fn build()

in core/src/services/fs/backend.rs [81:189]
88 lines of code
6 McCabe index (conditional complexity)

    fn build(self) -> Result<impl Access> {
        debug!("backend build started: {:?}", &self);

        let root = match self.config.root.map(PathBuf::from) {
            Some(root) => Ok(root),
            None => Err(Error::new(
                ErrorKind::ConfigInvalid,
                "root is not specified",
            )),
        }?;
        debug!("backend use root {}", root.to_string_lossy());

        // If root dir is not exist, we must create it.
        if let Err(e) = std::fs::metadata(&root) {
            if e.kind() == std::io::ErrorKind::NotFound {
                std::fs::create_dir_all(&root).map_err(|e| {
                    Error::new(ErrorKind::Unexpected, "create root dir failed")
                        .with_operation("Builder::build")
                        .with_context("root", root.to_string_lossy())
                        .set_source(e)
                })?;
            }
        }

        let atomic_write_dir = self.config.atomic_write_dir.map(PathBuf::from);

        // If atomic write dir is not exist, we must create it.
        if let Some(d) = &atomic_write_dir {
            if let Err(e) = std::fs::metadata(d) {
                if e.kind() == std::io::ErrorKind::NotFound {
                    std::fs::create_dir_all(d).map_err(|e| {
                        Error::new(ErrorKind::Unexpected, "create atomic write dir failed")
                            .with_operation("Builder::build")
                            .with_context("atomic_write_dir", d.to_string_lossy())
                            .set_source(e)
                    })?;
                }
            }
        }

        // Canonicalize the root directory. This should work since we already know that we can
        // get the metadata of the path.
        let root = root.canonicalize().map_err(|e| {
            Error::new(
                ErrorKind::Unexpected,
                "canonicalize of root directory failed",
            )
            .with_operation("Builder::build")
            .with_context("root", root.to_string_lossy())
            .set_source(e)
        })?;

        // Canonicalize the atomic_write_dir directory. This should work since we already know that
        // we can get the metadata of the path.
        let atomic_write_dir = atomic_write_dir
            .map(|p| {
                p.canonicalize().map(Some).map_err(|e| {
                    Error::new(
                        ErrorKind::Unexpected,
                        "canonicalize of atomic_write_dir directory failed",
                    )
                    .with_operation("Builder::build")
                    .with_context("root", root.to_string_lossy())
                    .set_source(e)
                })
            })
            .unwrap_or(Ok(None))?;

        Ok(FsBackend {
            core: Arc::new(FsCore {
                info: {
                    let am = AccessorInfo::default();
                    am.set_scheme(Scheme::Fs)
                        .set_root(&root.to_string_lossy())
                        .set_native_capability(Capability {
                            stat: true,
                            stat_has_content_length: true,
                            stat_has_last_modified: true,

                            read: true,

                            write: true,
                            write_can_empty: true,
                            write_can_append: true,
                            write_can_multi: true,
                            write_with_if_not_exists: true,

                            create_dir: true,
                            delete: true,

                            list: true,

                            copy: true,
                            rename: true,
                            blocking: true,

                            shared: true,

                            ..Default::default()
                        });

                    am.into()
                },
                root,
                atomic_write_dir,
                buf_pool: oio::PooledBuf::new(16).with_initial_capacity(256 * 1024),
            }),
        })
    }