|author||Jonathan Amsterdam <firstname.lastname@example.org>||Sun Jun 06 17:15:04 2021 -0400|
|committer||Jonathan Amsterdam <email@example.com>||Thu Jun 10 11:49:57 2021 +0000|
event: WIP: another try at metrics The code that is recording the metric is the best place to describe that metric. For example, an RPC layer knows that number of sent RPCs is a counter, and that bytes received is a distribution. We want to keep that information separate from the actual metric recoding, both to avoid duplication and to amortize any costs involved. The idea in this CL is to have a lightweight representation for metrics. The world seems to have converged on just three kinds: counter, gauge and distribution in the terminology of this CL. A package must first create the metrics it wants to record, by calling NewMetric with the metric kind, a name, and a description. We create a namespace for the metric using the import path of the caller of NewMetric. That can be overridden, but not to the empty string. By forcing a non-empty the namespace we can prevent ambiguous metric names, such has having many packages use the name "call_count". It's up to the package whether it creates the metrics globally and unconditionally, or each time a value of a certain type is created. A cache that has just one global instance would use the former, while and RPC package with a Client type would ask the caller of NewClient to pass a namespace, and store the created metrics in the Client. Builder.Metric records a metric value as before. Its first argument is one of the previously created metrics, from which it can extract whatever values it needs to build an Event. Its second argument is an event.Value, allowing any type to be a metric value. We provide convenience functions for two common cases: Count for marking a single instance of an event, like an RPC call or cache probe; and Since for recording the latency since a start time. Units are a necessary annoyance that we don't fully deal with here. For time we use time.Duration, which lets the exporter choose the unit and correctly convert values. Change-Id: I26d0ac095fa2cd8b19201edc47350704636de89c Reviewed-on: https://go-review.googlesource.com/c/exp/+/325490 Trust: Jonathan Amsterdam <firstname.lastname@example.org> Run-TryBot: Jonathan Amsterdam <email@example.com> TryBot-Result: Go Bot <firstname.lastname@example.org> Reviewed-by: Ian Cottrell <email@example.com>
This subrepository holds experimental and deprecated (in the
old directory) packages.
The idea for this subrepository originated as the
pkg/exp directory of the main repository, but its presence there made it unavailable to users of the binary downloads of the Go installation. The subrepository has therefore been created to make it possible to
go get these packages.
Warning: Packages here are experimental and unreliable. Some may one day be promoted to the main repository or other subrepository, or they may be modified arbitrarily or even disappear altogether.
In short, code in this subrepository is not subject to the Go 1 compatibility promise. (No subrepo is, but the promise is even more likely to be violated by go.exp than the others.)