observability

type AppMetrics interface {
	// IncCacheHits increments the cache hits counter for the given repository.
	IncCacheHits(repository string)

	// IncCacheMisses increments the cache misses counter for the given repository.
	IncCacheMisses(repository string)

	// IncCoalescedRequests increments the counter of requests served by coalescing
	// onto an in-flight upstream fetch, for the given repository.
	IncCoalescedRequests(repository string)

	// IncCacheEntryMissing increments the counter of serve-time cache misses for
	// the given repository: a fetch that stored or coalesced successfully but
	// found its entry gone when it went to serve it, and had to re-fetch.
	IncCacheEntryMissing(repository string)

	// IncCacheRebuilds increments the counter of local cache entries rebuilt from
	// the pack in object storage, for the given repository. It counts downloads, so
	// requests coalesced onto one rebuild record a single increment between them.
	IncCacheRebuilds(repository string)

	// IncNonCacheableRequests increments the non-cacheable requests counter for the given reason.
	IncNonCacheableRequests(reason string)

	// IncCacheEvictions increments the cache-evictions counter for the given reason
	// (ttl, size, reject). Reason distinguishes sliding-TTL expiration from
	// size-driven LFU eviction from admission-policy rejection.
	IncCacheEvictions(reason string)

	// ObserveFetchDuration records the end-to-end duration of a cacheable fetch,
	// labelled by result (hit, miss, coalesce, bypass).
	ObserveFetchDuration(result string, seconds float64)

	// IncErrors increments the error counter for the given type (upstream, cache, internal).
	IncErrors(errorType string)

	// IncDryRunWouldHit records that a dry-run request would have been served
	// from the cache (its key is already tracked in the shadow store).
	IncDryRunWouldHit(repository string)

	// IncDryRunWouldMiss records that a dry-run request would have been a
	// fresh upstream fetch (no shadow entry, no coalescing).
	IncDryRunWouldMiss(repository string)

	// IncDryRunWouldCoalesce records that a dry-run request would have
	// coalesced onto an in-flight fetch for the same key.
	IncDryRunWouldCoalesce(repository string)

	// IncDryRunNonCacheable records a dry-run request whose command shape
	// makes it ineligible for caching (empty key from the parser).
	IncDryRunNonCacheable(repository, reason string)

	// IncDryRunEvictions records a shadow-store eviction, labelled by reason
	// (ttl or size).
	IncDryRunEvictions(reason string)

	// ObserveDryRunWouldCacheBytes records the response size of a would-miss
	// request: the bytes that would have been admitted to the cache had
	// caching been on. Only observed on the leader (would-miss), since only
	// the leader would have populated the cache; followers ride on it.
	ObserveDryRunWouldCacheBytes(repository string, bytes float64)

	// AddDryRunShadowSizeBytes increases the per-repository shadow-store
	// size gauge, called on every would-miss admission.
	AddDryRunShadowSizeBytes(repository string, bytes float64)

	// SubDryRunShadowSizeBytes decreases the per-repository shadow-store
	// size gauge, called from the shadow's OnEvictSize callback on every
	// eviction so the gauge stays balanced with admissions.
	SubDryRunShadowSizeBytes(repository string, bytes int64)

	// IncPackfileURICacheHits increments the counter of URI-capable client
	// requests served as a `packfile-uri` (signed URL to the bucket), for the
	// given repository.
	IncPackfileURICacheHits(repository string)

	// IncPackfileURICacheMisses increments the counter of URI-capable client
	// requests that could not be served as a `packfile-uri` (no local cache
	// entry, no bucket-side pack yet), for the given repository.
	IncPackfileURICacheMisses(repository string)

	// IncPackfileURIOffloads increments the counter of successful background
	// pack uploads to object storage, for the given repository.
	IncPackfileURIOffloads(repository string)

	// IncPackfileURIOffloadFailures increments the counter of failed background
	// pack uploads to object storage, for the given repository.
	IncPackfileURIOffloadFailures(repository string)

	// ObservePackfileURIOffloadDuration records the wall-clock duration of one
	// background pack upload to object storage. Emitted regardless of success or
	// failure, so slow failures show up in the tail.
	ObservePackfileURIOffloadDuration(seconds float64)

	// AddPackfileURIBytesServed adds `bytes` to the cumulative pack bytes handed
	// off to clients as signed URLs (i.e. bytes that did NOT traverse Packhorse's
	// pod egress). This is the load-bearing benefit signal: divided by
	// http_response_size_bytes it gives the share of client-facing bytes moved
	// off Packhorse.
	AddPackfileURIBytesServed(repository string, bytes float64)

	// AddPackfileURIOffloadBytes adds `bytes` to the cumulative pack bytes
	// written to object storage on a successful background upload.
	AddPackfileURIOffloadBytes(repository string, bytes float64)
}

type CacheCollector struct {
	// contains filtered or unexported fields
}

type MockAppMetrics struct {
	// contains filtered or unexported fields
}

type NullAppMetrics struct{}

type PrometheusAppMetrics struct {
	// contains filtered or unexported fields
}

type PrometheusManager struct {
	// contains filtered or unexported fields
}