Exemplo n.º 1
0
func (self *CatFile) appendToLastBlock(b []byte, offset int64) (int, error) {
	blockOff := self.blockNumber() - 1 // index of the last block
	err := self.getBlock(blockOff)
	if err == ErrNoBlocks {
		return 0, nil
	}
	if err != nil {
		return 0, err
	}
	if len(self.curBlockContent) == int(config.BlockSize()) {
		// if the last block is full
		// nothing to write
		return 0, nil
	}
	if offset > int64(len(self.curBlockContent)) {
		offset = int64(len(self.curBlockContent))
	}
	blockRemain := int(config.BlockSize() - offset)
	self.curChanged = true
	if blockRemain >= len(b) {
		self.curBlockContent = append(self.curBlockContent[:offset], b...)
		return len(b), nil
	}
	self.curBlockContent = append(self.curBlockContent[:offset], b[:blockRemain]...)
	return blockRemain, nil
}
Exemplo n.º 2
0
func (self *CatFile) getBlock(blockOff int64) error {
	// if current block offset is the one we want to get
	if self.curBlockOff == blockOff {
		return nil
	}
	err := self.Sync()
	if err != nil {
		return err
	}
	master := self.pool.MasterServer()
	blockquery := &proc.BlockQueryParam{
		Path:   self.path,
		Offset: config.BlockSize() * blockOff,
		Length: config.BlockSize(),
		Lease:  self.lease,
	}
	// get block meta data
	var resp proc.GetBlocksLocationResponse
	err = master.GetBlockLocation(blockquery, &resp)
	if err != nil {
		return err
	}
	if len(resp.Blocks) == 0 {
		self.curBlock = nil
		return ErrNoBlocks
	}

	// contact data server
	location := resp.Blocks[0].Locations[0]
	dataServer := self.pool.DataServer(location)
	var lease proc.CatLease
	param := &proc.GetBlockParam{
		Block: resp.Blocks[0],
	}
	err = dataServer.GetBlock(param, &lease)
	if err != nil {
		return err
	}
	// get data
	blockClient := self.pool.NewBlockClient(location)
	ch := make(chan []byte)
	go blockClient.GetBlock(ch, lease.ID)
	var blockContent []byte
	for data := range ch {
		blockContent = append(blockContent, data...)
	}
	// set EOF and curBlock info
	self.isEOF = resp.EOF
	self.curBlock = resp.Blocks[0]
	self.curBlockContent = blockContent
	self.curBlockOff = blockOff
	return nil
}
Exemplo n.º 3
0
func (self *CatDFSFile) Status() *proc.CatFileStatus {
	status := &proc.CatFileStatus{
		Filename: self.filename,
		Length:   int64(len(self.blocks)) * config.BlockSize(),
		IsDir:    false,
	}
	return status
}
Exemplo n.º 4
0
// WriteAt writes len(b) bytes to the File starting at byte offset off. It
// returns the number of bytes written and an error, if any. WriteAt returns a
// non-nil error when n != len(b).
func (self *CatFile) WriteAt(b []byte, off int64) (int, error) {
	self.lock.Lock()
	defer self.lock.Unlock()

	dataWrite := 0
	// blockOffset of off
	blockOff := off / config.BlockSize()
	// ceiling of length / blocksize
	fileBlockNumber := self.blockNumber()
	offset := off % config.BlockSize()

	for {
		// if it is the last block or more
		if blockOff >= fileBlockNumber-1 {
			offset += (blockOff - fileBlockNumber + 1) * config.BlockSize()
			n, err := self.appendToLastBlock(b, offset)
			dataWrite += n
			// read enough or there is an err
			if err != nil || dataWrite == len(b) {
				return dataWrite, err
			}
			n, err = self.appendBlock(b[dataWrite:])
			return n + dataWrite, err
		}
		// get the block of blockOff
		err := self.getBlock(blockOff)
		if err != nil {
			return dataWrite, err
		}
		// this should work, because the size of curBlockContent should be the block size
		n := copy(self.curBlockContent[offset:], b[dataWrite:])
		dataWrite += n
		// set current has changed
		self.curChanged = true
		if dataWrite == len(b) {
			offset = int64(n)
			break
		}
		offset = 0
		blockOff++
		self.Sync()
		self.setFileOffset(blockOff, offset)
	}
	self.setFileOffset(blockOff, offset)
	return dataWrite, nil
}
Exemplo n.º 5
0
func (self *CatDFSFile) QueryBlocks(offset int64, length int64) (BlockList, bool) {
	blockSize := config.BlockSize()
	startBlockOff := offset / blockSize
	endBlockOff := (offset+length-1)/blockSize + 1 // not include
	eof := false
	if endBlockOff >= int64(len(self.blocks)) {
		endBlockOff = int64(len(self.blocks))
		eof = true
	}
	return self.blocks[startBlockOff:endBlockOff], eof
}
Exemplo n.º 6
0
// ReadAt reads len(b) bytes from the File starting at byte offset off. It
// returns the number of bytes read and the error, if any. ReadAt always returns
// a non-nil error when n < len(b). At end of file, that error is io.EOF.
func (self *CatFile) ReadAt(b []byte, off int64) (int, error) {
	self.lock.Lock()
	defer self.lock.Unlock()
	// blockOffset of off
	blockOff := off / config.BlockSize()
	err := self.getBlock(blockOff)
	if err != nil {
		return 0, err
	}

	// offset of off in a block
	offset := off % config.BlockSize()
	dataRead := 0
	for {
		n := copy(b[dataRead:], self.curBlockContent[self.offset():])
		dataRead += n
		// if read enough data
		if dataRead == len(b) {
			offset = int64(n)
			break
		}
		// if it is the end of file
		if self.isEOF {
			self.setFileOffset(blockOff, int64(len(self.curBlockContent)))
			return dataRead, io.EOF
		}
		// rest offset and blockOff
		offset = 0
		blockOff++
		// get next block
		err := self.getBlock(blockOff)
		if err != nil {
			return 0, err
		}
	}
	// set offset of the file
	self.setFileOffset(blockOff, offset)
	return dataRead, nil
}
Exemplo n.º 7
0
func (self *CatFile) appendBlock(b []byte) (int, error) {
	dataWrite := 0
	n := 0
	blockOff := self.blockNumber() - 1 // index of the last block
	master := self.pool.MasterServer()
	for dataWrite < len(b) {
		err := self.Sync()
		if err != nil && dataWrite == 0 {
			return dataWrite, err
		}
		if err != nil {
			// && dataWrite != 0
			// write new block failed
			// TODO abandom block ?
			return dataWrite, err
		}
		blockContent := make([]byte, config.BlockSize())
		n = copy(blockContent, b[dataWrite:])
		dataWrite += n
		blockContent = blockContent[:n]
		blockOff++ // add block offset by 1

		param := &proc.AddBlockParam{
			Path:  self.path,
			Lease: self.lease,
		}
		var block proc.CatBlock
		err = master.AddBlock(param, &block)
		if err != nil {
			return dataWrite, err
		}
		self.curBlock = &block
		self.curBlockContent = blockContent
		self.curChanged = true
	}
	self.setFileOffset(blockOff, int64(len(self.curBlockContent)))
	return n, nil
}
Exemplo n.º 8
0
func (self *CatFile) blockNumber() int64 {
	return (self.filestatus.Length-1)/config.BlockSize() + 1
}
Exemplo n.º 9
0
func (self *CatFile) setFileOffset(blockOff, offset int64) {
	self.fileOffset = blockOff*config.BlockSize() + offset
}
Exemplo n.º 10
0
func (self *CatFile) blockOffset() int64 {
	return self.fileOffset / config.BlockSize()
}