Fix sub-object ownership of python interface of IVFSpectralHash

Summary: Code would crash when deallocating the coarse quantizer for a IVFSpectralHash.

Reviewed By: algoriddle

Differential Revision: D40053030

fbshipit-source-id: 6a2987a6983f0e5fc5c5b6296d9000354176af83

faiss/python/__init__.py

@@ -105,6 +105,23 @@ def add_ref_in_method(the_class, method_name, parameter_no):
     setattr(the_class, method_name, replacement_method)
 
 
+def add_ref_in_method_explicit_own(the_class, method_name):
+    # for methods of format set_XXX(object, own)
+    original_method = getattr(the_class, method_name)
+
+    def replacement_method(self, ref, own=False):
+        if not own:
+            if not hasattr(self, 'referenced_objects'):
+                self.referenced_objects = [ref]
+            else:
+                self.referenced_objects.append(ref)
+        else:
+            # transfer ownership to C++ class
+            ref.this.disown()
+        return original_method(self, ref, own)
+    setattr(the_class, method_name, replacement_method)
+
+
 def add_ref_in_function(function_name, parameter_no):
     # assumes the function returns an object
     original_function = getattr(this_module, function_name)
@@ -128,6 +145,9 @@ add_ref_in_constructor(IndexIVFResidualQuantizer, 0)
 add_ref_in_constructor(IndexIVFLocalSearchQuantizer, 0)
 add_ref_in_constructor(IndexIVFResidualQuantizerFastScan, 0)
 add_ref_in_constructor(IndexIVFLocalSearchQuantizerFastScan, 0)
+add_ref_in_constructor(IndexIVFSpectralHash, 0)
+add_ref_in_method_explicit_own(IndexIVFSpectralHash, "replace_vt")
+
 add_ref_in_constructor(Index2Layer, 0)
 add_ref_in_constructor(Level1Quantizer, 0)
 add_ref_in_constructor(IndexIVFScalarQuantizer, 0)

tests/test_factory.py

@@ -6,6 +6,7 @@
 
 import numpy as np
 import unittest
+import gc
 import faiss
 
 from faiss.contrib import factory_tools
@@ -296,3 +297,17 @@ class TestQuantizerClone(unittest.TestCase):
 
         codes2 = quant2.compute_codes(ds.get_database())
         np.testing.assert_array_equal(codes, codes2)
+
+
+class TestIVFSpectralHashOwnerhsip(unittest.TestCase):
+
+    def test_constructor(self):
+        index = faiss.IndexIVFSpectralHash(faiss.IndexFlat(10), 10, 20, 10, 1)
+        gc.collect()
+        index.quantizer.ntotal   # this should not crash
+
+    def test_replace_vt(self):
+        index = faiss.IndexIVFSpectralHash(faiss.IndexFlat(10), 10, 20, 10, 1)
+        index.replace_vt(faiss.ITQTransform(10, 10))
+        gc.collect()
+        index.vt.d_out # this should not crash