use lock in mutikey getOne and get methods (#361)

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- [x] Bug fix (non-breaking change which fixes an issue)
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- [x] I have updated the [changelog](../CHANGELOG.md) accordingly.
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.github/workflows/build.yml

@@ -115,7 +115,7 @@ jobs:
           retention-days: 5
 
       - name: Upload coverage reports to Codecov
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v4
         with:
           fail_ci_if_error: true
           token: ${{ secrets.CODECOV_TOKEN }}

CHANGELOG.md

@@ -6,6 +6,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+- accessing a multikey may lead to IndexError [#359](https://github.com/Draegerwerk/sdc11073/issues/359)
+
 ## [1.3.2] - 2024-03-18
 
 ### Fixed

src/sdc11073/multikey.py

@@ -1,3 +1,4 @@
+from __future__ import annotations
 from collections import defaultdict, namedtuple
 from threading import RLock
 
@@ -43,17 +44,32 @@ def __init__(self, getKeyFunc, indexNoneValues=True):
         super(IndexDefinition, self).__init__()
         self._getKeyFunc = getKeyFunc
         self._indexNoneValues = indexNoneValues
+        self._lock: RLock | None = None
 
     def getOne(self, key, allowNone=False):
-        try:
-            result = self[key]
-            if len(result) > 1:
-                raise RuntimeError('getOne: key "{}" has {} objects'.format(key, len(result)))
-            return result[0]
-        except KeyError:
-            if allowNone:
-                return
-            raise RuntimeError('key "{}" not found'.format(key))
+        with self._lock:
+            try:
+                result = self[key]
+                if len(result) > 1:
+                    raise RuntimeError('getOne: key "{}" has {} objects'.format(key, len(result)))
+                return result[0]
+            except KeyError:
+                if allowNone:
+                    return
+                raise RuntimeError('key "{}" not found'.format(key))
+
+    def get(self, *args, **kwargs):
+        """Overwritten get method that uses lock."""
+        with self._lock:
+            return super().get(*args, **kwargs)
+
+    def __getitem__(self, key):
+        """Overwritten __getitem__ method that uses lock."""
+        with self._lock:
+            return super().__getitem__(key)
+
+    def set_lock(self, lock):
+        self._lock = lock
 
     def _mkKeys(self, obj):
         key = self._getKeyFunc(obj)
@@ -161,6 +177,7 @@ def __getattr__(self, name):
 
     def addIndex(self, indexName, indexDefinition):
         self._idxDefs[indexName] = indexDefinition
+        indexDefinition.set_lock(self._lock)
         # add existing objects to new lookup
         for obj in self._objects:
             keys = indexDefinition._mkKeys(obj)