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Re: timeout return value in Curl_poll, Curl_wait_ms

From: Peter Wang <novalazy_at_gmail.com>
Date: Mon, 11 Aug 2014 10:21:28 +1000

On Tue, 29 Jul 2014 14:33:07 +1000, Peter Wang <novalazy_at_gmail.com> wrote:
> Hi,
>
> I think Curl_poll and perhaps Curl_wait_ms require the fix applied to
> Curl_socket_check in commits b61e8b8 and c771968.
>
> That is, when poll or select are interrupted and coincides with the
> timeout elapsing, the functions return -1 indicating an error
> instead of 0 for the timeout.

Just a reminder about this.

I can reproduce the problem quite reliably in a multi-threaded
application that uses curl and Boehm GC. The GC uses signals
to pause and resume threads, which interrupts the poll call.

Peter

>
> diff --git a/lib/select.c b/lib/select.c
> index da3082d..bb9b8b0 100644
> --- a/lib/select.c
> +++ b/lib/select.c
> @@ -108,8 +108,10 @@ int Curl_wait_ms(int timeout_ms)
> if(error && error_not_EINTR)
> break;
> pending_ms = timeout_ms - elapsed_ms;
> - if(pending_ms <= 0)
> + if(pending_ms <= 0) {
> + r = 0; /* Simulate a "call timed out" case */
> break;
> + }
> } while(r == -1);
> #endif /* USE_WINSOCK */
> if(r)
> @@ -432,8 +434,10 @@ int Curl_poll(struct pollfd ufds[], unsigned int nfds, int timeout_ms)
> break;
> if(timeout_ms > 0) {
> pending_ms = timeout_ms - elapsed_ms;
> - if(pending_ms <= 0)
> + if(pending_ms <= 0) {
> + r = 0; /* Simulate a "call timed out" case */
> break;
> + }
> }
> } while(r == -1);
>
> @@ -517,8 +521,10 @@ int Curl_poll(struct pollfd ufds[], unsigned int nfds, int timeout_ms)
> break;
> if(timeout_ms > 0) {
> pending_ms = timeout_ms - elapsed_ms;
> - if(pending_ms <= 0)
> + if(pending_ms <= 0) {
> + r = 0; /* Simulate a "call timed out" case */
> break;
> + }
> }
> } while(r == -1);
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Received on 2014-08-11