Remove globalMaxCacheSize and globalCacheExpiry variables (#3826)

This patch fixes below

* Remove global variables globalMaxCacheSize and globalCacheExpiry.
* Make global variables into constant in objcache package.

cmd/globals.go

@@ -26,7 +26,6 @@ import (
 	"github.com/fatih/color"
 	"github.com/minio/cli"
 	"github.com/minio/mc/pkg/console"
-	"github.com/minio/minio/pkg/objcache"
 )
 
 // minio configuration related constants.
@@ -78,16 +77,9 @@ var (
 	// Set to true if credentials were passed from env, default is false.
 	globalIsEnvCreds = false
 
-	// Maximum cache size. Defaults to disabled.
-	// Caching is enabled only for RAM size > 8GiB.
-	globalMaxCacheSize = uint64(0)
-
 	// Maximum size of internal objects parts
 	globalPutPartSize = int64(64 * 1024 * 1024)
 
-	// Cache expiry.
-	globalCacheExpiry = objcache.DefaultExpiry
-
 	// Minio local server address (in `host:port` format)
 	globalMinioAddr = ""
 	// Minio default port, can be changed through command line.

cmd/server-main.go

@@ -138,16 +138,8 @@ func initServerConfig(c *cli.Context) {
 	// Load user supplied root CAs
 	loadRootCAs()
 
-	// Set maxOpenFiles, This is necessary since default operating
-	// system limits of 1024, 2048 are not enough for Minio server.
-	setMaxOpenFiles()
-
-	// Set maxMemory, This is necessary since default operating
-	// system limits might be changed and we need to make sure we
-	// do not crash the server so the set the maxCacheSize appropriately.
-	setMaxMemory()
-
-	// Do not fail if this is not allowed, lower limits are fine as well.
+	// Set system resources to maximum.
+	errorIf(setMaxResources(), "Unable to change resource limit")
 }
 
 // Validate if input disks are sufficient for initializing XL.

cmd/server-rlimit.go

@@ -16,17 +16,27 @@
 
 package cmd
 
-import (
-	"github.com/minio/minio/pkg/sys"
-)
+import "github.com/minio/minio/pkg/sys"
 
-func setMaxOpenFiles() error {
-	_, maxLimit, err := sys.GetMaxOpenFileLimit()
-	if err != nil {
+func setMaxResources() (err error) {
+	var maxLimit uint64
+
+	// Set open files limit to maximum.
+	if _, maxLimit, err = sys.GetMaxOpenFileLimit(); err != nil {
 		return err
 	}
 
-	return sys.SetMaxOpenFileLimit(maxLimit, maxLimit)
+	if err = sys.SetMaxOpenFileLimit(maxLimit, maxLimit); err != nil {
+		return err
+	}
+
+	// Set max memory limit as current memory limit.
+	if _, maxLimit, err = sys.GetMaxMemoryLimit(); err != nil {
+		return err
+	}
+
+	err = sys.SetMaxMemoryLimit(maxLimit, maxLimit)
+	return err
 }
 
 func getMaxCacheSize(curLimit, totalRAM uint64) (cacheSize uint64) {
@@ -45,29 +55,25 @@ func getMaxCacheSize(curLimit, totalRAM uint64) (cacheSize uint64) {
 	return cacheSize
 }
 
-func setMaxMemory() error {
+// GetMaxCacheSize returns maximum cache size based on current RAM size and memory limit.
+func GetMaxCacheSize() (cacheSize uint64, err error) {
 	// Get max memory limit
-	_, maxLimit, err := sys.GetMaxMemoryLimit()
-	if err != nil {
-		return err
-	}
-
-	// Set max memory limit as current memory limit.
-	if err = sys.SetMaxMemoryLimit(maxLimit, maxLimit); err != nil {
-		return err
+	var curLimit uint64
+	if curLimit, _, err = sys.GetMaxMemoryLimit(); err != nil {
+		return cacheSize, err
 	}
 
 	// Get total RAM.
-	stats, err := sys.GetStats()
-	if err != nil {
-		return err
+	var stats sys.Stats
+	if stats, err = sys.GetStats(); err != nil {
+		return cacheSize, err
 	}
 
 	// In some OS like windows, maxLimit is zero.  Set total RAM as maxLimit.
-	if maxLimit == 0 {
-		maxLimit = stats.TotalRAM
+	if curLimit == 0 {
+		curLimit = stats.TotalRAM
 	}
 
-	globalMaxCacheSize = getMaxCacheSize(maxLimit, stats.TotalRAM)
-	return nil
+	cacheSize = getMaxCacheSize(curLimit, stats.TotalRAM)
+	return cacheSize, err
 }

cmd/test-utils_test.go

@@ -65,8 +65,8 @@ func init() {
 	// Disable printing console messages during tests.
 	color.Output = ioutil.Discard
 
-	// Enable caching.
-	setMaxMemory()
+	// Set system resources to maximum.
+	setMaxResources()
 }
 
 func prepareFS() (ObjectLayer, string, error) {

cmd/xl-v1.go

@@ -127,14 +127,23 @@ func newXLObjects(storageDisks []StorageAPI) (ObjectLayer, error) {
 		listPool:     listPool,
 	}
 
-	// Object cache is enabled when _MINIO_CACHE env is missing.
-	// and cache size is > 0.
-	xl.objCacheEnabled = !objCacheDisabled && globalMaxCacheSize > 0
+	// Get cache size if _MINIO_CACHE environment variable is set.
+	var maxCacheSize uint64
+	if !objCacheDisabled {
+		maxCacheSize, err = GetMaxCacheSize()
+		errorIf(err, "Unable to get maximum cache size")
+
+		// Enable object cache if cache size is more than zero
+		xl.objCacheEnabled = maxCacheSize > 0
+	}
 
 	// Check if object cache is enabled.
 	if xl.objCacheEnabled {
 		// Initialize object cache.
-		objCache := objcache.New(globalMaxCacheSize, globalCacheExpiry)
+		objCache, err := objcache.New(maxCacheSize, objcache.DefaultExpiry)
+		if err != nil {
+			return nil, err
+		}
 		objCache.OnEviction = func(key string) {
 			debug.FreeOSMemory()
 		}