// Copyright 2015 The Vanadium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package stats defines an interface to access statistical information for
// troubleshooting and monitoring purposes.
package stats

import (
	"v.io/v23/security/access"
	"v.io/v23/services/watch"
)

// The Stats interface is used to access stats for troubleshooting and
// monitoring purposes. The stats objects are discoverable via the Globbable
// interface and watchable via the GlobWatcher interface.
//
// The types of the object values are implementation specific, but should be
// primarily numeric in nature, e.g. counters, memory usage, latency metrics,
// etc.
type Stats interface {
	// Stats objects can be watched. Updates are streamed to the watcher.
	watch.GlobWatcher
	// Value returns the current value of an object, or an error. The type
	// of the value is implementation specific.
	// Some objects may not have a value, in which case, Value() returns
	// a NoValue error.
	Value() (any | error) {access.Debug}
}

error (
	NoValue(suffix string) {"en": "object has no value, suffix: {suffix}"}
)