SF Patch #1463867: Improved generator finalization to allow generators

that are suspended outside of any try/except/finally blocks to be
garbage collected even if they are part of a cycle.  Generators that
suspend inside of an active try/except or try/finally block (including
those created by a ``with`` statement) are still not GC-able if they
are part of a cycle, however.

1 files changed, 20 insertions, 0 deletions

diff --git a/Objects/genobject.c b/Objects/genobject.c
index e7b8f87..a3eae6a 100644
--- a/Objects/genobject.c
+++ b/Objects/genobject.c
@@ -5,6 +5,7 @@
 #include "genobject.h"
 #include "ceval.h"
 #include "structmember.h"
+#include "opcode.h"
 
 static int
 gen_traverse(PyGenObject *gen, visitproc visit, void *arg)
@@ -358,3 +359,22 @@ PyGen_New(PyFrameObject *f)
 	_PyObject_GC_TRACK(gen);
 	return (PyObject *)gen;
 }
+
+int
+PyGen_NeedsFinalizing(PyGenObject *gen)
+{
+	int i;
+	PyFrameObject *f = gen->gi_frame;
+
+	if ((PyObject *)f == Py_None || f->f_stacktop==NULL || f->f_iblock<=0)
+		return 0; /* no frame or no blockstack == no finalization */
+
+	for (i=f->f_iblock; i>=0; i--) {
+		if (f->f_blockstack[i].b_type != SETUP_LOOP)
+			/* any block type besides a loop requires cleanup */
+			return 1;
+	}
+
+	/* No blocks except loops, it's safe to skip finalization */
+	return 0;
+}