file_handler.go

/*
Copyright 2018 Sourabh Bollapragada

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package ifs

import (
	"bazil.org/fuse"
	"github.com/orcaman/concurrent-map"
	"go.uber.org/zap"
	"os"
	"path"
	"strconv"
	"sync"
	"sync/atomic"
)

var (
	fh   *fileHandler
	once sync.Once
)

type fileHandler struct {
	FileDescriptor uint64
	Opened         cmap.ConcurrentMap
}

func FileHandler() *fileHandler {
	once.Do(func() {
		fh = &fileHandler{
			FileDescriptor: 0,
			Opened:         cmap.New(),
		}
	})

	return fh
}

func (fh *fileHandler) StartUp() {
	zap.L().Info("Starting File Handler")
}

func (fh *fileHandler) OpenFile(remotePath *RemotePath, flags fuse.OpenFlags, isDir bool) (uint64, error) {

	fd := atomic.AddUint64(&fh.FileDescriptor, 1)

	openInfo := &OpenInfo{
		FileDescriptor: fd,
		Path:           remotePath.Path,
		Flags:          flags,
	}

	if !isDir {
		go Hoarder().CacheOpen(remotePath, fd, flags)
	}

	resp := Talker().sendRequest(OpenRequest, remotePath.Hostname, openInfo)

	if err, ok := resp.Data.(Error); ok {
		return 0, err.Err
	}

	fh.Opened.Set(strconv.FormatUint(fd, 10), openInfo)

	return fd, nil
}

// TODO Skip Cache if io op fails
func (fh *fileHandler) ReadData(handle *FileHandle, offset int64, size int) ([]byte, error) {

	if _, ok := fh.Opened.Get(strconv.FormatUint(handle.FileDescriptor, 10)); ok {

		data, err := Hoarder().ReadCache(handle.FileDescriptor, offset, size)

		// If Read from Cache Failed then get from remote
		if err != nil {
			// Should Ask Agent for bytes
			fileReadInfo := &ReadInfo{
				Path:           handle.RemoteNode.RemotePath.Path,
				FileDescriptor: handle.FileDescriptor,
				Offset:         offset,
				Size:           size,
			}

			resp := Talker().sendRequest(ReadFileRequest, handle.RemoteNode.RemotePath.Hostname, fileReadInfo)

			if err, ok := resp.Data.(Error); ok {
				return nil, err.Err
			} else {
				// TODO If EOF is returned in Read then for some reason decompress is happening and failing
				fileChunk := resp.Data.(*FileChunk)
				//fileChunk.Decompress()
				return fileChunk.Chunk, nil
			}

		} else {
			return data, err
		}
	}

	return nil, os.ErrInvalid
}

func (fh *fileHandler) WriteData(handle *FileHandle, data []byte, offset int64) (int, error) {

	if _, ok := fh.Opened.Get(strconv.FormatUint(handle.FileDescriptor, 10)); ok {

		// Send Bytes to Agent
		writeInfo := &WriteInfo{
			Path:           handle.RemoteNode.RemotePath.Path,
			FileDescriptor: handle.FileDescriptor,
			Offset:         offset,
			Data:           data,
		}
		resp := Talker().sendRequest(WriteFileRequest, handle.RemoteNode.RemotePath.Hostname, writeInfo)
		if err, ok := resp.Data.(Error); ok {
			return 0, err.Err
		}

		writeResult := resp.Data.(*WriteResult)

		_, err := Hoarder().WriteCache(handle.FileDescriptor, offset, data)

		if err != nil {
			zap.L().Warn("Write Cache Failed",
				zap.Error(err),
			)
		}

		handle.RemoteNode.Size = uint64(writeResult.FileSize)

		return writeResult.Size, nil
	}

	return 0, os.ErrNotExist
}

func (fh *fileHandler) Truncate(remotePath *RemotePath, attrInfo *AttrInfo) error {

	resp := Talker().sendRequest(SetAttrRequest, remotePath.Hostname, attrInfo)

	if err, ok := resp.Data.(Error); ok {
		return err.Err
	}

	Hoarder().CacheTrunc(remotePath, attrInfo)

	return nil
}

func (fh *fileHandler) Release(handle *FileHandle) error {
	if _, ok := fh.Opened.Get(strconv.FormatUint(handle.FileDescriptor, 10)); ok {

		closeInfo := &CloseInfo{
			FileDescriptor: handle.FileDescriptor,
			Path:           handle.RemoteNode.RemotePath.Path,
		}

		resp := Talker().sendRequest(CloseRequest, handle.RemoteNode.RemotePath.Hostname, closeInfo)

		if err, ok := resp.Data.(Error); ok {
			return err.Err
		}

		if !handle.RemoteNode.IsDir {

			err := Hoarder().CacheClose(handle.FileDescriptor)

			if err != nil {
				zap.L().Warn("Cache Close Failed",
					zap.Error(err),
				)
			}

		}

		fh.Opened.Remove(strconv.FormatUint(handle.FileDescriptor, 10))

		return nil
	}

	return os.ErrNotExist
}

func (fh *fileHandler) Create(remotePath *RemotePath, name string) (uint64, error) {

	fd := atomic.AddUint64(&fh.FileDescriptor, 1)

	req := &CreateInfo{
		BaseDir:        remotePath.Path,
		Name:           name,
		IsDir:          false,
		FileDescriptor: fd,
	}

	resp := Talker().sendRequest(CreateRequest, remotePath.Hostname, req)

	if err, ok := resp.Data.(Error); ok {
		return 0, err.Err
	}

	newRemotePath := &RemotePath{
		Hostname: remotePath.Hostname,
		Port:     remotePath.Port,
		Path:     path.Join(remotePath.Path, name),
	}

	err := Hoarder().CacheCreate(newRemotePath, fd)

	if err != nil {
		zap.L().Warn("Cache Create Failed",
			zap.Error(err),
		)
	}

	fh.Opened.Set(strconv.FormatUint(fd, 10), req)

	return fd, nil
}

func (fh *fileHandler) Mkdir(remotePath *RemotePath, name string) error {
	req := &CreateInfo{
		BaseDir: remotePath.Path,
		Name:    name,
		IsDir:   true,
	}

	resp := Talker().sendRequest(CreateRequest, remotePath.Hostname, req)

	if err, ok := resp.Data.(Error); ok {
		return err.Err
	}

	return nil
}

func (fh *fileHandler) Remove(remotePath *RemotePath, name string, isDir bool) error {

	newRemotePath := &RemotePath{
		Hostname: remotePath.Hostname,
		Port:     remotePath.Port,
		Path:     path.Join(remotePath.Path, name),
	}

	resp := Talker().sendRequest(RemoveRequest, remotePath.Hostname, newRemotePath)

	if err, ok := resp.Data.(Error); ok {
		return err.Err
	}

	if !isDir {
		err := Hoarder().CacheDelete(remotePath)

		if err != nil {
			zap.L().Warn("Cache Remove Failed",
				zap.Error(err),
			)
		}
	}

	return nil
}
func (fh *fileHandler) Rename(remotePath *RemotePath, destPath string) error {

	req := &RenameInfo{
		Path:     remotePath.Path,
		DestPath: destPath,
	}

	resp := Talker().sendRequest(RenameRequest, remotePath.Hostname, req)

	if err, ok := resp.Data.(Error); ok {
		return err.Err
	}

	err := Hoarder().CacheRename(remotePath, destPath)

	if err != nil {
		zap.L().Warn("Cache Rename Failed",
			zap.Error(err),
		)
	}

	return nil
}

//func (fh *fileHandler) Flush(handle *FileHandle) error {
//	req := &FlushInfo{
//		RemotePath: handle.RemoteNode.RemotePath,
//		FileDescriptor: handle.FileDescriptor,
//	}
//
//	resp := fh.Ifs.Talker.sendRequest(FlushRequest, req)
//
//	if err, ok := resp.Data.(Error); ok {
//		return err.Err
//	}
//
//	fh.Ifs.Hoarder.CacheFlush(handle.FileDescriptor)
//
//	return nil
//}