d8ac79f643
This adds WithTrace function to the context package that allows users to trace a time span between a trace allocation and returned function call. The resulting context includes ids that will allow for future dapper-like analysis. Please see the godoc addition for details. Signed-off-by: Stephen J Day <stephen.day@docker.com>
85 lines
1.8 KiB
Go
85 lines
1.8 KiB
Go
package context
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import (
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"runtime"
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"testing"
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"time"
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)
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// TestWithTrace ensures that tracing has the expected values in the context.
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func TestWithTrace(t *testing.T) {
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pc, file, _, _ := runtime.Caller(0) // get current caller.
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f := runtime.FuncForPC(pc)
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base := []valueTestCase{
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{
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key: "trace.id",
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notnilorempty: true,
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},
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{
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key: "trace.file",
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expected: file,
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notnilorempty: true,
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},
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{
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key: "trace.line",
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notnilorempty: true,
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},
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{
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key: "trace.start",
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notnilorempty: true,
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},
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}
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ctx, done := WithTrace(Background())
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defer done("this will be emitted at end of test")
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checkContextForValues(t, ctx, append(base, valueTestCase{
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key: "trace.func",
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expected: f.Name(),
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}))
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traced := func() {
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parentID := ctx.Value("trace.id") // ensure the parent trace id is correct.
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pc, _, _, _ := runtime.Caller(0) // get current caller.
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f := runtime.FuncForPC(pc)
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ctx, done := WithTrace(ctx)
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defer done("this should be subordinate to the other trace")
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time.Sleep(time.Second)
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checkContextForValues(t, ctx, append(base, valueTestCase{
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key: "trace.func",
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expected: f.Name(),
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}, valueTestCase{
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key: "trace.parent.id",
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expected: parentID,
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}))
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}
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traced()
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time.Sleep(time.Second)
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}
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type valueTestCase struct {
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key string
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expected interface{}
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notnilorempty bool // just check not empty/not nil
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}
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func checkContextForValues(t *testing.T, ctx Context, values []valueTestCase) {
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for _, testcase := range values {
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v := ctx.Value(testcase.key)
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if testcase.notnilorempty {
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if v == nil || v == "" {
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t.Fatalf("value was nil or empty for %q: %#v", testcase.key, v)
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}
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continue
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}
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if v != testcase.expected {
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t.Fatalf("unexpected value for key %q: %v != %v", testcase.key, v, testcase.expected)
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}
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}
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}
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