// 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(id string) {
var tickChan <-chan time.Time
{
ticker := time.NewTicker(tc.heartbeatInterval)
tickChan = ticker.C
defer ticker.Stop()
}
defer func() {
tc.Lock()
tc.unregisterTxnLocked(id)
tc.Unlock()
}()
var closer <-chan struct{}
var trace *tracer.Trace
{
tc.Lock()
txnMeta := tc.txns[id] // do not leak to outer scope
closer = txnMeta.txnEnd
trace = tc.tracer.NewTrace(tracer.Coord, &txnMeta.txn)
defer trace.Finalize()
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 := tracer.ToCtx(context.Background(), trace)
// Loop with ticker for periodic heartbeats.
for {
select {
case <-tickChan:
if !tc.heartbeat(id, trace, ctx) {
return
}
case <-closer:
// Transaction finished normally.
return
case <-tc.stopper.ShouldDrain():
return
}
}
}
// heartbeat 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) heartbeat(id string) {
var tickChan <-chan time.Time
{
ticker := time.NewTicker(tc.heartbeatInterval)
tickChan = ticker.C
defer ticker.Stop()
}
defer tc.unregisterTxn(id)
var closer <-chan struct{}
var trace *tracer.Trace
{
tc.Lock()
txnMeta := tc.txns[id] // do not leak to outer scope
closer = txnMeta.txnEnd
trace = tc.tracer.NewTrace(&txnMeta.txn)
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 := tracer.ToCtx(context.Background(), trace)
defer trace.Finalize()
// Loop with ticker for periodic heartbeats.
for {
select {
case <-tickChan:
tc.Lock()
proceed := true
txnMeta := tc.txns[id]
// Before we send a heartbeat, determine whether this transaction
// should be considered abandoned. If so, exit heartbeat.
if txnMeta.hasClientAbandonedCoord(tc.clock.PhysicalNow()) {
// TODO(tschottdorf): should we be more proactive here?
// The client might be continuing the transaction
// through another coordinator, but in the most likely
// case it's just gone and the open transaction record
// could block concurrent operations.
if log.V(1) {
log.Infof("transaction %s abandoned; stopping heartbeat",
txnMeta.txn)
}
proceed = false
}
// txnMeta.txn is possibly replaced concurrently,
// so grab a copy before unlocking.
txn := txnMeta.txn
tc.Unlock()
if !proceed {
return
}
request := &proto.HeartbeatTxnRequest{
RequestHeader: proto.RequestHeader{
Key: txn.Key,
User: security.RootUser,
Txn: &txn,
},
}
request.Header().Timestamp = tc.clock.Now()
reply := &proto.HeartbeatTxnResponse{}
call := proto.Call{
Args: request,
Reply: reply,
}
epochEnds := trace.Epoch("heartbeat")
tc.wrapped.Send(ctx, call)
epochEnds()
// If the transaction is not in pending state, then we can stop
// the heartbeat. It's either aborted or committed, and we resolve
// write intents accordingly.
if reply.GoError() != nil {
log.Warningf("heartbeat to %s failed: %s", txn, reply.GoError())
} else if reply.Txn != nil && reply.Txn.Status != proto.PENDING {
// Signal cleanup. Doesn't do much but stop this goroutine, but
// let's be future-proof.
tc.cleanupTxn(trace, *reply.Txn)
return
}
case <-closer:
// Transaction finished normally.
return
}
}
}