add the possibility to use custom hash function

joblib/memory.py

@@ -33,7 +33,6 @@
 from ._store_backends import StoreBackendBase, FileSystemStoreBackend
 
 
-
 FIRST_LINE_TEXT = "# first line:"
 
 # TODO: The following object should have a data store object as a sub
@@ -136,7 +135,6 @@ def _store_backend_factory(backend, location, verbose=0, backend_options=None):
             "supported by joblib. Returning None instead.".format(
                 location.__class__.__name__), UserWarning)
 
-
     return None
 
 
@@ -219,6 +217,7 @@ class MemorizedResult(Logger):
     timestamp, metadata: string
         for internal use only.
     """
+
     def __init__(self, location, func, args_id, backend='local',
                  mmap_mode=None, verbose=0, timestamp=None, metadata=None):
         Logger.__init__(self)
@@ -345,6 +344,7 @@ class NotMemorizedFunc(object):
         Original undecorated function.
     """
     # Should be a light as possible (for speed)
+
     def __init__(self, func):
         self.func = func
 
@@ -402,13 +402,19 @@ class MemorizedFunc(Logger):
     verbose: int, optional
         The verbosity flag, controls messages that are issued as
         the function is evaluated.
+
+    hash_func: callable, optional
+        Parameters: (obj: object, hash_name: string, coerce_mmap: Boolean)
+        Return the hash from an object. Default is None.
+        If hash_func is None hashing.hash is used
     """
     # ------------------------------------------------------------------------
     # Public interface
     # ------------------------------------------------------------------------
 
     def __init__(self, func, location, backend='local', ignore=None,
-                 mmap_mode=None, compress=False, verbose=1, timestamp=None):
+                 mmap_mode=None, compress=False, verbose=1,
+                 timestamp=None, hash_func=None):
         Logger.__init__(self)
         self.mmap_mode = mmap_mode
         self.compress = compress
@@ -434,9 +440,11 @@ def __init__(self, func, location, backend='local', ignore=None,
         if timestamp is None:
             timestamp = time.time()
         self.timestamp = timestamp
+        self.hash_func = hashing.hash if hash_func is None else hash_func
+
         try:
             functools.update_wrapper(self, func)
-        except:
+        except BaseException:
             " Objects like ufunc don't like that "
         if inspect.isfunction(func):
             doc = pydoc.TextDoc().document(func)
@@ -611,8 +619,10 @@ def __getstate__(self):
     # ------------------------------------------------------------------------
 
     def _get_argument_hash(self, *args, **kwargs):
-        return hashing.hash(filter_args(self.func, self.ignore, args, kwargs),
-                            coerce_mmap=(self.mmap_mode is not None))
+        return self.hash_func(
+            filter_args(self.func, self.ignore, args, kwargs),
+            coerce_mmap=self.mmap_mode is not None
+        )
 
     def _get_output_identifiers(self, *args, **kwargs):
         """Return the func identifier and input parameter hash of a result."""
@@ -683,8 +693,8 @@ def _check_previous_func_code(self, stacklevel=2):
                 extract_first_line(
                     self.store_backend.get_cached_func_code([func_id]))
         except (IOError, OSError):  # some backend can also raise OSError
-                self._write_func_code(func_code, first_line)
-                return False
+            self._write_func_code(func_code, first_line)
+            return False
         if old_func_code == func_code:
             return True
 
@@ -887,14 +897,19 @@ class Memory(Logger):
         backend_options: dict, optional
             Contains a dictionnary of named parameters used to configure
             the store backend.
+
+        hash_func: callable, optional
+            Parameters: (obj: object, hash_name: string, coerce_mmap: Boolean)
+            Returns the hash from an object.
+            If hash_func is None (default), hashing.hash is used.
     """
     # ------------------------------------------------------------------------
     # Public interface
     # ------------------------------------------------------------------------
 
     def __init__(self, location=None, backend='local', cachedir=None,
                  mmap_mode=None, compress=False, verbose=1, bytes_limit=None,
-                 backend_options=None):
+                 backend_options=None, hash_func=None):
         # XXX: Bad explanation of the None value of cachedir
         Logger.__init__(self)
         self._verbose = verbose
@@ -906,6 +921,7 @@ def __init__(self, location=None, backend='local', cachedir=None,
         if backend_options is None:
             backend_options = {}
         self.backend_options = backend_options
+        self.hash_func = hash_func
 
         if compress and mmap_mode is not None:
             warnings.warn('Compressed results cannot be memmapped',
@@ -986,11 +1002,17 @@ def cache(self, func=None, ignore=None, verbose=None, mmap_mode=False):
             mmap_mode = self.mmap_mode
         if isinstance(func, MemorizedFunc):
             func = func.func
-        return MemorizedFunc(func, location=self.store_backend,
-                             backend=self.backend,
-                             ignore=ignore, mmap_mode=mmap_mode,
-                             compress=self.compress,
-                             verbose=verbose, timestamp=self.timestamp)
+        return MemorizedFunc(
+            func,
+            location=self.store_backend,
+            backend=self.backend,
+            ignore=ignore,
+            mmap_mode=mmap_mode,
+            compress=self.compress,
+            verbose=verbose,
+            timestamp=self.timestamp,
+            hash_func=self.hash_func
+        )
 
     def clear(self, warn=True):
         """ Erase the complete cache directory.