liuliu

static atomic_int executed_count;

void my_dispatch_async(dispatch_queue_t queue, dispatch_block_t block) {
    dispatch_block_t wrapped_block = ^{
        ++executed_count;
        block();
    };
    struct Block_layout *old_block_layout = (__bridge struct Block_layout *)block;
    if (old_block_layout->invoke == dispatch_block_special_invoke()) {
        wrapped_block = dispatch_block_create(DISPATCH_BLOCK_INHERIT_QOS_CLASS, wrapped_block);

liuliu

typedef void (*dispatch_f)(void*, ...);
dispatch_f dispatch_block_special_invoke()
{
    static dispatch_once_t onceToken;
    static dispatch_f f;
    dispatch_once(&onceToken, ^{
        f = (__bridge struct Block_layout *)dispatch_block_create(DISPATCH_BLOCK_INHERIT_QOS_CLASS, ^{})->invoke;
    });
    return f;
}

liuliu

dispatch_block_t
_dispatch_block_create(dispatch_block_flags_t flags, voucher_t voucher,
		pthread_priority_t pri, dispatch_block_t block)
{
	struct dispatch_block_private_data_s dbpds(flags, voucher, pri, block);
	return reinterpret_cast<dispatch_block_t>(_dispatch_Block_copy(^{
		// Capture stack object: invokes copy constructor (17094902)
		(void)dbpds;
		_dispatch_block_invoke_direct(&dbpds);
	}));

liuliu

// ...
struct Block_descriptor_1 {
    unsigned long int reserved;
    unsigned long int size;
};
// ...
struct Block_layout {
    void *isa;
    volatile int32_t flags; // contains ref count
    int32_t reserved; 

liuliu

dispatch_block_t block = dispatch_block_create_with_qos_class(DISPATCH_BLOCK_ENFORCE_QOS_CLASS, QOS_USER_INITIATED, 0, old_block);

liuliu

static atomic_int executed_count;

void my_dispatch_async(dispatch_queue_t queue, dispatch_block_t block) {
    dispatch_async(queue, ^{
        ++executed_count;
        block();
    });
}

liuliu

static co_decl_task(ab_t, _coroutine_a, (const int a, const int b), 

liuliu

static co_decl_task(ab_t, _coroutine_a, (const int a, const int b), private(
	int i;
)) {
	printf("param a %d\n", CO_P(a));
	printf("param b %d\n", CO_P(b));
	CO_V(i) = 2;
	printf("%d\n", CO_V(i));
	co_yield((ab_t){
		.a = CO_V(i)
	});

liuliu

static void g(task_t* const task)
{
	printf("start task %p\n", task);
	taskyield(task);
	printf("back to task %p to finish\n", task);
}

static void f(task_t* const task)
{
	printf("create a new task to resume %p\n", task);

liuliu

create a new task to resume 0x288d010
start task 0x289d410
done task 0x288d010
back to task 0x289d410 to finish