observability

type Counter interface {
	Inc()
	Add(float64)
}

type Histogram interface {
	Observe(float64)
}

type MetricFactory interface {
	Counter(name string) Counter
	Histogram(name string) Histogram
}

type MetricsExtension struct {

	// Plan metrics
	PlanCreated  Counter
	PlanUpdated  Counter
	PlanArchived Counter

	// Subscription metrics
	SubscriptionCreated    Counter
	SubscriptionUpgraded   Counter
	SubscriptionDowngraded Counter
	SubscriptionCanceled   Counter
	SubscriptionExpired    Counter
	// The lifecycle clock's transitions, and scheduled cancels, which
	// SubscriptionCanceled no longer counts: it counts cancels that took
	// effect.
	SubscriptionRenewed         Counter
	SubscriptionTrialEnded      Counter
	SubscriptionCancelScheduled Counter

	// Usage metrics
	UsageEventsIngested Counter
	UsageBatchSize      Histogram
	UsageFlushLatency   Histogram

	// Entitlement metrics
	EntitlementChecks      Counter
	EntitlementCacheHits   Counter
	EntitlementCacheMisses Counter
	EntitlementDenied      Counter
	EntitlementLatency     Histogram

	// Invoice metrics
	InvoiceGenerated Counter
	InvoiceFinalized Counter
	InvoicePaid      Counter
	InvoiceVoided    Counter
	InvoicePastDue   Counter
	InvoiceTotal     Histogram

	// Provider metrics
	ProviderSyncSuccess Counter
	ProviderSyncFailure Counter
	WebhookReceived     Counter
	WebhookProcessed    Counter

	// Error metrics
	StoreErrors  Counter
	PluginErrors Counter
	// contains filtered or unexported fields
}