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Add Cache metrics to groupcache #5352

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merged 1 commit into from
May 11, 2022
+31 −2
Merged

Add Cache metrics to groupcache #5352

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2 changes: 2 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,8 @@ We use *breaking :warning:* to mark changes that are not backward compatible (re

### Added

- [#5352](https://github.com/thanos-io/thanos/pull/5352) Cache: Add cache metrics to groupcache.

### Changed

### Removed
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31 changes: 29 additions & 2 deletions pkg/cache/groupcache.go
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Expand Up @@ -254,7 +254,7 @@ func NewGroupcacheWithConfig(logger log.Logger, reg prometheus.Registerer, conf
},
))

RegisterCacheStatsCollector(galaxy, reg)
RegisterCacheStatsCollector(galaxy, &conf, reg)

return &Groupcache{
logger: logger,
Expand Down Expand Up @@ -305,8 +305,13 @@ func (c *Groupcache) Name() string {

type CacheStatsCollector struct {
galaxy *galaxycache.Galaxy
conf *GroupcacheConfig

// GalaxyCache Metric descriptions.
bytes *prometheus.Desc
evictions *prometheus.Desc
items *prometheus.Desc
maxBytes *prometheus.Desc
gets *prometheus.Desc
loads *prometheus.Desc
peerLoads *prometheus.Desc
Expand All @@ -317,7 +322,16 @@ type CacheStatsCollector struct {
}

// RegisterCacheStatsCollector registers a groupcache metrics collector.
func RegisterCacheStatsCollector(galaxy *galaxycache.Galaxy, reg prometheus.Registerer) {
func RegisterCacheStatsCollector(galaxy *galaxycache.Galaxy, conf *GroupcacheConfig, reg prometheus.Registerer) {
// Cache metrics.
bytes := prometheus.NewDesc("thanos_cache_groupcache_bytes", "The number of bytes in the main cache.", []string{"cache"}, nil)
evictions := prometheus.NewDesc("thanos_cache_groupcache_evictions_total", "The number items evicted from the cache.", []string{"cache"}, nil)
items := prometheus.NewDesc("thanos_cache_groupcache_items", "The number of items in the cache.", []string{"cache"}, nil)

// Configuration Metrics.
maxBytes := prometheus.NewDesc("thanos_cache_groupcache_max_bytes", "The max number of bytes in the cache.", nil, nil)

// GroupCache metrics.
gets := prometheus.NewDesc("thanos_cache_groupcache_get_requests_total", "Total number of get requests, including from peers.", nil, nil)
loads := prometheus.NewDesc("thanos_cache_groupcache_loads_total", "Total number of loads from backend (gets - cacheHits).", nil, nil)
peerLoads := prometheus.NewDesc("thanos_cache_groupcache_peer_loads_total", "Total number of loads from peers (remote load or remote cache hit).", nil, nil)
Expand All @@ -328,6 +342,11 @@ func RegisterCacheStatsCollector(galaxy *galaxycache.Galaxy, reg prometheus.Regi

collector := &CacheStatsCollector{
galaxy: galaxy,
conf: conf,
bytes: bytes,
evictions: evictions,
items: items,
maxBytes: maxBytes,
gets: gets,
loads: loads,
peerLoads: peerLoads,
Expand All @@ -340,6 +359,14 @@ func RegisterCacheStatsCollector(galaxy *galaxycache.Galaxy, reg prometheus.Regi
}

func (s *CacheStatsCollector) Collect(ch chan<- prometheus.Metric) {
for _, cache := range []galaxycache.CacheType{galaxycache.MainCache, galaxycache.HotCache} {
cacheStats := s.galaxy.CacheStats(cache)
ch <- prometheus.MustNewConstMetric(s.bytes, prometheus.GaugeValue, float64(cacheStats.Bytes), cache.String())
ch <- prometheus.MustNewConstMetric(s.evictions, prometheus.GaugeValue, float64(cacheStats.Evictions), cache.String())
ch <- prometheus.MustNewConstMetric(s.items, prometheus.GaugeValue, float64(cacheStats.Items), cache.String())
}

ch <- prometheus.MustNewConstMetric(s.maxBytes, prometheus.GaugeValue, float64(s.conf.MaxSize))
ch <- prometheus.MustNewConstMetric(s.gets, prometheus.CounterValue, float64(s.galaxy.Stats.Gets.Get()))
ch <- prometheus.MustNewConstMetric(s.loads, prometheus.CounterValue, float64(s.galaxy.Stats.Loads.Get()))
ch <- prometheus.MustNewConstMetric(s.peerLoads, prometheus.CounterValue, float64(s.galaxy.Stats.PeerLoads.Get()))
Expand Down