syncthing/lib/util/utils.go

297 lines
6.1 KiB
Go

// Copyright (C) 2016 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at https://mozilla.org/MPL/2.0/.
package util
import (
"context"
"fmt"
"net/url"
"reflect"
"strconv"
"strings"
"github.com/syncthing/syncthing/lib/sync"
"github.com/thejerf/suture"
)
type defaultParser interface {
ParseDefault(string) error
}
// SetDefaults sets default values on a struct, based on the default annotation.
func SetDefaults(data interface{}) {
s := reflect.ValueOf(data).Elem()
t := s.Type()
for i := 0; i < s.NumField(); i++ {
f := s.Field(i)
tag := t.Field(i).Tag
v := tag.Get("default")
if len(v) > 0 {
if f.CanInterface() {
if parser, ok := f.Interface().(defaultParser); ok {
if err := parser.ParseDefault(v); err != nil {
panic(err)
}
continue
}
}
if f.CanAddr() && f.Addr().CanInterface() {
if parser, ok := f.Addr().Interface().(defaultParser); ok {
if err := parser.ParseDefault(v); err != nil {
panic(err)
}
continue
}
}
switch f.Interface().(type) {
case string:
f.SetString(v)
case int:
i, err := strconv.ParseInt(v, 10, 64)
if err != nil {
panic(err)
}
f.SetInt(i)
case float64:
i, err := strconv.ParseFloat(v, 64)
if err != nil {
panic(err)
}
f.SetFloat(i)
case bool:
f.SetBool(v == "true")
case []string:
// We don't do anything with string slices here. Any default
// we set will be appended to by the XML decoder, so we fill
// those after decoding.
default:
panic(f.Type())
}
}
}
}
// CopyMatchingTag copies fields tagged tag:"value" from "from" struct onto "to" struct.
func CopyMatchingTag(from interface{}, to interface{}, tag string, shouldCopy func(value string) bool) {
fromStruct := reflect.ValueOf(from).Elem()
fromType := fromStruct.Type()
toStruct := reflect.ValueOf(to).Elem()
toType := toStruct.Type()
if fromType != toType {
panic(fmt.Sprintf("non equal types: %s != %s", fromType, toType))
}
for i := 0; i < toStruct.NumField(); i++ {
fromField := fromStruct.Field(i)
toField := toStruct.Field(i)
if !toField.CanSet() {
// Unexported fields
continue
}
structTag := toType.Field(i).Tag
v := structTag.Get(tag)
if shouldCopy(v) {
toField.Set(fromField)
}
}
}
// UniqueTrimmedStrings returns a list on unique strings, trimming at the same time.
func UniqueTrimmedStrings(ss []string) []string {
// Trim all first
for i, v := range ss {
ss[i] = strings.Trim(v, " ")
}
var m = make(map[string]struct{}, len(ss))
var us = make([]string, 0, len(ss))
for _, v := range ss {
if _, ok := m[v]; ok {
continue
}
m[v] = struct{}{}
us = append(us, v)
}
return us
}
// FillNilSlices sets default value on slices that are still nil.
func FillNilSlices(data interface{}) error {
s := reflect.ValueOf(data).Elem()
t := s.Type()
for i := 0; i < s.NumField(); i++ {
f := s.Field(i)
tag := t.Field(i).Tag
v := tag.Get("default")
if len(v) > 0 {
switch f.Interface().(type) {
case []string:
if f.IsNil() {
// Treat the default as a comma separated slice
vs := strings.Split(v, ",")
for i := range vs {
vs[i] = strings.TrimSpace(vs[i])
}
rv := reflect.MakeSlice(reflect.TypeOf([]string{}), len(vs), len(vs))
for i, v := range vs {
rv.Index(i).SetString(v)
}
f.Set(rv)
}
}
}
}
return nil
}
// Address constructs a URL from the given network and hostname.
func Address(network, host string) string {
u := url.URL{
Scheme: network,
Host: host,
}
return u.String()
}
// AsService wraps the given function to implement suture.Service by calling
// that function on serve and closing the passed channel when Stop is called.
func AsService(fn func(ctx context.Context), creator string) suture.Service {
return asServiceWithError(func(ctx context.Context) error {
fn(ctx)
return nil
}, creator)
}
type ServiceWithError interface {
suture.Service
fmt.Stringer
Error() error
SetError(error)
}
// AsServiceWithError does the same as AsService, except that it keeps track
// of an error returned by the given function.
func AsServiceWithError(fn func(ctx context.Context) error, creator string) ServiceWithError {
return asServiceWithError(fn, creator)
}
func asServiceWithError(fn func(ctx context.Context) error, creator string) ServiceWithError {
ctx, cancel := context.WithCancel(context.Background())
s := &service{
serve: fn,
ctx: ctx,
cancel: cancel,
stopped: make(chan struct{}),
creator: creator,
mut: sync.NewMutex(),
}
close(s.stopped) // not yet started, don't block on Stop()
return s
}
type service struct {
creator string
serve func(ctx context.Context) error
ctx context.Context
cancel context.CancelFunc
stopped chan struct{}
err error
mut sync.Mutex
}
func (s *service) Serve() {
s.mut.Lock()
select {
case <-s.ctx.Done():
s.mut.Unlock()
return
default:
}
s.err = nil
s.stopped = make(chan struct{})
s.mut.Unlock()
var err error
defer func() {
if err == context.Canceled {
err = nil
}
s.mut.Lock()
s.err = err
close(s.stopped)
s.mut.Unlock()
}()
err = s.serve(s.ctx)
}
func (s *service) Stop() {
s.mut.Lock()
select {
case <-s.ctx.Done():
s.mut.Unlock()
panic(fmt.Sprintf("Stop called more than once on %v", s))
default:
s.cancel()
}
// Cache s.stopped in a variable while we hold the mutex
// to prevent a data race with Serve's resetting it.
stopped := s.stopped
s.mut.Unlock()
<-stopped
}
func (s *service) Error() error {
s.mut.Lock()
defer s.mut.Unlock()
return s.err
}
func (s *service) SetError(err error) {
s.mut.Lock()
s.err = err
s.mut.Unlock()
}
func (s *service) String() string {
return fmt.Sprintf("Service@%p created by %v", s, s.creator)
}
func CallWithContext(ctx context.Context, fn func() error) error {
var err error
done := make(chan struct{})
go func() {
err = fn()
close(done)
}()
select {
case <-done:
return err
case <-ctx.Done():
return ctx.Err()
}
}