1// Copyright 2019, OpenTelemetry Authors
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15package opentracing
16
17import (
18	"context"
19
20	oteltrace "go.opentelemetry.io/otel/api/trace"
21
22	"go.opentelemetry.io/otel/bridge/opentracing/migration"
23)
24
25type WrapperProvider struct {
26	wTracer *WrapperTracer
27}
28
29var _ oteltrace.Provider = (*WrapperProvider)(nil)
30
31// Tracer returns the WrapperTracer associated with the WrapperProvider.
32func (p *WrapperProvider) Tracer(name string) oteltrace.Tracer {
33	return p.wTracer
34}
35
36// NewWrappedProvider creates a new trace provider that creates a single
37// instance of WrapperTracer that wraps OpenTelemetry tracer.
38func NewWrappedProvider(bridge *BridgeTracer, tracer oteltrace.Tracer) *WrapperProvider {
39	return &WrapperProvider{
40		wTracer: NewWrapperTracer(bridge, tracer),
41	}
42}
43
44// WrapperTracer is a wrapper around an OpenTelemetry tracer. It
45// mostly forwards the calls to the wrapped tracer, but also does some
46// extra steps like setting up a context with the active OpenTracing
47// span.
48//
49// It does not need to be used when the OpenTelemetry tracer is also
50// aware how to operate in environment where OpenTracing API is also
51// used.
52type WrapperTracer struct {
53	bridge *BridgeTracer
54	tracer oteltrace.Tracer
55}
56
57var _ oteltrace.Tracer = &WrapperTracer{}
58var _ migration.DeferredContextSetupTracerExtension = &WrapperTracer{}
59
60// NewWrapperTracer wraps the passed tracer and also talks to the
61// passed bridge tracer when setting up the context with the new
62// active OpenTracing span.
63func NewWrapperTracer(bridge *BridgeTracer, tracer oteltrace.Tracer) *WrapperTracer {
64	return &WrapperTracer{
65		bridge: bridge,
66		tracer: tracer,
67	}
68}
69
70func (t *WrapperTracer) otelTracer() oteltrace.Tracer {
71	return t.tracer
72}
73
74// WithSpan forwards the call to the wrapped tracer with a modified
75// body callback, which sets the active OpenTracing span before
76// calling the original callback.
77func (t *WrapperTracer) WithSpan(ctx context.Context, name string, body func(context.Context) error) error {
78	return t.otelTracer().WithSpan(ctx, name, func(ctx context.Context) error {
79		span := oteltrace.SpanFromContext(ctx)
80		if spanWithExtension, ok := span.(migration.OverrideTracerSpanExtension); ok {
81			spanWithExtension.OverrideTracer(t)
82		}
83		ctx = t.bridge.ContextWithBridgeSpan(ctx, span)
84		return body(ctx)
85	})
86}
87
88// Start forwards the call to the wrapped tracer. It also tries to
89// override the tracer of the returned span if the span implements the
90// OverrideTracerSpanExtension interface.
91func (t *WrapperTracer) Start(ctx context.Context, name string, opts ...oteltrace.StartOption) (context.Context, oteltrace.Span) {
92	ctx, span := t.otelTracer().Start(ctx, name, opts...)
93	if spanWithExtension, ok := span.(migration.OverrideTracerSpanExtension); ok {
94		spanWithExtension.OverrideTracer(t)
95	}
96	if !migration.SkipContextSetup(ctx) {
97		ctx = t.bridge.ContextWithBridgeSpan(ctx, span)
98	}
99	return ctx, span
100}
101
102// DeferredContextSetupHook is a part of the implementation of the
103// DeferredContextSetupTracerExtension interface. It will try to
104// forward the call to the wrapped tracer if it implements the
105// interface.
106func (t *WrapperTracer) DeferredContextSetupHook(ctx context.Context, span oteltrace.Span) context.Context {
107	if tracerWithExtension, ok := t.otelTracer().(migration.DeferredContextSetupTracerExtension); ok {
108		ctx = tracerWithExtension.DeferredContextSetupHook(ctx, span)
109	}
110	ctx = oteltrace.ContextWithSpan(ctx, span)
111	return ctx
112}
113