Issue #10576: Add a progress callback to gcmodule
diff --git a/Modules/gcmodule.c b/Modules/gcmodule.c
index d8893d1..77c5c6e 100644
--- a/Modules/gcmodule.c
+++ b/Modules/gcmodule.c
@@ -65,14 +65,17 @@
/* Python string to use if unhandled exception occurs */
static PyObject *gc_str = NULL;
-/* This is the number of objects who survived the last full collection. It
+/* a list of callbacks to be invoked when collection is performed */
+static PyObject *callbacks = NULL;
+
+/* This is the number of objects that survived the last full collection. It
approximates the number of long lived objects tracked by the GC.
(by "full collection", we mean a collection of the oldest generation).
*/
static Py_ssize_t long_lived_total = 0;
-/* This is the number of objects who survived all "non-full" collections,
+/* This is the number of objects that survived all "non-full" collections,
and are awaiting to undergo a full collection for the first time.
*/
@@ -787,7 +790,7 @@
/* This is the main function. Read this to understand how the
* collection process works. */
static Py_ssize_t
-collect(int generation)
+collect(int generation, Py_ssize_t *n_collected, Py_ssize_t *n_uncollectable)
{
int i;
Py_ssize_t m = 0; /* # objects collected */
@@ -935,9 +938,64 @@
PyErr_WriteUnraisable(gc_str);
Py_FatalError("unexpected exception during garbage collection");
}
+
+ if (n_collected)
+ *n_collected = m;
+ if (n_uncollectable)
+ *n_uncollectable = n;
return n+m;
}
+/* Invoke progress callbacks to notify clients that garbage collection
+ * is starting or stopping
+ */
+static void
+invoke_gc_callback(const char *phase, int generation,
+ Py_ssize_t collected, Py_ssize_t uncollectable)
+{
+ Py_ssize_t i;
+ PyObject *info = NULL;
+
+ /* we may get called very early */
+ if (callbacks == NULL)
+ return;
+ /* The local variable cannot be rebound, check it for sanity */
+ assert(callbacks != NULL && PyList_CheckExact(callbacks));
+ if (PyList_GET_SIZE(callbacks) != 0) {
+ info = Py_BuildValue("{sisnsn}",
+ "generation", generation,
+ "collected", collected,
+ "uncollectable", uncollectable);
+ if (info == NULL) {
+ PyErr_WriteUnraisable(NULL);
+ return;
+ }
+ }
+ for (i=0; i<PyList_GET_SIZE(callbacks); i++) {
+ PyObject *r, *cb = PyList_GET_ITEM(callbacks, i);
+ Py_INCREF(cb); /* make sure cb doesn't go away */
+ r = PyObject_CallFunction(cb, "sO", phase, info);
+ Py_XDECREF(r);
+ if (r == NULL)
+ PyErr_WriteUnraisable(cb);
+ Py_DECREF(cb);
+ }
+ Py_XDECREF(info);
+}
+
+/* Perform garbage collection of a generation and invoke
+ * progress callbacks.
+ */
+static Py_ssize_t
+collect_with_callback(int generation)
+{
+ Py_ssize_t result, collected, uncollectable;
+ invoke_gc_callback("start", generation, 0, 0);
+ result = collect(generation, &collected, &uncollectable);
+ invoke_gc_callback("stop", generation, collected, uncollectable);
+ return result;
+}
+
static Py_ssize_t
collect_generations(void)
{
@@ -956,7 +1014,7 @@
if (i == NUM_GENERATIONS - 1
&& long_lived_pending < long_lived_total / 4)
continue;
- n = collect(i);
+ n = collect_with_callback(i);
break;
}
}
@@ -1027,7 +1085,7 @@
n = 0; /* already collecting, don't do anything */
else {
collecting = 1;
- n = collect(genarg);
+ n = collect_with_callback(genarg);
collecting = 0;
}
@@ -1320,6 +1378,15 @@
if (PyModule_AddObject(m, "garbage", garbage) < 0)
return NULL;
+ if (callbacks == NULL) {
+ callbacks = PyList_New(0);
+ if (callbacks == NULL)
+ return NULL;
+ }
+ Py_INCREF(callbacks);
+ if (PyModule_AddObject(m, "callbacks", callbacks) < 0)
+ return NULL;
+
/* Importing can't be done in collect() because collect()
* can be called via PyGC_Collect() in Py_Finalize().
* This wouldn't be a problem, except that <initialized> is
@@ -1352,7 +1419,7 @@
n = 0; /* already collecting, don't do anything */
else {
collecting = 1;
- n = collect(NUM_GENERATIONS - 1);
+ n = collect_with_callback(NUM_GENERATIONS - 1);
collecting = 0;
}
@@ -1389,6 +1456,7 @@
Py_XDECREF(bytes);
}
}
+ Py_CLEAR(callbacks);
}
/* for debugging */