Commit Graph

6 Commits

Author SHA1 Message Date
Martin Holst Swende
8b6cf128af
metrics: refactor metrics (#28035)
This change includes a lot of things, listed below. 

### Split up interfaces, write vs read

The interfaces have been split up into one write-interface and one read-interface, with `Snapshot` being the gateway from write to read. This simplifies the semantics _a lot_. 

Example of splitting up an interface into one readonly 'snapshot' part, and one updatable writeonly part: 

```golang
type MeterSnapshot interface {
	Count() int64
	Rate1() float64
	Rate5() float64
	Rate15() float64
	RateMean() float64
}

// Meters count events to produce exponentially-weighted moving average rates
// at one-, five-, and fifteen-minutes and a mean rate.
type Meter interface {
	Mark(int64)
	Snapshot() MeterSnapshot
	Stop()
}
```

### A note about concurrency

This PR makes the concurrency model clearer. We have actual meters and snapshot of meters. The `meter` is the thing which can be accessed from the registry, and updates can be made to it. 

- For all `meters`, (`Gauge`, `Timer` etc), it is assumed that they are accessed by different threads, making updates. Therefore, all `meters` update-methods (`Inc`, `Add`, `Update`, `Clear` etc) need to be concurrency-safe. 
- All `meters` have a `Snapshot()` method. This method is _usually_ called from one thread, a backend-exporter. But it's fully possible to have several exporters simultaneously: therefore this method should also be concurrency-safe. 

TLDR: `meter`s are accessible via registry, all their methods must be concurrency-safe. 

For all `Snapshot`s, it is assumed that an individual exporter-thread has obtained a `meter` from the registry, and called the `Snapshot` method to obtain a readonly snapshot. This snapshot is _not_ guaranteed to be concurrency-safe. There's no need for a snapshot to be concurrency-safe, since exporters should not share snapshots. 

Note, though: that by happenstance a lot of the snapshots _are_ concurrency-safe, being unmutable minimal representations of a value. Only the more complex ones are _not_ threadsafe, those that lazily calculate things like `Variance()`, `Mean()`.

Example of how a background exporter typically works, obtaining the snapshot and sequentially accessing the non-threadsafe methods in it: 
```golang
		ms := metric.Snapshot()
                ...
		fields := map[string]interface{}{
			"count":    ms.Count(),
			"max":      ms.Max(),
			"mean":     ms.Mean(),
			"min":      ms.Min(),
			"stddev":   ms.StdDev(),
			"variance": ms.Variance(),
```

TLDR: `snapshots` are not guaranteed to be concurrency-safe (but often are).

### Sample changes

I also changed the `Sample` type: previously, it iterated the samples fully every time `Mean()`,`Sum()`, `Min()` or `Max()` was invoked. Since we now have readonly base data, we can just iterate it once, in the constructor, and set all four values at once. 

The same thing has been done for runtimehistogram. 

### ResettingTimer API

Back when ResettingTImer was implemented, as part of https://github.com/ethereum/go-ethereum/pull/15910, Anton implemented a `Percentiles` on the new type. However, the method did not conform to the other existing types which also had a `Percentiles`. 

1. The existing ones, on input, took `0.5` to mean `50%`. Anton used `50` to mean `50%`. 
2. The existing ones returned `float64` outputs, thus interpolating between values. A value-set of `0, 10`, at `50%` would return `5`, whereas Anton's would return either `0` or `10`. 

This PR removes the 'new' version, and uses only the 'legacy' percentiles, also for the ResettingTimer type. 

The resetting timer snapshot was also defined so that it would expose the internal values. This has been removed, and getters for `Max, Min, Mean` have been added instead. 

### Unexport types

A lot of types were exported, but do not need to be. This PR unexports quite a lot of them.
2023-09-13 13:13:47 -04:00
Jorge
53f3c2ae65
metrics, cmd/geth: informational metrics (prometheus, influxdb, opentsb) (#24877)
This chang creates a GaugeInfo metrics type for registering informational (textual) metrics, e.g. geth version number. It also improves the testing for backend-exporters, and uses a shared subpackage in 'internal' to provide sample datasets and ordered registry. 

Implements #21783

---------

Co-authored-by: Martin Holst Swende <martin@swende.se>
2023-08-31 13:37:17 -04:00
turboboost55
7dc100714d
metrics: add cpu counters (#26796)
This PR adds counter metrics for the CPU system and the Geth process.
Currently the only metrics available for these items are gauges. Gauges are
fine when the consumer scrapes metrics data at the same interval as Geth
produces new values (every 3 seconds), but it is likely that most consumers
will not scrape that often. Intervals of 10, 15, or maybe even 30 seconds
are probably more common.

So the problem is, how does the consumer estimate what the CPU was doing in
between scrapes. With a counter, it's easy ... you just subtract two
successive values and divide by the time to get a nice, accurate average.
But with a gauge, you can't do that. A gauge reading is an instantaneous
picture of what was happening at that moment, but it gives you no idea
about what was going on between scrapes. Taking an average of values is
meaningless.
2023-03-23 14:13:50 +01:00
s7v7nislands
7caa2d8163
all: replace strings.Replace with string.ReplaceAll (#24835) 2022-05-09 13:13:23 +03:00
Richard Patel
2f66a8d614
metrics/prometheus: define TYPE once, add tests (#21068)
* metrics/prometheus: define type once for histograms

* metrics/prometheus: test collector
2020-05-26 12:00:09 +03:00
Maxim Krasilnikov
31bc2a2434 metrics/prometheus: expose metrics in prometheus format too (#17077)
* metrics/prometheus: added prometheus http server and metrics collector

* metrics/prometheus: minor cleanups

* metrics/prometheus: named keys instead name in tag

* metrics/prometheus: minor typo cleanups, sorted report
2019-04-11 12:56:19 +03:00