diff --git a/changelog.d/16570.feature b/changelog.d/16570.feature
new file mode 100644
index 0000000000..c807945fa8
--- /dev/null
+++ b/changelog.d/16570.feature
@@ -0,0 +1 @@
+Improve the performance of claiming encryption keys.
diff --git a/synapse/handlers/e2e_keys.py b/synapse/handlers/e2e_keys.py
index 8c6432035d..91c5fe007d 100644
--- a/synapse/handlers/e2e_keys.py
+++ b/synapse/handlers/e2e_keys.py
@@ -659,6 +659,20 @@ class E2eKeysHandler:
timeout: Optional[int],
always_include_fallback_keys: bool,
) -> JsonDict:
+ """
+ Args:
+ query: A chain of maps from (user_id, device_id, algorithm) to the requested
+ number of keys to claim.
+ user: The user who is claiming these keys.
+ timeout: How long to wait for any federation key claim requests before
+ giving up.
+ always_include_fallback_keys: always include a fallback key for local users'
+ devices, even if we managed to claim a one-time-key.
+
+ Returns: a heterogeneous dict with two keys:
+ one_time_keys: chain of maps user ID -> device ID -> key ID -> key.
+ failures: map from remote destination to a JsonDict describing the error.
+ """
local_query: List[Tuple[str, str, str, int]] = []
remote_queries: Dict[str, Dict[str, Dict[str, Dict[str, int]]]] = {}
diff --git a/synapse/storage/database.py b/synapse/storage/database.py
index b1ece63845..a4e7048368 100644
--- a/synapse/storage/database.py
+++ b/synapse/storage/database.py
@@ -420,6 +420,16 @@ class LoggingTransaction:
self._do_execute(self.txn.execute, sql, parameters)
def executemany(self, sql: str, *args: Any) -> None:
+ """Repeatedly execute the same piece of SQL with different parameters.
+
+ See https://peps.python.org/pep-0249/#executemany. Note in particular that
+
+ > Use of this method for an operation which produces one or more result sets
+ > constitutes undefined behavior
+
+ so you can't use this for e.g. a SELECT, an UPDATE ... RETURNING, or a
+ DELETE FROM... RETURNING.
+ """
# TODO: we should add a type for *args here. Looking at Cursor.executemany
# and DBAPI2 it ought to be Sequence[_Parameter], but we pass in
# Iterable[Iterable[Any]] in execute_batch and execute_values above, which mypy
diff --git a/synapse/storage/databases/main/end_to_end_keys.py b/synapse/storage/databases/main/end_to_end_keys.py
index f70f95eeba..08385d312f 100644
--- a/synapse/storage/databases/main/end_to_end_keys.py
+++ b/synapse/storage/databases/main/end_to_end_keys.py
@@ -24,6 +24,7 @@ from typing import (
Mapping,
Optional,
Sequence,
+ Set,
Tuple,
Union,
cast,
@@ -1260,6 +1261,65 @@ class EndToEndKeyWorkerStore(EndToEndKeyBackgroundStore, CacheInvalidationWorker
Returns:
A map of user ID -> a map device ID -> a map of key ID -> JSON.
"""
+ if isinstance(self.database_engine, PostgresEngine):
+ return await self.db_pool.runInteraction(
+ "_claim_e2e_fallback_keys_bulk",
+ self._claim_e2e_fallback_keys_bulk_txn,
+ query_list,
+ db_autocommit=True,
+ )
+ # Use an UPDATE FROM... RETURNING combined with a VALUES block to do
+ # everything in one query. Note: this is also supported in SQLite 3.33.0,
+ # (see https://www.sqlite.org/lang_update.html#update_from), but we do not
+ # have an equivalent of psycopg2's execute_values to do this in one query.
+ else:
+ return await self._claim_e2e_fallback_keys_simple(query_list)
+
+ def _claim_e2e_fallback_keys_bulk_txn(
+ self,
+ txn: LoggingTransaction,
+ query_list: Iterable[Tuple[str, str, str, bool]],
+ ) -> Dict[str, Dict[str, Dict[str, JsonDict]]]:
+ """Efficient implementation of claim_e2e_fallback_keys for Postgres.
+
+ Safe to autocommit: this is a single query.
+ """
+ results: Dict[str, Dict[str, Dict[str, JsonDict]]] = {}
+
+ sql = """
+ WITH claims(user_id, device_id, algorithm, mark_as_used) AS (
+ VALUES ?
+ )
+ UPDATE e2e_fallback_keys_json k
+ SET used = used OR mark_as_used
+ FROM claims
+ WHERE (k.user_id, k.device_id, k.algorithm) = (claims.user_id, claims.device_id, claims.algorithm)
+ RETURNING k.user_id, k.device_id, k.algorithm, k.key_id, k.key_json;
+ """
+ claimed_keys = cast(
+ List[Tuple[str, str, str, str, str]],
+ txn.execute_values(sql, query_list),
+ )
+
+ seen_user_device: Set[Tuple[str, str]] = set()
+ for user_id, device_id, algorithm, key_id, key_json in claimed_keys:
+ device_results = results.setdefault(user_id, {}).setdefault(device_id, {})
+ device_results[f"{algorithm}:{key_id}"] = json_decoder.decode(key_json)
+
+ if (user_id, device_id) in seen_user_device:
+ continue
+ seen_user_device.add((user_id, device_id))
+ self._invalidate_cache_and_stream(
+ txn, self.get_e2e_unused_fallback_key_types, (user_id, device_id)
+ )
+
+ return results
+
+ async def _claim_e2e_fallback_keys_simple(
+ self,
+ query_list: Iterable[Tuple[str, str, str, bool]],
+ ) -> Dict[str, Dict[str, Dict[str, JsonDict]]]:
+ """Naive, inefficient implementation of claim_e2e_fallback_keys for SQLite."""
results: Dict[str, Dict[str, Dict[str, JsonDict]]] = {}
for user_id, device_id, algorithm, mark_as_used in query_list:
row = await self.db_pool.simple_select_one(
diff --git a/tests/handlers/test_e2e_keys.py b/tests/handlers/test_e2e_keys.py
index c5556f2844..24e405f429 100644
--- a/tests/handlers/test_e2e_keys.py
+++ b/tests/handlers/test_e2e_keys.py
@@ -322,6 +322,83 @@ class E2eKeysHandlerTestCase(unittest.HomeserverTestCase):
{"failures": {}, "one_time_keys": {local_user: {device_id: fallback_key3}}},
)
+ def test_fallback_key_bulk(self) -> None:
+ """Like test_fallback_key, but claims multiple keys in one handler call."""
+ alice = f"@alice:{self.hs.hostname}"
+ brian = f"@brian:{self.hs.hostname}"
+ chris = f"@chris:{self.hs.hostname}"
+
+ # Have three users upload fallback keys for two devices.
+ fallback_keys = {
+ alice: {
+ "alice_dev_1": {"alg1:k1": "fallback_key1"},
+ "alice_dev_2": {"alg2:k2": "fallback_key2"},
+ },
+ brian: {
+ "brian_dev_1": {"alg1:k3": "fallback_key3"},
+ "brian_dev_2": {"alg2:k4": "fallback_key4"},
+ },
+ chris: {
+ "chris_dev_1": {"alg1:k5": "fallback_key5"},
+ "chris_dev_2": {"alg2:k6": "fallback_key6"},
+ },
+ }
+
+ for user_id, devices in fallback_keys.items():
+ for device_id, key_dict in devices.items():
+ self.get_success(
+ self.handler.upload_keys_for_user(
+ user_id,
+ device_id,
+ {"fallback_keys": key_dict},
+ )
+ )
+
+ # Each device should have an unused fallback key.
+ for user_id, devices in fallback_keys.items():
+ for device_id in devices:
+ fallback_res = self.get_success(
+ self.store.get_e2e_unused_fallback_key_types(user_id, device_id)
+ )
+ expected_algorithm_name = f"alg{device_id[-1]}"
+ self.assertEqual(fallback_res, [expected_algorithm_name])
+
+ # Claim the fallback key for one device per user.
+ claim_res = self.get_success(
+ self.handler.claim_one_time_keys(
+ {
+ alice: {"alice_dev_1": {"alg1": 1}},
+ brian: {"brian_dev_2": {"alg2": 1}},
+ chris: {"chris_dev_2": {"alg2": 1}},
+ },
+ self.requester,
+ timeout=None,
+ always_include_fallback_keys=False,
+ )
+ )
+ expected_claims = {
+ alice: {"alice_dev_1": {"alg1:k1": "fallback_key1"}},
+ brian: {"brian_dev_2": {"alg2:k4": "fallback_key4"}},
+ chris: {"chris_dev_2": {"alg2:k6": "fallback_key6"}},
+ }
+ self.assertEqual(
+ claim_res,
+ {"failures": {}, "one_time_keys": expected_claims},
+ )
+
+ for user_id, devices in fallback_keys.items():
+ for device_id in devices:
+ fallback_res = self.get_success(
+ self.store.get_e2e_unused_fallback_key_types(user_id, device_id)
+ )
+ # Claimed fallback keys should no longer show up as unused.
+ # Unclaimed fallback keys should still be unused.
+ if device_id in expected_claims[user_id]:
+ self.assertEqual(fallback_res, [])
+ else:
+ expected_algorithm_name = f"alg{device_id[-1]}"
+ self.assertEqual(fallback_res, [expected_algorithm_name])
+
def test_fallback_key_always_returned(self) -> None:
local_user = "@boris:" + self.hs.hostname
device_id = "xyz"
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