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opentelemetry-go/trace/trace.go

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// Copyright The OpenTelemetry Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package trace // import "go.opentelemetry.io/otel/trace"
import (
"bytes"
"context"
"encoding/hex"
"encoding/json"
"go.opentelemetry.io/otel/attribute"
"go.opentelemetry.io/otel/codes"
)
const (
// FlagsSampled is a bitmask with the sampled bit set. A SpanContext
// with the sampling bit set means the span is sampled.
FlagsSampled = TraceFlags(0x01)
errInvalidHexID errorConst = "trace-id and span-id can only contain [0-9a-f] characters, all lowercase"
errInvalidTraceIDLength errorConst = "hex encoded trace-id must have length equals to 32"
errNilTraceID errorConst = "trace-id can't be all zero"
errInvalidSpanIDLength errorConst = "hex encoded span-id must have length equals to 16"
errNilSpanID errorConst = "span-id can't be all zero"
)
type errorConst string
func (e errorConst) Error() string {
return string(e)
}
// TraceID is a unique identity of a trace.
// nolint:revive // revive complains about stutter of `trace.TraceID`.
type TraceID [16]byte
var nilTraceID TraceID
var _ json.Marshaler = nilTraceID
// IsValid checks whether the trace TraceID is valid. A valid trace ID does
// not consist of zeros only.
func (t TraceID) IsValid() bool {
return !bytes.Equal(t[:], nilTraceID[:])
}
// MarshalJSON implements a custom marshal function to encode TraceID
// as a hex string.
func (t TraceID) MarshalJSON() ([]byte, error) {
return json.Marshal(t.String())
}
// String returns the hex string representation form of a TraceID
func (t TraceID) String() string {
return hex.EncodeToString(t[:])
}
// SpanID is a unique identity of a span in a trace.
type SpanID [8]byte
var nilSpanID SpanID
var _ json.Marshaler = nilSpanID
// IsValid checks whether the SpanID is valid. A valid SpanID does not consist
// of zeros only.
func (s SpanID) IsValid() bool {
return !bytes.Equal(s[:], nilSpanID[:])
}
// MarshalJSON implements a custom marshal function to encode SpanID
// as a hex string.
func (s SpanID) MarshalJSON() ([]byte, error) {
return json.Marshal(s.String())
}
// String returns the hex string representation form of a SpanID
func (s SpanID) String() string {
return hex.EncodeToString(s[:])
}
// TraceIDFromHex returns a TraceID from a hex string if it is compliant with
// the W3C trace-context specification. See more at
// https://www.w3.org/TR/trace-context/#trace-id
// nolint:revive // revive complains about stutter of `trace.TraceIDFromHex`.
func TraceIDFromHex(h string) (TraceID, error) {
t := TraceID{}
if len(h) != 32 {
return t, errInvalidTraceIDLength
}
if err := decodeHex(h, t[:]); err != nil {
return t, err
}
if !t.IsValid() {
return t, errNilTraceID
}
return t, nil
}
// SpanIDFromHex returns a SpanID from a hex string if it is compliant
// with the w3c trace-context specification.
// See more at https://www.w3.org/TR/trace-context/#parent-id
func SpanIDFromHex(h string) (SpanID, error) {
s := SpanID{}
if len(h) != 16 {
return s, errInvalidSpanIDLength
}
if err := decodeHex(h, s[:]); err != nil {
return s, err
}
if !s.IsValid() {
return s, errNilSpanID
}
return s, nil
}
func decodeHex(h string, b []byte) error {
for _, r := range h {
switch {
case 'a' <= r && r <= 'f':
continue
case '0' <= r && r <= '9':
continue
default:
return errInvalidHexID
}
}
decoded, err := hex.DecodeString(h)
if err != nil {
return err
}
copy(b, decoded)
return nil
}
// TraceFlags contains flags that can be set on a SpanContext
type TraceFlags byte //nolint:revive // revive complains about stutter of `trace.TraceFlags`.
// IsSampled returns if the sampling bit is set in the TraceFlags.
func (tf TraceFlags) IsSampled() bool {
return tf&FlagsSampled == FlagsSampled
}
// WithSampled sets the sampling bit in a new copy of the TraceFlags.
func (tf TraceFlags) WithSampled(sampled bool) TraceFlags {
if sampled {
return tf | FlagsSampled
}
return tf &^ FlagsSampled
}
// MarshalJSON implements a custom marshal function to encode TraceFlags
// as a hex string.
func (tf TraceFlags) MarshalJSON() ([]byte, error) {
return json.Marshal(tf.String())
}
// String returns the hex string representation form of TraceFlags
func (tf TraceFlags) String() string {
return hex.EncodeToString([]byte{byte(tf)}[:])
}
// SpanContextConfig contains mutable fields usable for constructing
// an immutable SpanContext.
type SpanContextConfig struct {
TraceID TraceID
SpanID SpanID
TraceFlags TraceFlags
TraceState TraceState
Remote bool
}
// NewSpanContext constructs a SpanContext using values from the provided
// SpanContextConfig.
func NewSpanContext(config SpanContextConfig) SpanContext {
return SpanContext{
traceID: config.TraceID,
spanID: config.SpanID,
traceFlags: config.TraceFlags,
traceState: config.TraceState,
remote: config.Remote,
}
}
// SpanContext contains identifying trace information about a Span.
type SpanContext struct {
traceID TraceID
spanID SpanID
traceFlags TraceFlags
traceState TraceState
remote bool
}
var _ json.Marshaler = SpanContext{}
// IsValid returns if the SpanContext is valid. A valid span context has a
// valid TraceID and SpanID.
func (sc SpanContext) IsValid() bool {
return sc.HasTraceID() && sc.HasSpanID()
}
// IsRemote indicates whether the SpanContext represents a remotely-created Span.
func (sc SpanContext) IsRemote() bool {
return sc.remote
}
// WithRemote returns a copy of sc with the Remote property set to remote.
func (sc SpanContext) WithRemote(remote bool) SpanContext {
return SpanContext{
traceID: sc.traceID,
spanID: sc.spanID,
traceFlags: sc.traceFlags,
traceState: sc.traceState,
remote: remote,
}
}
// TraceID returns the TraceID from the SpanContext.
func (sc SpanContext) TraceID() TraceID {
return sc.traceID
}
// HasTraceID checks if the SpanContext has a valid TraceID.
func (sc SpanContext) HasTraceID() bool {
return sc.traceID.IsValid()
}
// WithTraceID returns a new SpanContext with the TraceID replaced.
func (sc SpanContext) WithTraceID(traceID TraceID) SpanContext {
return SpanContext{
traceID: traceID,
spanID: sc.spanID,
traceFlags: sc.traceFlags,
traceState: sc.traceState,
remote: sc.remote,
}
}
// SpanID returns the SpanID from the SpanContext.
func (sc SpanContext) SpanID() SpanID {
return sc.spanID
}
// HasSpanID checks if the SpanContext has a valid SpanID.
func (sc SpanContext) HasSpanID() bool {
return sc.spanID.IsValid()
}
// WithSpanID returns a new SpanContext with the SpanID replaced.
func (sc SpanContext) WithSpanID(spanID SpanID) SpanContext {
return SpanContext{
traceID: sc.traceID,
spanID: spanID,
traceFlags: sc.traceFlags,
traceState: sc.traceState,
remote: sc.remote,
}
}
// TraceFlags returns the flags from the SpanContext.
func (sc SpanContext) TraceFlags() TraceFlags {
return sc.traceFlags
}
// IsSampled returns if the sampling bit is set in the SpanContext's TraceFlags.
func (sc SpanContext) IsSampled() bool {
return sc.traceFlags.IsSampled()
}
// WithTraceFlags returns a new SpanContext with the TraceFlags replaced.
func (sc SpanContext) WithTraceFlags(flags TraceFlags) SpanContext {
return SpanContext{
traceID: sc.traceID,
spanID: sc.spanID,
traceFlags: flags,
traceState: sc.traceState,
remote: sc.remote,
}
}
// TraceState returns the TraceState from the SpanContext.
func (sc SpanContext) TraceState() TraceState {
return sc.traceState
}
// WithTraceState returns a new SpanContext with the TraceState replaced.
func (sc SpanContext) WithTraceState(state TraceState) SpanContext {
return SpanContext{
traceID: sc.traceID,
spanID: sc.spanID,
traceFlags: sc.traceFlags,
traceState: state,
remote: sc.remote,
}
}
// Equal is a predicate that determines whether two SpanContext values are equal.
func (sc SpanContext) Equal(other SpanContext) bool {
return sc.traceID == other.traceID &&
sc.spanID == other.spanID &&
sc.traceFlags == other.traceFlags &&
sc.traceState.String() == other.traceState.String() &&
sc.remote == other.remote
}
// MarshalJSON implements a custom marshal function to encode a SpanContext.
func (sc SpanContext) MarshalJSON() ([]byte, error) {
return json.Marshal(SpanContextConfig{
TraceID: sc.traceID,
SpanID: sc.spanID,
TraceFlags: sc.traceFlags,
TraceState: sc.traceState,
Remote: sc.remote,
})
}
// Span is the individual component of a trace. It represents a single named
// and timed operation of a workflow that is traced. A Tracer is used to
// create a Span and it is then up to the operation the Span represents to
// properly end the Span when the operation itself ends.
//
// Warning: methods may be added to this interface in minor releases.
type Span interface {
// End completes the Span. The Span is considered complete and ready to be
// delivered through the rest of the telemetry pipeline after this method
// is called. Therefore, updates to the Span are not allowed after this
// method has been called.
End(options ...SpanEndOption)
// AddEvent adds an event with the provided name and options.
AddEvent(name string, options ...EventOption)
// IsRecording returns the recording state of the Span. It will return
// true if the Span is active and events can be recorded.
IsRecording() bool
// RecordError will record err as an exception span event for this span. An
// additional call to SetStatus is required if the Status of the Span should
// be set to Error, as this method does not change the Span status. If this
// span is not being recorded or err is nil then this method does nothing.
RecordError(err error, options ...EventOption)
// SpanContext returns the SpanContext of the Span. The returned SpanContext
// is usable even after the End method has been called for the Span.
SpanContext() SpanContext
// SetStatus sets the status of the Span in the form of a code and a
// description, overriding previous values set. The description is only
// included in a status when the code is for an error.
SetStatus(code codes.Code, description string)
// SetName sets the Span name.
SetName(name string)
// SetAttributes sets kv as attributes of the Span. If a key from kv
// already exists for an attribute of the Span it will be overwritten with
// the value contained in kv.
SetAttributes(kv ...attribute.KeyValue)
// TracerProvider returns a TracerProvider that can be used to generate
// additional Spans on the same telemetry pipeline as the current Span.
TracerProvider() TracerProvider
}
// Link is the relationship between two Spans. The relationship can be within
// the same Trace or across different Traces.
//
// For example, a Link is used in the following situations:
//
// 1. Batch Processing: A batch of operations may contain operations
// associated with one or more traces/spans. Since there can only be one
// parent SpanContext, a Link is used to keep reference to the
// SpanContext of all operations in the batch.
// 2. Public Endpoint: A SpanContext for an in incoming client request on a
// public endpoint should be considered untrusted. In such a case, a new
// trace with its own identity and sampling decision needs to be created,
// but this new trace needs to be related to the original trace in some
// form. A Link is used to keep reference to the original SpanContext and
// track the relationship.
type Link struct {
// SpanContext of the linked Span.
SpanContext SpanContext
// Attributes describe the aspects of the link.
Attributes []attribute.KeyValue
}
// LinkFromContext returns a link encapsulating the SpanContext in the provided ctx.
func LinkFromContext(ctx context.Context, attrs ...attribute.KeyValue) Link {
return Link{
SpanContext: SpanContextFromContext(ctx),
Attributes: attrs,
}
}
// SpanKind is the role a Span plays in a Trace.
type SpanKind int
// As a convenience, these match the proto definition, see
// https://github.com/open-telemetry/opentelemetry-proto/blob/30d237e1ff3ab7aa50e0922b5bebdd93505090af/opentelemetry/proto/trace/v1/trace.proto#L101-L129
//
// The unspecified value is not a valid `SpanKind`. Use `ValidateSpanKind()`
// to coerce a span kind to a valid value.
const (
// SpanKindUnspecified is an unspecified SpanKind and is not a valid
// SpanKind. SpanKindUnspecified should be replaced with SpanKindInternal
// if it is received.
SpanKindUnspecified SpanKind = 0
// SpanKindInternal is a SpanKind for a Span that represents an internal
// operation within an application.
SpanKindInternal SpanKind = 1
// SpanKindServer is a SpanKind for a Span that represents the operation
// of handling a request from a client.
SpanKindServer SpanKind = 2
// SpanKindClient is a SpanKind for a Span that represents the operation
// of client making a request to a server.
SpanKindClient SpanKind = 3
// SpanKindProducer is a SpanKind for a Span that represents the operation
// of a producer sending a message to a message broker. Unlike
// SpanKindClient and SpanKindServer, there is often no direct
// relationship between this kind of Span and a SpanKindConsumer kind. A
// SpanKindProducer Span will end once the message is accepted by the
// message broker which might not overlap with the processing of that
// message.
SpanKindProducer SpanKind = 4
// SpanKindConsumer is a SpanKind for a Span that represents the operation
// of a consumer receiving a message from a message broker. Like
// SpanKindProducer Spans, there is often no direct relationship between
// this Span and the Span that produced the message.
SpanKindConsumer SpanKind = 5
)
// ValidateSpanKind returns a valid span kind value. This will coerce
// invalid values into the default value, SpanKindInternal.
func ValidateSpanKind(spanKind SpanKind) SpanKind {
switch spanKind {
case SpanKindInternal,
SpanKindServer,
SpanKindClient,
SpanKindProducer,
SpanKindConsumer:
// valid
return spanKind
default:
return SpanKindInternal
}
}
// String returns the specified name of the SpanKind in lower-case.
func (sk SpanKind) String() string {
switch sk {
case SpanKindInternal:
return "internal"
case SpanKindServer:
return "server"
case SpanKindClient:
return "client"
case SpanKindProducer:
return "producer"
case SpanKindConsumer:
return "consumer"
default:
return "unspecified"
}
}
// Tracer is the creator of Spans.
//
// Warning: methods may be added to this interface in minor releases.
type Tracer interface {
// Start creates a span and a context.Context containing the newly-created span.
//
// If the context.Context provided in `ctx` contains a Span then the newly-created
// Span will be a child of that span, otherwise it will be a root span. This behavior
// can be overridden by providing `WithNewRoot()` as a SpanOption, causing the
// newly-created Span to be a root span even if `ctx` contains a Span.
//
// When creating a Span it is recommended to provide all known span attributes using
// the `WithAttributes()` SpanOption as samplers will only have access to the
// attributes provided when a Span is created.
//
// Any Span that is created MUST also be ended. This is the responsibility of the user.
// Implementations of this API may leak memory or other resources if Spans are not ended.
Start(ctx context.Context, spanName string, opts ...SpanStartOption) (context.Context, Span)
}
// TracerProvider provides access to instrumentation Tracers.
//
// Warning: methods may be added to this interface in minor releases.
type TracerProvider interface {
// Tracer creates an implementation of the Tracer interface.
// The instrumentationName must be the name of the library providing
// instrumentation. This name may be the same as the instrumented code
// only if that code provides built-in instrumentation. If the
// instrumentationName is empty, then a implementation defined default
// name will be used instead.
//
// This method must be concurrency safe.
Tracer(instrumentationName string, opts ...TracerOption) Tracer
}