Automatically purge old upload files.

When the registry starts a background timer will periodically
scan the upload directories on the file system every 24 hours
and delete any files older than 1 week. An initial jitter
intends to avoid contention on the filesystem where multiple
registries with the same storage driver are started
simultaneously.

docs/storage/walk_test.go

@@ -0,0 +1,119 @@
+package storage
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/docker/distribution/registry/storage/driver"
+	"github.com/docker/distribution/registry/storage/driver/inmemory"
+)
+
+func testFS(t *testing.T) (driver.StorageDriver, map[string]string) {
+	d := inmemory.New()
+	c := []byte("")
+	if err := d.PutContent("/a/b/c/d", c); err != nil {
+		t.Fatalf("Unable to put to inmemory fs")
+	}
+	if err := d.PutContent("/a/b/c/e", c); err != nil {
+		t.Fatalf("Unable to put to inmemory fs")
+	}
+
+	expected := map[string]string{
+		"/a":       "dir",
+		"/a/b":     "dir",
+		"/a/b/c":   "dir",
+		"/a/b/c/d": "file",
+		"/a/b/c/e": "file",
+	}
+
+	return d, expected
+}
+
+func TestWalkErrors(t *testing.T) {
+	d, expected := testFS(t)
+	fileCount := len(expected)
+	err := Walk(d, "", func(fileInfo driver.FileInfo) error {
+		return nil
+	})
+	if err == nil {
+		t.Error("Expected invalid root err")
+	}
+
+	err = Walk(d, "/", func(fileInfo driver.FileInfo) error {
+		// error on the 2nd file
+		if fileInfo.Path() == "/a/b" {
+			return fmt.Errorf("Early termination")
+		}
+		delete(expected, fileInfo.Path())
+		return nil
+	})
+	if len(expected) != fileCount-1 {
+		t.Error("Walk failed to terminate with error")
+	}
+	if err != nil {
+		t.Error(err.Error())
+	}
+
+	err = Walk(d, "/nonexistant", func(fileInfo driver.FileInfo) error {
+		return nil
+	})
+	if err == nil {
+		t.Errorf("Expected missing file err")
+	}
+
+}
+
+func TestWalk(t *testing.T) {
+	d, expected := testFS(t)
+	err := Walk(d, "/", func(fileInfo driver.FileInfo) error {
+		filePath := fileInfo.Path()
+		filetype, ok := expected[filePath]
+		if !ok {
+			t.Fatalf("Unexpected file in walk: %q", filePath)
+		}
+
+		if fileInfo.IsDir() {
+			if filetype != "dir" {
+				t.Errorf("Unexpected file type: %q", filePath)
+			}
+		} else {
+			if filetype != "file" {
+				t.Errorf("Unexpected file type: %q", filePath)
+			}
+		}
+		delete(expected, filePath)
+		return nil
+	})
+	if len(expected) > 0 {
+		t.Errorf("Missed files in walk: %q", expected)
+	}
+	if err != nil {
+		t.Fatalf(err.Error())
+	}
+}
+
+func TestWalkSkipDir(t *testing.T) {
+	d, expected := testFS(t)
+	err := Walk(d, "/", func(fileInfo driver.FileInfo) error {
+		filePath := fileInfo.Path()
+		if filePath == "/a/b" {
+			// skip processing /a/b/c and /a/b/c/d
+			return ErrSkipDir
+		}
+		delete(expected, filePath)
+		return nil
+	})
+	if err != nil {
+		t.Fatalf(err.Error())
+	}
+	if _, ok := expected["/a/b/c"]; !ok {
+		t.Errorf("/a/b/c not skipped")
+	}
+	if _, ok := expected["/a/b/c/d"]; !ok {
+		t.Errorf("/a/b/c/d not skipped")
+	}
+	if _, ok := expected["/a/b/c/e"]; !ok {
+		t.Errorf("/a/b/c/e not skipped")
+	}
+
+}