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>
71 lines
1.6 KiB
Go
71 lines
1.6 KiB
Go
package metrics
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import "sync/atomic"
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// GaugeSnapshot is a read-only copy of a Gauge.
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type GaugeSnapshot int64
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// Value returns the value at the time the snapshot was taken.
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func (g GaugeSnapshot) Value() int64 { return int64(g) }
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// GetOrRegisterGauge returns an existing Gauge or constructs and registers a
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// new Gauge.
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func GetOrRegisterGauge(name string, r Registry) *Gauge {
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if r == nil {
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r = DefaultRegistry
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}
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return r.GetOrRegister(name, NewGauge).(*Gauge)
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}
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// NewGauge constructs a new Gauge.
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func NewGauge() *Gauge {
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return &Gauge{}
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}
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// NewRegisteredGauge constructs and registers a new Gauge.
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func NewRegisteredGauge(name string, r Registry) *Gauge {
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c := NewGauge()
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if r == nil {
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r = DefaultRegistry
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}
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r.Register(name, c)
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return c
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}
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// Gauge holds an int64 value that can be set arbitrarily.
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type Gauge atomic.Int64
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// Snapshot returns a read-only copy of the gauge.
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func (g *Gauge) Snapshot() GaugeSnapshot {
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return GaugeSnapshot((*atomic.Int64)(g).Load())
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}
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// Update updates the gauge's value.
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func (g *Gauge) Update(v int64) {
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(*atomic.Int64)(g).Store(v)
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}
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// UpdateIfGt updates the gauge's value if v is larger then the current value.
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func (g *Gauge) UpdateIfGt(v int64) {
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value := (*atomic.Int64)(g)
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for {
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exist := value.Load()
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if exist >= v {
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break
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}
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if value.CompareAndSwap(exist, v) {
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break
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}
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}
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}
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// Dec decrements the gauge's current value by the given amount.
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func (g *Gauge) Dec(i int64) {
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(*atomic.Int64)(g).Add(-i)
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}
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// Inc increments the gauge's current value by the given amount.
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func (g *Gauge) Inc(i int64) {
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(*atomic.Int64)(g).Add(i)
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}
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