fix concurrent access to self.cache in nosqldict (#121)

* fix concurrent access to self.cache in nosqldict

* bump version to 0.4.2

* add -d to docker run in CI

.github/workflows/pythonapp.yml

@@ -29,6 +29,7 @@ jobs:
         if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
     - name: pytest
       run: |
+        docker run -d -p 27017:27017 mongo
         pip install -r dev-requirements.txt
         make test
     - name: lint

Makefile

@@ -18,5 +18,9 @@ format:
 
 test:
 	pip3 install .
-	coverage run -m pytest
+ifdef GITHUB_ACTIONS
+	coverage run -m pytest -v --with_nosqldict
+else
+	coverage run -m pytest -v
+endif
 	coverage report -m

setup.py

@@ -9,7 +9,7 @@
 
 setuptools.setup(
     name="enochecker",
-    version="0.4.1",
+    version="0.4.2",
     author="domenukk",
     author_email="dmaier@sect.tu-berlin.de",
     description="Library to build checker scripts for EnoEngine A/D CTF Framework in Python",

src/enochecker/enochecker.py

@@ -178,7 +178,7 @@ def __init__(
         self.storage_dir = storage_dir
 
         self._setup_logger()
-        if use_db_cache:
+        if use_db_cache and not os.getenv("MONGO_ENABLED"):
             self._active_dbs: Dict[str, Union[NoSqlDict, StoredDict]] = global_db_cache
         else:
             self._active_dbs = {}

src/enochecker/nosqldict.py

@@ -4,7 +4,7 @@
 import logging
 from collections.abc import MutableMapping
 from functools import wraps
-from threading import RLock, current_thread
+from threading import Lock, RLock, current_thread
 from typing import TYPE_CHECKING, Any, Callable, Dict, Iterable, Optional, Union
 
 from . import utils
@@ -135,16 +135,16 @@ def __init__(
         self.checker_name = checker_name
         self.cache: Dict[Any, Any] = {}
         self.hash_cache: Dict[Any, Any] = {}
+        self._lock: Lock = Lock()
         host_: str = host or DB_DEFAULT_HOST
         if isinstance(port, int):
             port_: int = port
         else:
             port_ = int(port or DB_DEFAULT_PORT)
         username_: Optional[str] = username or DB_DEFAULT_USER
         password_: Optional[str] = password or DB_DEFAULT_PASS
-        self.db = self.get_client(host_, port_, username_, password_, self.logger)[
-            checker_name
-        ][self.dict_name]
+        self.client = self.get_client(host_, port_, username_, password_, self.logger)
+        self.db = self.client[checker_name][self.dict_name]
         try:
             self.db.index_information()["checker_key"]
         except KeyError:
@@ -162,14 +162,17 @@ def __setitem__(self, key: str, value: Any) -> None:
         :param key: key in the dictionary
         :param value: value in the dictionary
         """
-        key = str(key)
+        with self._lock:
+            key = str(key)
 
-        self.cache[key] = value
-        hash_ = value_to_hash(value)
-        if hash_:
-            self.hash_cache[key] = hash_
+            self.cache[key] = value
+            hash_ = value_to_hash(value)
+            if hash_:
+                self.hash_cache[key] = hash_
+            elif key in self.hash_cache:
+                del self.hash_cache[key]
 
-        self._upsert(key, value)
+            self._upsert(key, value)
 
     def _upsert(self, key: Any, value: Any) -> None:
         query_dict = {
@@ -198,28 +201,31 @@ def __getitem__(self, key: str, print_result: bool = False) -> Any:
         :param print_result: TODO
         :return: retrieved value
         """
-        key = str(key)
-        if key in self.cache.items():
-            return self.cache[key]
+        with self._lock:
+            key = str(key)
 
-        to_extract = {
-            "key": key,
-            "checker": self.checker_name,
-            "name": self.dict_name,
-        }
+            if key in self.cache:
+                return self.cache[key]
 
-        result = self.db.find_one(to_extract)
+            to_extract = {
+                "key": key,
+                "checker": self.checker_name,
+                "name": self.dict_name,
+            }
 
-        if print_result:
-            self.logger.debug(result)
+            result = self.db.find_one(to_extract)
 
-        if result:
-            self.cache[key] = result["value"]
-            hash_ = value_to_hash(result)
-            if hash_:
-                self.hash_cache[key] = hash_
-            return result["value"]
-        raise KeyError("Could not find {} in {}".format(key, self))
+            if print_result:
+                self.logger.debug(result)
+
+            if result:
+                val = result["value"]
+                self.cache[key] = val
+                hash_ = value_to_hash(val)
+                if hash_:
+                    self.hash_cache[key] = hash_
+                return val
+            raise KeyError("Could not find {} in {}".format(key, self))
 
     @_try_n_times
     def __delitem__(self, key: str) -> None:
@@ -230,16 +236,19 @@ def __delitem__(self, key: str) -> None:
 
         :param key: key to delete
         """
-        key = str(key)
-        if key in self.cache:
-            del self.cache[key]
-
-        to_extract = {
-            "key": key,
-            "checker": self.checker_name,
-            "name": self.dict_name,
-        }
-        self.db.delete_one(to_extract)
+        with self._lock:
+            key = str(key)
+            if key in self.cache:
+                del self.cache[key]
+            if key in self.hash_cache:
+                del self.hash_cache[key]
+
+            to_extract = {
+                "key": key,
+                "checker": self.checker_name,
+                "name": self.dict_name,
+            }
+            self.db.delete_one(to_extract)
 
     @_try_n_times
     def __len__(self) -> int:
@@ -267,14 +276,18 @@ def persist(self) -> None:
         """
         Persist the changes in the backend.
         """
-        for (key, value) in self.cache.items():
-            hash_ = value_to_hash(value)
-            if (
-                (not hash_)
-                or (key not in self.hash_cache)
-                or (self.hash_cache[key] != hash_)
-            ):
-                self._upsert(key, value)
+        with self._lock:
+            for (key, value) in list(self.cache.items()):
+                hash_ = value_to_hash(value)
+                if (
+                    (not hash_)
+                    or (key not in self.hash_cache)
+                    or (self.hash_cache[key] != hash_)
+                ):
+                    self._upsert(key, value)
+                del self.cache[key]
+                if key in self.hash_cache:
+                    del self.hash_cache[key]
 
     def __del__(self) -> None:
         """

tests/conftest.py

@@ -0,0 +1,20 @@
+import pytest
+
+
+def pytest_addoption(parser):
+    parser.addoption(
+        "--with_nosqldict", action="store_true", help="Run the tests with the nosqldict"
+    )
+
+
+def pytest_configure(config):
+    config.addinivalue_line("markers", "nosqldict: mark test as requiring MongoDB")
+
+
+def pytest_collection_modifyitems(config, items):
+    if config.getoption("--with_nosqldict"):
+        return
+    skip_nosqldict = pytest.mark.skip(reason="need --with_nosqldict option to run")
+    for item in items:
+        if "nosqldict" in item.keywords:
+            item.add_marker(skip_nosqldict)

tests/test_enochecker.py

@@ -1,9 +1,11 @@
 #!/usr/bin/env python3
 import functools
 import hashlib
+import secrets
 import sys
 import tempfile
 from logging import DEBUG
+from unittest import mock
 
 import pytest
 from enochecker_core import CheckerMethod, CheckerTaskMessage, CheckerTaskResult
@@ -310,6 +312,44 @@ def putflagfn(self: CheckerExampleImpl):
     assert result.attack_info == attack_info
 
 
+@pytest.mark.nosqldict
+def test_nested_change_enochecker():
+    import os
+
+    with mock.patch.dict(
+        os.environ,
+        {
+            "MONGO_ENABLED": "1",
+        },
+    ):
+        dict_name = secrets.token_hex(8)
+
+        def putflagfn(self: CheckerExampleImpl):
+            db = self.db(dict_name)
+            x = {
+                "asd": 123,
+            }
+            db["test"] = x
+
+            x["asd"] = 456
+
+        def getflagfn(self: CheckerExampleImpl):
+            db = self.db(dict_name)
+            assert db["test"]["asd"] == 456
+
+        setattr(CheckerExampleImpl, "putflag", putflagfn)
+        checker = CheckerExampleImpl(method="putflag")
+
+        result = checker.run()
+        assert result.result == CheckerTaskResult.OK
+
+        setattr(CheckerExampleImpl, "getflag", getflagfn)
+        checker = CheckerExampleImpl(method="getflag")
+
+        result = checker.run()
+        assert result.result == CheckerTaskResult.OK
+
+
 def main():
     pytest.main(sys.argv)
 

tests/test_nosqldict.py

@@ -0,0 +1,55 @@
+import secrets
+
+import pytest
+
+from enochecker.nosqldict import NoSqlDict
+
+
+@pytest.fixture
+def nosqldict():
+    dict_name = secrets.token_hex(8)
+    checker_name = secrets.token_hex(8)
+    return NoSqlDict(dict_name, checker_name)
+
+
+@pytest.mark.nosqldict
+def test_basic(nosqldict):
+    nosqldict["abc"] = "xyz"
+    assert nosqldict["abc"] == "xyz"
+
+    with pytest.raises(KeyError):
+        _ = nosqldict["xyz"]
+
+    nosqldict["abc"] = {"stuff": b"asd"}
+    assert nosqldict["abc"] == {"stuff": b"asd"}
+
+    del nosqldict["abc"]
+    with pytest.raises(KeyError):
+        _ = nosqldict["abc"]
+
+
+@pytest.mark.nosqldict
+def test_nested_change():
+    dict_name = secrets.token_hex(8)
+    checker_name = secrets.token_hex(8)
+
+    def scoped_access(dict_name, checker_name):
+        nosqldict = NoSqlDict(dict_name, checker_name)
+
+        x = {
+            "asd": 123,
+        }
+        nosqldict["test"] = x
+        x["asd"] = 456
+
+        assert nosqldict["test"] == {
+            "asd": 456,
+        }
+
+    scoped_access(dict_name, checker_name)
+
+    nosqldict_new = NoSqlDict(dict_name, checker_name)
+
+    assert nosqldict_new["test"] == {
+        "asd": 456,
+    }