cost-model/pkg/storage/storage.go

package storage

import (
	"os"
	"time"
)

// DoesNotExistError is used as a generic error to return when a target path does not
// exist in storage. Equivalent to os.ErrorNotExist such that it will work with os.IsNotExist(err)
var DoesNotExistError = os.ErrNotExist

// StorageInfo is a data object containing basic information about the path in storage.
type StorageInfo struct {
	Name    string    // base name of the file
	Size    int64     // length in bytes for regular files
	ModTime time.Time // modification time
}

// Storage provides an API for storing binary data
type Storage interface {
	// FullPath returns the storage working path combined with the path provided
	FullPath(path string) string

	// Stat returns the StorageStats for the specific path.
	Stat(path string) (*StorageInfo, error)

	// Read uses the relative path of the storage combined with the provided path to
	// read the contents.
	Read(path string) ([]byte, error)

	// Write uses the relative path of the storage combined with the provided path
	// to write a new file or overwrite an existing file.
	Write(path string, data []byte) error

	// Remove uses the relative path of the storage combined with the provided path to
	// remove a file from storage permanently.
	Remove(path string) error

	// Exists uses the relative path of the storage combined with the provided path to
	// determine if the file exists.
	Exists(path string) (bool, error)

	// List uses the relative path of the storage combined with the provided path to return
	// storage information for the files.
	List(path string) ([]*StorageInfo, error)
}

// IsNotExist returns true if the error provided from a storage object is DoesNotExist
func IsNotExist(err error) bool {
	if err == nil {
		return false
	}

	return err.Error() == DoesNotExistError.Error()
}