// EnsureContext checks whether the given context.Context contains a Span. If
// not, it creates one using the provided Tracer and wraps it in the returned
// Span. The returned closure must be called after the request has been fully
// processed.
func EnsureContext(ctx context.Context, tracer opentracing.Tracer) (context.Context, func()) {
_, _, funcName := caller.Lookup(1)
if opentracing.SpanFromContext(ctx) == nil {
sp := tracer.StartSpan(funcName)
return opentracing.ContextWithSpan(ctx, sp), sp.Finish
}
return ctx, func() {}
}
// SpanFromContext returns the Span obtained from the context or, if none is
// found, a new one started through the tracer. Callers should call (or defer)
// the returned cleanup func as well to ensure that the span is Finish()ed, but
// callers should *not* attempt to call Finish directly -- in the case where the
// span was obtained from the context, it is not the caller's to Finish.
func SpanFromContext(opName string, tracer opentracing.Tracer, ctx context.Context) (opentracing.Span, func()) {
sp := opentracing.SpanFromContext(ctx)
if sp == nil {
sp = tracer.StartSpan(opName)
return sp, sp.Finish
}
return sp, func() {}
}
// JoinOrNew creates a new Span joined to the provided DelegatingCarrier or
// creates Span from the given tracer.
func JoinOrNew(tr opentracing.Tracer, carrier *Span, opName string) (opentracing.Span, error) {
if carrier != nil {
sp, err := tr.Join(opName, basictracer.Delegator, carrier)
switch err {
case nil:
sp.LogEvent(opName)
return sp, nil
case opentracing.ErrTraceNotFound:
default:
return nil, err
}
}
return tr.StartSpan(opName), nil
}
// InitSenderForLocalTestCluster initializes a TxnCoordSender that can be used
// with LocalTestCluster.
func InitSenderForLocalTestCluster(
nodeDesc *roachpb.NodeDescriptor,
tracer opentracing.Tracer,
clock *hlc.Clock,
latency time.Duration,
stores client.Sender,
stopper *stop.Stopper,
gossip *gossip.Gossip,
) client.Sender {
var rpcSend rpcSendFn = func(_ SendOptions, _ ReplicaSlice,
args roachpb.BatchRequest, _ *rpc.Context) (*roachpb.BatchResponse, error) {
if latency > 0 {
time.Sleep(latency)
}
sp := tracer.StartSpan("node")
defer sp.Finish()
ctx := opentracing.ContextWithSpan(context.Background(), sp)
log.Trace(ctx, args.String())
br, pErr := stores.Send(ctx, args)
if br == nil {
br = &roachpb.BatchResponse{}
}
if br.Error != nil {
panic(roachpb.ErrorUnexpectedlySet(stores, br))
}
br.Error = pErr
if pErr != nil {
log.Trace(ctx, "error: "+pErr.String())
}
return br, nil
}
retryOpts := GetDefaultDistSenderRetryOptions()
retryOpts.Closer = stopper.ShouldDrain()
distSender := NewDistSender(&DistSenderContext{
Clock: clock,
RangeDescriptorCacheSize: defaultRangeDescriptorCacheSize,
RangeLookupMaxRanges: defaultRangeLookupMaxRanges,
LeaderCacheSize: defaultLeaderCacheSize,
RPCRetryOptions: &retryOpts,
nodeDescriptor: nodeDesc,
RPCSend: rpcSend, // defined above
RangeDescriptorDB: stores.(RangeDescriptorDB), // for descriptor lookup
}, gossip)
return NewTxnCoordSender(distSender, clock, false /* !linearizable */, tracer,
stopper, NewTxnMetrics(metric.NewRegistry()))
}
func TestTracer(t *testing.T) {
log.SetFlags(0)
var tracer ot.Tracer
tracer = &Tracer{}
ot.InitGlobalTracer(tracer)
ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
serverSpan, err := tracer.Join(
"serverSpan",
ot.TextMap,
ot.HTTPHeaderTextMapCarrier(r.Header))
if err != nil {
panic(err)
}
time.Sleep(time.Second * 1)
serverSpan.Finish()
fmt.Fprintln(w, "Hello, client")
}))
defer ts.Close()
span, nctx := ot.StartSpanFromContext(context.TODO(), "main_test")
defer span.Finish()
foo(nctx, "bar", 0)
httpClient := &http.Client{}
httpReq, _ := http.NewRequest("GET", ts.URL, nil)
// Transmit the span's TraceContext as HTTP headers on our
// outbound request.
tracer.Inject(
span,
ot.TextMap,
ot.HTTPHeaderTextMapCarrier(httpReq.Header))
if _, err := httpClient.Do(httpReq); err != nil {
panic(err)
}
}
// JoinOrNew creates a new Span joined to the provided DelegatingCarrier or
// creates Span from the given tracer.
func JoinOrNew(tr opentracing.Tracer, carrier *Span, opName string) (opentracing.Span, error) {
if carrier != nil {
wireContext, err := tr.Extract(basictracer.Delegator, carrier)
switch err {
case nil:
sp := tr.StartSpan(opName, opentracing.FollowsFrom(wireContext))
sp.LogEvent(opName)
return sp, nil
case opentracing.ErrSpanContextNotFound:
default:
return nil, err
}
}
return tr.StartSpan(opName), nil
}
// JoinOrNew creates a new Span joined to the provided DelegatingCarrier or
// creates Span from the given tracer.
func JoinOrNew(
tr opentracing.Tracer, carrier *SpanContextCarrier, opName string,
) (opentracing.Span, error) {
if carrier != nil {
wireContext, err := tr.Extract(basictracer.Delegator, carrier)
switch err {
case nil:
sp := tr.StartSpan(opName, opentracing.FollowsFrom(wireContext))
// Copy baggage items to tags so they show up in the Lightstep UI.
sp.Context().ForeachBaggageItem(func(k, v string) bool { sp.SetTag(k, v); return true })
sp.LogFields(otlog.String("event", opName))
return sp, nil
case opentracing.ErrSpanContextNotFound:
default:
return nil, err
}
}
return tr.StartSpan(opName), nil
}
// Send implements the batch.Sender interface. If the request is part of a
// transaction, the TxnCoordSender adds the transaction to a map of active
// transactions and begins heartbeating it. Every subsequent request for the
// same transaction updates the lastUpdate timestamp to prevent live
// transactions from being considered abandoned and garbage collected.
// Read/write mutating requests have their key or key range added to the
// transaction's interval tree of key ranges for eventual cleanup via resolved
// write intents; they're tagged to an outgoing EndTransaction request, with
// the receiving replica in charge of resolving them.
func (tc *TxnCoordSender) Send(
ctx context.Context, ba roachpb.BatchRequest,
) (*roachpb.BatchResponse, *roachpb.Error) {
// Start new or pick up active trace. From here on, there's always an active
// Trace, though its overhead is small unless it's sampled.
sp := opentracing.SpanFromContext(ctx)
var tracer opentracing.Tracer
if sp == nil {
tracer = tc.AmbientContext.Tracer
sp = tracer.StartSpan(opTxnCoordSender)
defer sp.Finish()
ctx = opentracing.ContextWithSpan(ctx, sp)
} else {
tracer = sp.Tracer()
}
startNS := tc.clock.PhysicalNow()
if ba.Txn != nil {
// If this request is part of a transaction...
if err := tc.maybeBeginTxn(&ba); err != nil {
return nil, roachpb.NewError(err)
}
txnID := *ba.Txn.ID
// Associate the txnID with the trace. We need to do this after the
// maybeBeginTxn call. We set both a baggage item and a tag because only
// tags show up in the LIghtstep UI.
txnIDStr := txnID.String()
sp.SetTag("txnID", txnIDStr)
sp.SetBaggageItem("txnID", txnIDStr)
var et *roachpb.EndTransactionRequest
var hasET bool
{
var rArgs roachpb.Request
rArgs, hasET = ba.GetArg(roachpb.EndTransaction)
if hasET {
et = rArgs.(*roachpb.EndTransactionRequest)
if len(et.Key) != 0 {
return nil, roachpb.NewErrorf("EndTransaction must not have a Key set")
}
et.Key = ba.Txn.Key
if len(et.IntentSpans) > 0 {
// TODO(tschottdorf): it may be useful to allow this later.
// That would be part of a possible plan to allow txns which
// write on multiple coordinators.
return nil, roachpb.NewErrorf("client must not pass intents to EndTransaction")
}
}
}
if pErr := func() *roachpb.Error {
tc.Lock()
defer tc.Unlock()
if pErr := tc.maybeRejectClientLocked(ctx, *ba.Txn); pErr != nil {
return pErr
}
if !hasET {
return nil
}
// Everything below is carried out only when trying to commit.
// Populate et.IntentSpans, taking into account both any existing
// and new writes, and taking care to perform proper deduplication.
txnMeta := tc.txns[txnID]
distinctSpans := true
if txnMeta != nil {
et.IntentSpans = txnMeta.keys
// Defensively set distinctSpans to false if we had any previous
// requests in this transaction. This effectively limits the distinct
// spans optimization to 1pc transactions.
distinctSpans = len(txnMeta.keys) == 0
}
// We can't pass in a batch response here to better limit the key
// spans as we don't know what is going to be affected. This will
// affect queries such as `DELETE FROM my.table LIMIT 10` when
// executed as a 1PC transaction. e.g.: a (BeginTransaction,
// DeleteRange, EndTransaction) batch.
ba.IntentSpanIterate(nil, func(key, endKey roachpb.Key) {
et.IntentSpans = append(et.IntentSpans, roachpb.Span{
Key: key,
EndKey: endKey,
})
})
// TODO(peter): Populate DistinctSpans on all batches, not just batches
// which contain an EndTransactionRequest.
var distinct bool
// The request might already be used by an outgoing goroutine, so
// we can't safely mutate anything in-place (as MergeSpans does).
et.IntentSpans = append([]roachpb.Span(nil), et.IntentSpans...)
et.IntentSpans, distinct = roachpb.MergeSpans(et.IntentSpans)
ba.Header.DistinctSpans = distinct && distinctSpans
if len(et.IntentSpans) == 0 {
// If there aren't any intents, then there's factually no
// transaction to end. Read-only txns have all of their state
// in the client.
return roachpb.NewErrorf("cannot commit a read-only transaction")
}
if txnMeta != nil {
txnMeta.keys = et.IntentSpans
}
return nil
}(); pErr != nil {
return nil, pErr
}
if hasET && log.V(1) {
for _, intent := range et.IntentSpans {
log.Eventf(ctx, "intent: [%s,%s)", intent.Key, intent.EndKey)
}
}
}
// Embed the trace metadata into the header for use by RPC recipients. We need
// to do this after the maybeBeginTxn call above.
// TODO(tschottdorf): To get rid of the spurious alloc below we need to
// implement the carrier interface on ba.Header or make Span non-nullable,
// both of which force all of ba on the Heap. It's already there, so may
// not be a big deal, but ba should live on the stack. Also not easy to use
// a buffer pool here since anything that goes into the RPC layer could be
// used by goroutines we didn't wait for.
if ba.TraceContext == nil {
ba.TraceContext = &tracing.SpanContextCarrier{}
} else {
// We didn't make this object but are about to mutate it, so we
// have to take a copy - the original might already have been
// passed to the RPC layer.
ba.TraceContext = protoutil.Clone(ba.TraceContext).(*tracing.SpanContextCarrier)
}
if err := tracer.Inject(sp.Context(), basictracer.Delegator, ba.TraceContext); err != nil {
return nil, roachpb.NewError(err)
}
// Send the command through wrapped sender, taking appropriate measures
// on error.
var br *roachpb.BatchResponse
{
var pErr *roachpb.Error
br, pErr = tc.wrapped.Send(ctx, ba)
if _, ok := pErr.GetDetail().(*roachpb.OpRequiresTxnError); ok {
// TODO(tschottdorf): needs to keep the trace.
br, pErr = tc.resendWithTxn(ba)
}
if pErr = tc.updateState(ctx, startNS, ba, br, pErr); pErr != nil {
log.Eventf(ctx, "error: %s", pErr)
return nil, pErr
}
}
if br.Txn == nil {
return br, nil
}
if _, ok := ba.GetArg(roachpb.EndTransaction); !ok {
return br, nil
}
// If the --linearizable flag is set, we want to make sure that
// all the clocks in the system are past the commit timestamp
// of the transaction. This is guaranteed if either
// - the commit timestamp is MaxOffset behind startNS
// - MaxOffset ns were spent in this function
// when returning to the client. Below we choose the option
// that involves less waiting, which is likely the first one
// unless a transaction commits with an odd timestamp.
if tsNS := br.Txn.Timestamp.WallTime; startNS > tsNS {
startNS = tsNS
}
sleepNS := tc.clock.MaxOffset() -
time.Duration(tc.clock.PhysicalNow()-startNS)
if tc.linearizable && sleepNS > 0 {
defer func() {
if log.V(1) {
log.Infof(ctx, "%v: waiting %s on EndTransaction for linearizability", br.Txn.Short(), util.TruncateDuration(sleepNS, time.Millisecond))
}
time.Sleep(sleepNS)
}()
}
if br.Txn.Status != roachpb.PENDING {
tc.Lock()
tc.cleanupTxnLocked(ctx, *br.Txn)
tc.Unlock()
}
return br, nil
}
