Update 2025-04-24_11:44:19

venv/lib/python3.11/site-packages/greenlet/TGreenletGlobals.cpp

@@ -0,0 +1,94 @@
+/* -*- indent-tabs-mode: nil; tab-width: 4; -*- */
+/**
+ * Implementation of GreenletGlobals.
+ *
+ * Format with:
+ *  clang-format -i --style=file src/greenlet/greenlet.c
+ *
+ *
+ * Fix missing braces with:
+ *   clang-tidy src/greenlet/greenlet.c -fix -checks="readability-braces-around-statements"
+*/
+#ifndef T_GREENLET_GLOBALS
+#define T_GREENLET_GLOBALS
+
+#include "greenlet_refs.hpp"
+#include "greenlet_exceptions.hpp"
+#include "greenlet_thread_support.hpp"
+#include "greenlet_internal.hpp"
+
+namespace greenlet {
+
+// This encapsulates what were previously module global "constants"
+// established at init time.
+// This is a step towards Python3 style module state that allows
+// reloading.
+//
+// In an earlier iteration of this code, we used placement new to be
+// able to allocate this object statically still, so that references
+// to its members don't incur an extra pointer indirection.
+// But under some scenarios, that could result in crashes at
+// shutdown because apparently the destructor was getting run twice?
+class GreenletGlobals
+{
+
+public:
+    const greenlet::refs::ImmortalEventName event_switch;
+    const greenlet::refs::ImmortalEventName event_throw;
+    const greenlet::refs::ImmortalException PyExc_GreenletError;
+    const greenlet::refs::ImmortalException PyExc_GreenletExit;
+    const greenlet::refs::ImmortalObject empty_tuple;
+    const greenlet::refs::ImmortalObject empty_dict;
+    const greenlet::refs::ImmortalString str_run;
+    Mutex* const thread_states_to_destroy_lock;
+    greenlet::cleanup_queue_t thread_states_to_destroy;
+
+    GreenletGlobals() :
+        event_switch("switch"),
+        event_throw("throw"),
+        PyExc_GreenletError("greenlet.error"),
+        PyExc_GreenletExit("greenlet.GreenletExit", PyExc_BaseException),
+        empty_tuple(Require(PyTuple_New(0))),
+        empty_dict(Require(PyDict_New())),
+        str_run("run"),
+        thread_states_to_destroy_lock(new Mutex())
+    {}
+
+    ~GreenletGlobals()
+    {
+        // This object is (currently) effectively immortal, and not
+        // just because of those placement new tricks; if we try to
+        // deallocate the static object we allocated, and overwrote,
+        // we would be doing so at C++ teardown time, which is after
+        // the final Python GIL is released, and we can't use the API
+        // then.
+        // (The members will still be destructed, but they also don't
+        // do any deallocation.)
+    }
+
+    void queue_to_destroy(ThreadState* ts) const
+    {
+        // we're currently accessed through a static const object,
+        // implicitly marking our members as const, so code can't just
+        // call push_back (or pop_back) without casting away the
+        // const.
+        //
+        // Do that for callers.
+        greenlet::cleanup_queue_t& q = const_cast<greenlet::cleanup_queue_t&>(this->thread_states_to_destroy);
+        q.push_back(ts);
+    }
+
+    ThreadState* take_next_to_destroy() const
+    {
+        greenlet::cleanup_queue_t& q = const_cast<greenlet::cleanup_queue_t&>(this->thread_states_to_destroy);
+        ThreadState* result = q.back();
+        q.pop_back();
+        return result;
+    }
+};
+
+}; // namespace greenlet
+
+static const greenlet::GreenletGlobals* mod_globs;
+
+#endif // T_GREENLET_GLOBALS