run go1.19 gofmt and make adjustments as needed
(Go 1.19 expanded doc comment syntax)
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@@ -1,6 +1,6 @@
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// package trace provides activity tracing via ctx through Tasks and Spans
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//
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// Basic Concepts
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// # Basic Concepts
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//
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// Tracing can be used to identify where a piece of code spends its time.
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//
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@@ -10,51 +10,50 @@
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// to tech-savvy users (albeit not developers).
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//
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// This package provides the concept of Tasks and Spans to express what activity is happening within an application:
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//
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// - Neither task nor span is really tangible but instead contained within the context.Context tree
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// - Tasks represent concurrent activity (i.e. goroutines).
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// - Spans represent a semantic stack trace within a task.
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//
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// - Neither task nor span is really tangible but instead contained within the context.Context tree
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// - Tasks represent concurrent activity (i.e. goroutines).
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// - Spans represent a semantic stack trace within a task.
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// As a consequence, whenever a context is propagated across goroutine boundary, you need to create a child task:
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//
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// go func(ctx context.Context) {
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// ctx, endTask = WithTask(ctx, "what-happens-inside-the-child-task")
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// defer endTask()
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// // ...
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// }(ctx)
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// go func(ctx context.Context) {
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// ctx, endTask = WithTask(ctx, "what-happens-inside-the-child-task")
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// defer endTask()
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// // ...
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// }(ctx)
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//
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// Within the task, you can open up a hierarchy of spans.
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// In contrast to tasks, which have can multiple concurrently running child tasks,
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// spans must nest and not cross the goroutine boundary.
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//
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// ctx, endSpan = WithSpan(ctx, "copy-dir")
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// defer endSpan()
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// for _, f := range dir.Files() {
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// func() {
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// ctx, endSpan := WithSpan(ctx, fmt.Sprintf("copy-file %q", f))
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// defer endspan()
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// b, _ := ioutil.ReadFile(f)
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// _ = ioutil.WriteFile(f + ".copy", b, 0600)
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// }()
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// }
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// ctx, endSpan = WithSpan(ctx, "copy-dir")
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// defer endSpan()
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// for _, f := range dir.Files() {
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// func() {
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// ctx, endSpan := WithSpan(ctx, fmt.Sprintf("copy-file %q", f))
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// defer endspan()
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// b, _ := ioutil.ReadFile(f)
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// _ = ioutil.WriteFile(f + ".copy", b, 0600)
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// }()
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// }
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//
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// In combination:
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// ctx, endTask = WithTask(ctx, "copy-dirs")
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// defer endTask()
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// for i := range dirs {
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// go func(dir string) {
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// ctx, endTask := WithTask(ctx, "copy-dir")
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// defer endTask()
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// for _, f := range filesIn(dir) {
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// func() {
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// ctx, endSpan := WithSpan(ctx, fmt.Sprintf("copy-file %q", f))
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// defer endspan()
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// b, _ := ioutil.ReadFile(f)
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// _ = ioutil.WriteFile(f + ".copy", b, 0600)
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// }()
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// }
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// }()
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// }
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//
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// ctx, endTask = WithTask(ctx, "copy-dirs")
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// defer endTask()
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// for i := range dirs {
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// go func(dir string) {
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// ctx, endTask := WithTask(ctx, "copy-dir")
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// defer endTask()
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// for _, f := range filesIn(dir) {
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// func() {
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// ctx, endSpan := WithSpan(ctx, fmt.Sprintf("copy-file %q", f))
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// defer endspan()
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// b, _ := ioutil.ReadFile(f)
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// _ = ioutil.WriteFile(f + ".copy", b, 0600)
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// }()
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// }
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// }()
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// }
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//
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// Note that a span ends at the time you call endSpan - not before and not after that.
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// If you violate the stack-like nesting of spans by forgetting an endSpan() invocation,
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@@ -65,8 +64,7 @@
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//
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// Recovering from endSpan() or endTask() panics will corrupt the trace stack and lead to corrupt tracefile output.
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//
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//
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// Best Practices For Naming Tasks And Spans
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// # Best Practices For Naming Tasks And Spans
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//
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// Tasks should always have string constants as names, and must not contain the `#` character. WHy?
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// First, the visualization by chrome://tracing draws a horizontal bar for each task in the trace.
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@@ -74,8 +72,7 @@
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// Note that the `#NUM` suffix will be reused if a task has ended, in order to avoid an
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// infinite number of horizontal bars in the visualization.
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//
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//
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// Chrome-compatible Tracefile Support
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// # Chrome-compatible Tracefile Support
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//
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// The activity trace generated by usage of WithTask and WithSpan can be rendered to a JSON output file
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// that can be loaded into chrome://tracing .
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@@ -11,8 +11,6 @@ import (
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// use like this:
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//
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// defer WithSpanFromStackUpdateCtx(&existingCtx)()
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//
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//
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func WithSpanFromStackUpdateCtx(ctx *context.Context) DoneFunc {
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childSpanCtx, end := WithSpan(*ctx, getMyCallerOrPanic())
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*ctx = childSpanCtx
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