Merge branch 'feat/raft'

# Conflicts:
#	cluster/cluster.go
#	cluster/router.go
#	config/config.go
#	database/database.go
#	database/server.go

database/database.go

@@ -30,6 +30,10 @@ type DB struct {
 
 	// addaof is used to add command to aof
 	addAof func(CmdLine)
+
+	// callbacks
+	insertCallback database.KeyEventCallback
+	deleteCallback database.KeyEventCallback
 }
 
 // ExecFunc is interface for command executor
@@ -159,7 +163,13 @@ func (db *DB) GetEntity(key string) (*database.DataEntity, bool) {
 
 // PutEntity a DataEntity into DB
 func (db *DB) PutEntity(key string, entity *database.DataEntity) int {
-	return db.data.PutWithLock(key, entity)
+	ret := db.data.PutWithLock(key, entity)
+	// db.insertCallback may be set as nil, during `if` and actually callback
+	// so introduce a local variable `cb`
+	if cb := db.insertCallback; ret > 0 && cb != nil {
+		cb(db.index, key, entity)
+	}
+	return ret
 }
 
 // PutIfExists edit an existing DataEntity
@@ -169,15 +179,28 @@ func (db *DB) PutIfExists(key string, entity *database.DataEntity) int {
 
 // PutIfAbsent insert an DataEntity only if the key not exists
 func (db *DB) PutIfAbsent(key string, entity *database.DataEntity) int {
-	return db.data.PutIfAbsentWithLock(key, entity)
+	ret := db.data.PutIfAbsentWithLock(key, entity)
+	// db.insertCallback may be set as nil, during `if` and actually callback
+	// so introduce a local variable `cb`
+	if cb := db.insertCallback; ret > 0 && cb != nil {
+		cb(db.index, key, entity)
+	}
+	return ret
 }
 
 // Remove the given key from db
 func (db *DB) Remove(key string) {
-	db.data.RemoveWithLock(key)
+	raw, deleted := db.data.RemoveWithLock(key)
 	db.ttlMap.Remove(key)
 	taskKey := genExpireTask(key)
 	timewheel.Cancel(taskKey)
+	if cb := db.deleteCallback; cb != nil {
+		var entity *database.DataEntity
+		if deleted > 0 {
+			entity = raw.(*database.DataEntity)
+		}
+		cb(db.index, key, entity)
+	}
 }
 
 // Removes the given keys from db