Merge pull request #13 from xoeye/bugfix/versioned-diffed-update-item…

…-retries-transaction-conflicts

fix: versioned updates should also be resilient to concurrent transactions

CHANGES.md

@@ -1,3 +1,8 @@
+### 1.10.2
+
+- Fixed `versioned_diffed_update_item` to support concurrent use with
+  transactions.
+
 ### 1.10.1
 
 - Fixed bug in `versioned_transact_write_items` where un-effected

xoto3/__about__.py

@@ -1,4 +1,4 @@
 """xoto3"""
-__version__ = "1.10.1"
+__version__ = "1.10.2"
 __author__ = "Peter Gaultney"
 __author_email__ = "[email protected]"

xoto3/dynamodb/update/versioned.py

@@ -22,7 +22,10 @@
     strongly_consistent_get_item_if_exists,
 )
 from xoto3.dynamodb.types import AttrDict, Item, ItemKey, TableResource
-from xoto3.errors import client_error_name
+from xoto3.dynamodb.write_versioned.ddb_api import (
+    is_cancelled_and_retryable,
+    versioned_item_expression,
+)
 from xoto3.utils.dt import iso8601strict
 from xoto3.utils.tree_map import SimpleTransform
 
@@ -157,7 +160,7 @@ def versioned_diffed_update_item(
             update_item(table, item_key, **update_arguments, **expr)
             return updated_item
         except ClientError as ce:
-            if client_error_name(ce) == "ConditionalCheckFailedException":
+            if is_cancelled_and_retryable(ce):
                 msg = (
                     "Attempt %d to update %s in table %s was beaten "
                     + "by a different update. Sleeping for %s seconds."
@@ -187,36 +190,6 @@ def versioned_diffed_update_item(
     )
 
 
-# this could be used in a put_item scenario as well, or even with a batch_writer
-def versioned_item_expression(
-    item_version: int, item_version_key: str = "item_version", id_that_exists: str = ""
-) -> dict:
-    """Assembles a DynamoDB ConditionExpression with ExprAttrNames and
-    Values that will ensure that you are the only caller of
-    versioned_item_diffed_update that has updated this item.
-
-    In general it would be a silly thing to not pass id_that_exists if
-    your item_version is not also 0.  However, since this is just a
-    helper function and is only used (currently) by the local consumer
-    versioned_item_diffed_update, there is no need to enforce this.
-
-    """
-    expr_names = {"#itemVersion": item_version_key}
-    expr_vals = {":curItemVersion": item_version}
-    item_version_condition = "#itemVersion = :curItemVersion"
-    first_time_version_condition = "attribute_not_exists(#itemVersion)"
-    if id_that_exists:
-        expr_names["#idThatExists"] = id_that_exists
-        first_time_version_condition = (
-            f"( {first_time_version_condition} AND attribute_exists(#idThatExists) )"
-        )
-    return dict(
-        ExpressionAttributeNames=expr_names,
-        ExpressionAttributeValues=expr_vals,
-        ConditionExpression=item_version_condition + " OR " + first_time_version_condition,
-    )
-
-
 def make_prefetched_get_item(
     item: Item,
     refetch_getter: ItemGetter = strongly_consistent_get_item,

xoto3/dynamodb/write_versioned/ddb_api.py

@@ -9,7 +9,6 @@
 from typing_extensions import Protocol, TypedDict
 
 from xoto3.dynamodb.types import Item
-from xoto3.dynamodb.update.versioned import versioned_item_expression
 from xoto3.dynamodb.utils.serde import serialize_item
 from xoto3.dynamodb.utils.table import table_primary_keys
 from xoto3.errors import client_error_name
@@ -134,6 +133,36 @@ def _serialize_versioned_expr(expr: dict) -> dict:
     return dict(expr, ExpressionAttributeValues=serialize_item(expr["ExpressionAttributeValues"]))
 
 
+# this could be used in a put_item scenario as well, or even with a batch_writer
+def versioned_item_expression(
+    item_version: int, item_version_key: str = "item_version", id_that_exists: str = ""
+) -> dict:
+    """Assembles a DynamoDB ConditionExpression with ExprAttrNames and
+    Values that will ensure that you are the only caller of
+    versioned_item_diffed_update that has updated this item.
+
+    In general it would be a silly thing to not pass id_that_exists if
+    your item_version is not also 0.  However, since this is just a
+    helper function and is only used (currently) by the local consumer
+    versioned_item_diffed_update, there is no need to enforce this.
+
+    """
+    expr_names = {"#itemVersion": item_version_key}
+    expr_vals = {":curItemVersion": item_version}
+    item_version_condition = "#itemVersion = :curItemVersion"
+    first_time_version_condition = "attribute_not_exists(#itemVersion)"
+    if id_that_exists:
+        expr_names["#idThatExists"] = id_that_exists
+        first_time_version_condition = (
+            f"( {first_time_version_condition} AND attribute_exists(#idThatExists) )"
+        )
+    return dict(
+        ExpressionAttributeNames=expr_names,
+        ExpressionAttributeValues=expr_vals,
+        ConditionExpression=item_version_condition + " OR " + first_time_version_condition,
+    )
+
+
 def built_transaction_to_transact_write_items_args(
     transaction: VersionedTransaction,
     last_written_at_str: str,