[#72] Support soft memory limit setting

Signed-off-by: Roman Loginov <r.loginov@yadro.com>

settings.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/hex"
 	"fmt"
+	"math"
 	"os"
 	"path"
 	"runtime"
@@ -36,6 +37,8 @@ const (
 
 	defaultPoolErrorThreshold uint32 = 100
 
+	defaultSoftMemoryLimit = math.MaxInt64
+
 	cfgServer      = "server"
 	cfgTLSEnabled  = "tls.enabled"
 	cfgTLSCertFile = "tls.cert_file"
@@ -90,6 +93,9 @@ const (
 	// Zip compression.
 	cfgZipCompression = "zip.compression"
 
+	// Runtime.
+	cfgSoftMemoryLimit = "runtime.soft_memory_limit"
+
 	// Command line args.
 	cmdHelp          = "help"
 	cmdVersion       = "version"
@@ -516,3 +522,12 @@ func fetchPeers(l *zap.Logger, v *viper.Viper) []pool.NodeParam {
 
 	return nodes
 }
+
+func fetchSoftMemoryLimit(cfg *viper.Viper) int64 {
+	softMemoryLimit := cfg.GetSizeInBytes(cfgSoftMemoryLimit)
+	if softMemoryLimit <= 0 {
+		softMemoryLimit = defaultSoftMemoryLimit
+	}
+
+	return int64(softMemoryLimit)
+}