// heartbeatLoop periodically sends a HeartbeatTxn RPC to an extant
// transaction, stopping in the event the transaction is aborted or
// committed after attempting to resolve the intents. When the
// heartbeat stops, the transaction is unregistered from the
// coordinator,
func (tc *TxnCoordSender) heartbeatLoop(txnID uuid.UUID) {
var tickChan <-chan time.Time
{
ticker := time.NewTicker(tc.heartbeatInterval)
tickChan = ticker.C
defer ticker.Stop()
}
defer func() {
tc.Lock()
duration, restarts, status := tc.unregisterTxnLocked(txnID)
tc.Unlock()
tc.updateStats(duration, int64(restarts), status)
}()
var closer <-chan struct{}
var sp opentracing.Span
{
tc.Lock()
txnMeta := tc.txns[txnID] // do not leak to outer scope
closer = txnMeta.txnEnd
// TODO(tschottdorf): this should join to the trace of the request
// which starts this goroutine.
sp = tc.tracer.StartSpan(opHeartbeatLoop)
defer sp.Finish()
tc.Unlock()
}
if closer == nil {
// Avoid race in which a Txn is cleaned up before the heartbeat
// goroutine gets a chance to start.
return
}
ctx := opentracing.ContextWithSpan(context.Background(), sp)
// Loop with ticker for periodic heartbeats.
for {
select {
case <-tickChan:
if !tc.heartbeat(txnID, sp, ctx) {
return
}
case <-closer:
// Transaction finished normally.
return
case <-tc.stopper.ShouldDrain():
return
}
}
}
// FinishSpan closes the given span (if not nil). It is a convenience wrapper
// for span.Finish() which tolerates nil spans.
func FinishSpan(span opentracing.Span) {
if span != nil {
span.Finish()
}
}