Files
mgmt/resources/refresh.go
2017-02-16 01:34:32 -05:00

105 lines
3.4 KiB
Go

// Mgmt
// Copyright (C) 2013-2017+ James Shubin and the project contributors
// Written by James Shubin <james@shubin.ca> and the project contributors
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package resources
import (
"fmt"
"io/ioutil"
"os"
"strings"
errwrap "github.com/pkg/errors"
)
// Refresh returns the pending state of a notification. It should only be called
// in the CheckApply portion of a resource where a refresh should be acted upon.
func (obj *BaseRes) Refresh() bool {
return obj.refresh
}
// SetRefresh sets the pending state of a notification. It should only be called
// by the mgmt engine.
func (obj *BaseRes) SetRefresh(b bool) {
obj.refresh = b
}
// StatefulBool is an interface for storing a boolean flag in a permanent spot.
type StatefulBool interface {
Get() (bool, error) // get value of token
Set() error // set token to true
Del() error // rm token if it exists
}
// DiskBool stores a boolean variable on disk for stateful access across runs.
// The absence of the path is treated as false. If the path contains a special
// value, then it is treated as true. All the other non-error cases are false.
type DiskBool struct {
Path string // path to token
}
// str returns the string data which represents true (aka set).
func (obj *DiskBool) str() string {
const TrueToken = "true"
const newline = "\n"
return TrueToken + newline
}
// Get returns if the boolean setting, if no error reading the value occurs.
func (obj *DiskBool) Get() (bool, error) {
file, err := os.Open(obj.Path) // open a handle to read the file
if err != nil {
if os.IsNotExist(err) {
return false, nil // no token means value is false
}
return false, errwrap.Wrapf(err, "could not read token")
}
defer file.Close()
data, err := ioutil.ReadAll(file)
if err != nil {
return false, errwrap.Wrapf(err, "could not read from file")
}
return strings.TrimSpace(string(data)) == strings.TrimSpace(obj.str()), nil
}
// Set stores the true boolean value, if no error setting the value occurs.
func (obj *DiskBool) Set() error {
file, err := os.Create(obj.Path) // open a handle to create the file
if err != nil {
return errwrap.Wrapf(err, "can't create file")
}
defer file.Close()
str := obj.str()
if c, err := file.Write([]byte(str)); err != nil {
return errwrap.Wrapf(err, "error writing to file")
} else if l := len(str); c != l {
return fmt.Errorf("wrote %d bytes instead of %d", c, l)
}
return file.Sync() // guarantee it!
}
// Del stores the false boolean value, if no error clearing the value occurs.
func (obj *DiskBool) Del() error {
if err := os.Remove(obj.Path); err != nil { // remove the file
if os.IsNotExist(err) {
return nil // no file means this is already fine
}
return errwrap.Wrapf(err, "could not delete token")
}
return nil
}