Cache JSON definitions in memory LFU cache provided by cachetools

- Path and modified time of JSON file are used as the cache key
- Global state is hidden away inside a root-class for re-use
- Maximum size is 150 considering the number of JSON definitions

During my tests the memory usage of the test suites was halved.

Pipfile.lock

@@ -31,6 +31,13 @@
             ],
             "version": "==4.8.0"
         },
+        "cachetools": {
+            "hashes": [
+                "sha256:428266a1c0d36dc5aca63a2d7c5942e88c2c898d72139fca0e97fdd2380517ae",
+                "sha256:8ea2d3ce97850f31e4a08b0e2b5e6c34997d7216a9d2c98e0f3978630d4da69a"
+            ],
+            "version": "==3.1.1"
+        },
         "certifi": {
             "hashes": [
                 "sha256:046832c04d4e752f37383b628bc601a7ea7211496b4638f6514d0e5b9acc4939",
@@ -266,6 +273,13 @@
             ],
             "version": "==4.8.0"
         },
+        "cachetools": {
+            "hashes": [
+                "sha256:428266a1c0d36dc5aca63a2d7c5942e88c2c898d72139fca0e97fdd2380517ae",
+                "sha256:8ea2d3ce97850f31e4a08b0e2b5e6c34997d7216a9d2c98e0f3978630d4da69a"
+            ],
+            "version": "==3.1.1"
+        },
         "certifi": {
             "hashes": [
                 "sha256:046832c04d4e752f37383b628bc601a7ea7211496b4638f6514d0e5b9acc4939",

pymisp/abstract.py

@@ -4,9 +4,11 @@
 import sys
 import datetime
 import json
+import os
 from json import JSONEncoder
 import logging
 from enum import Enum
+import cachetools
 
 from .exceptions import PyMISPInvalidFormat
 
@@ -38,6 +40,12 @@ if sys.version_info < (3, 0):
             return timedelta(0)
 
 
+if (3, 0) <= sys.version_info < (3, 6):
+    OLD_PY3 = True
+else:
+    OLD_PY3 = False
+
+
 class Distribution(Enum):
     your_organisation_only = 0
     this_community_only = 1
@@ -80,7 +88,30 @@ class MISPEncode(JSONEncoder):
         return JSONEncoder.default(self, obj)
 
 
-class AbstractMISP(MutableMapping):
+class MISPFileCache(object):
+    # cache up to 150 JSON structures in class attribute
+    _file_cache = cachetools.LFUCache(150)
+
+    @staticmethod
+    def _load_json(path):
+        # use hard-coded root class attribute
+        file_cache = MISPFileCache._file_cache
+        # use modified time with path as cache key
+        mtime = os.path.getmtime(path)
+        if path in file_cache:
+            ctime, data = file_cache[path]
+            if ctime == mtime:
+                return data
+        with open(path, 'rb') as f:
+            if OLD_PY3:
+                data = json.loads(f.read().decode())
+            else:
+                data = json.load(f)
+        file_cache[path] = (mtime, data)
+        return data
+
+
+class AbstractMISP(MutableMapping, MISPFileCache):
 
     def __init__(self, **kwargs):
         """Abstract class for all the MISP objects"""

pymisp/api.py

@@ -19,7 +19,7 @@ from deprecated import deprecated
 from . import __version__, warning_2020
 from .exceptions import PyMISPError, SearchError, NoURL, NoKey, PyMISPEmptyResponse
 from .mispevent import MISPEvent, MISPAttribute, MISPUser, MISPOrganisation, MISPSighting, MISPFeed, MISPObject, MISPSharingGroup
-from .abstract import AbstractMISP, MISPEncode
+from .abstract import AbstractMISP, MISPEncode, MISPFileCache
 
 logger = logging.getLogger('pymisp')
 
@@ -37,11 +37,6 @@ try:
 except ImportError:
     HAVE_REQUESTS = False
 
-if (3, 0) <= sys.version_info < (3, 6):
-    OLD_PY3 = True
-else:
-    OLD_PY3 = False
-
 try:
     from requests_futures.sessions import FuturesSession
     ASYNC_OK = True
@@ -58,7 +53,7 @@ Response (if any):
 {}'''
 
 
-class PyMISP(object):  # pragma: no cover
+class PyMISP(MISPFileCache):  # pragma: no cover
     """Python API for MISP
 
     :param url: URL of the MISP instance you want to connect to
@@ -140,11 +135,7 @@ class PyMISP(object):  # pragma: no cover
 
     @deprecated(reason="Use ExpandedPyMISP.describe_types_local", version='2.4.110')
     def get_local_describe_types(self):
-        with open(os.path.join(self.resources_path, 'describeTypes.json'), 'rb') as f:
-            if OLD_PY3:
-                describe_types = json.loads(f.read().decode())
-            else:
-                describe_types = json.load(f)
+        describe_types = self._load_json(os.path.join(self.resources_path, 'describeTypes.json'))
         return describe_types['result']
 
     @deprecated(reason="Use ExpandedPyMISP.describe_types_remote", version='2.4.110')

pymisp/aping.py

@@ -105,8 +105,7 @@ class ExpandedPyMISP(PyMISP):
     @property
     def describe_types_local(self):
         '''Returns the content of describe types from the package'''
-        with (self.resources_path / 'describeTypes.json').open() as f:
-            describe_types = json.load(f)
+        describe_types = self._load_json(str(self.resources_path / 'describeTypes.json'))
         return describe_types['result']
 
     @property

pymisp/mispevent.py

@@ -109,11 +109,7 @@ class MISPAttribute(AbstractMISP):
         super(MISPAttribute, self).__init__()
         if not describe_types:
             ressources_path = os.path.join(os.path.abspath(os.path.dirname(__file__)), 'data')
-            with open(os.path.join(ressources_path, 'describeTypes.json'), 'rb') as f:
-                if OLD_PY3:
-                    t = json.loads(f.read().decode())
-                else:
-                    t = json.load(f)
+            t = self._load_json(os.path.join(ressources_path, 'describeTypes.json'))
             describe_types = t['result']
         self.__categories = describe_types['categories']
         self._types = describe_types['types']
@@ -411,26 +407,14 @@ class MISPEvent(AbstractMISP):
         super(MISPEvent, self).__init__(**kwargs)
         ressources_path = os.path.join(os.path.abspath(os.path.dirname(__file__)), 'data')
         if strict_validation:
-            with open(os.path.join(ressources_path, 'schema.json'), 'rb') as f:
-                if OLD_PY3:
-                    self.__json_schema = json.loads(f.read().decode())
-                else:
-                    self.__json_schema = json.load(f)
+            self.__json_schema = self._load_json(os.path.join(ressources_path, 'schema.json'))
         else:
-            with open(os.path.join(ressources_path, 'schema-lax.json'), 'rb') as f:
-                if OLD_PY3:
-                    self.__json_schema = json.loads(f.read().decode())
-                else:
-                    self.__json_schema = json.load(f)
+            self.__json_schema = self._load_json(os.path.join(ressources_path, 'schema-lax.json'))
         if describe_types:
             # This variable is used in add_attribute in order to avoid duplicating the structure
             self._describe_types = describe_types
         else:
-            with open(os.path.join(ressources_path, 'describeTypes.json'), 'rb') as f:
-                if OLD_PY3:
-                    t = json.loads(f.read().decode())
-                else:
-                    t = json.load(f)
+            t = self._load_json(os.path.join(ressources_path, 'describeTypes.json'))
             self._describe_types = t['result']
 
         self._types = self._describe_types['types']
@@ -1190,11 +1174,7 @@ class MISPObject(AbstractMISP):
     def _load_template_path(self, template_path):
         if not os.path.exists(template_path):
             return False
-        with open(template_path, 'rb') as f:
-            if OLD_PY3:
-                self._definition = json.loads(f.read().decode())
-            else:
-                self._definition = json.load(f)
+        self._definition = self._load_json(template_path)
         setattr(self, 'meta-category', self._definition['meta-category'])
         self.template_uuid = self._definition['uuid']
         self.description = self._definition['description']

setup.py

@@ -41,7 +41,7 @@ setup(
     ],
     install_requires=['six', 'requests', 'python-dateutil', 'jsonschema',
                       'python-dateutil', 'enum34;python_version<"3.4"',
-                      'functools32;python_version<"3.0"', 'deprecated'],
+                      'functools32;python_version<"3.0"', 'deprecated', 'cachetools'],
     extras_require={'fileobjects': ['lief>=0.8,<0.10;python_version<"3.5"', 'lief>=0.10.0.dev0;python_version>"3.5"', 'python-magic', 'pydeep'],
                     'neo': ['py2neo'],
                     'openioc': ['beautifulsoup4'],