Enable caching functions arising from exec of strings (continued)

numba/core/caching.py

@@ -308,6 +308,47 @@ def from_function(cls, py_func, py_file):
         return self
 
 
+class _StringSrcCacheLocator(_UserProvidedCacheLocator):
+
+    def __init__(self, py_func, py_file):
+        self._identifier = self._hash(py_func)
+        super().__init__(py_func, py_file)
+        # FIXME: this is a bit of a hack, but we need to ensure the cache
+
+    def get_source_stamp(self):
+        return self._identifier
+
+    def get_disambiguator(self):
+        # have to be quite fussy about this as there's very little aliasing
+        # protection with strings (no module or source to check).
+        return self._identifier
+
+    @classmethod
+    def from_function(cls, py_func, py_file):
+        if not py_file == "<string>":
+            return
+        fname = '<string>-' + str(cls._hash(py_func))
+        self = cls(py_func, fname)
+        try:
+            self.ensure_cache_path()
+        except OSError:
+            # Cannot ensure the cache directory exists or is writable
+            return
+        return self
+
+    @classmethod
+    def _hash(cls, py_func):
+        py_code = py_func.__code__
+        # skip builtin attrs and methods
+        data = "".join(
+            repr(getattr(py_code, attr))
+            for attr in dir(py_code)
+            if not attr.startswith('__') and \
+                not callable(getattr(py_code, attr))
+        )
+        return hashlib.sha256(data.encode()).hexdigest()
+
+
 class CacheImpl(metaclass=ABCMeta):
     """
     Provides the core machinery for caching.
@@ -318,7 +359,9 @@ class CacheImpl(metaclass=ABCMeta):
     _locator_classes = [_UserProvidedCacheLocator,
                         _InTreeCacheLocator,
                         _UserWideCacheLocator,
-                        _IPythonCacheLocator]
+                        _IPythonCacheLocator,
+                        _StringSrcCacheLocator,
+                        ]
 
     def __init__(self, py_func):
         self._lineno = py_func.__code__.co_firstlineno