Merge pull request #420 from icon-project/IS-1021-dict-db-iteration-c…

…auses-infinite-loop

IS-1021: DictDB iteration causes infinite loop

iconservice/iconscore/icon_container_db.py

@@ -216,6 +216,9 @@ def __remove(self, key: K) -> None:
             raise InvalidContainerAccessException('DictDB depth mismatch')
         self._db.delete(get_encoded_key(key))
 
+    def __iter__(self):
+        raise InvalidContainerAccessException("Not Supported iter function on DictDB")
+
 
 class ArrayDB(object):
     """

tests/icon_score/test_icon_container_db.py

@@ -339,3 +339,53 @@ def test_container_util(self):
         with self.assertRaises(InvalidParamsException):
             prefix: bytes = ContainerUtil.create_db_prefix(VarDB, 'vardb')
 
+
+"""
+Dict DB infinity infinite case
+implement __getitem__ function means can be iter
+https://www.python.org/dev/peps/pep-0234
+https://docs.python.org/3/reference/datamodel.html#object.__getitem__
+"""
+
+
+class TestOnlyGetItemObj:
+    """
+    Override getitem function
+    If you don't consider this case, this logic will always have an infinite loop.
+    https://stackoverflow.com/questions/926574/why-does-defining-getitem-on-a-class-make-it-iterable-in-python
+    """
+    def __init__(self, limit):
+        self._limit = limit
+
+    def __getitem__(self, key):
+        if key > self._limit:
+            raise IndexError(key)
+
+
+class TestIterObj(TestOnlyGetItemObj):
+    """
+    Override the iter function.
+    This logic prevents the above infinite loop situation.
+    https://stackoverflow.com/questions/926574/why-does-defining-getitem-on-a-class-make-it-iterable-in-python
+    """
+    def __iter__(self):
+        pass
+
+
+class TestIsAvailableToIterator(unittest.TestCase):
+    def test_getitem(self):
+        # it is possible to use foreach by using getitem
+        limit = 100_000
+        datas = TestOnlyGetItemObj(limit)
+        index = 0
+        for index, e in enumerate(datas):
+            pass
+        self.assertEqual(index, limit)
+
+    def test_iter(self):
+        # prevent infinite loop by using empty __iter function
+        limit = 100_000
+        datas = TestIterObj(limit)
+        with self.assertRaises(TypeError) as e:
+            for e in datas:
+                pass

tests/integrate_test/samples/sample_scores/sample_dict_db/package.json

@@ -0,0 +1,5 @@
+{
+    "version": "0.0.1",
+    "main_file": "sample_dict_db",
+    "main_score": "IterableDictDB"
+}

tests/integrate_test/samples/sample_scores/sample_dict_db/sample_dict_db.py

@@ -0,0 +1,39 @@
+# -*- coding: utf-8 -*-
+
+"""
+Example
+
+Problem with DictDB : cannot iterate
+https://forum.icon.community/t/problem-with-dictdb-cannot-iterate/484
+"""
+
+from iconservice import *
+TAG = 'IterableDictDB'
+
+
+class IterableDictDB(IconScoreBase):
+    """ IterableDictDB SCORE Base implementation """
+
+    # ================================================
+    #  Initialization
+    # ================================================
+    def __init__(self, db: IconScoreDatabase) -> None:
+        super().__init__(db)
+        self._dict = DictDB('DICT', db, value_type=int)
+
+    def on_install(self) -> None:
+        super().on_install()
+
+    def on_update(self) -> None:
+        super().on_update()
+
+    @external
+    def create_item(self, key: str, value: int) -> None:
+        self._dict[key] = value
+
+    @external(readonly=True)
+    def get_items(self) -> list:
+        items = []
+        for item in self._dict:
+            items.append(item)
+        return items

tests/integrate_test/test_integrate_array_db_patch.py → tests/integrate_test/test_integrate_container_db_patch.py

@@ -21,6 +21,7 @@
 
 from iconservice.base.address import GOVERNANCE_SCORE_ADDRESS
 from iconservice.icon_constant import Revision
+from iconservice.base.exception import InvalidContainerAccessException
 from tests.integrate_test.test_integrate_base import TestIntegrateBase
 
 if TYPE_CHECKING:
@@ -112,3 +113,45 @@ def test_array_db_patch(self):
         )
 
         self.assertEqual(len(response), 2)
+
+
+class TestIntegrateDictDBPatch(TestIntegrateBase):
+    def test_dict_db_defective(self):
+        self.update_governance("0_0_4")
+
+        expected_status = {
+            "code": Revision.TWO.value,
+            "name": "1.1.0"
+        }
+
+        query_request = {
+            "version": self._version,
+            "from": self._accounts[0],
+            "to": GOVERNANCE_SCORE_ADDRESS,
+            "dataType": "call",
+            "data": {
+                "method": "getRevision",
+                "params": {}
+            }
+        }
+        response = self._query(query_request)
+        self.assertEqual(expected_status, response)
+
+        tx_results: List['TransactionResult'] = self.deploy_score("sample_scores",
+                                                                  "sample_dict_db",
+                                                                  self._accounts[0])
+        score_address: 'Address' = tx_results[0].score_address
+
+        self.score_call(self._accounts[0], score_address, "create_item", params={"key": "a", "value": hex(1)})
+
+        with self.assertRaises(InvalidContainerAccessException) as e:
+            self._query(
+                {
+                    'to': score_address,
+                    'dataType': 'call',
+                    'data': {
+                        'method': 'get_items'
+                    }
+                }
+            )
+        self.assertEqual(e.exception.message, "Not Supported on DictDB")