Expand php-wasm/node multi-worker support to Asyncify builds

[brandonpayton]

Motivation for the change, related issues

We want to be able to use multiple workers in places that don't have JSPI support.

Implementation details

TBD

Testing Instructions (or ideally a Blueprint)

TBD

[brandonpayton]

I am encountering a null-or-signature-mismatch error here:

The line is this, the zend_rc_dtor_func call in this function:

ZEND_API void ZEND_FASTCALL rc_dtor_func(zend_refcounted *p)
{
	ZEND_ASSERT(GC_TYPE(p) <= IS_CONSTANT_AST);
	zend_rc_dtor_func[GC_TYPE(p)](p);
}

I was able to find the GC_TYPE by expanding the refcounted pointer struct while debugging in Cursor. The GH type num was 7, which is an offset in this array:

static const zend_rc_dtor_func_t zend_rc_dtor_func[] = {
	[IS_UNDEF] =        (zend_rc_dtor_func_t)zend_empty_destroy,
	[IS_NULL] =         (zend_rc_dtor_func_t)zend_empty_destroy,
	[IS_FALSE] =        (zend_rc_dtor_func_t)zend_empty_destroy,
	[IS_TRUE] =         (zend_rc_dtor_func_t)zend_empty_destroy,
	[IS_LONG] =         (zend_rc_dtor_func_t)zend_empty_destroy,
	[IS_DOUBLE] =       (zend_rc_dtor_func_t)zend_empty_destroy,
	[IS_STRING] =       (zend_rc_dtor_func_t)zend_string_destroy,
	[IS_ARRAY] =        (zend_rc_dtor_func_t)zend_array_destroy,
	[IS_OBJECT] =       (zend_rc_dtor_func_t)zend_objects_store_del,
	[IS_RESOURCE] =     (zend_rc_dtor_func_t)zend_list_free,
	[IS_REFERENCE] =    (zend_rc_dtor_func_t)zend_reference_destroy,
	[IS_CONSTANT_AST] = (zend_rc_dtor_func_t)zend_ast_ref_destroy
};

If the GC type is indeed 7, then it looks like the dtor is zend_array_destroy(). Its signature doesn't look that different from the other dtor signatures I've examined, but I can instrument that function and its caller above to see if we can learn more.

[adamziel]

Any chance it would work on trunk with @mho22 wrapper? Or was that a completely different code path?

[brandonpayton]

Any chance it would work on trunk with @mho22 wrapper? Or was that a completely different code path?

It might! I think it is a different path, but it feels like it could be a similar thing. Will try shortly. :)

[brandonpayton]

After merging trunk into this branch, I'm still seeing the same issue. Will instrument php-src and see what can be found.

[mho22]

@adamziel @brandonpayton For the record, my wrapper is only targeting PHP7.4 and PHP7.3 to replace the old EMULATE_FUNCTION_POINTER_CASTS option applied to PHP versions lower than 8 :

RUN if [ "${PHP_VERSION:0:1}" -lt "8" ]; then \
	echo -n ' -s EMULATE_FUNCTION_POINTER_CASTS=1' >> /root/.emcc-php-wasm-flags; \
fi

It may be the same issue but Brandon is right, that's a new one. And the zend_array_destroy function seems to have a correct signature :

ZEND_API void ZEND_FASTCALL zend_array_destroy(HashTable *ht)

But maybe not, I think HashTable *ht should be replaced with zend_array to fit with the zend_refcounted *p from :

typedef void (ZEND_FASTCALL *zend_rc_dtor_func_t)(zend_refcounted *p);

So maybe you'll need to apply a new patch [ to PHP8.4 and PHP8.3 at least ] like this :

+ static void zend_array_destroy_wrapper(zend_refcounted *p) {
+    HashTable *ht = (HashTable*)p;
+    zend_array_destroy(ht);
+}

static const zend_rc_dtor_func_t zend_rc_dtor_func[] = {
	[IS_UNDEF] =        (zend_rc_dtor_func_t)zend_empty_destroy,
	[IS_NULL] =         (zend_rc_dtor_func_t)zend_empty_destroy,
	[IS_FALSE] =        (zend_rc_dtor_func_t)zend_empty_destroy,
	[IS_TRUE] =         (zend_rc_dtor_func_t)zend_empty_destroy,
	[IS_LONG] =         (zend_rc_dtor_func_t)zend_empty_destroy,
	[IS_DOUBLE] =       (zend_rc_dtor_func_t)zend_empty_destroy,
	[IS_STRING] =       (zend_rc_dtor_func_t)zend_string_destroy,
-	[IS_ARRAY] =        (zend_rc_dtor_func_t)zend_array_destroy,
+	[IS_ARRAY] =        zend_array_destroy_wrapper
	[IS_OBJECT] =       (zend_rc_dtor_func_t)zend_objects_store_del,
	[IS_RESOURCE] =     (zend_rc_dtor_func_t)zend_list_free,
	[IS_REFERENCE] =    (zend_rc_dtor_func_t)zend_reference_destroy,
	[IS_CONSTANT_AST] = (zend_rc_dtor_func_t)zend_ast_ref_destroy
};

I hope this helps.

[brandonpayton]

But maybe not, I think HashTable *ht should be replaced with zend_array to fit with the zend_refcounted *p from :

Thank you, @mho22. 🙇 This discussion is helpful. Hopefully, we are close to where the problem is.

I took a look at the HashTable and zend_array types, and they are both type aliases for the same struct like:

typedef struct _zend_array HashTable;
typedef struct _zend_array      zend_array;

My mental model suggests those types are equivalent and would not conflict, but it would be good to try a wrapper to confirm. Also, maybe there is some other type that is marked with IS_ARRAY that is not a HashTable or zend_array... We'll see!