9045b79bc2
This PR modifies how the metrics library handles `Enabled`: previously, the package `init` decided whether to serve real metrics or just dummy-types. This has several drawbacks: - During pkg init, we need to determine whether metrics are enabled or not. So we first hacked in a check if certain geth-specific commandline-flags were enabled. Then we added a similar check for geth-env-vars. Then we almost added a very elaborate check for toml-config-file, plus toml parsing. - Using "real" types and dummy types interchangeably means that everything is hidden behind interfaces. This has a performance penalty, and also it just adds a lot of code. This PR removes the interface stuff, uses concrete types, and allows for the setting of Enabled to happen later. It is still assumed that `metrics.Enable()` is invoked early on. The somewhat 'heavy' operations, such as ticking meters and exp-decay, now checks the enable-flag to prevent resource leak. The change may be large, but it's mostly pretty trivial, and from the last time I gutted the metrics, I ensured that we have fairly good test coverage. --------- Co-authored-by: Felix Lange <fjl@twurst.com>
25 lines
725 B
Go
25 lines
725 B
Go
package metrics
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// ResettingSample converts an ordinary sample into one that resets whenever its
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// snapshot is retrieved. This will break for multi-monitor systems, but when only
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// a single metric is being pushed out, this ensure that low-frequency events don't
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// skew th charts indefinitely.
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func ResettingSample(sample Sample) Sample {
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return &resettingSample{
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Sample: sample,
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}
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}
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// resettingSample is a simple wrapper around a sample that resets it upon the
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// snapshot retrieval.
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type resettingSample struct {
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Sample
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}
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// Snapshot returns a read-only copy of the sample with the original reset.
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func (rs *resettingSample) Snapshot() *sampleSnapshot {
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s := rs.Sample.Snapshot()
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rs.Sample.Clear()
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return s
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}
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