Fix HostDBInfo::is_down condition

[masaori335]

The condition of HostDBInfo::is_down seems opposite.

This function is only used by HostDBRecord::select_best_srv() , so only SRV record case is affected.

trafficserver/src/iocore/hostdb/HostDB.cc

Lines 1609 to 1611 in 2a30bcc

	// skip down targets.
	if (rr[i].is_down(now, fail_window)) {
	continue;

[Copilot]

Pull request overview

This PR fixes a logical error in the HostDBInfo::is_down method where the condition was inverted, causing it to incorrectly determine when a host should be considered down based on its failure window.

Changes:

• Corrected the comparison operator in is_down() from < to >= to properly check if a host is still within its failure window

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[bryancall]

Please make comments, it is confusing

[bneradt]

Approved. Maybe check with @serrislew and @cmcfarlen as well since it sounds like they looked into this previously.

[masaori335]

I wrote comment to clarify. Please take another look.

[masaori335]

I talked with @serrislew and @cmcfarlen, we found her patch has almost the same change in this function with other changes. And we agreed with shipping this PR first.

[bryancall]

LGTM. The inverted condition is clearly a bug — last_fail + fail_window < now returns true when the fail window has expired (host should be UP), not when the host is still down. The fix correctly flips this to now <= last_fail + fail_window.

The ASCII timeline diagram in the comment is a nice addition — makes the time-window semantics immediately clear.

SRV-only impact, CI green, straightforward fix.