cloudflare/pint
Publicmirrored from https://github.com/cloudflare/pintAvailable
internal/promapi/cache.go
192lines · modecode
| 1 | package promapi |
| 2 | |
| 3 | import ( |
| 4 | "sync" |
| 5 | "time" |
| 6 | |
| 7 | "github.com/prometheus/client_golang/prometheus" |
| 8 | ) |
| 9 | |
| 10 | func newQueryCache(maxSize int, maxSinceLastRequest time.Duration) *queryCache { |
| 11 | return &queryCache{ |
| 12 | requests: map[uint64]cacheRequest{}, |
| 13 | entries: map[uint64]queryResult{}, |
| 14 | maxSize: maxSize, |
| 15 | maxSinceLastRequest: maxSinceLastRequest, |
| 16 | hits: map[string]int{}, |
| 17 | misses: map[string]int{}, |
| 18 | } |
| 19 | } |
| 20 | |
| 21 | type cacheRequest struct { |
| 22 | lastGet time.Time |
| 23 | count int |
| 24 | } |
| 25 | |
| 26 | type queryCache struct { |
| 27 | mu sync.Mutex |
| 28 | requests map[uint64]cacheRequest |
| 29 | entries map[uint64]queryResult |
| 30 | maxSize int |
| 31 | maxSinceLastRequest time.Duration |
| 32 | hits map[string]int |
| 33 | misses map[string]int |
| 34 | evictions int |
| 35 | } |
| 36 | |
| 37 | func (c *queryCache) get(key uint64, endpoint string) (v queryResult, ok bool) { |
| 38 | c.mu.Lock() |
| 39 | defer c.mu.Unlock() |
| 40 | |
| 41 | var r cacheRequest |
| 42 | r, ok = c.requests[key] |
| 43 | if ok { |
| 44 | r.lastGet = time.Now() |
| 45 | r.count++ |
| 46 | c.requests[key] = r |
| 47 | } else { |
| 48 | c.requests[key] = cacheRequest{ |
| 49 | lastGet: time.Now(), |
| 50 | count: 1, |
| 51 | } |
| 52 | } |
| 53 | |
| 54 | v, ok = c.entries[key] |
| 55 | if ok { |
| 56 | c.hits[endpoint]++ |
| 57 | } else { |
| 58 | c.misses[endpoint]++ |
| 59 | } |
| 60 | |
| 61 | return v, ok |
| 62 | } |
| 63 | |
| 64 | func (c *queryCache) set(key uint64, val queryResult, minRequests int) { |
| 65 | c.mu.Lock() |
| 66 | defer c.mu.Unlock() |
| 67 | |
| 68 | if minRequests > 0 { |
| 69 | if r, ok := c.requests[key]; !ok || r.count <= minRequests { |
| 70 | return |
| 71 | } |
| 72 | } |
| 73 | |
| 74 | if len(c.entries) >= c.maxSize { |
| 75 | c.purgeOne() |
| 76 | } |
| 77 | |
| 78 | c.entries[key] = val |
| 79 | } |
| 80 | |
| 81 | func (c *queryCache) purgeOne() { |
| 82 | var purgeKey uint64 |
| 83 | purgeRequests := -100 |
| 84 | var purgeLastGet time.Time |
| 85 | for k, r := range c.requests { |
| 86 | if r.count < purgeRequests || purgeRequests < 0 || (r.count == purgeRequests && r.lastGet.Before(purgeLastGet)) { |
| 87 | purgeKey = k |
| 88 | purgeRequests = r.count |
| 89 | purgeLastGet = r.lastGet |
| 90 | } |
| 91 | } |
| 92 | delete(c.entries, purgeKey) |
| 93 | delete(c.requests, purgeKey) |
| 94 | c.evictions++ |
| 95 | } |
| 96 | |
| 97 | func (c *queryCache) gc() { |
| 98 | c.mu.Lock() |
| 99 | defer c.mu.Unlock() |
| 100 | |
| 101 | var r cacheRequest |
| 102 | var ok bool |
| 103 | |
| 104 | requests := map[uint64]cacheRequest{} |
| 105 | entries := map[uint64]queryResult{} |
| 106 | now := time.Now() |
| 107 | for k, v := range c.entries { |
| 108 | r, ok = c.requests[k] |
| 109 | if !ok || (ok && now.Sub(r.lastGet) >= c.maxSinceLastRequest) { |
| 110 | c.evictions++ |
| 111 | continue |
| 112 | } |
| 113 | if v.expires.IsZero() || !v.expires.Before(now) { |
| 114 | if ok { |
| 115 | requests[k] = r |
| 116 | } |
| 117 | entries[k] = v |
| 118 | } else { |
| 119 | c.evictions++ |
| 120 | } |
| 121 | } |
| 122 | |
| 123 | for k, r := range c.requests { |
| 124 | if _, ok = requests[k]; ok { |
| 125 | continue |
| 126 | } |
| 127 | if now.Sub(r.lastGet) < c.maxSinceLastRequest { |
| 128 | requests[k] = r |
| 129 | } |
| 130 | } |
| 131 | |
| 132 | c.requests = requests |
| 133 | c.entries = entries |
| 134 | } |
| 135 | |
| 136 | type cacheCollector struct { |
| 137 | cache *queryCache |
| 138 | entries *prometheus.Desc |
| 139 | hits *prometheus.Desc |
| 140 | misses *prometheus.Desc |
| 141 | evictions *prometheus.Desc |
| 142 | } |
| 143 | |
| 144 | func newCacheCollector(cache *queryCache, name string) *cacheCollector { |
| 145 | return &cacheCollector{ |
| 146 | cache: cache, |
| 147 | entries: prometheus.NewDesc( |
| 148 | "pint_prometheus_cache_size", |
| 149 | "Total number of entries currently stored in Prometheus query cache", |
| 150 | nil, |
| 151 | prometheus.Labels{"name": name}, |
| 152 | ), |
| 153 | hits: prometheus.NewDesc( |
| 154 | "pint_prometheus_cache_hits_total", |
| 155 | "Total number of query cache hits", |
| 156 | []string{"endpoint"}, |
| 157 | prometheus.Labels{"name": name}, |
| 158 | ), |
| 159 | misses: prometheus.NewDesc( |
| 160 | "pint_prometheus_cache_miss_total", |
| 161 | "Total number of query cache misses", |
| 162 | []string{"endpoint"}, |
| 163 | prometheus.Labels{"name": name}, |
| 164 | ), |
| 165 | evictions: prometheus.NewDesc( |
| 166 | "pint_prometheus_cache_evictions_total", |
| 167 | "Total number of times an entry was evicted from query cache due to size limit or TTL", |
| 168 | nil, |
| 169 | prometheus.Labels{"name": name}, |
| 170 | ), |
| 171 | } |
| 172 | } |
| 173 | |
| 174 | func (c *cacheCollector) Describe(ch chan<- *prometheus.Desc) { |
| 175 | ch <- c.entries |
| 176 | ch <- c.hits |
| 177 | ch <- c.misses |
| 178 | ch <- c.evictions |
| 179 | } |
| 180 | |
| 181 | func (c *cacheCollector) Collect(ch chan<- prometheus.Metric) { |
| 182 | c.cache.mu.Lock() |
| 183 | defer c.cache.mu.Unlock() |
| 184 | ch <- prometheus.MustNewConstMetric(c.entries, prometheus.GaugeValue, float64(len(c.cache.entries))) |
| 185 | for endpoint, hits := range c.cache.hits { |
| 186 | ch <- prometheus.MustNewConstMetric(c.hits, prometheus.CounterValue, float64(hits), endpoint) |
| 187 | } |
| 188 | for endpoint, misses := range c.cache.misses { |
| 189 | ch <- prometheus.MustNewConstMetric(c.misses, prometheus.CounterValue, float64(misses), endpoint) |
| 190 | } |
| 191 | ch <- prometheus.MustNewConstMetric(c.evictions, prometheus.CounterValue, float64(c.cache.evictions)) |
| 192 | } |
| 193 | |