use /proc/self/statm to get current usage

server/cache/memory.go

@@ -1,7 +1,9 @@
 package cache
 
 import (
-	"runtime"
+	"os"
+	"strconv"
+	"strings"
 	"time"
 
 	"github.com/OrlovEvgeny/go-mcache"
@@ -10,7 +12,7 @@ import (
 
 type Cache struct {
 	mcache      *mcache.CacheDriver
-	memoryLimit uint64
+	memoryLimit int
 	lastCheck   time.Time
 }
 
@@ -21,7 +23,7 @@ func NewInMemoryCache() ICache {
 
 // NewInMemoryCache returns a new mcache with a memory limit.
 // If the limit is exceeded, the cache will be cleared.
-func NewInMemoryCacheWithLimit(memoryLimit uint64) ICache {
+func NewInMemoryCacheWithLimit(memoryLimit int) ICache {
 	return &Cache{
 		mcache:      mcache.New(),
 		memoryLimit: memoryLimit,
@@ -31,11 +33,10 @@ func NewInMemoryCacheWithLimit(memoryLimit uint64) ICache {
 func (c *Cache) Set(key string, value interface{}, ttl time.Duration) error {
 	now := time.Now()
 
-	// checking memory limit is a "stop the world" operation
-	// so we don't want to do it too often
+	// we don't want to do it too often
 	if now.Sub(c.lastCheck) > (time.Second * 3) {
 		if c.memoryLimitOvershot() {
-			log.Debug().Msg("memory limit exceeded, clearing cache")
+			log.Info().Msg("[cache] memory limit exceeded, clearing cache")
 			c.mcache.Truncate()
 		}
 		c.lastCheck = now
@@ -53,10 +54,31 @@ func (c *Cache) Remove(key string) {
 }
 
 func (c *Cache) memoryLimitOvershot() bool {
-	var stats runtime.MemStats
-	runtime.ReadMemStats(&stats)
+	mem := getCurrentMemory()
 
-	log.Debug().Uint64("bytes", stats.HeapAlloc).Msg("current memory usage")
+	log.Debug().Int("kB", mem).Msg("[cache] current memory usage")
 
-	return stats.HeapAlloc > c.memoryLimit
+	return mem > c.memoryLimit
+}
+
+// getCurrentMemory returns the current memory in KB
+func getCurrentMemory() int {
+	b, err := os.ReadFile("/proc/self/statm")
+	if err != nil {
+		log.Error().Err(err).Msg("[cache] could not read /proc/self/statm")
+		return 0
+	}
+
+	str := string(b)
+	arr := strings.Split(str, " ")
+
+	// convert to pages
+	res, err := strconv.Atoi(arr[1])
+	if err != nil {
+		log.Error().Err(err).Msg("[cache] could not convert string to int")
+		return 0
+	}
+
+	// convert to KB
+	return (res * os.Getpagesize()) / 1024
 }