_timings(
+        self,
+        destination: str,
+    ) -> Optional[DestinationRetryTimings]:
         """Gets the current retry timings (if any) for a given destination.
 
         Args:
@@ -156,34 +162,29 @@ class TransactionStore(TransactionWorkerStore):
             Otherwise a dict for the retry scheme
         """
 
-        result = self._destination_retry_cache.get(destination, SENTINEL)
-        if result is not SENTINEL:
-            return result
-
         result = await self.db_pool.runInteraction(
             "get_destination_retry_timings",
             self._get_destination_retry_timings,
             destination,
         )
 
-        # We don't hugely care about race conditions between getting and
-        # invalidating the cache, since we time out fairly quickly anyway.
-        self._destination_retry_cache[destination] = result
         return result
 
-    def _get_destination_retry_timings(self, txn, destination):
+    def _get_destination_retry_timings(
+        self, txn, destination: str
+    ) -> Optional[DestinationRetryTimings]:
         result = self.db_pool.simple_select_one_txn(
             txn,
             table="destinations",
             keyvalues={"destination": destination},
-            retcols=("destination", "failure_ts", "retry_last_ts", "retry_interval"),
+            retcols=("failure_ts", "retry_last_ts", "retry_interval"),
             allow_none=True,
         )
 
         # check we have a row and retry_last_ts is not null or zero
         # (retry_last_ts can't be negative)
         if result and result["retry_last_ts"]:
-            return result
+            return DestinationRetryTimings(**result)
         else:
             return None
 
@@ -204,7 +205,6 @@ class TransactionStore(TransactionWorkerStore):
             retry_interval: how long until next retry in ms
         """
 
-        self._destination_retry_cache.pop(destination, None)
         if self.database_engine.can_native_upsert:
             return await self.db_pool.runInteraction(
                 "set_destination_retry_timings",
@@ -252,6 +252,10 @@ class TransactionStore(TransactionWorkerStore):
 
         txn.execute(sql, (destination, failure_ts, retry_last_ts, retry_interval))
 
+        self._invalidate_cache_and_stream(
+            txn, self.get_destination_retry_timings, (destination,)
+        )
+
     def _set_destination_retry_timings_emulated(
         self, txn, destination, failure_ts, retry_last_ts, retry_interval
     ):
@@ -295,6 +299,10 @@ class TransactionStore(TransactionWorkerStore):
                 },
             )
 
+        self._invalidate_cache_and_stream(
+            txn, self.get_destination_retry_timings, (destination,)
+        )
+
     async def store_destination_rooms_entries(
         self,
         destinations: Iterable[str],