fix golint issues in core/executors (#484)

core/executors/chunkexecutor.go

@@ -5,8 +5,12 @@ import "time"
 const defaultChunkSize = 1024 * 1024 // 1M
 
 type (
+	// ChunkOption defines the method to customize a ChunkExecutor.
 	ChunkOption func(options *chunkOptions)
 
+	// A ChunkExecutor is an executor to execute tasks when either requirement meets:
+	// 1. up to given chunk size
+	// 2. flush interval elapsed
 	ChunkExecutor struct {
 		executor  *PeriodicalExecutor
 		container *chunkContainer
@@ -18,6 +22,7 @@ type (
 	}
 )
 
+// NewChunkExecutor returns a ChunkExecutor.
 func NewChunkExecutor(execute Execute, opts ...ChunkOption) *ChunkExecutor {
 	options := newChunkOptions()
 	for _, opt := range opts {
@@ -36,6 +41,7 @@ func NewChunkExecutor(execute Execute, opts ...ChunkOption) *ChunkExecutor {
 	return executor
 }
 
+// Add adds task with given chunk size into ce.
 func (ce *ChunkExecutor) Add(task interface{}, size int) error {
 	ce.executor.Add(chunk{
 		val:  task,
@@ -44,20 +50,24 @@ func (ce *ChunkExecutor) Add(task interface{}, size int) error {
 	return nil
 }
 
+// Flush forces ce to flush and execute tasks.
 func (ce *ChunkExecutor) Flush() {
 	ce.executor.Flush()
 }
 
+// Wait waits the execution to be done.
 func (ce *ChunkExecutor) Wait() {
 	ce.executor.Wait()
 }
 
+// WithChunkBytes customizes a ChunkExecutor with the given chunk size.
 func WithChunkBytes(size int) ChunkOption {
 	return func(options *chunkOptions) {
 		options.chunkSize = size
 	}
 }
 
+// WithFlushInterval customizes a ChunkExecutor with the given flush interval.
 func WithFlushInterval(duration time.Duration) ChunkOption {
 	return func(options *chunkOptions) {
 		options.flushInterval = duration