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[UDP] try upstreams in round-robin fashion when all yupstreams have failed

This commit is contained in:
Robert Groenenberg 2018-02-26 16:46:57 +01:00 committed by Willem Toorop
parent f787c87137
commit eec6ec29dd
1 changed files with 9 additions and 4 deletions
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13
src/stub.c
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@ -2158,6 +2158,7 @@ upstream_select_stateful(getdns_network_req *netreq, getdns_transport_list_t tra
return upstream; return upstream;
} }
/* Used for UDP only */
static getdns_upstream * static getdns_upstream *
upstream_select(getdns_network_req *netreq) upstream_select(getdns_network_req *netreq)
{ {
@ -2167,6 +2168,7 @@ upstream_select(getdns_network_req *netreq)
if (!upstreams->count) if (!upstreams->count)
return NULL; return NULL;
/* First UPD/TCP upstream is always at i=0 and then start of each upstream block*/ /* First UPD/TCP upstream is always at i=0 and then start of each upstream block*/
/* TODO: Have direct access to sets of upstreams for different transports*/ /* TODO: Have direct access to sets of upstreams for different transports*/
for (i = 0; i < upstreams->count; i+=GETDNS_UPSTREAM_TRANSPORTS) for (i = 0; i < upstreams->count; i+=GETDNS_UPSTREAM_TRANSPORTS)
@ -2184,14 +2186,17 @@ upstream_select(getdns_network_req *netreq)
i = 0; i = 0;
} while (i != upstreams->current_udp); } while (i != upstreams->current_udp);
/* Select upstream with the lowest back_off value */
upstream = upstreams->upstreams; upstream = upstreams->upstreams;
for (i = 0; i < upstreams->count; i+=GETDNS_UPSTREAM_TRANSPORTS) for (i = 0; i < upstreams->count; i+=GETDNS_UPSTREAM_TRANSPORTS)
if (upstreams->upstreams[i].back_off < if (upstreams->upstreams[i].back_off < upstream->back_off)
upstream->back_off)
upstream = &upstreams->upstreams[i]; upstream = &upstreams->upstreams[i];
if (upstream->back_off > 1) /* Restrict back_off in case no upstream is available to achieve
upstream->back_off--; (more or less) round-robin retry on all upstreams. */
if (upstream->back_off > 4)
for (i = 0; i < upstreams->count; i+=GETDNS_UPSTREAM_TRANSPORTS)
upstreams->upstreams[i].back_off = 2;
upstream->to_retry = 1; upstream->to_retry = 1;
upstreams->current_udp = upstream - upstreams->upstreams; upstreams->current_udp = upstream - upstreams->upstreams;
return upstream; return upstream;