telegraf/plugins/inputs/vsphere/tscache.go

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package vsphere
import (
"log"
"sync"
"time"
)
// TSCache is a cache of timestamps used to determine the validity of datapoints
type TSCache struct {
ttl time.Duration
table map[string]time.Time
mux sync.RWMutex
}
// NewTSCache creates a new TSCache with a specified time-to-live after which timestamps are discarded.
func NewTSCache(ttl time.Duration) *TSCache {
return &TSCache{
ttl: ttl,
table: make(map[string]time.Time),
}
}
// Purge removes timestamps that are older than the time-to-live
func (t *TSCache) Purge() {
t.mux.Lock()
defer t.mux.Unlock()
n := 0
for k, v := range t.table {
if time.Now().Sub(v) > t.ttl {
delete(t.table, k)
n++
}
}
log.Printf("D! [inputs.vsphere] purged timestamp cache. %d deleted with %d remaining", n, len(t.table))
}
// IsNew returns true if the supplied timestamp for the supplied key is more recent than the
// timestamp we have on record.
func (t *TSCache) IsNew(key string, metricName string, tm time.Time) bool {
t.mux.RLock()
defer t.mux.RUnlock()
v, ok := t.table[makeKey(key, metricName)]
if !ok {
return true // We've never seen this before, so consider everything a new sample
}
return !tm.Before(v)
}
// Get returns a timestamp (if present)
func (t *TSCache) Get(key string, metricName string) (time.Time, bool) {
t.mux.RLock()
defer t.mux.RUnlock()
ts, ok := t.table[makeKey(key, metricName)]
return ts, ok
}
// Put updates the latest timestamp for the supplied key.
func (t *TSCache) Put(key string, metricName string, time time.Time) {
t.mux.Lock()
defer t.mux.Unlock()
t.table[makeKey(key, metricName)] = time
}
func makeKey(resource string, metric string) string {
return resource + "|" + metric
}