From c8906362b4a64fa59a5a31d170970d9ad9a81a6d Mon Sep 17 00:00:00 2001
From: Moonsik Park <moonsik.park@estsoft.com>
Date: Wed, 26 Jun 2024 11:45:11 +0900
Subject: [PATCH] Remove circular reference between `Graph` and `FilterContext`

---
 av/filter/context.pxd |  2 +-
 av/filter/context.pyi |  3 +++
 av/filter/context.pyx | 11 ++++++++++-
 av/filter/graph.pxd   |  2 ++
 4 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/av/filter/context.pxd b/av/filter/context.pxd
index 18954fbdd..ae9f27c99 100644
--- a/av/filter/context.pxd
+++ b/av/filter/context.pxd
@@ -7,7 +7,7 @@ from av.filter.graph cimport Graph
 cdef class FilterContext:
 
     cdef lib.AVFilterContext *ptr
-    cdef readonly Graph graph
+    cdef readonly object _graph
     cdef readonly Filter filter
 
     cdef object _inputs
diff --git a/av/filter/context.pyi b/av/filter/context.pyi
index 0d70c0095..7c00087a9 100644
--- a/av/filter/context.pyi
+++ b/av/filter/context.pyi
@@ -1,3 +1,4 @@
+from av.filter import Graph
 from av.frame import Frame
 
 from .pad import FilterContextPad
@@ -11,5 +12,7 @@ class FilterContext:
     def link_to(
         self, input_: FilterContext, output_idx: int = 0, input_idx: int = 0
     ) -> None: ...
+    @property
+    def graph(self) -> Graph: ...
     def push(self, frame: Frame) -> None: ...
     def pull(self) -> Frame: ...
diff --git a/av/filter/context.pyx b/av/filter/context.pyx
index 54ed710ab..b820d3d18 100644
--- a/av/filter/context.pyx
+++ b/av/filter/context.pyx
@@ -1,3 +1,5 @@
+import weakref
+
 from av.audio.frame cimport alloc_audio_frame
 from av.dictionary cimport _Dictionary
 from av.dictionary import Dictionary
@@ -13,7 +15,7 @@ cdef object _cinit_sentinel = object()
 
 cdef FilterContext wrap_filter_context(Graph graph, Filter filter, lib.AVFilterContext *ptr):
     cdef FilterContext self = FilterContext(_cinit_sentinel)
-    self.graph = graph
+    self._graph = weakref.ref(graph)
     self.filter = filter
     self.ptr = ptr
     return self
@@ -72,6 +74,13 @@ cdef class FilterContext:
 
     def link_to(self, FilterContext input_, int output_idx=0, int input_idx=0):
         err_check(lib.avfilter_link(self.ptr, output_idx, input_.ptr, input_idx))
+    
+    @property
+    def graph(self):
+        if (graph := self._graph()):
+            return graph
+        else:
+            raise RuntimeError("graph is unallocated")
 
     def push(self, Frame frame):
         cdef int res
diff --git a/av/filter/graph.pxd b/av/filter/graph.pxd
index b3bf352a3..2e52bd6ec 100644
--- a/av/filter/graph.pxd
+++ b/av/filter/graph.pxd
@@ -4,6 +4,8 @@ from av.filter.context cimport FilterContext
 
 
 cdef class Graph:
+    cdef object __weakref__
+
     cdef lib.AVFilterGraph *ptr
 
     cdef readonly bint configured