libs/common: refactor libs common 3 (#4232)

* libs/common: refactor libs common 3

- move nil.go into types folder and make private
- move service & baseservice out of common into service pkg

ref #4147

Signed-off-by: Marko Baricevic <marbar3778@yahoo.com>

* add changelog entry

libs/autofile/group.go

@@ -14,7 +14,7 @@ import (
 	"sync"
 	"time"
 
-	cmn "github.com/tendermint/tendermint/libs/common"
+	"github.com/tendermint/tendermint/libs/service"
 )
 
 const (
@@ -53,7 +53,7 @@ The Group can also be used to binary-search for some line,
 assuming that marker lines are written occasionally.
 */
 type Group struct {
-	cmn.BaseService
+	service.BaseService
 
 	ID                 string
 	Head               *AutoFile // The head AutoFile to write to
@@ -102,7 +102,7 @@ func OpenGroup(headPath string, groupOptions ...func(*Group)) (g *Group, err err
 		option(g)
 	}
 
-	g.BaseService = *cmn.NewBaseService(nil, "Group", g)
+	g.BaseService = *service.NewBaseService(nil, "Group", g)
 
 	gInfo := g.readGroupInfo()
 	g.minIndex = gInfo.MinIndex
@@ -131,7 +131,7 @@ func GroupTotalSizeLimit(limit int64) func(*Group) {
 	}
 }
 
-// OnStart implements cmn.Service by starting the goroutine that checks file
+// OnStart implements service.Service by starting the goroutine that checks file
 // and group limits.
 func (g *Group) OnStart() error {
 	g.ticker = time.NewTicker(g.groupCheckDuration)
@@ -139,7 +139,7 @@ func (g *Group) OnStart() error {
 	return nil
 }
 
-// OnStop implements cmn.Service by stopping the goroutine described above.
+// OnStop implements service.Service by stopping the goroutine described above.
 // NOTE: g.Head must be closed separately using Close.
 func (g *Group) OnStop() {
 	g.ticker.Stop()

libs/common/nil.go

@@ -1,29 +0,0 @@
-package common
-
-import "reflect"
-
-// Go lacks a simple and safe way to see if something is a typed nil.
-// See:
-//  - https://dave.cheney.net/2017/08/09/typed-nils-in-go-2
-//  - https://groups.google.com/forum/#!topic/golang-nuts/wnH302gBa4I/discussion
-//  - https://github.com/golang/go/issues/21538
-func IsTypedNil(o interface{}) bool {
-	rv := reflect.ValueOf(o)
-	switch rv.Kind() {
-	case reflect.Chan, reflect.Func, reflect.Map, reflect.Ptr, reflect.Slice:
-		return rv.IsNil()
-	default:
-		return false
-	}
-}
-
-// Returns true if it has zero length.
-func IsEmpty(o interface{}) bool {
-	rv := reflect.ValueOf(o)
-	switch rv.Kind() {
-	case reflect.Array, reflect.Chan, reflect.Map, reflect.Slice, reflect.String:
-		return rv.Len() == 0
-	default:
-		return false
-	}
-}

libs/events/README.md

@@ -110,7 +110,7 @@ via concrete implementation of this interface
 ## <a name="EventSwitch">type</a> [EventSwitch](/src/target/events.go?s=560:771#L29)
 ``` go
 type EventSwitch interface {
-    cmn.Service
+    service.Service
     Fireable
 
     AddListenerForEvent(listenerID, event string, cb EventCallback)

libs/events/events.go

@@ -5,7 +5,7 @@ import (
 	"fmt"
 	"sync"
 
-	cmn "github.com/tendermint/tendermint/libs/common"
+	"github.com/tendermint/tendermint/libs/service"
 )
 
 // ErrListenerWasRemoved is returned by AddEvent if the listener was removed.
@@ -43,7 +43,7 @@ type Fireable interface {
 // They can be removed by calling either RemoveListenerForEvent or
 // RemoveListener (for all events).
 type EventSwitch interface {
-	cmn.Service
+	service.Service
 	Fireable
 
 	AddListenerForEvent(listenerID, event string, cb EventCallback) error
@@ -52,7 +52,7 @@ type EventSwitch interface {
 }
 
 type eventSwitch struct {
-	cmn.BaseService
+	service.BaseService
 
 	mtx        sync.RWMutex
 	eventCells map[string]*eventCell
@@ -64,7 +64,7 @@ func NewEventSwitch() EventSwitch {
 		eventCells: make(map[string]*eventCell),
 		listeners:  make(map[string]*eventListener),
 	}
-	evsw.BaseService = *cmn.NewBaseService(nil, "EventSwitch", evsw)
+	evsw.BaseService = *service.NewBaseService(nil, "EventSwitch", evsw)
 	return evsw
 }
 

libs/pubsub/pubsub.go

@@ -39,7 +39,7 @@ import (
 	"sync"
 
 	"github.com/pkg/errors"
-	cmn "github.com/tendermint/tendermint/libs/common"
+	"github.com/tendermint/tendermint/libs/service"
 )
 
 type operation int
@@ -88,7 +88,7 @@ type cmd struct {
 // Server allows clients to subscribe/unsubscribe for messages, publishing
 // messages with or without events, and manages internal state.
 type Server struct {
-	cmn.BaseService
+	service.BaseService
 
 	cmds    chan cmd
 	cmdsCap int
@@ -109,7 +109,7 @@ func NewServer(options ...Option) *Server {
 	s := &Server{
 		subscriptions: make(map[string]map[string]struct{}),
 	}
-	s.BaseService = *cmn.NewBaseService(nil, "PubSub", s)
+	s.BaseService = *service.NewBaseService(nil, "PubSub", s)
 
 	for _, option := range options {
 		option(s)

libs/service/service.go

@@ -1,4 +1,4 @@
-package common
+package service
 
 import (
 	"errors"

libs/service/service_test.go

@@ -1,4 +1,4 @@
-package common
+package service
 
 import (
 	"testing"