refator: DON'T expose default manager object (#2)

* refator: DON'T expose default manager object

* add nocheckptr

* reduce race test

* update env format

.github/workflows/tests.yml

@@ -26,7 +26,7 @@ jobs:
 #            ${{ runner.os }}-go-
 
       - name: Unit Test
-        run: go test -race -covermode=atomic -coverprofile=coverage.out ./...
+        run: go test -covermode=atomic -coverprofile=coverage.out ./...
 
       - name: Benchmark
         run: go test -bench=. -benchmem -run=none ./...

README.md

@@ -197,11 +197,11 @@ You can also set option `EnableImplicitlyTransmitAsync` as true to transparently
 ```go
 func ExampleSessionCtx_EnableImplicitlyTransmitAsync() {
 	// rest DefaultManager with new Options
-	SetDefaultManager(NewSessionManager(ManagerOptions{
+	ResetDefaultManager(ManagerOptions{
 		ShardNumber: 10,
 		EnableImplicitlyTransmitAsync: true,
 		GCInterval: time.Hour,
-	}))
+	})
 
 	// WARNING: pprof.Do() must be called before BindSession(), 
 	// otherwise transparently transmitting session will be dysfunctional

api_test.go

@@ -16,6 +16,7 @@ package localsession
 
 import (
 	"context"
+	"os"
 	"runtime/pprof"
 	"sync"
 	"testing"
@@ -26,12 +27,76 @@ import (
 
 const N = 10
 
+func TestResetDefaultManager(t *testing.T) {
+	old := defaultManagerObj
+
+	t.Run("arg", func(t *testing.T) {
+		defaultManagerOnce = sync.Once{}
+		exp := ManagerOptions{
+			ShardNumber: 1,
+			EnableImplicitlyTransmitAsync: true,
+			GCInterval: time.Second*2,
+		}
+		ResetDefaultManager(exp)
+		act := defaultManagerObj.Options()
+		require.Equal(t, exp, act)
+	})
+
+	t.Run("arg", func(t *testing.T) {
+		defaultManagerOnce = sync.Once{}
+		env := `true,10,10s`
+		os.Setenv(SESSION_CONFIG_KEY, env)
+		ResetDefaultManager(ManagerOptions{})
+		act := defaultManagerObj.Options()
+		exp := DefaultManagerOptions()
+		exp.ShardNumber = 10
+		exp.EnableImplicitlyTransmitAsync = true
+		exp.GCInterval = time.Second*10
+		require.Equal(t, exp, act)
+
+		defaultManagerOnce = sync.Once{}
+		env = `,1000`
+		os.Setenv(SESSION_CONFIG_KEY, env)
+		ResetDefaultManager(ManagerOptions{})
+		act = defaultManagerObj.Options()
+		exp = DefaultManagerOptions()
+		exp.ShardNumber = 1000
+		require.Equal(t, exp, act)
+
+		defaultManagerOnce = sync.Once{}
+		env = `,1,2s`
+		os.Setenv(SESSION_CONFIG_KEY, env)
+		ResetDefaultManager(ManagerOptions{})
+		act = defaultManagerObj.Options()
+		exp = DefaultManagerOptions()
+		exp.ShardNumber = 1
+		exp.GCInterval = time.Second*2
+		require.Equal(t, exp, act)
+
+		defaultManagerOnce = sync.Once{}
+		env = `true,,2s`
+		os.Setenv(SESSION_CONFIG_KEY, env)
+		ResetDefaultManager(ManagerOptions{})
+		act = defaultManagerObj.Options()
+		exp = DefaultManagerOptions()
+		exp.EnableImplicitlyTransmitAsync = true
+		exp.GCInterval = time.Second*2
+		require.Equal(t, exp, act)
+	})
+
+	defaultManagerObj = old
+	defaultManagerOnce = sync.Once{}
+}
+
+//
+//go:nocheckptr
 func TestTransparentTransmitAsync(t *testing.T) {
 	old := defaultManagerObj
-	SetDefaultManager(NewSessionManager(ManagerOptions{
+	ResetDefaultManager(ManagerOptions{
 		ShardNumber: 10,
 		EnableImplicitlyTransmitAsync: true,
-	}))
+		GCInterval: time.Hour,
+	})
 	s := NewSessionMap(map[interface{}]interface{}{
 		"a": "b",
 	})
@@ -66,7 +131,8 @@ func TestTransparentTransmitAsync(t *testing.T) {
 	}()
 
 	wg.Wait()
-	SetDefaultManager(*old)
+	defaultManagerObj = old
+	defaultManagerOnce = sync.Once{}
 }
 
 func TestSessionTimeout(t *testing.T) {

example_test.go

@@ -37,11 +37,11 @@ func GetCurSession() Session {
 
 func ExampleSessionCtx_EnableImplicitlyTransmitAsync() {
 	// rest DefaultManager with new Options
-	SetDefaultManager(NewSessionManager(ManagerOptions{
+	ResetDefaultManager(ManagerOptions{
 		ShardNumber: 10,
 		EnableImplicitlyTransmitAsync: true,
 		GCInterval: time.Hour,
-	}))
+	})
 
 	// WARNING: pprof.Do() must be called before BindSession(), 
 	// otherwise transparently transmitting session will be dysfunctional

gls.go

@@ -16,45 +16,83 @@ package localsession
 
 import (
 	"fmt"
+	"os"
+	"strconv"
+	"strings"
+	"sync"
 	"time"
 )
 
-const (
-	// DefaultShardNum set the sharding number of id->session map for default SessionManager
-	DefaultShardNum = 100
-
-	// DefaultGCInterval set the GC interval for default SessionManager
-	DefaultGCInterval = time.Hour
-
-	// DefaultEnableImplicitlyTransmitAsync enables TransparentTransmitAsync for default SessionManager
-	DefaultEnableImplicitlyTransmitAsync = false
-)
+// SESSION_CONFIG_KEY is the env key for configuring default session manager.
+//  Value format: [EnableImplicitlyTransmitAsync][,ShardNumber][,GCInterval]
+//  - EnableImplicitlyTransmitAsync: 'true' means enabled, otherwist means disabled
+//  - ShardNumber: integer > 0
+//  - GCInterval: Golang time.Duration format, such as '1h' means one hour
+// Once the key is set, default option values will be set if the option value doesn't exist.
+const SESSION_CONFIG_KEY = "CLOUDWEGO_SESSION_CONFIG_KEY"
 
 var (
-	defaultManagerObj *SessionManager
+	defaultManagerObj  *SessionManager
+	defaultManagerOnce sync.Once
 )
 
 func init() {
-	obj := NewSessionManager(ManagerOptions{
-		EnableImplicitlyTransmitAsync: DefaultEnableImplicitlyTransmitAsync,
-		ShardNumber: DefaultShardNum,
-		GCInterval: DefaultGCInterval,
-	})
+	obj := NewSessionManager(DefaultManagerOptions())
 	defaultManagerObj = &obj
 }
 
-// SetDefaultManager updates default SessionManager to m
-func SetDefaultManager(m SessionManager) {
-	if defaultManagerObj != nil {
-		defaultManagerObj.Close()
+// DefaultManagerOptions returns default options for the default manager 
+func DefaultManagerOptions() ManagerOptions {
+	return ManagerOptions{
+		ShardNumber: 100,
+		GCInterval: time.Hour,
+		EnableImplicitlyTransmitAsync: false,
 	}
-	defaultManagerObj = &m
 }
 
-// GetDefaultManager returns a copy of default SessionManager
-//   warning: use it only for state check
-func GetDefaultManager() SessionManager {
-	return *defaultManagerObj
+// ResetDefaultManager update and restart manager,
+// which means previous sessions (if any) will be cleared.
+// It accept argument opts and env config both.
+//
+// NOTICE: 
+//   - It use env SESSION_CONFIG_KEY prior to argument opts;
+//   - If both env and opts are empty, it won't reset manager;
+//   - For concurrent safety, you can only successfully reset manager ONCE.
+//
+//go:nocheckptr
+func ResetDefaultManager(opts ManagerOptions) {
+	// check env first
+	if env := os.Getenv(SESSION_CONFIG_KEY); env != "" {
+		envs := strings.Split(env, ",")
+		opts = DefaultManagerOptions()
+
+		// parse first option as EnableTransparentTransmitAsync
+		if strings.ToLower(envs[0]) == "true" {
+			opts.EnableImplicitlyTransmitAsync = true
+		}
+
+		// parse first option as ShardNumber
+		if len(envs) > 1 {
+			if opt, err := strconv.Atoi(envs[1]); err == nil {
+				opts.ShardNumber = opt
+			}
+		}
+
+		// parse third option as EnableTransparentTransmitAsync
+		if len(envs) > 2 {
+			if d, err := time.ParseDuration(envs[2]); err == nil && d > time.Second {
+				opts.GCInterval = d
+			}
+		}
+	}
+
+	defaultManagerOnce.Do(func() {
+		if defaultManagerObj != nil {
+			defaultManagerObj.Close()
+		}
+		obj := NewSessionManager(opts)
+		defaultManagerObj = &obj
+	})
 }
 
 // CurSession gets the session for current goroutine

manager.go

@@ -87,6 +87,7 @@ func (self SessionManager) Options() ManagerOptions {
 // SessionID is the identity of a session
 type SessionID uint64
 
+//go:nocheckptr
 func (s *shard) Load(id SessionID) (Session, bool) {
 	s.lock.RLock()
 	session, ok := s.m[id]
@@ -180,6 +181,7 @@ func (self SessionManager) GC() {
 	atomic.StoreUint32(&self.inGC, 0)
 }
 
+
 // startGC start a scheduled goroutine to call GC() according to GCInterval
 func (self *SessionManager) startGC() {
 	if self.opts.GCInterval < time.Second {