> On Feb 9, 2021, at 6:03 AM, Marton Balint <c...@passwd.hu> wrote:
>
>>
>> The wait_start was about POLLING_TIME larger which leads to timeout
>> 100ms late than the option setting.
>> ---
>> libavformat/network.c | 13 ++++++-------
>> 1 file changed, 6 insertions(+), 7 deletions(-)
>>
>> diff --git a/libavformat/network.c b/libavformat/network.c
>> index 0f5a575f77..7a9a4be5bb 100644
>> --- a/libavformat/network.c
>> +++ b/libavformat/network.c
>> @@ -78,7 +78,10 @@ int ff_network_wait_fd(int fd, int write)
>> int ff_network_wait_fd_timeout(int fd, int write, int64_t timeout,
>> AVIOInterruptCB *int_cb)
>> {
>> int ret;
>> - int64_t wait_start = 0;
>> + int64_t wait_start;
>> +
>> + if (timeout > 0)
>> + wait_start = av_gettime_relative();
>
> I think we intentionally wanted to avoid calling gettime on the fast path.
>
>>
>> while (1) {
>> if (ff_check_interrupt(int_cb))
>> @@ -86,12 +89,8 @@ int ff_network_wait_fd_timeout(int fd, int write, int64_t
>> timeout, AVIOInterrupt
>> ret = ff_network_wait_fd(fd, write);
>> if (ret != AVERROR(EAGAIN))
>> return ret;
>> - if (timeout > 0) {
>> - if (!wait_start)
>> - wait_start = av_gettime_relative();
>
> Why not simply wait_start = av_gettime_relative() - POLLING_TIME? It seems to
> achieve the same result.
Then it depends on the implementation of ff_network_wait_fd. After adding
wait_fd as a callback,
there is no guarantee that it takes POLLING_TIME. It can be solved by adding a
polling_time field
to NetworkWaitFdCB:
typedef struct NetworkWaitFdCB {
int (*wait_fd)(int /*fd*/, int /*write*/, void* /*opaque*/);
void *opaque;
int polling_time;
} NetworkWaitFdCB;
This is trying to get rid of calling gettime once. We can go further and
sacrifice the accuracy by:
int64_t loop_count = (timeout > 0) ? (timeout / polling_time) : timeout;
for (int64_t i = 0; loop_count <= 0 || i < loop_count; i++) {
...
}
In my opinion, either depends on gettime or loop_count, but not both.
>
> Thanks,
> Marton
>
>> - else if (av_gettime_relative() - wait_start > timeout)
>> - return AVERROR(ETIMEDOUT);
>> - }
>> + if (timeout > 0 && (av_gettime_relative() - wait_start > timeout))
>> + return AVERROR(ETIMEDOUT);
>> }
>> }
>> --
>> 2.28.0
>>
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