Simple is better than complex

src/olympia/blocklist/mlbf.py

@@ -310,46 +310,24 @@ def generate_and_write_stash(self, previous_mlbf: 'MLBF' = None):
         stash_json = {key: [] for key in [UNBLOCKED_STASH_KEY, *STASH_KEYS.values()]}
 
         diffs = self.generate_diffs(previous_mlbf)
-        soft_block_enabled = waffle.switch_is_active('enable-soft-blocking')
-        set_blocked_any_type = set()
-        # Build the stash json from the diff of each block type
-        for block_type in BlockType:
-            skip_no_changes = not self.should_upload_stash(block_type, previous_mlbf)
-            skip_soft_block = (
-                block_type == BlockType.SOFT_BLOCKED and not soft_block_enabled
-            )
-
-            # If there are no additions or removals, or if soft blocking is disabled.
-            if any([skip_no_changes, skip_soft_block]):
-                continue
-
-            added, removed, _ = diffs[block_type]
-            # Keep track of items added to all block types
-            # regardless if we will end up writing to the stash or not.
-            # This is used to filter out items from the unblocked list.
-            set_blocked_any_type.update(added)
-
-            # If we are not going to upload a filter for this block type,
-            # include the added items in the stash for this block type.
-            if not self.should_upload_filter(block_type, previous_mlbf):
-                stash_json[STASH_KEYS[block_type]] = added
-                # For now, add all items removed from the block type to the
-                # unblocked list. Items that are also added to another block list
-                # will be filtered out after we have collected all added items.
-                stash_json[UNBLOCKED_STASH_KEY].extend(removed)
-
-        # Filter out any items that are removed from one block type
-        # and added to another. We do not support transitions from one
-        # block type to another so we should not include those items in the
-        # unblocked list.
-        stash_json[UNBLOCKED_STASH_KEY] = [
-            item
-            for item in stash_json[UNBLOCKED_STASH_KEY]
-            if item not in set_blocked_any_type
-        ]
-
-        # Write the stash json to the stash file, even if there are no changes.
-        # We should be able to inspect that the changes even if there are none.
+        blocked_added, blocked_removed, _ = diffs[BlockType.BLOCKED]
+
+        if not self.should_upload_filter(BlockType.BLOCKED):
+            stash_json[STASH_KEYS[BlockType.BLOCKED]] = blocked_added
+            stash_json[UNBLOCKED_STASH_KEY] = blocked_removed
+
+        if waffle.switch_is_active('enable-soft-blocking'):
+            soft_blocked_added, soft_blocked_removed, _ = diffs[BlockType.SOFT_BLOCKED]
+            if not self.should_upload_filter(BlockType.SOFT_BLOCKED):
+                stash_json[STASH_KEYS[BlockType.SOFT_BLOCKED]] = soft_blocked_added
+                added_items = set(blocked_added + soft_blocked_added)
+                stash_json[UNBLOCKED_STASH_KEY] = [
+                    unblocked
+                    for unblocked in (blocked_removed + soft_blocked_removed)
+                    if unblocked not in added_items
+                ]
+
+        # write stash
         stash_path = self.stash_path
         with self.storage.open(stash_path, 'w') as json_file:
             log.info(f'Writing to file {stash_path}')