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webassembly: Register PyProxy objects for JS-side finalisation.

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And clear the corresponding `proxy_c_ref[c_ref]` entry when the finaliser
runs.  This then allows the C side to (eventually) garbage collect the
corresponding Python object.

Signed-off-by: Damien George <damien@micropython.org>
This commit is contained in:
Damien George 2024-05-21 11:42:51 +10:00
parent 5c7a414574
commit 57a9ffa632
3 changed files with 38 additions and 1 deletions
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1
ports/webassembly/Makefile
View File

@ -54,6 +54,7 @@ EXPORTED_FUNCTIONS_EXTRA += ,\
_mp_js_do_exec_async,\
_mp_js_do_import,\
_mp_js_register_js_module,\
_proxy_c_free_obj,\
_proxy_c_init,\
_proxy_c_to_js_call,\
_proxy_c_to_js_delete_attr,\

32
ports/webassembly/proxy_c.c
View File

@ -32,6 +32,9 @@
#include "py/runtime.h"
#include "proxy_c.h"
// Number of static entries at the start of proxy_c_ref.
#define PROXY_C_REF_NUM_STATIC (1)
// These constants should match the constants in proxy_js.js.
enum {
@ -71,16 +74,36 @@ static const mp_obj_base_t mp_const_undefined_obj = {&mp_type_undefined};
MP_DEFINE_EXCEPTION(JsException, Exception)
// Index to start searching for the next available slot in proxy_c_ref.
static size_t proxy_c_ref_next;
void proxy_c_init(void) {
MP_STATE_PORT(proxy_c_ref) = mp_obj_new_list(0, NULL);
mp_obj_list_append(MP_STATE_PORT(proxy_c_ref), MP_OBJ_NULL);
proxy_c_ref_next = PROXY_C_REF_NUM_STATIC;
}
MP_REGISTER_ROOT_POINTER(mp_obj_t proxy_c_ref);
// obj cannot be MP_OBJ_NULL.
static inline size_t proxy_c_add_obj(mp_obj_t obj) {
size_t id = ((mp_obj_list_t *)MP_OBJ_TO_PTR(MP_STATE_PORT(proxy_c_ref)))->len;
// Search for the first free slot in proxy_c_ref.
mp_obj_list_t *l = (mp_obj_list_t *)MP_OBJ_TO_PTR(MP_STATE_PORT(proxy_c_ref));
while (proxy_c_ref_next < l->len) {
if (l->items[proxy_c_ref_next] == MP_OBJ_NULL) {
// Free slot found, reuse it.
size_t id = proxy_c_ref_next;
++proxy_c_ref_next;
l->items[id] = obj;
return id;
}
++proxy_c_ref_next;
}
// No free slots, so grow proxy_c_ref by one (append at the end of the list).
size_t id = l->len;
mp_obj_list_append(MP_STATE_PORT(proxy_c_ref), obj);
proxy_c_ref_next = l->len;
return id;
}
@ -88,6 +111,13 @@ static inline mp_obj_t proxy_c_get_obj(uint32_t c_ref) {
return ((mp_obj_list_t *)MP_OBJ_TO_PTR(MP_STATE_PORT(proxy_c_ref)))->items[c_ref];
}
void proxy_c_free_obj(uint32_t c_ref) {
if (c_ref >= PROXY_C_REF_NUM_STATIC) {
((mp_obj_list_t *)MP_OBJ_TO_PTR(MP_STATE_PORT(proxy_c_ref)))->items[c_ref] = MP_OBJ_NULL;
proxy_c_ref_next = MIN(proxy_c_ref_next, c_ref);
}
}
mp_obj_t proxy_convert_js_to_mp_obj_cside(uint32_t *value) {
if (value[0] == PROXY_KIND_JS_UNDEFINED) {
return mp_const_undefined;

6
ports/webassembly/proxy_js.js
View File

@ -61,6 +61,11 @@ class PythonError extends Error {
function proxy_js_init() {
globalThis.proxy_js_ref = [globalThis, undefined];
globalThis.proxy_js_ref_next = PROXY_JS_REF_NUM_STATIC;
globalThis.pyProxyFinalizationRegistry = new FinalizationRegistry(
(cRef) => {
Module.ccall("proxy_c_free_obj", "null", ["number"], [cRef]);
},
);
}
// js_obj cannot be undefined
@ -251,6 +256,7 @@ function proxy_convert_mp_to_js_obj_jsside(value) {
const target = new PyProxy(id);
obj = new Proxy(target, py_proxy_handler);
}
globalThis.pyProxyFinalizationRegistry.register(obj, id);
}
return obj;
}