bpo-33608: Factor out a private, per-interpreter _Py_AddPendingCall(). (GH-11617)

This involves moving the global "pending calls" state to PyInterpreterState.

https://bugs.python.org/issue33608

Author: ericsnowcurrently

Include/ceval.h

@@ -221,7 +221,7 @@ PyAPI_FUNC(Py_ssize_t) _PyEval_RequestCodeExtraIndex(freefunc);
 #ifndef Py_LIMITED_API
 PyAPI_FUNC(int) _PyEval_SliceIndex(PyObject *, Py_ssize_t *);
 PyAPI_FUNC(int) _PyEval_SliceIndexNotNone(PyObject *, Py_ssize_t *);
-PyAPI_FUNC(void) _PyEval_SignalAsyncExc(void);
+PyAPI_FUNC(void) _PyEval_SignalAsyncExc(PyInterpreterState *);
 #endif
 
 /* Masks and values used by FORMAT_VALUE opcode. */

Include/internal/pycore_ceval.h

@@ -11,8 +11,12 @@ extern "C" {
 #include "pycore_atomic.h"
 #include "pythread.h"
 
+struct _is;  // See PyInterpreterState in cpython/pystate.h.
+
+PyAPI_FUNC(int) _Py_AddPendingCall(struct _is*, unsigned long, int (*)(void *), void *);
+PyAPI_FUNC(int) _Py_MakePendingCalls(struct _is*);
+
 struct _pending_calls {
-    unsigned long main_thread;
     PyThread_type_lock lock;
     /* Request for running pending calls. */
     _Py_atomic_int calls_to_do;
@@ -22,13 +26,21 @@ struct _pending_calls {
     int async_exc;
 #define NPENDINGCALLS 32
     struct {
+        unsigned long thread_id;
         int (*func)(void *);
         void *arg;
     } calls[NPENDINGCALLS];
     int first;
     int last;
 };
 
+struct _ceval_interpreter_state {
+    /* This single variable consolidates all requests to break out of
+       the fast path in the eval loop. */
+    _Py_atomic_int eval_breaker;
+    struct _pending_calls pending;
+};
+
 #include "pycore_gil.h"
 
 struct _ceval_runtime_state {
@@ -39,12 +51,8 @@ struct _ceval_runtime_state {
        c_tracefunc.  This speeds up the if statement in
        PyEval_EvalFrameEx() after fast_next_opcode. */
     int tracing_possible;
-    /* This single variable consolidates all requests to break out of
-       the fast path in the eval loop. */
-    _Py_atomic_int eval_breaker;
     /* Request for dropping the GIL */
     _Py_atomic_int gil_drop_request;
-    struct _pending_calls pending;
     /* Request for checking signals. */
     _Py_atomic_int signals_pending;
     struct _gil_runtime_state gil;

Include/internal/pycore_pystate.h

@@ -11,6 +11,7 @@ extern "C" {
 #include "pystate.h"
 #include "pythread.h"
 
+#include "pycore_atomic.h"
 #include "pycore_ceval.h"
 #include "pycore_pathconfig.h"
 #include "pycore_pymem.h"
@@ -31,6 +32,8 @@ struct _is {
     int64_t id_refcount;
     PyThread_type_lock id_mutex;
 
+    int finalizing;
+
     PyObject *modules;
     PyObject *modules_by_index;
     PyObject *sysdict;
@@ -78,6 +81,8 @@ struct _is {
     PyObject *pyexitmodule;
 
     uint64_t tstate_next_unique_id;
+
+    struct _ceval_interpreter_state ceval;
 };
 
 PyAPI_FUNC(struct _is*) _PyInterpreterState_LookUpID(PY_INT64_T);
@@ -207,6 +212,8 @@ typedef struct pyruntimestate {
         struct _xidregitem *head;
     } xidregistry;
 
+    unsigned long main_thread;
+
 #define NEXITFUNCS 32
     void (*exitfuncs[NEXITFUNCS])(void);
     int nexitfuncs;

Misc/NEWS.d/next/Core and Builtins/2018-09-15-12-13-46.bpo-33608.avmvVP.rst

@@ -0,0 +1,5 @@
+We added a new internal _Py_AddPendingCall() that operates relative to the
+provided interpreter.  This allows us to use the existing implementation to
+ask another interpreter to do work that cannot be done in the current
+interpreter, like decref an object the other interpreter owns.  The existing
+Py_AddPendingCall() only operates relative to the main interpreter.

Modules/_testcapimodule.c

@@ -2445,6 +2445,7 @@ pending_threadfunc(PyObject *self, PyObject *arg)
     Py_INCREF(callable);
 
     Py_BEGIN_ALLOW_THREADS
+    /* XXX Use the internal _Py_AddPendingCall(). */
     r = Py_AddPendingCall(&_pending_callback, callable);
     Py_END_ALLOW_THREADS
 

Modules/signalmodule.c

@@ -19,6 +19,7 @@
 #include <process.h>
 #endif
 #endif
+#include "internal/pycore_pystate.h"
 
 #ifdef HAVE_SIGNAL_H
 #include <signal.h>
@@ -295,8 +296,10 @@ trip_signal(int sig_num)
                 {
                     /* Py_AddPendingCall() isn't signal-safe, but we
                        still use it for this exceptional case. */
-                    Py_AddPendingCall(report_wakeup_send_error,
-                                      (void *)(intptr_t) last_error);
+                    _Py_AddPendingCall(_PyRuntime.interpreters.main,
+                                       main_thread,
+                                       report_wakeup_send_error,
+                                       (void *)(intptr_t) last_error);
                 }
             }
         }
@@ -313,8 +316,10 @@ trip_signal(int sig_num)
                 {
                     /* Py_AddPendingCall() isn't signal-safe, but we
                        still use it for this exceptional case. */
-                    Py_AddPendingCall(report_wakeup_write_error,
-                                      (void *)(intptr_t)errno);
+                    _Py_AddPendingCall(_PyRuntime.interpreters.main,
+                                       main_thread,
+                                       report_wakeup_write_error,
+                                       (void *)(intptr_t)errno);
                 }
             }
         }