Adds a delete method to reader.iter types

The video reader was not closing the video files
when iteration did not finish all the way to the end.

Fixes #14

bob/io/video/reader.cpp

@@ -480,6 +480,12 @@ static PyMappingMethods PyBobIoVideoReader_Mapping = {
 static const char* s_videoreaderiterator(BOB_EXT_MODULE_PREFIX ".reader.iter");
 
 
+static void PyBobIoVideoReaderIterator_Delete (PyBobIoVideoReaderIteratorObject* self) {
+  self->iter->reset();
+  self->iter.reset();
+  Py_XDECREF((PyObject*)self->pyreader);
+}
+
 static PyObject* PyBobIoVideoReaderIterator_Iter (PyBobIoVideoReaderIteratorObject* self) {
   return Py_BuildValue("O", self);
 }
@@ -488,9 +494,6 @@ static PyObject* PyBobIoVideoReaderIterator_Next (PyBobIoVideoReaderIteratorObje
 
   if ((*self->iter == self->pyreader->v->end()) ||
       (self->iter->cur() == self->pyreader->v->numberOfFrames())) {
-    self->iter->reset();
-    self->iter.reset();
-    Py_XDECREF((PyObject*)self->pyreader);
     return 0;
   }
 
@@ -586,6 +589,7 @@ bool init_BobIoVideoReader(PyObject* module){
   PyBobIoVideoReaderIterator_Type.tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_ITER;
 
   PyBobIoVideoReaderIterator_Type.tp_new = PyType_GenericNew;
+  PyBobIoVideoReaderIterator_Type.tp_dealloc = reinterpret_cast<destructor>(PyBobIoVideoReaderIterator_Delete);
   PyBobIoVideoReaderIterator_Type.tp_iter = reinterpret_cast<getiterfunc>(PyBobIoVideoReaderIterator_Iter);
   PyBobIoVideoReaderIterator_Type.tp_iternext = reinterpret_cast<getiterfunc>(PyBobIoVideoReaderIterator_Next);
 

bob/io/video/test.py

@@ -119,6 +119,60 @@ def test_memory_leak():
   assert (last - first) / first < 0.003, "Looks like we have a memory leak!"
 
 
+def test_open_file_leak():
+  import psutil
+  import tempfile
+  import gc
+
+  from . import reader
+  from bob.io.base import save
+
+  my_video = numpy.random.random_integers(0, 255, (10, 3, 256 * 4, 256 * 4))
+
+  process = psutil.Process()
+
+  def open_files_count(path):
+    return len([f for f in process.open_files() if f.path == path])
+
+  with tempfile.NamedTemporaryFile(suffix='.avi') as f:
+    path = f.name
+    save(my_video.astype('uint8'), path)
+
+    # Get a count before doing anything. This following count is 1 because
+    # NamedTemporaryFile keeps a pointer to this file. We will check if the
+    # count goes to 0 in the end!
+    last_count = open_files_count(path)
+
+    # load the video at once and see if the count is constant
+    load(path)
+    gc.collect()
+    new_count = open_files_count(path)
+    assert new_count == last_count, \
+        ('We did not close all the files when loading the video at once. '
+         'old count: {}, new count: {}'.format(last_count, new_count))
+
+    # iterate over all frames and see if the count is constant
+    for frame in reader(path):
+      pass
+    gc.collect()
+    new_count = open_files_count(path)
+    assert new_count == last_count, \
+        ('We did not close all the files when iterating over all frames. '
+         'old count: {}, new count: {}'.format(last_count, new_count))
+
+    # iterate over one frame and see if the count is constant
+    for frame in reader(path):
+      break
+    gc.collect()
+    new_count = open_files_count(path)
+    assert new_count == last_count, \
+        ('We did not close all the files when iterating over one frame. '
+         'old count: {}, new count: {}'.format(last_count, new_count))
+
+  count = open_files_count(path)
+  assert count == 0, 'The temporary file was not closed! {}'.format(count)
+
+
 def write_unicode_temp_file():
 
   prefix = 'bobtest_straße_'