shinrich commented on a change in pull request #7276:
URL: https://github.com/apache/trafficserver/pull/7276#discussion_r512659302
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File path: proxy/http/HttpTransact.cc
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@@ -1856,12 +1852,9 @@ HttpTransact::ReDNSRoundRobin(State *s)
void
HttpTransact::OSDNSLookup(State *s)
{
- static const int max_dns_lookups = 3;
-
ink_assert(s->dns_info.looking_up == ORIGIN_SERVER);
- TxnDebug("http_trans", "[HttpTransact::OSDNSLookup] This was attempt %d",
s->dns_info.attempts);
Review comment:
I removed DNS_ATTEMPTS_EXHAUSTED because the current
try_to_expand_host_name() never returns that. It only returns
EXPANSION_NOT_ALLOWED in the non-parent selection case or RETRY_EXPANDED_NAME
in the parent selection case. So got rid of the extra cases and inlined the
contents of try_to_expand host name.
With the most of the expandomatic logic gone, only the parent select case
exercises this path, and it will only exercise it once to check the IP address
of the parent machine rather than the parent path directly (here is where my
knowledge of why the parent select logic flips over to OSDNSLookup becomes
shakey).
The underlying DNS lookup logic in iocore/DNS will still do multiple DNS
requests.
The origin server look up logic will pass through OSDNSLookup multiple times
for a transaction if the connection for an IP address fails . Then OSDNSLookup
will be triggered again and either the same address is selected again or if it
failed too many times, the logic will move onto the next address (assuming DNS
returns multiple addresses for the name)
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