QUEUE_ADD(h, n) append n to h, after QUEUE_ADDing, h is a valid queue head,
but n is not a valid queue and is not iteratable
On Thursday, March 24, 2016 at 10:30:06 AM UTC+8, Xiaomao Lan wrote:
>
> Is QUEUE_ADD(h, n) to add n to h, rather than to add h to n ?
>
>
>
> 在 2016年3月23日星期三 UTC+8下午7:00:43，Xiaomao Lan写道：
>>
>>
>>
>> Modify the code: modify macro QUEUE_ADD, and not to traverse wq, then it
>> is ok.
>>
>>
>> #define QUEUE_NEXT_NEXT(q) (QUEUE_NEXT(QUEUE_NEXT(q)))
>>
>> Modify:
>> #define QUEUE_ADD(h, n)
>> \
>> do {
>> \
>> QUEUE_PREV_NEXT(h) = QUEUE_NEXT(n);
>> \
>> QUEUE_NEXT_PREV(n) = QUEUE_PREV(h);
>> \
>> QUEUE_PREV(h) = QUEUE_PREV(n);
>> \
>> QUEUE_PREV_NEXT(h) = (h);
>> \
>> }
>> \
>> while (0)
>>
>> to:
>> #define QUEUE_ADD(h, n)
>> \
>> do {
>> \
>> QUEUE_PREV_NEXT(h) = (n);
>> \
>> QUEUE_NEXT_PREV(h) = QUEUE_PREV(n);
>> \
>> QUEUE_NEXT_NEXT(n) = QUEUE_NEXT(h);
>> \
>> QUEUE_PREV(n) = QUEUE_PREV(h);
>> \
>> }
>> \
>> while (0)
>>
>>
>>
>> int main()
>> {
>> ......
>>
>> QUEUE_ADD(&wq, &wq2); // add wq to wq2
>>
>> // can not traverse wq, its data pointer wq2.
>> /* QUEUE_FOREACH(q, &wq)
>> {
>> pw = QUEUE_DATA(q, uv__work, wq);
>> printf("queue wq data is %d.\n", pw->id);
>> }
>> */ printf("-----------------------------\n");
>>
>>
>> .....
>> return 0;
>> }
>>
>>
>> The program output:
>> queue wq data is 1.
>> queue wq data is 2.
>> queue wq data is 3.
>> -----------------------------
>> queue wq2 data is 4.
>> -----------------------------
>> -----------------------------
>> queue wq2 data is 4.
>> queue wq2 data is 1.
>> queue wq2 data is 2.
>> queue wq2 data is 3.
>> -----------------------------
>>
>>
>>
>>
>>
>>
>> 在 2016年3月15日星期二 UTC+8上午9:52:46，Xiaomao Lan写道：
>>>
>>> QUEUE wq2;
>>> QUEUE_INIT(&wq2);
>>>
>>> In the codes, had written.
>>>
>>> 在 2016年3月9日星期三 UTC+8下午3:13:28，Xy Wang写道：
>>>>
>>>> after `QUEUE_ADD(&wq, &wq2)`, `wq2` is not iterable and it is not still
>>>> a valid queue header, all you should do is `QUEUE_INIT(&wq2);`
>>>>
>>>> On Tuesday, March 8, 2016 at 6:03:11 PM UTC+8, Xiaomao Lan wrote:
>>>>>
>>>>>
>>>>> The submitted at github:
>>>>> https://github.com/libuv/libuv/issues/754
>>>>>
>>>>> The code is modified, but the issue still exist.
>>>>> New code: add QUEUE_INIT(&w1.wq); .... QUEUE_INIT(&w4.wq);
>>>>>
>>>>>
>>>>> #include "queue.h"
>>>>> #include <stdio.h>
>>>>>
>>>>> struct uv__work {
>>>>> int id;
>>>>> void* wq[2];
>>>>> };
>>>>>
>>>>> #define QUEUE_DATA(ptr, type, field) \
>>>>> ((type *) ((char *) (ptr) - offsetof(type, field)))
>>>>>
>>>>>
>>>>> static QUEUE wq;
>>>>>
>>>>> int main()
>>>>> {
>>>>> struct uv__work *pw;
>>>>> QUEUE* q;
>>>>>
>>>>> QUEUE_INIT(&wq);
>>>>>
>>>>> struct uv__work w1;
>>>>> w1.id = 1;
>>>>> QUEUE_INIT(&w1.wq);
>>>>> QUEUE_INSERT_TAIL(&wq, &w1.wq);
>>>>>
>>>>> struct uv__work w2;
>>>>> w2.id = 2;
>>>>> QUEUE_INIT(&w2.wq);
>>>>> QUEUE_INSERT_TAIL(&wq, &w2.wq);
>>>>>
>>>>> struct uv__work w3;
>>>>> w3.id = 3;
>>>>> QUEUE_INIT(&w3.wq);
>>>>> QUEUE_INSERT_TAIL(&wq, &w3.wq);
>>>>>
>>>>>
>>>>> QUEUE_FOREACH(q, &wq)
>>>>> {
>>>>> pw = QUEUE_DATA(q, uv__work, wq);
>>>>> printf("queue wq data is %d.\n", pw->id);
>>>>> }
>>>>> printf("-----------------------------\n");
>>>>>
>>>>> QUEUE wq2;
>>>>> QUEUE_INIT(&wq2);
>>>>>
>>>>> struct uv__work w4;
>>>>> w4.id = 4;
>>>>> QUEUE_INIT(&w4.wq);
>>>>> QUEUE_INSERT_TAIL(&wq2, &w4.wq);
>>>>>
>>>>> QUEUE_FOREACH(q, &wq2)
>>>>> {
>>>>> pw = QUEUE_DATA(q, uv__work, wq);
>>>>> printf("queue wq2 data is %d.\n", pw->id);
>>>>> }
>>>>> printf("-----------------------------\n");
>>>>>
>>>>>
>>>>> QUEUE_ADD(&wq, &wq2); // add
>>>>>
>>>>> QUEUE_FOREACH(q, &wq)
>>>>> {
>>>>> pw = QUEUE_DATA(q, uv__work, wq);
>>>>> printf("queue wq data is %d.\n", pw->id);
>>>>> }
>>>>> printf("-----------------------------\n");
>>>>>
>>>>> QUEUE_FOREACH(q, &wq2)
>>>>> {
>>>>> pw = QUEUE_DATA(q, uv__work, wq);
>>>>> printf("queue wq2 data is %d.\n", pw->id);
>>>>> }
>>>>> printf("-----------------------------\n");
>>>>>
>>>>> return 0;
>>>>> }
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
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