func applyTransaction(kv mvcc.KV, lessor lease.Lessor, req *etcdserverpb.TxnRequest) (*etcdserverpb.TxnResponse, error) {
var revision int64
ok := true
for _, c := range req.Compare {
if revision, ok = applyCompare(kv, c); !ok {
break
}
}
var reqs []*etcdserverpb.RequestUnion
if ok {
reqs = req.Success
} else {
reqs = req.Failure
}
if err := checkRequestLeases(lessor, reqs); err != nil {
return nil, err
}
if err := checkRequestRange(kv, reqs); err != nil {
return nil, err
}
// When executing the operations of txn, we need to hold the txn lock.
// So the reader will not see any intermediate results.
txnID := kv.TxnBegin()
defer func() {
err := kv.TxnEnd(txnID)
if err != nil {
panic(fmt.Sprint("unexpected error when closing txn", txnID))
}
}()
resps := make([]*etcdserverpb.ResponseUnion, len(reqs))
for i := range reqs {
resps[i] = applyUnion(txnID, kv, reqs[i])
}
if len(resps) != 0 {
revision++
}
txnResp := &etcdserverpb.TxnResponse{}
txnResp.Header = &etcdserverpb.ResponseHeader{}
txnResp.Header.Revision = revision
txnResp.Responses = resps
txnResp.Succeeded = ok
return txnResp, nil
}
