Refactor how data dir is initialized

1 files changed, 74 insertions, 0 deletions

diff --git a/srv/src/cfg/data_dir.go b/srv/src/cfg/data_dir.go
new file mode 100644
index 0000000..649bc15
--- /dev/null
+++ b/srv/src/cfg/data_dir.go
@@ -0,0 +1,74 @@
+package cfg
+
+import (
+	"context"
+	"fmt"
+	"os"
+
+	"github.com/mediocregopher/mediocre-go-lib/v2/mctx"
+)
+
+// DataDir manages the blog's data directory.
+type DataDir struct {
+	Path string
+
+	deleteOnClose bool
+}
+
+// Init initializes the data directory, creating the directory named at path if
+// it doesn't exist.
+//
+// If Path is not set, then a temporary directory will be created and its path
+// set to the Path field. This directory will be removed when Close is called.
+func (d *DataDir) Init() error {
+	if d.Path == "" {
+
+		d.deleteOnClose = true
+		var err error
+
+		if d.Path, err = os.MkdirTemp("", "mediocre-blog-data-*"); err != nil {
+			return fmt.Errorf("creating temporary directory: %w", err)
+		}
+
+		return nil
+	}
+
+	if err := os.MkdirAll(d.Path, 0700); err != nil {
+		return fmt.Errorf(
+			"creating directory (and parents) of %q: %w",
+			d.Path,
+			err,
+		)
+	}
+
+	return nil
+}
+
+// SetupCfg implement the cfg.Cfger interface.
+func (d *DataDir) SetupCfg(cfg *Cfg) {
+
+	cfg.StringVar(&d.Path, "data-dir", "", "Directory to use for persistent storage. If unset a temp directory will be created, and will be deleted when the process exits.")
+
+	cfg.OnInit(func(ctx context.Context) error {
+		return d.Init()
+	})
+}
+
+// Annotate implements mctx.Annotator interface.
+func (d *DataDir) Annotate(a mctx.Annotations) {
+	a["dataDirPath"] = d.Path
+}
+
+// Close cleans up any temporary state created by DataDir.
+func (d *DataDir) Close() error {
+
+	if !d.deleteOnClose {
+		return nil
+	}
+
+	if err := os.RemoveAll(d.Path); err != nil {
+		return fmt.Errorf("removing temp dir %q: %w", d.Path, err)
+	}
+
+	return nil
+}