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| 1 | +package traceandtracego |
| 2 | + |
| 3 | +import ( |
| 4 | + logger "log" |
| 5 | + |
| 6 | + opentracing "github.com/opentracing/opentracing-go" |
| 7 | + "golang.org/x/net/context" |
| 8 | + "google.golang.org/grpc" |
| 9 | + "google.golang.org/grpc/metadata" |
| 10 | +) |
| 11 | + |
| 12 | +//声明 tracer |
| 13 | +var tracer opentracing.Tracer |
| 14 | + |
| 15 | +//text map reader |
| 16 | +type TextMapReader struct { |
| 17 | + metadata.MD |
| 18 | +} |
| 19 | + |
| 20 | +//text map writer |
| 21 | +type TextMapWriter struct { |
| 22 | + metadata.MD |
| 23 | +} |
| 24 | + |
| 25 | +//RPC Client Dial Option |
| 26 | +func ClientDialOption(parentTracer opentracing.Tracer) grpc.DialOption { |
| 27 | + tracer = parentTracer |
| 28 | + return grpc.WithUnaryInterceptor(grpcClientInterceptor) |
| 29 | +} |
| 30 | + |
| 31 | +//RPC Server Dial Option |
| 32 | +func ServerDialOption(tracer opentracing.Tracer) grpc.ServerOption { |
| 33 | + return grpc.UnaryInterceptor(grpcServerInterceptor) |
| 34 | +} |
| 35 | + |
| 36 | +//RPC Client 拦截器 |
| 37 | +func grpcClientInterceptor( |
| 38 | + ctx context.Context, |
| 39 | + method string, |
| 40 | + req, reply interface{}, |
| 41 | + cc *grpc.ClientConn, |
| 42 | + invoker grpc.UnaryInvoker, |
| 43 | + opts ...grpc.CallOption) (err error) { |
| 44 | + |
| 45 | + //从context中获取metadata |
| 46 | + md, ok := metadata.FromIncomingContext(ctx) |
| 47 | + if !ok { |
| 48 | + md = metadata.New(nil) |
| 49 | + } else { |
| 50 | + //如果对metadata进行修改，那么需要用拷贝的副本进行修改 |
| 51 | + md = md.Copy() |
| 52 | + } |
| 53 | + //carrier := opentracing.TextMapCarrier{} |
| 54 | + carrier := TextMapWriter{md} |
| 55 | + //父类 context |
| 56 | + var currentContext opentracing.SpanContext |
| 57 | + //从 context 中获取原始的 span |
| 58 | + parentSpan := opentracing.SpanFromContext(ctx) |
| 59 | + if parentSpan != nil { |
| 60 | + currentContext = parentSpan.Context() |
| 61 | + } else { |
| 62 | + //否则创建 span |
| 63 | + span := tracer.StartSpan(method) |
| 64 | + defer span.Finish() |
| 65 | + currentContext = span.Context() |
| 66 | + } |
| 67 | + //将 span 的 context 信息注入到 carrier 中 |
| 68 | + e := tracer.Inject(currentContext, opentracing.TextMap, carrier) |
| 69 | + if e != nil { |
| 70 | + logger.Fatalln("tracer inject failed", e) |
| 71 | + } |
| 72 | + //创建一个新的 context，把 metadata 附带上 |
| 73 | + ctx = metadata.NewOutgoingContext(ctx, md) |
| 74 | + return invoker(ctx, method, req, reply, cc, opts...) |
| 75 | +} |
| 76 | + |
| 77 | +//RPC Server 拦截器 |
| 78 | +func grpcServerInterceptor( |
| 79 | + ctx context.Context, |
| 80 | + req interface{}, |
| 81 | + info *grpc.UnaryServerInfo, |
| 82 | + handler grpc.UnaryHandler) (resp interface{}, err error) { |
| 83 | + //从context中获取metadata。md.(type) == map[string][]string |
| 84 | + md, ok := metadata.FromIncomingContext(ctx) |
| 85 | + if !ok { |
| 86 | + md = metadata.New(nil) |
| 87 | + } else { |
| 88 | + //如果对metadata进行修改，那么需要用拷贝的副本进行修改。（FromIncomingContext的注释） |
| 89 | + md = md.Copy() |
| 90 | + } |
| 91 | + carrier := TextMapReader{md} |
| 92 | + tracer := opentracing.GlobalTracer() |
| 93 | + spanContext, e := tracer.Extract(opentracing.TextMap, carrier) |
| 94 | + if e != nil { |
| 95 | + logger.Fatalln("extract span context err", e) |
| 96 | + } |
| 97 | + |
| 98 | + span := tracer.StartSpan(info.FullMethod, opentracing.ChildOf(spanContext)) |
| 99 | + defer span.Finish() |
| 100 | + ctx = opentracing.ContextWithSpan(ctx, span) |
| 101 | + |
| 102 | + return handler(ctx, req) |
| 103 | +} |
| 104 | + |
| 105 | +//text map writer set |
| 106 | +func (t TextMapWriter) Set(key, val string) { |
| 107 | + t.MD[key] = append(t.MD[key], val) |
| 108 | +} |
| 109 | + |
| 110 | +// 读取 metadata 中的 span 信息 |
| 111 | +func (t TextMapReader) ForeachKey(handler func(key, val string) error) error { //不能是指针 |
| 112 | + for key, val := range t.MD { |
| 113 | + for _, v := range val { |
| 114 | + if err := handler(key, v); err != nil { |
| 115 | + return err |
| 116 | + } |
| 117 | + } |
| 118 | + } |
| 119 | + return nil |
| 120 | +} |
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