Add Client#ping(timeout:) for FreeTDS-bounded liveness checks - #609
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Temporarily lower DBSETTIME for SELECT 1 so dead/idle-RST handles fail in seconds instead of the connection's long query timeout; restore on success. Returns false on failure so callers can discard the client. Addresses the liveness-probe discussion in rails-sqlserver/activerecord-sqlserver-adapter#1396 without changing passive active?/dead? semantics. Co-authored-by: Cursor <cursoragent@cursor.com>
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Tracking discussion / attention request on the adapter side: rails-sqlserver/activerecord-sqlserver-adapter#1413 (also links this PR and adapter #1412). |
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Summary
TinyTds::Client#ping(timeout:)that temporarily sets FreeTDSDBSETTIME, runsSELECT 1, restores the previous timeout on success, and returnsfalseon timeout/failure so callers can discard the handle.query_timeout/query_timeout=(shared helper also used at connect) so a live client can change query timeout without reconnecting.active?/dead?(dbdead) — explicit#pingkeeps the opt-in clear for adapters/apps.This is meant as the driver-level answer to the checkout-liveness question in activerecord-sqlserver-adapter#1396: idle TCP RST (TCP reset — peer or middlebox abruptly closes the socket while the client still believes the session is alive) plus passive FreeTDS
dbdead. RubyTimeoutaroundexecutedoes not reliably interrupt TinyTDS/C I/O; the short bound has to be FreeTDS-level. Policy for when to call#ping(e.g. adapterverify!/active?) can live in the adapter — see follow-up activerecord-sqlserver-adapter#1412.Test plan
bundle exec rake compiletest/client_test.rb:query_timeoutfrom connect;query_timeout=bounds WaitFor;#pingreturns true and restores timeout;#pingreturns false when round-trip exceeds ping timeout; ArgumentError / closed client cases