Revert "Add experimental support for sharding event persister. (#8170)" (#8242)

* Revert "Add experimental support for sharding event persister. (#8170)"

This reverts commit 82c1ee1c22a87b9e6e3179947014b0f11c0a1ac3.

* Changelog

1 files changed, 3 insertions, 18 deletions

diff --git a/synapse/config/_base.py b/synapse/config/_base.py

index 73f0717b0d..1417487427 100644
--- a/synapse/config/_base.py
+++ b/synapse/config/_base.py
@@ -832,26 +832,11 @@ class ShardedWorkerHandlingConfig:
     def should_handle(self, instance_name: str, key: str) -> bool:
         """Whether this instance is responsible for handling the given key.
         """
-        # If multiple instances are not defined we always return true
+
+        # If multiple instances are not defined we always return true.
         if not self.instances or len(self.instances) == 1:
             return True
 
-        return self.get_instance(key) == instance_name
-
-    def get_instance(self, key: str) -> str:
-        """Get the instance responsible for handling the given key.
-
-        Note: For things like federation sending the config for which instance
-        is sending is known only to the sender instance if there is only one.
-        Therefore `should_handle` should be used where possible.
-        """
-
-        if not self.instances:
-            return "master"
-
-        if len(self.instances) == 1:
-            return self.instances[0]
-
         # We shard by taking the hash, modulo it by the number of instances and
         # then checking whether this instance matches the instance at that
         # index.
@@ -861,7 +846,7 @@ class ShardedWorkerHandlingConfig:
         dest_hash = sha256(key.encode("utf8")).digest()
         dest_int = int.from_bytes(dest_hash, byteorder="little")
         remainder = dest_int % (len(self.instances))
-        return self.instances[remainder]
+        return self.instances[remainder] == instance_name
 
 
 __all__ = ["Config", "RootConfig", "ShardedWorkerHandlingConfig"]