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67 lines
2.3 KiB
67 lines
2.3 KiB
// Copyright 2018 PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package tracing
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import (
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"context"
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"github.com/opentracing/basictracer-go"
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"github.com/opentracing/opentracing-go"
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)
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// TiDBTrace is set as Baggage on traces which are used for tidb tracing.
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const TiDBTrace = "tr"
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// A CallbackRecorder immediately invokes itself on received trace spans.
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type CallbackRecorder func(sp basictracer.RawSpan)
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// RecordSpan implements basictracer.SpanRecorder.
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func (cr CallbackRecorder) RecordSpan(sp basictracer.RawSpan) {
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cr(sp)
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}
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// NewRecordedTrace returns a Span which records directly via the specified
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// callback.
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func NewRecordedTrace(opName string, callback func(sp basictracer.RawSpan)) opentracing.Span {
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tr := basictracer.New(CallbackRecorder(callback))
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opentracing.SetGlobalTracer(tr)
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sp := tr.StartSpan(opName)
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sp.SetBaggageItem(TiDBTrace, "1")
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return sp
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}
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// noopSpan returns a Span which discards all operations.
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func noopSpan() opentracing.Span {
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return (opentracing.NoopTracer{}).StartSpan("DefaultSpan")
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}
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// SpanFromContext returns the span obtained from the context or, if none is found, a new one started through tracer.
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func SpanFromContext(ctx context.Context) (sp opentracing.Span) {
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if sp = opentracing.SpanFromContext(ctx); sp == nil {
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return noopSpan()
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}
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return sp
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}
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// ChildSpanFromContxt return a non-nil span. If span can be got from ctx, then returned span is
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// a child of such span. Otherwise, returned span is a noop span.
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func ChildSpanFromContxt(ctx context.Context, opName string) (opentracing.Span, context.Context) {
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if sp := opentracing.SpanFromContext(ctx); sp != nil {
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if _, ok := sp.Tracer().(opentracing.NoopTracer); !ok {
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child := opentracing.StartSpan(opName, opentracing.ChildOf(sp.Context()))
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return child, opentracing.ContextWithSpan(ctx, child)
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}
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}
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return noopSpan(), ctx
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}
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