/
metrics_store.go
142 lines (113 loc) · 3.4 KB
/
metrics_store.go
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package metricsstore
import (
"io"
"sync"
"k8s.io/apimachinery/pkg/api/meta"
"k8s.io/apimachinery/pkg/types"
)
// FamilyStringer represents a metric family that can be converted to its string
// representation.
type FamilyStringer interface {
String() string
}
// MetricsStore implements the k8s.io/kubernetes/client-go/tools/cache.Store
// interface. Instead of storing entire Kubernetes objects, it stores metrics
// generated based on those objects.
type MetricsStore struct {
// Protects metrics
mutex sync.RWMutex
// metrics is a map indexed by Kubernetes object id, containing a slice of
// metric families, containing a slice of metrics. We need to keep metrics
// grouped by metric families in order to zip families with their help text in
// MetricsStore.WriteAll().
metrics map[types.UID][]string
// headers contains the header (TYPE and HELP) of each metric family. It is
// later on zipped with with their corresponding metric families in
// MetricStore.WriteAll().
headers []string
// generateMetricsFunc generates metrics based on a given Kubernetes object
// and returns them grouped by metric family.
generateMetricsFunc func(interface{}) []FamilyStringer
}
// NewMetricsStore returns a new MetricsStore
func NewMetricsStore(headers []string, generateFunc func(interface{}) []FamilyStringer) *MetricsStore {
return &MetricsStore{
generateMetricsFunc: generateFunc,
headers: headers,
metrics: map[types.UID][]string{},
}
}
// Implementing k8s.io/kubernetes/client-go/tools/cache.Store interface
// TODO: Proper comments on all functions below.
func (s *MetricsStore) Add(obj interface{}) error {
o, err := meta.Accessor(obj)
if err != nil {
return err
}
s.mutex.Lock()
defer s.mutex.Unlock()
families := s.generateMetricsFunc(obj)
familyStrings := make([]string, len(families))
for i, f := range families {
familyStrings[i] = f.String()
}
s.metrics[o.GetUID()] = familyStrings
return nil
}
func (s *MetricsStore) Update(obj interface{}) error {
// For now, just call Add, in the future one could check if the resource
// version changed?
return s.Add(obj)
}
func (s *MetricsStore) Delete(obj interface{}) error {
o, err := meta.Accessor(obj)
if err != nil {
return err
}
s.mutex.Lock()
defer s.mutex.Unlock()
delete(s.metrics, o.GetUID())
return nil
}
func (s *MetricsStore) List() []interface{} {
return nil
}
func (s *MetricsStore) ListKeys() []string {
return nil
}
func (s *MetricsStore) Get(obj interface{}) (item interface{}, exists bool, err error) {
return nil, false, nil
}
func (s *MetricsStore) GetByKey(key string) (item interface{}, exists bool, err error) {
return nil, false, nil
}
// Replace will delete the contents of the store, using instead the
// given list.
func (s *MetricsStore) Replace(list []interface{}, _ string) error {
s.mutex.Lock()
s.metrics = map[types.UID][]string{}
s.mutex.Unlock()
for _, o := range list {
err := s.Add(o)
if err != nil {
return err
}
}
return nil
}
func (s *MetricsStore) Resync() error {
return nil
}
// WriteAll writes all metrics of the store into the given writer, zipped with the
// help text of each metric family.
func (s *MetricsStore) WriteAll(w io.Writer) {
s.mutex.RLock()
defer s.mutex.RUnlock()
for i, help := range s.headers {
w.Write([]byte(help))
w.Write([]byte{'\n'})
for _, metricFamilies := range s.metrics {
w.Write([]byte(metricFamilies[i]))
}
}
}