67 lines
1.8 KiB
Markdown
67 lines
1.8 KiB
Markdown
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# Trace
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This package provides an interface for recording the latency of operations and logging details
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about all operations where the latency exceeds a limit.
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## Usage
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To create a trace:
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```go
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func doSomething() {
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opTrace := trace.New("operation", Field{Key: "fieldKey1", Value: "fieldValue1"})
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defer opTrace.LogIfLong(100 * time.Millisecond)
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// do something
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}
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```
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To split an trace into multiple steps:
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```go
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func doSomething() {
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opTrace := trace.New("operation")
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defer opTrace.LogIfLong(100 * time.Millisecond)
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// do step 1
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opTrace.Step("step1", Field{Key: "stepFieldKey1", Value: "stepFieldValue1"})
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// do step 2
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opTrace.Step("step2")
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}
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```
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To nest traces:
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```go
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func doSomething() {
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rootTrace := trace.New("rootOperation")
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defer rootTrace.LogIfLong(100 * time.Millisecond)
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func() {
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nestedTrace := rootTrace.Nest("nested", Field{Key: "nestedFieldKey1", Value: "nestedFieldValue1"})
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defer nestedTrace.LogIfLong(50 * time.Millisecond)
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// do nested operation
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}()
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}
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```
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Traces can also be logged unconditionally or introspected:
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```go
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opTrace.TotalTime() // Duration since the Trace was created
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opTrace.Log() // unconditionally log the trace
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```
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### Using context.Context to nest traces
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`context.Context` can be used to manage nested traces. Create traces by calling `trace.GetTraceFromContext(ctx).Nest`.
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This is safe even if there is no parent trace already in the context because `(*(Trace)nil).Nest()` returns
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a top level trace.
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```go
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func doSomething(ctx context.Context) {
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opTrace := trace.FromContext(ctx).Nest("operation") // create a trace, possibly nested
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ctx = trace.ContextWithTrace(ctx, opTrace) // make this trace the parent trace of the context
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defer opTrace.LogIfLong(50 * time.Millisecond)
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doSomethingElse(ctx)
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}
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```
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