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frristfrrist
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add usage to godoc, fixes #27 
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‎log.go

+67-66
Original file line numberDiff line numberDiff line change
@@ -60,19 +60,86 @@ type EventLogger interface {
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// DEPRECATED
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EventBegin(ctx context.Context, event string, m ...Loggable) *EventInProgress
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63+
// Start starts an opentracing span with `name`, using
64+
// any Span found within `ctx` as a ChildOfRef. If no such parent could be
65+
// found, Start creates a root (parentless) Span.
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//
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// The return value is a context.Context object built around the
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// returned Span.
69+
//
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// Example usage:
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//
72+
// SomeFunction(ctx context.Context, ...) {
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// ctx := log.Start(ctx, "SomeFunction")
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// defer log.Finish(ctx)
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// ...
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// }
6377
Start(ctx context.Context, name string) context.Context
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79+
// StartFromParentState starts an opentracing span with `name`, using
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// any Span found within `ctx` as a ChildOfRef. If no such parent could be
81+
// found, StartSpanFromParentState creates a root (parentless) Span.
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//
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// StartFromParentState will attempt to deserialize a SpanContext from `parent`,
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// using any Span found within to continue the trace
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//
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// The return value is a context.Context object built around the
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// returned Span.
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//
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// An error is returned when `parent` cannot be deserialized to a SpanContext
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//
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// Example usage:
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//
93+
// SomeFunction(ctx context.Context, bParent []byte) {
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// ctx := log.StartFromParentState(ctx, "SomeFunction", bParent)
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// defer log.Finish(ctx)
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// ...
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// }
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StartFromParentState(ctx context.Context, name string, parent []byte) (context.Context, error)
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100+
// Finish completes the span associated with `ctx`.
101+
//
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// Finish() must be the last call made to any span instance, and to do
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// otherwise leads to undefined behavior.
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// Finish will do its best to notify (log) when used in correctly
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// .e.g called twice, or called on a spanless `ctx`
66106
Finish(ctx context.Context)
107+
108+
// FinishWithErr completes the span associated with `ctx` and also calls
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// SetErr if `err` is non-nil
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//
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// FinishWithErr() must be the last call made to any span instance, and to do
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// otherwise leads to undefined behavior.
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// FinishWithErr will do its best to notify (log) when used in correctly
114+
// .e.g called twice, or called on a spanless `ctx`
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FinishWithErr(ctx context.Context, err error)
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117+
// SetErr tags the span associated with `ctx` to reflect an error occured, and
118+
// logs the value `err` under key `error`.
69119
SetErr(ctx context.Context, err error)
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// LogKV records key:value logging data about an event stored in `ctx`
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// Eexample:
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// log.LogKV(
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// "error", "resolve failure",
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// "type", "cache timeout",
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// "waited.millis", 1500)
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LogKV(ctx context.Context, alternatingKeyValues ...interface{})
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129+
// SetTag tags key `k` and value `v` on the span associated with `ctx`
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SetTag(ctx context.Context, key string, value interface{})
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// SetTags tags keys from the `tags` maps on the span associated with `ctx`
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// Example:
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// log.SetTags(ctx, map[string]{
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// "type": bizStruct,
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// "request": req,
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// })
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SetTags(ctx context.Context, tags map[string]interface{})
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// SerializeContext takes the SpanContext instance stored in `ctx` and Seralizes
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// it to bytes. An error is returned if the `ctx` cannot be serialized to
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// a bytes array
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SerializeContext(ctx context.Context) ([]byte, error)
77144
}
78145

@@ -100,46 +167,12 @@ type eventLogger struct {
100167
// TODO add log-level
101168
}
102169

103-
// Start starts an opentracing span with `operationName`, using
104-
// any Span found within `ctx` as a ChildOfRef. If no such parent could be
105-
// found, StartSpanFromContext creates a root (parentless) Span.
106-
//
107-
// The return value is a context.Context object built around the
108-
// returned Span.
109-
//
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// Example usage:
111-
//
112-
// SomeFunction(ctx context.Context, ...) {
113-
// ctx := log.Start(ctx, "SomeFunction")
114-
// defer log.Finish(ctx)
115-
// ...
116-
// }
117170
func (el *eventLogger) Start(ctx context.Context, operationName string) context.Context {
118171
span, ctx := opentrace.StartSpanFromContext(ctx, operationName)
119172
span.SetTag("system", el.system)
120173
return ctx
121174
}
122175

123-
// TODO: need clearer examples and description
124-
// StartFromParentState starts an opentracing span with `operationName`, using
125-
// any Span found within `ctx` as a ChildOfRef. If no such parent could be
126-
// found, StartSpanFromContext creates a root (parentless) Span.
127-
//
128-
// StartFromParentState will attempt to deserialize a SpanContext from `parent`,
129-
// using any Span found within to continue the trace
130-
//
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// The return value is a context.Context object built around the
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// returned Span.
133-
//
134-
// An error is returned when `parent` cannot be deserialized to a SpanContext
135-
//
136-
// Example usage:
137-
//
138-
// SomeFunction(ctx context.Context, ...) {
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// ctx := log.StartFromParentState(ctx, "SomeFunction", bParent)
140-
// defer log.Finish(ctx)
141-
// ...
142-
// }
143176
func (el *eventLogger) StartFromParentState(ctx context.Context, operationName string, parent []byte) (context.Context, error) {
144177
sc, err := deserializeContext(parent)
145178
if err != nil {
@@ -152,8 +185,6 @@ func (el *eventLogger) StartFromParentState(ctx context.Context, operationName s
152185
return ctx, nil
153186
}
154187

155-
// SerializeContext takes the SpanContext instance stored in `ctx`, and Seralizes
156-
// it to bytes.
157188
func (el *eventLogger) SerializeContext(ctx context.Context) ([]byte, error) {
158189
gTracer := opentrace.GlobalTracer()
159190
b := make([]byte, 0)
@@ -165,12 +196,6 @@ func (el *eventLogger) SerializeContext(ctx context.Context) ([]byte, error) {
165196
return carrier.Bytes(), nil
166197
}
167198

168-
// LogKV records key:value logging data about an event stored in `ctx`
169-
// Eexample:
170-
// log.LogKV(
171-
// "error", "resolve failure",
172-
// "type", "cache timeout",
173-
// "waited.millis", 1500)
174199
func (el *eventLogger) LogKV(ctx context.Context, alternatingKeyValues ...interface{}) {
175200
span := opentrace.SpanFromContext(ctx)
176201
if span == nil {
@@ -181,7 +206,6 @@ func (el *eventLogger) LogKV(ctx context.Context, alternatingKeyValues ...interf
181206
span.LogKV(alternatingKeyValues...)
182207
}
183208

184-
// SetTag tags key `k` and value `v` on the span associated with `ctx`
185209
func (el *eventLogger) SetTag(ctx context.Context, k string, v interface{}) {
186210
span := opentrace.SpanFromContext(ctx)
187211
if span == nil {
@@ -192,12 +216,6 @@ func (el *eventLogger) SetTag(ctx context.Context, k string, v interface{}) {
192216
span.SetTag(k, v)
193217
}
194218

195-
// SetTags tags keys from the `tags` maps on the span associated with `ctx`
196-
// Example:
197-
// log.SetTags(ctx, map[string]{
198-
// "tag": bizStruct,
199-
// "bar": fizStruct,
200-
// })
201219
func (el *eventLogger) SetTags(ctx context.Context, tags map[string]interface{}) {
202220
span := opentrace.SpanFromContext(ctx)
203221
if span == nil {
@@ -210,8 +228,6 @@ func (el *eventLogger) SetTags(ctx context.Context, tags map[string]interface{})
210228
}
211229
}
212230

213-
// SetErr tags the span associated with `ctx` to reflect an error occured, and
214-
// logs the value `err` under key `error`
215231
func (el *eventLogger) SetErr(ctx context.Context, err error) {
216232
span := opentrace.SpanFromContext(ctx)
217233
if span == nil {
@@ -227,13 +243,6 @@ func (el *eventLogger) SetErr(ctx context.Context, err error) {
227243
span.LogKV("error", err.Error())
228244
}
229245

230-
// Finish completes the span associated with `ctx` by
231-
// setting the end timestamp and finalizing the Span state.
232-
//
233-
// Finish() must be the last call made to any span instance, and to do
234-
// otherwise leads to undefined behavior.
235-
// Finish will do its best to notify (log) when used in correctly
236-
// .e.g called twice, or called on a spanless `ctx`
237246
func (el *eventLogger) Finish(ctx context.Context) {
238247
span := opentrace.SpanFromContext(ctx)
239248
if span == nil {
@@ -244,14 +253,6 @@ func (el *eventLogger) Finish(ctx context.Context) {
244253
span.Finish()
245254
}
246255

247-
// FinishWithErr completes the span associated with `ctx` by
248-
// setting the end timestamp and finalizing the Span state, in addition to
249-
// calling the `SetErr` method first
250-
//
251-
// FinishWithErr() must be the last call made to any span instance, and to do
252-
// otherwise leads to undefined behavior.
253-
// FinishWithErr will do its best to notify (log) when used in correctly
254-
// .e.g called twice, or called on a spanless `ctx`
255256
func (el *eventLogger) FinishWithErr(ctx context.Context, err error) {
256257
el.SetErr(ctx, err)
257258
el.Finish(ctx)

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