Method Write

cmd/cql-fuse/node.go:287–337

Write writes data to 'n'. It may overwrite existing data, or grow it.

(ctx context.Context, req *fuse.WriteRequest, resp *fuse.WriteResponse)

// Write writes data to 'n'. It may overwrite existing data, or grow it.
func (n *Node) Write(ctx context.Context, req *fuse.WriteRequest, resp *fuse.WriteResponse) error {
	if !n.isRegular() {
		return fuse.Errno(syscall.EINVAL)
	}
	if req.Offset < 0 {
		return fuse.Errno(syscall.EINVAL)
	}
	if len(req.Data) == 0 {
		return nil
	}

	n.mu.Lock()
	defer n.mu.Unlock()

	newSize := uint64(req.Offset) + uint64(len(req.Data))
	if newSize > maxSize {
		return fuse.Errno(syscall.EFBIG)
	}

	// Store the current size in case we need to rollback.
	originalSize := n.Size

	// Wrap everything inside a transaction.
	err := client.ExecuteTx(ctx, n.cfs.db, nil /* txopts */, func(tx *sql.Tx) error {

		// Update blocks. They will be added as needed.
		if err := write(tx, n.ID, n.Size, uint64(req.Offset), req.Data); err != nil {
			return err
		}

		if newSize > originalSize {
			// This was an append, commit the size change.
			n.Size = newSize
			if err := updateNode(tx, n); err != nil {
				return err
			}
		}
		return nil
	})

	if err != nil {
		// Reset our size.
		log.Print(err)
		n.Size = originalSize
		return err
	}

	// We always write everything.
	resp.Size = len(req.Data)
	return nil
}

// Read reads data from 'n'.
func (n *Node) Read(ctx context.Context, req *fuse.ReadRequest, resp *fuse.ReadResponse) error {