mirror of
https://github.com/restic/restic.git
synced 2024-09-08 12:29:39 +02:00
819 lines
25 KiB
Go
819 lines
25 KiB
Go
// Copyright 2016 Google Inc. All Rights Reserved.
|
|
//
|
|
// 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 is a Google Stackdriver Trace library.
|
|
//
|
|
// This package is still experimental and subject to change.
|
|
//
|
|
// See https://cloud.google.com/trace/api/#data_model for a discussion of traces
|
|
// and spans.
|
|
//
|
|
// To initialize a client that connects to the Stackdriver Trace server, use the
|
|
// NewClient function. Generally you will want to do this on program
|
|
// initialization.
|
|
//
|
|
// import "cloud.google.com/go/trace"
|
|
// ...
|
|
// traceClient, err = trace.NewClient(ctx, projectID)
|
|
//
|
|
// Calling SpanFromRequest will create a new trace span for an incoming HTTP
|
|
// request. If the request contains a trace context header, it is used to
|
|
// determine the trace ID. Otherwise, a new trace ID is created.
|
|
//
|
|
// func handler(w http.ResponseWriter, r *http.Request) {
|
|
// span := traceClient.SpanFromRequest(r)
|
|
// defer span.Finish()
|
|
// ...
|
|
// }
|
|
//
|
|
// SpanFromRequest and NewSpan returns nil if the *Client is nil, so you can disable
|
|
// tracing by not initializing your *Client variable. All of the exported
|
|
// functions on *Span do nothing when the *Span is nil.
|
|
//
|
|
// If you need to start traces that don't correspond to an incoming HTTP request,
|
|
// you can use NewSpan to create a root-level span.
|
|
//
|
|
// span := traceClient.NewSpan("span name")
|
|
// defer span.Finish()
|
|
//
|
|
// Although a trace span object is created for every request, only a subset of
|
|
// traces are uploaded to the server, for efficiency. By default, the requests
|
|
// that are traced are those with the tracing bit set in the options field of
|
|
// the trace context header. Ideally, you should override this behaviour by
|
|
// calling SetSamplingPolicy. NewLimitedSampler returns an implementation of
|
|
// SamplingPolicy which traces requests that have the tracing bit set, and also
|
|
// randomly traces a specified fraction of requests. Additionally, it sets a
|
|
// limit on the number of requests traced per second. The following example
|
|
// traces one in every thousand requests, up to a limit of 5 per second.
|
|
//
|
|
// p, err := trace.NewLimitedSampler(0.001, 5)
|
|
// traceClient.SetSamplingPolicy(p)
|
|
//
|
|
// You can create a new span as a child of an existing span with NewChild.
|
|
//
|
|
// childSpan := span.NewChild(name)
|
|
// ...
|
|
// childSpan.Finish()
|
|
//
|
|
// When sending an HTTP request to another server, NewRemoteChild will create
|
|
// a span to represent the time the current program waits for the request to
|
|
// complete, and attach a header to the outgoing request so that the trace will
|
|
// be propagated to the destination server.
|
|
//
|
|
// childSpan := span.NewRemoteChild(&httpRequest)
|
|
// ...
|
|
// childSpan.Finish()
|
|
//
|
|
// Alternatively, if you have access to the X-Cloud-Trace-Context header value
|
|
// but not the underlying HTTP request (this can happen if you are using a
|
|
// different transport or messaging protocol, such as gRPC), you can use
|
|
// SpanFromHeader instead of SpanFromRequest. In that case, you will need to
|
|
// specify the span name explicility, since it cannot be constructed from the
|
|
// HTTP request's URL and method.
|
|
//
|
|
// func handler(r *somepkg.Request) {
|
|
// span := traceClient.SpanFromHeader("span name", r.TraceContext())
|
|
// defer span.Finish()
|
|
// ...
|
|
// }
|
|
//
|
|
// Spans can contain a map from keys to values that have useful information
|
|
// about the span. The elements of this map are called labels. Some labels,
|
|
// whose keys all begin with the string "trace.cloud.google.com/", are set
|
|
// automatically in the following ways:
|
|
//
|
|
// - SpanFromRequest sets some labels to data about the incoming request.
|
|
//
|
|
// - NewRemoteChild sets some labels to data about the outgoing request.
|
|
//
|
|
// - Finish sets a label to a stack trace, if the stack trace option is enabled
|
|
// in the incoming trace header.
|
|
//
|
|
// - The WithResponse option sets some labels to data about a response.
|
|
// You can also set labels using SetLabel. If a label is given a value
|
|
// automatically and by SetLabel, the automatically-set value is used.
|
|
//
|
|
// span.SetLabel(key, value)
|
|
//
|
|
// The WithResponse option can be used when Finish is called.
|
|
//
|
|
// childSpan := span.NewRemoteChild(outgoingReq)
|
|
// resp, err := http.DefaultClient.Do(outgoingReq)
|
|
// ...
|
|
// childSpan.Finish(trace.WithResponse(resp))
|
|
//
|
|
// When a span created by SpanFromRequest or SpanFromHeader is finished, the
|
|
// finished spans in the corresponding trace -- the span itself and its
|
|
// descendants -- are uploaded to the Stackdriver Trace server using the
|
|
// *Client that created the span. Finish returns immediately, and uploading
|
|
// occurs asynchronously. You can use the FinishWait function instead to wait
|
|
// until uploading has finished.
|
|
//
|
|
// err := span.FinishWait()
|
|
//
|
|
// Using contexts to pass *trace.Span objects through your program will often
|
|
// be a better approach than passing them around explicitly. This allows trace
|
|
// spans, and other request-scoped or part-of-request-scoped values, to be
|
|
// easily passed through API boundaries. Various Google Cloud libraries will
|
|
// retrieve trace spans from contexts and automatically create child spans for
|
|
// API requests.
|
|
// See https://blog.golang.org/context for more discussion of contexts.
|
|
// A derived context containing a trace span can be created using NewContext.
|
|
//
|
|
// span := traceClient.SpanFromRequest(r)
|
|
// ctx = trace.NewContext(ctx, span)
|
|
//
|
|
// The span can be retrieved from a context elsewhere in the program using
|
|
// FromContext.
|
|
//
|
|
// func foo(ctx context.Context) {
|
|
// span := trace.FromContext(ctx).NewChild("in foo")
|
|
// defer span.Finish()
|
|
// ...
|
|
// }
|
|
//
|
|
package trace // import "cloud.google.com/go/trace"
|
|
|
|
import (
|
|
"crypto/rand"
|
|
"encoding/binary"
|
|
"encoding/json"
|
|
"fmt"
|
|
"log"
|
|
"net/http"
|
|
"runtime"
|
|
"strconv"
|
|
"strings"
|
|
"sync"
|
|
"sync/atomic"
|
|
"time"
|
|
|
|
"golang.org/x/net/context"
|
|
api "google.golang.org/api/cloudtrace/v1"
|
|
"google.golang.org/api/gensupport"
|
|
"google.golang.org/api/option"
|
|
"google.golang.org/api/support/bundler"
|
|
htransport "google.golang.org/api/transport/http"
|
|
)
|
|
|
|
const (
|
|
httpHeader = `X-Cloud-Trace-Context`
|
|
userAgent = `gcloud-golang-trace/20160501`
|
|
cloudPlatformScope = `https://www.googleapis.com/auth/cloud-platform`
|
|
spanKindClient = `RPC_CLIENT`
|
|
spanKindServer = `RPC_SERVER`
|
|
spanKindUnspecified = `SPAN_KIND_UNSPECIFIED`
|
|
maxStackFrames = 20
|
|
labelHost = `trace.cloud.google.com/http/host`
|
|
labelMethod = `trace.cloud.google.com/http/method`
|
|
labelStackTrace = `trace.cloud.google.com/stacktrace`
|
|
labelStatusCode = `trace.cloud.google.com/http/status_code`
|
|
labelURL = `trace.cloud.google.com/http/url`
|
|
labelSamplingPolicy = `trace.cloud.google.com/sampling_policy`
|
|
labelSamplingWeight = `trace.cloud.google.com/sampling_weight`
|
|
)
|
|
|
|
const (
|
|
// ScopeTraceAppend grants permissions to write trace data for a project.
|
|
ScopeTraceAppend = "https://www.googleapis.com/auth/trace.append"
|
|
|
|
// ScopeCloudPlatform grants permissions to view and manage your data
|
|
// across Google Cloud Platform services.
|
|
ScopeCloudPlatform = "https://www.googleapis.com/auth/cloud-platform"
|
|
)
|
|
|
|
type contextKey struct{}
|
|
|
|
type stackLabelValue struct {
|
|
Frames []stackFrame `json:"stack_frame"`
|
|
}
|
|
|
|
type stackFrame struct {
|
|
Class string `json:"class_name,omitempty"`
|
|
Method string `json:"method_name"`
|
|
Filename string `json:"file_name"`
|
|
Line int64 `json:"line_number"`
|
|
}
|
|
|
|
var (
|
|
spanIDCounter uint64
|
|
spanIDIncrement uint64
|
|
)
|
|
|
|
func init() {
|
|
// Set spanIDCounter and spanIDIncrement to random values. nextSpanID will
|
|
// return an arithmetic progression using these values, skipping zero. We set
|
|
// the LSB of spanIDIncrement to 1, so that the cycle length is 2^64.
|
|
binary.Read(rand.Reader, binary.LittleEndian, &spanIDCounter)
|
|
binary.Read(rand.Reader, binary.LittleEndian, &spanIDIncrement)
|
|
spanIDIncrement |= 1
|
|
// Attach hook for autogenerated Google API calls. This will automatically
|
|
// create trace spans for API calls if there is a trace in the context.
|
|
gensupport.RegisterHook(requestHook)
|
|
}
|
|
|
|
func requestHook(ctx context.Context, req *http.Request) func(resp *http.Response) {
|
|
span := FromContext(ctx)
|
|
if span == nil || req == nil {
|
|
return nil
|
|
}
|
|
span = span.NewRemoteChild(req)
|
|
return func(resp *http.Response) {
|
|
if resp != nil {
|
|
span.Finish(WithResponse(resp))
|
|
} else {
|
|
span.Finish()
|
|
}
|
|
}
|
|
}
|
|
|
|
// nextSpanID returns a new span ID. It will never return zero.
|
|
func nextSpanID() uint64 {
|
|
var id uint64
|
|
for id == 0 {
|
|
id = atomic.AddUint64(&spanIDCounter, spanIDIncrement)
|
|
}
|
|
return id
|
|
}
|
|
|
|
// nextTraceID returns a new trace ID.
|
|
func nextTraceID() string {
|
|
id1 := nextSpanID()
|
|
id2 := nextSpanID()
|
|
return fmt.Sprintf("%016x%016x", id1, id2)
|
|
}
|
|
|
|
// Client is a client for uploading traces to the Google Stackdriver Trace service.
|
|
// A nil Client will no-op for all of its methods.
|
|
type Client struct {
|
|
service *api.Service
|
|
projectID string
|
|
policy SamplingPolicy
|
|
bundler *bundler.Bundler
|
|
}
|
|
|
|
// NewClient creates a new Google Stackdriver Trace client.
|
|
func NewClient(ctx context.Context, projectID string, opts ...option.ClientOption) (*Client, error) {
|
|
o := []option.ClientOption{
|
|
option.WithScopes(cloudPlatformScope),
|
|
option.WithUserAgent(userAgent),
|
|
}
|
|
o = append(o, opts...)
|
|
hc, basePath, err := htransport.NewClient(ctx, o...)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("creating HTTP client for Google Stackdriver Trace API: %v", err)
|
|
}
|
|
apiService, err := api.New(hc)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("creating Google Stackdriver Trace API client: %v", err)
|
|
}
|
|
if basePath != "" {
|
|
// An option set a basepath, so override api.New's default.
|
|
apiService.BasePath = basePath
|
|
}
|
|
c := &Client{
|
|
service: apiService,
|
|
projectID: projectID,
|
|
}
|
|
bundler := bundler.NewBundler((*api.Trace)(nil), func(bundle interface{}) {
|
|
traces := bundle.([]*api.Trace)
|
|
err := c.upload(traces)
|
|
if err != nil {
|
|
log.Printf("failed to upload %d traces to the Cloud Trace server: %v", len(traces), err)
|
|
}
|
|
})
|
|
bundler.DelayThreshold = 2 * time.Second
|
|
bundler.BundleCountThreshold = 100
|
|
// We're not measuring bytes here, we're counting traces and spans as one "byte" each.
|
|
bundler.BundleByteThreshold = 1000
|
|
bundler.BundleByteLimit = 1000
|
|
bundler.BufferedByteLimit = 10000
|
|
c.bundler = bundler
|
|
return c, nil
|
|
}
|
|
|
|
// SetSamplingPolicy sets the SamplingPolicy that determines how often traces
|
|
// are initiated by this client.
|
|
func (c *Client) SetSamplingPolicy(p SamplingPolicy) {
|
|
if c != nil {
|
|
c.policy = p
|
|
}
|
|
}
|
|
|
|
// SpanFromHeader returns a new trace span based on a provided request header
|
|
// value or nil iff the client is nil.
|
|
//
|
|
// The trace information and identifiers will be read from the header value.
|
|
// Otherwise, a new trace ID is made and the parent span ID is zero.
|
|
// For the exact format of the header value, see
|
|
// https://cloud.google.com/trace/docs/support#how_do_i_force_a_request_to_be_traced
|
|
//
|
|
// The name of the new span is provided as an argument.
|
|
//
|
|
// If a non-nil sampling policy has been set in the client, it can override
|
|
// the options set in the header and choose whether to trace the request.
|
|
//
|
|
// If the header doesn't have existing tracing information, then a *Span is
|
|
// returned anyway, but it will not be uploaded to the server, just as when
|
|
// calling SpanFromRequest on an untraced request.
|
|
//
|
|
// Most users using HTTP should use SpanFromRequest, rather than
|
|
// SpanFromHeader, since it provides additional functionality for HTTP
|
|
// requests. In particular, it will set various pieces of request information
|
|
// as labels on the *Span, which is not available from the header alone.
|
|
func (c *Client) SpanFromHeader(name string, header string) *Span {
|
|
if c == nil {
|
|
return nil
|
|
}
|
|
traceID, parentSpanID, options, _, ok := traceInfoFromHeader(header)
|
|
if !ok {
|
|
traceID = nextTraceID()
|
|
}
|
|
t := &trace{
|
|
traceID: traceID,
|
|
client: c,
|
|
globalOptions: options,
|
|
localOptions: options,
|
|
}
|
|
span := startNewChild(name, t, parentSpanID)
|
|
span.span.Kind = spanKindServer
|
|
span.rootSpan = true
|
|
configureSpanFromPolicy(span, c.policy, ok)
|
|
return span
|
|
}
|
|
|
|
// SpanFromRequest returns a new trace span for an HTTP request or nil
|
|
// iff the client is nil.
|
|
//
|
|
// If the incoming HTTP request contains a trace context header, the trace ID,
|
|
// parent span ID, and tracing options will be read from that header.
|
|
// Otherwise, a new trace ID is made and the parent span ID is zero.
|
|
//
|
|
// If a non-nil sampling policy has been set in the client, it can override the
|
|
// options set in the header and choose whether to trace the request.
|
|
//
|
|
// If the request is not being traced, then a *Span is returned anyway, but it
|
|
// will not be uploaded to the server -- it is only useful for propagating
|
|
// trace context to child requests and for getting the TraceID. All its
|
|
// methods can still be called -- the Finish, FinishWait, and SetLabel methods
|
|
// do nothing. NewChild does nothing, and returns the same *Span. TraceID
|
|
// works as usual.
|
|
func (c *Client) SpanFromRequest(r *http.Request) *Span {
|
|
if c == nil {
|
|
return nil
|
|
}
|
|
traceID, parentSpanID, options, _, ok := traceInfoFromHeader(r.Header.Get(httpHeader))
|
|
if !ok {
|
|
traceID = nextTraceID()
|
|
}
|
|
t := &trace{
|
|
traceID: traceID,
|
|
client: c,
|
|
globalOptions: options,
|
|
localOptions: options,
|
|
}
|
|
span := startNewChildWithRequest(r, t, parentSpanID)
|
|
span.span.Kind = spanKindServer
|
|
span.rootSpan = true
|
|
configureSpanFromPolicy(span, c.policy, ok)
|
|
return span
|
|
}
|
|
|
|
// NewSpan returns a new trace span with the given name or nil iff the
|
|
// client is nil.
|
|
//
|
|
// A new trace and span ID is generated to trace the span.
|
|
// Returned span need to be finished by calling Finish or FinishWait.
|
|
func (c *Client) NewSpan(name string) *Span {
|
|
if c == nil {
|
|
return nil
|
|
}
|
|
t := &trace{
|
|
traceID: nextTraceID(),
|
|
client: c,
|
|
localOptions: optionTrace,
|
|
globalOptions: optionTrace,
|
|
}
|
|
span := startNewChild(name, t, 0)
|
|
span.span.Kind = spanKindUnspecified
|
|
span.rootSpan = true
|
|
configureSpanFromPolicy(span, c.policy, false)
|
|
return span
|
|
}
|
|
|
|
func configureSpanFromPolicy(s *Span, p SamplingPolicy, ok bool) {
|
|
if p == nil {
|
|
return
|
|
}
|
|
d := p.Sample(Parameters{HasTraceHeader: ok})
|
|
if d.Trace {
|
|
// Turn on tracing locally, and in child requests.
|
|
s.trace.localOptions |= optionTrace
|
|
s.trace.globalOptions |= optionTrace
|
|
} else {
|
|
// Turn off tracing locally.
|
|
s.trace.localOptions = 0
|
|
return
|
|
}
|
|
if d.Sample {
|
|
// This trace is in the random sample, so set the labels.
|
|
s.SetLabel(labelSamplingPolicy, d.Policy)
|
|
s.SetLabel(labelSamplingWeight, fmt.Sprint(d.Weight))
|
|
}
|
|
}
|
|
|
|
// NewContext returns a derived context containing the span.
|
|
func NewContext(ctx context.Context, s *Span) context.Context {
|
|
if s == nil {
|
|
return ctx
|
|
}
|
|
return context.WithValue(ctx, contextKey{}, s)
|
|
}
|
|
|
|
// FromContext returns the span contained in the context, or nil.
|
|
func FromContext(ctx context.Context) *Span {
|
|
s, _ := ctx.Value(contextKey{}).(*Span)
|
|
return s
|
|
}
|
|
|
|
func traceInfoFromHeader(h string) (traceID string, spanID uint64, options optionFlags, optionsOk bool, ok bool) {
|
|
// See https://cloud.google.com/trace/docs/faq for the header format.
|
|
// Return if the header is empty or missing, or if the header is unreasonably
|
|
// large, to avoid making unnecessary copies of a large string.
|
|
if h == "" || len(h) > 200 {
|
|
return "", 0, 0, false, false
|
|
|
|
}
|
|
|
|
// Parse the trace id field.
|
|
slash := strings.Index(h, `/`)
|
|
if slash == -1 {
|
|
return "", 0, 0, false, false
|
|
|
|
}
|
|
traceID, h = h[:slash], h[slash+1:]
|
|
|
|
// Parse the span id field.
|
|
spanstr := h
|
|
semicolon := strings.Index(h, `;`)
|
|
if semicolon != -1 {
|
|
spanstr, h = h[:semicolon], h[semicolon+1:]
|
|
}
|
|
spanID, err := strconv.ParseUint(spanstr, 10, 64)
|
|
if err != nil {
|
|
return "", 0, 0, false, false
|
|
|
|
}
|
|
|
|
// Parse the options field, options field is optional.
|
|
if !strings.HasPrefix(h, "o=") {
|
|
return traceID, spanID, 0, false, true
|
|
|
|
}
|
|
o, err := strconv.ParseUint(h[2:], 10, 64)
|
|
if err != nil {
|
|
return "", 0, 0, false, false
|
|
|
|
}
|
|
options = optionFlags(o)
|
|
return traceID, spanID, options, true, true
|
|
}
|
|
|
|
type optionFlags uint32
|
|
|
|
const (
|
|
optionTrace optionFlags = 1 << iota
|
|
optionStack
|
|
)
|
|
|
|
type trace struct {
|
|
mu sync.Mutex
|
|
client *Client
|
|
traceID string
|
|
globalOptions optionFlags // options that will be passed to any child requests
|
|
localOptions optionFlags // options applied in this server
|
|
spans []*Span // finished spans for this trace.
|
|
}
|
|
|
|
// finish appends s to t.spans. If s is the root span, uploads the trace to the
|
|
// server.
|
|
func (t *trace) finish(s *Span, wait bool, opts ...FinishOption) error {
|
|
for _, o := range opts {
|
|
o.modifySpan(s)
|
|
}
|
|
s.end = time.Now()
|
|
t.mu.Lock()
|
|
t.spans = append(t.spans, s)
|
|
spans := t.spans
|
|
t.mu.Unlock()
|
|
if s.rootSpan {
|
|
if wait {
|
|
return t.client.upload([]*api.Trace{t.constructTrace(spans)})
|
|
}
|
|
go func() {
|
|
tr := t.constructTrace(spans)
|
|
err := t.client.bundler.Add(tr, 1+len(spans))
|
|
if err == bundler.ErrOversizedItem {
|
|
err = t.client.upload([]*api.Trace{tr})
|
|
}
|
|
if err != nil {
|
|
log.Println("error uploading trace:", err)
|
|
}
|
|
}()
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (t *trace) constructTrace(spans []*Span) *api.Trace {
|
|
apiSpans := make([]*api.TraceSpan, len(spans))
|
|
for i, sp := range spans {
|
|
sp.span.StartTime = sp.start.In(time.UTC).Format(time.RFC3339Nano)
|
|
sp.span.EndTime = sp.end.In(time.UTC).Format(time.RFC3339Nano)
|
|
if t.localOptions&optionStack != 0 {
|
|
sp.setStackLabel()
|
|
}
|
|
sp.SetLabel(labelHost, sp.host)
|
|
sp.SetLabel(labelURL, sp.url)
|
|
sp.SetLabel(labelMethod, sp.method)
|
|
if sp.statusCode != 0 {
|
|
sp.SetLabel(labelStatusCode, strconv.Itoa(sp.statusCode))
|
|
}
|
|
apiSpans[i] = &sp.span
|
|
}
|
|
|
|
return &api.Trace{
|
|
ProjectId: t.client.projectID,
|
|
TraceId: t.traceID,
|
|
Spans: apiSpans,
|
|
}
|
|
}
|
|
|
|
func (c *Client) upload(traces []*api.Trace) error {
|
|
_, err := c.service.Projects.PatchTraces(c.projectID, &api.Traces{Traces: traces}).Do()
|
|
return err
|
|
}
|
|
|
|
// Span contains information about one span of a trace.
|
|
type Span struct {
|
|
trace *trace
|
|
|
|
spanMu sync.Mutex // guards span.Labels
|
|
span api.TraceSpan
|
|
|
|
start time.Time
|
|
end time.Time
|
|
rootSpan bool
|
|
stack [maxStackFrames]uintptr
|
|
host string
|
|
method string
|
|
url string
|
|
statusCode int
|
|
}
|
|
|
|
// Traced reports whether the current span is sampled to be traced.
|
|
func (s *Span) Traced() bool {
|
|
if s == nil {
|
|
return false
|
|
}
|
|
return s.trace.localOptions&optionTrace != 0
|
|
}
|
|
|
|
// NewChild creates a new span with the given name as a child of s.
|
|
// If s is nil, does nothing and returns nil.
|
|
func (s *Span) NewChild(name string) *Span {
|
|
if s == nil {
|
|
return nil
|
|
}
|
|
if !s.Traced() {
|
|
// TODO(jbd): Document this behavior in godoc here and elsewhere.
|
|
return s
|
|
}
|
|
return startNewChild(name, s.trace, s.span.SpanId)
|
|
}
|
|
|
|
// NewRemoteChild creates a new span as a child of s.
|
|
//
|
|
// Some labels in the span are set from the outgoing *http.Request r.
|
|
//
|
|
// A header is set in r so that the trace context is propagated to the
|
|
// destination. The parent span ID in that header is set as follows:
|
|
// - If the request is being traced, then the ID of s is used.
|
|
// - If the request is not being traced, but there was a trace context header
|
|
// in the incoming request for this trace (the request passed to
|
|
// SpanFromRequest), the parent span ID in that header is used.
|
|
// - Otherwise, the parent span ID is zero.
|
|
// The tracing bit in the options is set if tracing is enabled, or if it was
|
|
// set in the incoming request.
|
|
//
|
|
// If s is nil, does nothing and returns nil.
|
|
func (s *Span) NewRemoteChild(r *http.Request) *Span {
|
|
if s == nil {
|
|
return nil
|
|
}
|
|
if !s.Traced() {
|
|
r.Header[httpHeader] = []string{spanHeader(s.trace.traceID, s.span.ParentSpanId, s.trace.globalOptions)}
|
|
return s
|
|
}
|
|
newSpan := startNewChildWithRequest(r, s.trace, s.span.SpanId)
|
|
r.Header[httpHeader] = []string{spanHeader(s.trace.traceID, newSpan.span.SpanId, s.trace.globalOptions)}
|
|
return newSpan
|
|
}
|
|
|
|
// Header returns the value of the X-Cloud-Trace-Context header that
|
|
// should be used to propagate the span. This is the inverse of
|
|
// SpanFromHeader.
|
|
//
|
|
// Most users should use NewRemoteChild unless they have specific
|
|
// propagation needs or want to control the naming of their span.
|
|
// Header() does not create a new span.
|
|
func (s *Span) Header() string {
|
|
if s == nil {
|
|
return ""
|
|
}
|
|
return spanHeader(s.trace.traceID, s.span.SpanId, s.trace.globalOptions)
|
|
}
|
|
|
|
func startNewChildWithRequest(r *http.Request, trace *trace, parentSpanID uint64) *Span {
|
|
name := r.URL.Host + r.URL.Path // drop scheme and query params
|
|
newSpan := startNewChild(name, trace, parentSpanID)
|
|
if r.Host == "" {
|
|
newSpan.host = r.URL.Host
|
|
} else {
|
|
newSpan.host = r.Host
|
|
}
|
|
newSpan.method = r.Method
|
|
newSpan.url = r.URL.String()
|
|
return newSpan
|
|
}
|
|
|
|
func startNewChild(name string, trace *trace, parentSpanID uint64) *Span {
|
|
spanID := nextSpanID()
|
|
for spanID == parentSpanID {
|
|
spanID = nextSpanID()
|
|
}
|
|
newSpan := &Span{
|
|
trace: trace,
|
|
span: api.TraceSpan{
|
|
Kind: spanKindClient,
|
|
Name: name,
|
|
ParentSpanId: parentSpanID,
|
|
SpanId: spanID,
|
|
},
|
|
start: time.Now(),
|
|
}
|
|
if trace.localOptions&optionStack != 0 {
|
|
_ = runtime.Callers(1, newSpan.stack[:])
|
|
}
|
|
return newSpan
|
|
}
|
|
|
|
// TraceID returns the ID of the trace to which s belongs.
|
|
func (s *Span) TraceID() string {
|
|
if s == nil {
|
|
return ""
|
|
}
|
|
return s.trace.traceID
|
|
}
|
|
|
|
// SetLabel sets the label for the given key to the given value.
|
|
// If the value is empty, the label for that key is deleted.
|
|
// If a label is given a value automatically and by SetLabel, the
|
|
// automatically-set value is used.
|
|
// If s is nil, does nothing.
|
|
//
|
|
// SetLabel shouldn't be called after Finish or FinishWait.
|
|
func (s *Span) SetLabel(key, value string) {
|
|
if s == nil {
|
|
return
|
|
}
|
|
if !s.Traced() {
|
|
return
|
|
}
|
|
s.spanMu.Lock()
|
|
defer s.spanMu.Unlock()
|
|
|
|
if value == "" {
|
|
if s.span.Labels != nil {
|
|
delete(s.span.Labels, key)
|
|
}
|
|
return
|
|
}
|
|
if s.span.Labels == nil {
|
|
s.span.Labels = make(map[string]string)
|
|
}
|
|
s.span.Labels[key] = value
|
|
}
|
|
|
|
type FinishOption interface {
|
|
modifySpan(s *Span)
|
|
}
|
|
|
|
type withResponse struct {
|
|
*http.Response
|
|
}
|
|
|
|
// WithResponse returns an option that can be passed to Finish that indicates
|
|
// that some labels for the span should be set using the given *http.Response.
|
|
func WithResponse(resp *http.Response) FinishOption {
|
|
return withResponse{resp}
|
|
}
|
|
func (u withResponse) modifySpan(s *Span) {
|
|
if u.Response != nil {
|
|
s.statusCode = u.StatusCode
|
|
}
|
|
}
|
|
|
|
// Finish declares that the span has finished.
|
|
//
|
|
// If s is nil, Finish does nothing and returns nil.
|
|
//
|
|
// If the option trace.WithResponse(resp) is passed, then some labels are set
|
|
// for s using information in the given *http.Response. This is useful when the
|
|
// span is for an outgoing http request; s will typically have been created by
|
|
// NewRemoteChild in this case.
|
|
//
|
|
// If s is a root span (one created by SpanFromRequest) then s, and all its
|
|
// descendant spans that have finished, are uploaded to the Google Stackdriver
|
|
// Trace server asynchronously.
|
|
func (s *Span) Finish(opts ...FinishOption) {
|
|
if s == nil {
|
|
return
|
|
}
|
|
if !s.Traced() {
|
|
return
|
|
}
|
|
s.trace.finish(s, false, opts...)
|
|
}
|
|
|
|
// FinishWait is like Finish, but if s is a root span, it waits until uploading
|
|
// is finished, then returns an error if one occurred.
|
|
func (s *Span) FinishWait(opts ...FinishOption) error {
|
|
if s == nil {
|
|
return nil
|
|
}
|
|
if !s.Traced() {
|
|
return nil
|
|
}
|
|
return s.trace.finish(s, true, opts...)
|
|
}
|
|
|
|
func spanHeader(traceID string, spanID uint64, options optionFlags) string {
|
|
// See https://cloud.google.com/trace/docs/faq for the header format.
|
|
return fmt.Sprintf("%s/%d;o=%d", traceID, spanID, options)
|
|
}
|
|
|
|
func (s *Span) setStackLabel() {
|
|
var stack stackLabelValue
|
|
lastSigPanic, inTraceLibrary := false, true
|
|
for _, pc := range s.stack {
|
|
if pc == 0 {
|
|
break
|
|
}
|
|
if !lastSigPanic {
|
|
pc--
|
|
}
|
|
fn := runtime.FuncForPC(pc)
|
|
file, line := fn.FileLine(pc)
|
|
// Name has one of the following forms:
|
|
// path/to/package.Foo
|
|
// path/to/package.(Type).Foo
|
|
// For the first form, we store the whole name in the Method field of the
|
|
// stack frame. For the second form, we set the Method field to "Foo" and
|
|
// the Class field to "path/to/package.(Type)".
|
|
name := fn.Name()
|
|
if inTraceLibrary && !strings.HasPrefix(name, "cloud.google.com/go/trace.") {
|
|
inTraceLibrary = false
|
|
}
|
|
var class string
|
|
if i := strings.Index(name, ")."); i != -1 {
|
|
class, name = name[:i+1], name[i+2:]
|
|
}
|
|
frame := stackFrame{
|
|
Class: class,
|
|
Method: name,
|
|
Filename: file,
|
|
Line: int64(line),
|
|
}
|
|
if inTraceLibrary && len(stack.Frames) == 1 {
|
|
stack.Frames[0] = frame
|
|
} else {
|
|
stack.Frames = append(stack.Frames, frame)
|
|
}
|
|
lastSigPanic = fn.Name() == "runtime.sigpanic"
|
|
}
|
|
if label, err := json.Marshal(stack); err == nil {
|
|
s.SetLabel(labelStackTrace, string(label))
|
|
}
|
|
}
|