[Python-checkins] gh-100227: Use an Array for _PyRuntime's Set of Locks During Init (gh-103315)

[ericsnowcurrently]

https://github.com/python/cpython/commit/52e9b389a8773f485c3b0f1d62bf3cce4812d44d
commit: 52e9b389a8773f485c3b0f1d62bf3cce4812d44d
branch: main
author: Eric Snow <ericsnowcurrently at gmail.com>
committer: ericsnowcurrently <ericsnowcurrently at gmail.com>
date: 2023-04-06T12:00:49-06:00
summary:

gh-100227: Use an Array for _PyRuntime's Set of Locks During Init (gh-103315)

This cleans things up a bit and simplifies adding new granular global locks.

files:
M Python/pystate.c

diff --git a/Python/pystate.c b/Python/pystate.c
index 1e59a8c5f897..d09c1d5743a4 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -354,47 +354,29 @@ _Py_COMP_DIAG_IGNORE_DEPR_DECLS
 static const _PyRuntimeState initial = _PyRuntimeState_INIT(_PyRuntime);
 _Py_COMP_DIAG_POP
 
+#define NUMLOCKS 4
+
 static int
-alloc_for_runtime(PyThread_type_lock *plock1, PyThread_type_lock *plock2,
-                  PyThread_type_lock *plock3, PyThread_type_lock *plock4)
+alloc_for_runtime(PyThread_type_lock locks[NUMLOCKS])
 {
     /* Force default allocator, since _PyRuntimeState_Fini() must
        use the same allocator than this function. */
     PyMemAllocatorEx old_alloc;
     _PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
 
-    PyThread_type_lock lock1 = PyThread_allocate_lock();
-    if (lock1 == NULL) {
-        return -1;
-    }
-
-    PyThread_type_lock lock2 = PyThread_allocate_lock();
-    if (lock2 == NULL) {
-        PyThread_free_lock(lock1);
-        return -1;
-    }
-
-    PyThread_type_lock lock3 = PyThread_allocate_lock();
-    if (lock3 == NULL) {
-        PyThread_free_lock(lock1);
-        PyThread_free_lock(lock2);
-        return -1;
-    }
-
-    PyThread_type_lock lock4 = PyThread_allocate_lock();
-    if (lock4 == NULL) {
-        PyThread_free_lock(lock1);
-        PyThread_free_lock(lock2);
-        PyThread_free_lock(lock3);
-        return -1;
+    for (int i = 0; i < NUMLOCKS; i++) {
+        PyThread_type_lock lock = PyThread_allocate_lock();
+        if (lock == NULL) {
+            for (int j = 0; j < i; j++) {
+                PyThread_free_lock(locks[j]);
+                locks[j] = NULL;
+            }
+            break;
+        }
+        locks[i] = lock;
     }
 
     PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
-
-    *plock1 = lock1;
-    *plock2 = lock2;
-    *plock3 = lock3;
-    *plock4 = lock4;
     return 0;
 }
 
@@ -403,10 +385,7 @@ init_runtime(_PyRuntimeState *runtime,
              void *open_code_hook, void *open_code_userdata,
              _Py_AuditHookEntry *audit_hook_head,
              Py_ssize_t unicode_next_index,
-             PyThread_type_lock unicode_ids_mutex,
-             PyThread_type_lock interpreters_mutex,
-             PyThread_type_lock xidregistry_mutex,
-             PyThread_type_lock getargs_mutex)
+             PyThread_type_lock locks[NUMLOCKS])
 {
     if (runtime->_initialized) {
         Py_FatalError("runtime already initialized");
@@ -424,17 +403,21 @@ init_runtime(_PyRuntimeState *runtime,
 
     PyPreConfig_InitPythonConfig(&runtime->preconfig);
 
-    runtime->interpreters.mutex = interpreters_mutex;
-
-    runtime->xidregistry.mutex = xidregistry_mutex;
-
-    runtime->getargs.mutex = getargs_mutex;
+    PyThread_type_lock *lockptrs[NUMLOCKS] = {
+        &runtime->interpreters.mutex,
+        &runtime->xidregistry.mutex,
+        &runtime->getargs.mutex,
+        &runtime->unicode_state.ids.lock,
+    };
+    for (int i = 0; i < NUMLOCKS; i++) {
+        assert(locks[i] != NULL);
+        *lockptrs[i] = locks[i];
+    }
 
     // Set it to the ID of the main thread of the main interpreter.
     runtime->main_thread = PyThread_get_thread_ident();
 
     runtime->unicode_state.ids.next_index = unicode_next_index;
-    runtime->unicode_state.ids.lock = unicode_ids_mutex;
 
     runtime->_initialized = 1;
 }
@@ -452,8 +435,8 @@ _PyRuntimeState_Init(_PyRuntimeState *runtime)
     // is called multiple times.
     Py_ssize_t unicode_next_index = runtime->unicode_state.ids.next_index;
 
-    PyThread_type_lock lock1, lock2, lock3, lock4;
-    if (alloc_for_runtime(&lock1, &lock2, &lock3, &lock4) != 0) {
+    PyThread_type_lock locks[NUMLOCKS];
+    if (alloc_for_runtime(locks) != 0) {
         return _PyStatus_NO_MEMORY();
     }
 
@@ -474,7 +457,7 @@ _PyRuntimeState_Init(_PyRuntimeState *runtime)
     }
 
     init_runtime(runtime, open_code_hook, open_code_userdata, audit_hook_head,
-                 unicode_next_index, lock1, lock2, lock3, lock4);
+                 unicode_next_index, locks);
 
     return _PyStatus_OK();
 }
@@ -504,10 +487,15 @@ _PyRuntimeState_Fini(_PyRuntimeState *runtime)
         LOCK = NULL; \
     }
 
-    FREE_LOCK(runtime->interpreters.mutex);
-    FREE_LOCK(runtime->xidregistry.mutex);
-    FREE_LOCK(runtime->unicode_state.ids.lock);
-    FREE_LOCK(runtime->getargs.mutex);
+    PyThread_type_lock *lockptrs[NUMLOCKS] = {
+        &runtime->interpreters.mutex,
+        &runtime->xidregistry.mutex,
+        &runtime->getargs.mutex,
+        &runtime->unicode_state.ids.lock,
+    };
+    for (int i = 0; i < NUMLOCKS; i++) {
+        FREE_LOCK(*lockptrs[i]);
+    }
 
 #undef FREE_LOCK
     PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
@@ -527,25 +515,25 @@ _PyRuntimeState_ReInitThreads(_PyRuntimeState *runtime)
     PyMemAllocatorEx old_alloc;
     _PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
 
-    int reinit_interp = _PyThread_at_fork_reinit(&runtime->interpreters.mutex);
-    int reinit_xidregistry = _PyThread_at_fork_reinit(&runtime->xidregistry.mutex);
-    int reinit_unicode_ids = _PyThread_at_fork_reinit(&runtime->unicode_state.ids.lock);
-    int reinit_getargs = _PyThread_at_fork_reinit(&runtime->getargs.mutex);
+    PyThread_type_lock *lockptrs[NUMLOCKS] = {
+        &runtime->interpreters.mutex,
+        &runtime->xidregistry.mutex,
+        &runtime->getargs.mutex,
+        &runtime->unicode_state.ids.lock,
+    };
+    int reinit_err = 0;
+    for (int i = 0; i < NUMLOCKS; i++) {
+        reinit_err += _PyThread_at_fork_reinit(lockptrs[i]);
+    }
 
     PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
 
     /* bpo-42540: id_mutex is freed by _PyInterpreterState_Delete, which does
      * not force the default allocator. */
-    int reinit_main_id = _PyThread_at_fork_reinit(&runtime->interpreters.main->id_mutex);
+    reinit_err += _PyThread_at_fork_reinit(&runtime->interpreters.main->id_mutex);
 
-    if (reinit_interp < 0
-        || reinit_main_id < 0
-        || reinit_xidregistry < 0
-        || reinit_unicode_ids < 0
-        || reinit_getargs < 0)
-    {
+    if (reinit_err < 0) {
         return _PyStatus_ERR("Failed to reinitialize runtime locks");
-
     }
 
     PyStatus status = gilstate_tss_reinit(runtime);