[skip ci]Add chunk manager comment (#7833)

Signed-off-by: godchen <qingxiang.chen@zilliz.com>

internal/storage/local_chunk_manager.go

@@ -22,16 +22,19 @@ import (
 	"github.com/milvus-io/milvus/internal/log"
 )
 
+// LocalChunkManager is responsible for read and write local file.
 type LocalChunkManager struct {
 	localPath string
 }
 
+// NewLocalChunkManager create a new local manager object.
 func NewLocalChunkManager(localPath string) *LocalChunkManager {
 	return &LocalChunkManager{
 		localPath: localPath,
 	}
 }
 
+// GetPath returns the path of local data if exist.
 func (lcm *LocalChunkManager) GetPath(key string) (string, error) {
 	if !lcm.Exist(key) {
 		return "", errors.New("local file cannot be found with key:" + key)
@@ -40,6 +43,7 @@ func (lcm *LocalChunkManager) GetPath(key string) (string, error) {
 	return path, nil
 }
 
+// Write writes the data to local storage.
 func (lcm *LocalChunkManager) Write(key string, content []byte) error {
 	filePath := path.Join(lcm.localPath, key)
 	dir := path.Dir(filePath)
@@ -56,6 +60,7 @@ func (lcm *LocalChunkManager) Write(key string, content []byte) error {
 	return nil
 }
 
+// Exist checks whether chunk is saved to local storage.
 func (lcm *LocalChunkManager) Exist(key string) bool {
 	path := path.Join(lcm.localPath, key)
 	_, err := os.Stat(path)
@@ -65,6 +70,7 @@ func (lcm *LocalChunkManager) Exist(key string) bool {
 	return true
 }
 
+// Read reads the local storage data if exist.
 func (lcm *LocalChunkManager) Read(key string) ([]byte, error) {
 	path := path.Join(lcm.localPath, key)
 	file, err := os.Open(path)
@@ -79,6 +85,7 @@ func (lcm *LocalChunkManager) Read(key string) ([]byte, error) {
 	return content, nil
 }
 
+// ReadAt reads specific position data of local storage if exist.
 func (lcm *LocalChunkManager) ReadAt(key string, p []byte, off int64) (n int, err error) {
 	path := path.Join(lcm.localPath, key)
 	at, err := mmap.Open(path)

internal/storage/minio_chunk_manager.go

@@ -18,16 +18,19 @@ import (
 	miniokv "github.com/milvus-io/milvus/internal/kv/minio"
 )
 
+// MinioChunkManager is responsible for read and write data stored in minio.
 type MinioChunkManager struct {
 	minio *miniokv.MinIOKV
 }
 
+// NewMinioChunkManager create a new local manager object.
 func NewMinioChunkManager(minio *miniokv.MinIOKV) *MinioChunkManager {
 	return &MinioChunkManager{
 		minio: minio,
 	}
 }
 
+// GetPath returns the path of minio data if exist.
 func (mcm *MinioChunkManager) GetPath(key string) (string, error) {
 	if !mcm.Exist(key) {
 		return "", errors.New("minio file manage cannot be found with key:" + key)
@@ -35,19 +38,23 @@ func (mcm *MinioChunkManager) GetPath(key string) (string, error) {
 	return key, nil
 }
 
+// Write writes the data to minio storage.
 func (mcm *MinioChunkManager) Write(key string, content []byte) error {
 	return mcm.minio.Save(key, string(content))
 }
 
+// Exist checks whether chunk is saved to minio storage.
 func (mcm *MinioChunkManager) Exist(key string) bool {
 	return mcm.minio.Exist(key)
 }
 
+// Read reads the minio storage data if exist.
 func (mcm *MinioChunkManager) Read(key string) ([]byte, error) {
 	results, err := mcm.minio.Load(key)
 	return []byte(results), err
 }
 
+// ReadAt reads specific position data of minio storage if exist.
 func (mcm *MinioChunkManager) ReadAt(key string, p []byte, off int64) (int, error) {
 	results, err := mcm.minio.Load(key)
 	if err != nil {

internal/storage/vector_chunk_manager.go

@@ -20,6 +20,7 @@ import (
 	"github.com/milvus-io/milvus/internal/proto/etcdpb"
 )
 
+// VectorChunkManager is responsible for read and write vector data.
 type VectorChunkManager struct {
 	localChunkManager  ChunkManager
 	remoteChunkManager ChunkManager
@@ -29,6 +30,7 @@ type VectorChunkManager struct {
 	localCacheEnable bool
 }
 
+// NewVectorChunkManager create a new vector manager object.
 func NewVectorChunkManager(localChunkManager ChunkManager, remoteChunkManager ChunkManager, schema *etcdpb.CollectionMeta, localCacheEnable bool) *VectorChunkManager {
 	return &VectorChunkManager{
 		localChunkManager:  localChunkManager,
@@ -39,6 +41,9 @@ func NewVectorChunkManager(localChunkManager ChunkManager, remoteChunkManager Ch
 	}
 }
 
+// For vector data, we will download vector file from storage. And we will
+// deserialize the file for it has binlog style. At last we store pure vector
+// data to local storage as cache.
 func (vcm *VectorChunkManager) downloadVectorFile(key string) ([]byte, error) {
 	if vcm.localChunkManager.Exist(key) {
 		return vcm.localChunkManager.Read(key)
@@ -78,6 +83,8 @@ func (vcm *VectorChunkManager) downloadVectorFile(key string) ([]byte, error) {
 	return results, nil
 }
 
+// GetPath returns the path of vector data. If cached, return local path.
+// If not cached return remote path.
 func (vcm *VectorChunkManager) GetPath(key string) (string, error) {
 	if vcm.localChunkManager.Exist(key) && vcm.localCacheEnable {
 		return vcm.localChunkManager.GetPath(key)
@@ -85,6 +92,7 @@ func (vcm *VectorChunkManager) GetPath(key string) (string, error) {
 	return vcm.remoteChunkManager.GetPath(key)
 }
 
+// Write writes the vector data to local cache if cache enabled.
 func (vcm *VectorChunkManager) Write(key string, content []byte) error {
 	if !vcm.localCacheEnable {
 		return errors.New("Cannot write local file for local cache is not allowed")
@@ -92,10 +100,12 @@ func (vcm *VectorChunkManager) Write(key string, content []byte) error {
 	return vcm.localChunkManager.Write(key, content)
 }
 
+// Exist checks whether vector data is saved to local cache.
 func (vcm *VectorChunkManager) Exist(key string) bool {
 	return vcm.localChunkManager.Exist(key)
 }
 
+// Read reads the pure vector data. If cached, it reads from local.
 func (vcm *VectorChunkManager) Read(key string) ([]byte, error) {
 	if vcm.localCacheEnable {
 		if vcm.localChunkManager.Exist(key) {
@@ -114,6 +124,7 @@ func (vcm *VectorChunkManager) Read(key string) ([]byte, error) {
 	return vcm.downloadVectorFile(key)
 }
 
+// ReadAt reads specific position data of vector. If cached, it reads from local.
 func (vcm *VectorChunkManager) ReadAt(key string, p []byte, off int64) (int, error) {
 	if vcm.localCacheEnable {
 		if vcm.localChunkManager.Exist(key) {