Revert the deletion of stale devices due to performance issues. (#14662)

7 files changed, 5 insertions, 152 deletions

diff --git a/changelog.d/14595.misc b/changelog.d/14595.misc
deleted file mode 100644
index f9bfc581ad..0000000000
--- a/changelog.d/14595.misc
+++ /dev/null
@@ -1 +0,0 @@
-Prune user's old devices on login if they have too many.
diff --git a/changelog.d/14649.misc b/changelog.d/14649.misc
deleted file mode 100644
index f9bfc581ad..0000000000
--- a/changelog.d/14649.misc
+++ /dev/null
@@ -1 +0,0 @@
-Prune user's old devices on login if they have too many.
diff --git a/changelog.d/14662.removal b/changelog.d/14662.removal
new file mode 100644
index 0000000000..19a387bbb4
--- /dev/null
+++ b/changelog.d/14662.removal
@@ -0,0 +1 @@
+(remove from changelog: unreleased) Revert the deletion of stale devices due to performance issues.
\ No newline at end of file
diff --git a/synapse/handlers/device.py b/synapse/handlers/device.py
index c935c7be90..d4750a32e6 100644
--- a/synapse/handlers/device.py
+++ b/synapse/handlers/device.py
@@ -52,7 +52,6 @@ from synapse.util import stringutils
 from synapse.util.async_helpers import Linearizer
 from synapse.util.caches.expiringcache import ExpiringCache
 from synapse.util.cancellation import cancellable
-from synapse.util.iterutils import batch_iter
 from synapse.util.metrics import measure_func
 from synapse.util.retryutils import NotRetryingDestination
 
@@ -422,9 +421,6 @@ class DeviceHandler(DeviceWorkerHandler):
 
         self._check_device_name_length(initial_device_display_name)
 
-        # Prune the user's device list if they already have a lot of devices.
-        await self._prune_too_many_devices(user_id)
-
         if device_id is not None:
             new_device = await self.store.store_device(
                 user_id=user_id,
@@ -456,33 +452,6 @@ class DeviceHandler(DeviceWorkerHandler):
 
         raise errors.StoreError(500, "Couldn't generate a device ID.")
 
-    async def _prune_too_many_devices(self, user_id: str) -> None:
-        """Delete any excess old devices this user may have."""
-        device_ids = await self.store.check_too_many_devices_for_user(user_id, 100)
-        if not device_ids:
-            return
-
-        logger.info("Pruning %d old devices for user %s", len(device_ids), user_id)
-
-        # We don't want to block and try and delete tonnes of devices at once,
-        # so we cap the number of devices we delete synchronously.
-        first_batch, remaining_device_ids = device_ids[:10], device_ids[10:]
-        await self.delete_devices(user_id, first_batch)
-
-        if not remaining_device_ids:
-            return
-
-        # Now spawn a background loop that deletes the rest.
-        async def _prune_too_many_devices_loop() -> None:
-            for batch in batch_iter(remaining_device_ids, 10):
-                await self.delete_devices(user_id, batch)
-
-                await self.clock.sleep(1)
-
-        run_as_background_process(
-            "_prune_too_many_devices_loop", _prune_too_many_devices_loop
-        )
-
     async def _delete_stale_devices(self) -> None:
         """Background task that deletes devices which haven't been accessed for more than
         a configured time period.
@@ -512,7 +481,7 @@ class DeviceHandler(DeviceWorkerHandler):
             device_ids = [d for d in device_ids if d != except_device_id]
         await self.delete_devices(user_id, device_ids)
 
-    async def delete_devices(self, user_id: str, device_ids: Collection[str]) -> None:
+    async def delete_devices(self, user_id: str, device_ids: List[str]) -> None:
         """Delete several devices
 
         Args:
diff --git a/synapse/storage/databases/main/devices.py b/synapse/storage/databases/main/devices.py
index 95d4c0622d..a5bb4d404e 100644
--- a/synapse/storage/databases/main/devices.py
+++ b/synapse/storage/databases/main/devices.py
@@ -1569,77 +1569,6 @@ class DeviceBackgroundUpdateStore(SQLBaseStore):
 
         return rows
 
-    async def check_too_many_devices_for_user(
-        self, user_id: str, limit: int
-    ) -> List[str]:
-        """Check if the user has a lot of devices, and if so return the set of
-        devices we can prune.
-
-        This does *not* return hidden devices or devices with E2E keys.
-
-        Returns at most `limit` number of devices, ordered by last seen.
-        """
-
-        num_devices = await self.db_pool.simple_select_one_onecol(
-            table="devices",
-            keyvalues={"user_id": user_id, "hidden": False},
-            retcol="COALESCE(COUNT(*), 0)",
-            desc="count_devices",
-        )
-
-        # We let users have up to ten devices without pruning.
-        if num_devices <= 10:
-            return []
-
-        # We prune everything older than N days.
-        max_last_seen = self._clock.time_msec() - 14 * 24 * 60 * 60 * 1000
-
-        if num_devices > 50:
-            # If the user has more than 50 devices, then we chose a last seen
-            # that ensures we keep at most 50 devices.
-            sql = """
-                SELECT last_seen FROM devices
-                LEFT JOIN e2e_device_keys_json USING (user_id, device_id)
-                WHERE
-                    user_id = ?
-                    AND NOT hidden
-                    AND last_seen IS NOT NULL
-                    AND key_json IS NULL
-                ORDER BY last_seen DESC
-                LIMIT 1
-                OFFSET 50
-            """
-
-            rows = await self.db_pool.execute(
-                "check_too_many_devices_for_user_last_seen", None, sql, (user_id,)
-            )
-            if rows:
-                max_last_seen = max(rows[0][0], max_last_seen)
-
-        # Now fetch the devices to delete.
-        sql = """
-            SELECT device_id FROM devices
-            LEFT JOIN e2e_device_keys_json USING (user_id, device_id)
-            WHERE
-                user_id = ?
-                AND NOT hidden
-                AND last_seen < ?
-                AND key_json IS NULL
-            ORDER BY last_seen
-            LIMIT ?
-        """
-
-        def check_too_many_devices_for_user_txn(
-            txn: LoggingTransaction,
-        ) -> List[str]:
-            txn.execute(sql, (user_id, max_last_seen, limit))
-            return [device_id for device_id, in txn]
-
-        return await self.db_pool.runInteraction(
-            "check_too_many_devices_for_user",
-            check_too_many_devices_for_user_txn,
-        )
-
 
 class DeviceStore(DeviceWorkerStore, DeviceBackgroundUpdateStore):
     # Because we have write access, this will be a StreamIdGenerator
@@ -1698,7 +1627,6 @@ class DeviceStore(DeviceWorkerStore, DeviceBackgroundUpdateStore):
                 values={},
                 insertion_values={
                     "display_name": initial_device_display_name,
-                    "last_seen": self._clock.time_msec(),
                     "hidden": False,
                 },
                 desc="store_device",
@@ -1744,15 +1672,7 @@ class DeviceStore(DeviceWorkerStore, DeviceBackgroundUpdateStore):
             )
             raise StoreError(500, "Problem storing device.")
 
-    @cached(max_entries=0)
-    async def delete_device(self, user_id: str, device_id: str) -> None:
-        raise NotImplementedError()
-
-    # Note: sometimes deleting rows out of `device_inbox` can take a long time,
-    # so we use a cache so that we deduplicate in flight requests to delete
-    # devices.
-    @cachedList(cached_method_name="delete_device", list_name="device_ids")
-    async def delete_devices(self, user_id: str, device_ids: Collection[str]) -> dict:
+    async def delete_devices(self, user_id: str, device_ids: List[str]) -> None:
         """Deletes several devices.
 
         Args:
@@ -1789,8 +1709,6 @@ class DeviceStore(DeviceWorkerStore, DeviceBackgroundUpdateStore):
         for device_id in device_ids:
             self.device_id_exists_cache.invalidate((user_id, device_id))
 
-        return {}
-
     async def update_device(
         self, user_id: str, device_id: str, new_display_name: Optional[str] = None
     ) -> None:
diff --git a/tests/handlers/test_device.py b/tests/handlers/test_device.py
index e51cac9b33..ce7525e29c 100644
--- a/tests/handlers/test_device.py
+++ b/tests/handlers/test_device.py
@@ -20,8 +20,6 @@ from twisted.test.proto_helpers import MemoryReactor
 
 from synapse.api.errors import NotFoundError, SynapseError
 from synapse.handlers.device import MAX_DEVICE_DISPLAY_NAME_LEN, DeviceHandler
-from synapse.rest import admin
-from synapse.rest.client import account, login
 from synapse.server import HomeServer
 from synapse.util import Clock
 
@@ -32,12 +30,6 @@ user2 = "@theresa:bbb"
 
 
 class DeviceTestCase(unittest.HomeserverTestCase):
-    servlets = [
-        login.register_servlets,
-        admin.register_servlets,
-        account.register_servlets,
-    ]
-
     def make_homeserver(self, reactor: MemoryReactor, clock: Clock) -> HomeServer:
         hs = self.setup_test_homeserver("server", federation_http_client=None)
         handler = hs.get_device_handler()
@@ -123,7 +115,7 @@ class DeviceTestCase(unittest.HomeserverTestCase):
                 "device_id": "xyz",
                 "display_name": "display 0",
                 "last_seen_ip": None,
-                "last_seen_ts": 1000000,
+                "last_seen_ts": None,
             },
             device_map["xyz"],
         )
@@ -237,29 +229,6 @@ class DeviceTestCase(unittest.HomeserverTestCase):
             NotFoundError,
         )
 
-    def test_login_delete_old_devices(self) -> None:
-        """Delete old devices if the user already has too many."""
-
-        user_id = self.register_user("user", "pass")
-
-        # Create a bunch of devices
-        for _ in range(50):
-            self.login("user", "pass")
-            self.reactor.advance(1)
-
-        # Advance the clock for ages (as we only delete old devices)
-        self.reactor.advance(60 * 60 * 24 * 300)
-
-        # Log in again to start the pruning
-        self.login("user", "pass")
-
-        # Give the background job time to do its thing
-        self.reactor.pump([1.0] * 100)
-
-        # We should now only have the most recent device.
-        devices = self.get_success(self.handler.get_devices_by_user(user_id))
-        self.assertEqual(len(devices), 1)
-
     def _record_users(self) -> None:
         # check this works for both devices which have a recorded client_ip,
         # and those which don't.
diff --git a/tests/storage/test_client_ips.py b/tests/storage/test_client_ips.py
index 81e4e596e4..7f7f4ef892 100644
--- a/tests/storage/test_client_ips.py
+++ b/tests/storage/test_client_ips.py
@@ -170,8 +170,6 @@ class ClientIpStoreTestCase(unittest.HomeserverTestCase):
             )
         )
 
-        last_seen = self.clock.time_msec()
-
         if after_persisting:
             # Trigger the storage loop
             self.reactor.advance(10)
@@ -192,7 +190,7 @@ class ClientIpStoreTestCase(unittest.HomeserverTestCase):
                         "device_id": device_id,
                         "ip": None,
                         "user_agent": None,
-                        "last_seen": last_seen,
+                        "last_seen": None,
                     },
                 ],
             )