github.com/whtcorpsinc/MilevaDB-Prod@v0.0.0-20211104133533-f57f4be3b597/soliton/tracing/util.go (about)

     1  // Copyright 2020 WHTCORPS INC, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package tracing
    15  
    16  import (
    17  	"context"
    18  
    19  	"github.com/opentracing/basictracer-go"
    20  	"github.com/opentracing/opentracing-go"
    21  )
    22  
    23  // MilevaDBTrace is set as Baggage on traces which are used for milevadb tracing.
    24  const MilevaDBTrace = "tr"
    25  
    26  // A CallbackRecorder immediately invokes itself on received trace spans.
    27  type CallbackRecorder func(sp basictracer.RawSpan)
    28  
    29  // RecordSpan implements basictracer.SpanRecorder.
    30  func (cr CallbackRecorder) RecordSpan(sp basictracer.RawSpan) {
    31  	cr(sp)
    32  }
    33  
    34  // NewRecordedTrace returns a Span which records directly via the specified
    35  // callback.
    36  func NewRecordedTrace(opName string, callback func(sp basictracer.RawSpan)) opentracing.Span {
    37  	tr := basictracer.New(CallbackRecorder(callback))
    38  	opentracing.SetGlobalTracer(tr)
    39  	sp := tr.StartSpan(opName)
    40  	sp.SetBaggageItem(MilevaDBTrace, "1")
    41  	return sp
    42  }
    43  
    44  // noopSpan returns a Span which discards all operations.
    45  func noopSpan() opentracing.Span {
    46  	return (opentracing.NoopTracer{}).StartSpan("DefaultSpan")
    47  }
    48  
    49  // SpanFromContext returns the span obtained from the context or, if none is found, a new one started through tracer.
    50  func SpanFromContext(ctx context.Context) (sp opentracing.Span) {
    51  	if sp = opentracing.SpanFromContext(ctx); sp == nil {
    52  		return noopSpan()
    53  	}
    54  	return sp
    55  }
    56  
    57  // ChildSpanFromContxt return a non-nil span. If span can be got from ctx, then returned span is
    58  // a child of such span. Otherwise, returned span is a noop span.
    59  func ChildSpanFromContxt(ctx context.Context, opName string) (opentracing.Span, context.Context) {
    60  	if sp := opentracing.SpanFromContext(ctx); sp != nil {
    61  		if _, ok := sp.Tracer().(opentracing.NoopTracer); !ok {
    62  			child := opentracing.StartSpan(opName, opentracing.ChildOf(sp.Context()))
    63  			return child, opentracing.ContextWithSpan(ctx, child)
    64  		}
    65  	}
    66  	return noopSpan(), ctx
    67  }