Re: [PATCH v4 3/6] block-copy: improve comments of BlockCopyTask and BlockCopyState types and functions

[Emanuele Giuseppe Esposito <eesposit@redhat.com>]

On 19/06/2021 19:27, Vladimir Sementsov-Ogievskiy wrote:
> 14.06.2021 10:33, Emanuele Giuseppe Esposito wrote:
>> As done in BlockCopyCallState, categorize BlockCopyTask
>> and BlockCopyState in IN, State and OUT fields.
>> This is just to understand which field has to be protected with a lock.
>>
>> .sleep_state is handled in the series "coroutine: new sleep/wake API"
>> and thus here left as TODO.
>>
>> Signed-off-by: Emanuele Giuseppe Esposito<eesposit@redhat.com>
>> ---
>>   block/block-copy.c | 49 +++++++++++++++++++++++++++++-----------------
>>   1 file changed, 31 insertions(+), 18 deletions(-)
>>
>> diff --git a/block/block-copy.c b/block/block-copy.c
>> index 3f26be8ddc..5ff7764e87 100644
>> --- a/block/block-copy.c
>> +++ b/block/block-copy.c
>> @@ -52,29 +52,35 @@ typedef struct BlockCopyCallState {
>>       /* Coroutine where async block-copy is running */
>>       Coroutine *co;
>> -    /* To reference all call states from BlockCopyState */
>> -    QLIST_ENTRY(BlockCopyCallState) list;
>> -
>>       /* State */
>> -    int ret;
>>       bool finished;
>> -    QemuCoSleep sleep;
>> -    bool cancelled;
>> +    QemuCoSleep sleep; /* TODO: protect API with a lock */
>> +
>> +    /* To reference all call states from BlockCopyState */
>> +    QLIST_ENTRY(BlockCopyCallState) list;
>>       /* OUT parameters */
>> +    bool cancelled;
> 
> actually, cancelled is not OUT field. It's set by user to cancel the 
> operation. And block-copy tracks the field to understand should it 
> cancel at the moment or not. So, it's part of state.

Makes sense.

> 
> Also, I just now understand, that "out parameter" sounds strange here. 
> As "parameter" is an input by general meaning.. We may have "out 
> parameters" for functions, as all parameters of a function are generally 
> called "parameters" anyway. I think "OUT fields" is more correct here. I 
> don't insist, as I'm not an expert in English (for sure, you'll find 
> mistakes even in this paragraph :\
> 
Actually I am using the terminology that was already there :)
Anyways, I am not expert here either but fields do sounds better.
I will change parameter -> field replacement to this patch.

Emanuele