[tracer] allowing SetMeta at tracer level #56
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ufoot
added
the
enhancement
tracer/tracer.go
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| t.metaMu.RLock() | ||
| if t.meta != nil { | ||
| meta = make(map[string]string) |
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make(map[string]string, len(t.meta)) to ensure we only need one alloc
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| // getAllMeta returns all the meta set by this tracer. | ||
| // In most cases, it is nil. | ||
| func (t *Tracer) getAllMeta() map[string]string { |
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Any reason to implement this one? We are dealing without it in Python and Ruby, so I'd vote to keep the API simple if we can.
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The reason it's here is locking, this way we use RLock within the tracer code, the span code does not have to worry about it. Should we not do this I think span code would have to deal internally with the private mutex. This is perfectly doable, but I tend to prefer having objects dealing with their mutex internally, and not require others to care about it.
Additionnally, Python code uses https://github.com/DataDog/dd-trace-py/blob/master/ddtrace/tracer.py#L164 which calls https://github.com/DataDog/dd-trace-py/blob/master/ddtrace/span.py#L145 so it also has this deep copy, only it's done in span.py instead of tracer.py.
I can move the code to span.go if you want to, just exposing the reason it's here. Note that getAllMeta is private, it's not part of the API anyway.
| @@ -282,6 +282,28 @@ func TestTracerServicesDisabled(t *testing.T) { | |||
| assert.Equal(0, len(transport.services)) | |||
| } | |||
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| func TestTracerMeta(t *testing.T) { | |||
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One case to test: when we set a meta at the span-level which has the same key as one set as the tracer-level.
And to test something closer to user-land, we should do asserts on spans only (and don't need getAllMeta)
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Agree, will update the tests, thanks for feedback.
Release 2.1
This should make the go client on par with the Python & Ruby ones, allowing application to set per tracer meta values (AKA tags).