py/modthread: Return thread id from start_new_thread().

In CPython, `_thread.start_new_thread()` returns an ID that is the same ID
that is returned by `_thread.get_ident()`.  The current MicroPython
implementation of `_thread.start_new_thread()` always returns `None`.

This modifies the required functions to return a value. The native thread
id is returned since this can be used for interop with other functions, for
example, `pthread_kill()` on *nix. `_thread.get_ident()` is also modified
to return the native thread id so that the values match and avoids the need
for a separate `native_id` attribute.

Fixes issue #12153.

Signed-off-by: David Lechner <david@pybricks.com>

ports/cc3200/mpthreadport.c

@@ -89,6 +89,10 @@ void mp_thread_set_state(mp_state_thread_t *state) {
     vTaskSetThreadLocalStoragePointer(NULL, 0, state);
 }
 
+mp_uint_t mp_thread_get_id(void) {
+    return (mp_uint_t)xTaskGetCurrentTaskHandle();
+}
+
 void mp_thread_start(void) {
     mp_thread_mutex_lock(&thread_mutex, 1);
     for (mp_thread_t *th = thread; th != NULL; th = th->next) {
@@ -111,7 +115,7 @@ STATIC void freertos_entry(void *arg) {
     }
 }
 
-void mp_thread_create(void *(*entry)(void *), void *arg, size_t *stack_size) {
+mp_uint_t mp_thread_create(void *(*entry)(void *), void *arg, size_t *stack_size) {
     // store thread entry function into a global variable so we can access it
     ext_thread_entry = entry;
 
@@ -148,6 +152,9 @@ void mp_thread_create(void *(*entry)(void *), void *arg, size_t *stack_size) {
 
     // adjust stack_size to provide room to recover from hitting the limit
     *stack_size -= 512;
+
+    MP_STATIC_ASSERT(sizeof(mp_uint_t) >= sizeof(TaskHandle_t));
+    return (mp_uint_t)id;
 }
 
 void mp_thread_finish(void) {

ports/esp32/mpthreadport.c

@@ -98,6 +98,10 @@ void mp_thread_set_state(mp_state_thread_t *state) {
     vTaskSetThreadLocalStoragePointer(NULL, 1, state);
 }
 
+mp_uint_t mp_thread_get_id(void) {
+    return (mp_uint_t)xTaskGetCurrentTaskHandle();
+}
+
 void mp_thread_start(void) {
     mp_thread_mutex_lock(&thread_mutex, 1);
     for (mp_thread_t *th = thread; th != NULL; th = th->next) {
@@ -120,7 +124,7 @@ STATIC void freertos_entry(void *arg) {
     }
 }
 
-void mp_thread_create_ex(void *(*entry)(void *), void *arg, size_t *stack_size, int priority, char *name) {
+mp_uint_t mp_thread_create_ex(void *(*entry)(void *), void *arg, size_t *stack_size, int priority, char *name) {
     // store thread entry function into a global variable so we can access it
     ext_thread_entry = entry;
 
@@ -154,10 +158,12 @@ void mp_thread_create_ex(void *(*entry)(void *), void *arg, size_t *stack_size,
     *stack_size -= 1024;
 
     mp_thread_mutex_unlock(&thread_mutex);
+
+    return (mp_uint_t)th->id;
 }
 
-void mp_thread_create(void *(*entry)(void *), void *arg, size_t *stack_size) {
-    mp_thread_create_ex(entry, arg, stack_size, MP_THREAD_PRIORITY, "mp_thread");
+mp_uint_t mp_thread_create(void *(*entry)(void *), void *arg, size_t *stack_size) {
+    return mp_thread_create_ex(entry, arg, stack_size, MP_THREAD_PRIORITY, "mp_thread");
 }
 
 void mp_thread_finish(void) {

ports/renesas-ra/mpthreadport.c

@@ -54,7 +54,11 @@ void mp_thread_gc_others(void) {
     mp_thread_mutex_unlock(&thread_mutex);
 }
 
-void mp_thread_create(void *(*entry)(void *), void *arg, size_t *stack_size) {
+mp_uint_t mp_thread_get_id(void) {
+    return (uint32_t)pyb_thread_cur;
+}
+
+mp_uint_t mp_thread_create(void *(*entry)(void *), void *arg, size_t *stack_size) {
     if (*stack_size == 0) {
         *stack_size = 4096; // default stack size
     } else if (*stack_size < 2048) {
@@ -82,6 +86,8 @@ void mp_thread_create(void *(*entry)(void *), void *arg, size_t *stack_size) {
 
     // adjust stack_size to provide room to recover from hitting the limit
     *stack_size -= 1024;
+
+    return id;
 }
 
 void mp_thread_start(void) {

ports/rp2/mpthreadport.c

@@ -116,7 +116,13 @@ STATIC void core1_entry_wrapper(void) {
     // returning from here will loop the core forever (WFI)
 }
 
-void mp_thread_create(void *(*entry)(void *), void *arg, size_t *stack_size) {
+mp_uint_t mp_thread_get_id(void) {
+    // On RP2, there are only two threads, one for each core, so the thread id
+    // is the core number.
+    return get_core_num();
+}
+
+mp_uint_t mp_thread_create(void *(*entry)(void *), void *arg, size_t *stack_size) {
     // Check if core1 is already in use.
     if (core1_entry != NULL) {
         mp_raise_msg(&mp_type_OSError, MP_ERROR_TEXT("core1 in use"));
@@ -144,6 +150,8 @@ void mp_thread_create(void *(*entry)(void *), void *arg, size_t *stack_size) {
 
     // Adjust stack_size to provide room to recover from hitting the limit.
     *stack_size -= 512;
+
+    return 1;
 }
 
 void mp_thread_start(void) {

ports/stm32/mpthreadport.c

@@ -54,7 +54,11 @@ void mp_thread_gc_others(void) {
     mp_thread_mutex_unlock(&thread_mutex);
 }
 
-void mp_thread_create(void *(*entry)(void *), void *arg, size_t *stack_size) {
+mp_uint_t mp_thread_get_id(void) {
+    return (uint32_t)pyb_thread_cur;
+}
+
+mp_uint_t mp_thread_create(void *(*entry)(void *), void *arg, size_t *stack_size) {
     if (*stack_size == 0) {
         *stack_size = 4096; // default stack size
     } else if (*stack_size < 2048) {
@@ -82,6 +86,8 @@ void mp_thread_create(void *(*entry)(void *), void *arg, size_t *stack_size) {
 
     // adjust stack_size to provide room to recover from hitting the limit
     *stack_size -= 1024;
+
+    return id;
 }
 
 void mp_thread_start(void) {

ports/unix/mpthreadport.c

@@ -191,6 +191,10 @@ void mp_thread_set_state(mp_state_thread_t *state) {
     pthread_setspecific(tls_key, state);
 }
 
+mp_uint_t mp_thread_get_id(void) {
+    return (mp_uint_t)pthread_self();
+}
+
 void mp_thread_start(void) {
     // enable realtime priority if `-X realtime` command line parameter was set
     #if defined(__APPLE__)
@@ -210,7 +214,7 @@ void mp_thread_start(void) {
     mp_thread_unix_end_atomic_section();
 }
 
-void mp_thread_create(void *(*entry)(void *), void *arg, size_t *stack_size) {
+mp_uint_t mp_thread_create(void *(*entry)(void *), void *arg, size_t *stack_size) {
     // default stack size is 8k machine-words
     if (*stack_size == 0) {
         *stack_size = 8192 * sizeof(void *);
@@ -265,7 +269,8 @@ void mp_thread_create(void *(*entry)(void *), void *arg, size_t *stack_size) {
 
     mp_thread_unix_end_atomic_section();
 
-    return;
+    MP_STATIC_ASSERT(sizeof(mp_uint_t) >= sizeof(pthread_t));
+    return (mp_uint_t)id;
 
 er:
     mp_raise_OSError(ret);

py/modthread.c

@@ -129,7 +129,7 @@ STATIC MP_DEFINE_CONST_OBJ_TYPE(
 STATIC size_t thread_stack_size = 0;
 
 STATIC mp_obj_t mod_thread_get_ident(void) {
-    return mp_obj_new_int_from_uint((uintptr_t)mp_thread_get_state());
+    return mp_obj_new_int_from_uint(mp_thread_get_id());
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_0(mod_thread_get_ident_obj, mod_thread_get_ident);
 
@@ -268,9 +268,7 @@ STATIC mp_obj_t mod_thread_start_new_thread(size_t n_args, const mp_obj_t *args)
     th_args->fun = args[0];
 
     // spawn the thread!
-    mp_thread_create(thread_entry, th_args, &th_args->stack_size);
-
-    return mp_const_none;
+    return mp_obj_new_int_from_uint(mp_thread_create(thread_entry, th_args, &th_args->stack_size));
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_thread_start_new_thread_obj, 2, 3, mod_thread_start_new_thread);
 

py/mpthread.h

@@ -40,7 +40,8 @@ struct _mp_state_thread_t;
 
 struct _mp_state_thread_t *mp_thread_get_state(void);
 void mp_thread_set_state(struct _mp_state_thread_t *state);
-void mp_thread_create(void *(*entry)(void *), void *arg, size_t *stack_size);
+mp_uint_t mp_thread_create(void *(*entry)(void *), void *arg, size_t *stack_size);
+mp_uint_t mp_thread_get_id(void);
 void mp_thread_start(void);
 void mp_thread_finish(void);
 void mp_thread_mutex_init(mp_thread_mutex_t *mutex);

tests/thread/thread_ident1.py

@@ -5,7 +5,11 @@
 import _thread
 
 
+tid = None
+
+
 def thread_entry():
+    global tid
     tid = _thread.get_ident()
     print("thread", type(tid) == int, tid != 0, tid != tid_main)
     global finished
@@ -16,8 +20,9 @@ tid_main = _thread.get_ident()
 print("main", type(tid_main) == int, tid_main != 0)
 
 finished = False
-_thread.start_new_thread(thread_entry, ())
+new_tid = _thread.start_new_thread(thread_entry, ())
 
 while not finished:
     pass
-print("done")
+
+print("done", type(new_tid) == int, new_tid == tid)