Merge pull request #156 from zhenlineo/1.2-not-retry-on-user-canceled-tx

Support transient but not terminated by user errors in retry

Author: zhenlineo

neo4j/v1/api.py

@@ -27,14 +27,12 @@
 
 from neo4j.bolt import ProtocolError, ServiceUnavailable
 from neo4j.compat import urlparse
-from neo4j.exceptions import CypherError
+from neo4j.exceptions import CypherError, TransientError
 
 from .exceptions import DriverError, SessionError, SessionExpired, TransactionError
 
-
 _warned_about_transaction_bookmarks = False
 
-
 READ_ACCESS = "READ"
 WRITE_ACCESS = "WRITE"
 
@@ -53,7 +51,6 @@ def retry_delay_generator(initial_delay, multiplier, jitter_factor):
 
 
 class ValueSystem(object):
-
     def hydrate(self, values):
         """ Hydrate values from raw representations into client objects.
         """
@@ -435,6 +432,11 @@ def _run_transaction(self, access_mode, unit_of_work, *args, **kwargs):
                     return unit_of_work(tx, *args, **kwargs)
             except (ServiceUnavailable, SessionExpired) as error:
                 last_error = error
+            except TransientError as error:
+                if is_retriable_transientError(error):
+                    last_error = error
+                else:
+                    raise error
             sleep(next(retry_delay))
             t1 = clock()
         raise last_error
@@ -461,6 +463,14 @@ def __bookmark__(self, result):
         pass
 
 
+def is_retriable_transientError(error):
+    """
+    :type error: TransientError
+    """
+    return not (error.code in ("Neo.TransientError.Transaction.Terminated",
+                               "Neo.TransientError.Transaction.LockClientStopped"))
+
+
 class Transaction(object):
     """ Container for multiple Cypher queries to be executed within
     a single context. Transactions can be used within a :py:const:`with`

test/stub/scripts/user_canceled_tx.script.script

@@ -0,0 +1,20 @@
+!: AUTO INIT
+!: AUTO RESET
+
+C: RUN "BEGIN" {}
+   PULL_ALL
+S: SUCCESS {"fields": []}
+   SUCCESS {}
+
+C: RUN "RETURN 1" {}
+   PULL_ALL
+S: FAILURE {"code": "Neo.TransientError.Transaction.LockClientStopped", "message": "X"}
+   IGNORED {}
+
+C: ACK_FAILURE
+S: SUCCESS {}
+
+C: RUN "ROLLBACK" {}
+   PULL_ALL
+S: SUCCESS {}
+   SUCCESS {}

test/stub/test_accesslevel.py

@@ -19,7 +19,7 @@
 # limitations under the License.
 
 
-from neo4j.v1 import GraphDatabase, CypherError
+from neo4j.v1 import GraphDatabase, CypherError, TransientError
 
 from test.stub.tools import StubTestCase, StubCluster
 
@@ -159,3 +159,25 @@ def unit_of_work_2(tx):
                     assert value == 1
                     value = session.read_transaction(unit_of_work_2)
                     assert value == 2
+
+    def test_no_retry_read_on_user_canceled_tx(self):
+        with StubCluster({9001: "router.script", 9004: "user_canceled_tx.script.script"}):
+            uri = "bolt+routing://127.0.0.1:9001"
+            with GraphDatabase.driver(uri, auth=self.auth_token, encrypted=False) as driver:
+                with driver.session() as session:
+                    def unit_of_work(tx):
+                        tx.run("RETURN 1")
+
+                    with self.assertRaises(TransientError):
+                        _ = session.read_transaction(unit_of_work)
+
+    def test_no_retry_write_on_user_canceled_tx(self):
+        with StubCluster({9001: "router.script", 9006: "user_canceled_tx.script.script"}):
+            uri = "bolt+routing://127.0.0.1:9001"
+            with GraphDatabase.driver(uri, auth=self.auth_token, encrypted=False) as driver:
+                with driver.session() as session:
+                    def unit_of_work(tx):
+                        tx.run("RETURN 1")
+
+                    with self.assertRaises(TransientError):
+                        _ = session.write_transaction(unit_of_work)