micro/config/loader/memory/memory.go

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package memory
import (
"bytes"
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"container/list"
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"errors"
"fmt"
"strings"
"sync"
"time"
"github.com/micro/go-micro/v3/config/loader"
"github.com/micro/go-micro/v3/config/reader"
"github.com/micro/go-micro/v3/config/reader/json"
"github.com/micro/go-micro/v3/config/source"
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)
type memory struct {
exit chan bool
opts loader.Options
sync.RWMutex
// the current snapshot
snap *loader.Snapshot
// the current values
vals reader.Values
// all the sets
sets []*source.ChangeSet
// all the sources
sources []source.Source
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watchers *list.List
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}
type updateValue struct {
version string
value reader.Value
}
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type watcher struct {
exit chan bool
path []string
value reader.Value
reader reader.Reader
version string
updates chan updateValue
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}
func (m *memory) watch(idx int, s source.Source) {
// watches a source for changes
watch := func(idx int, s source.Watcher) error {
for {
// get changeset
cs, err := s.Next()
if err != nil {
return err
}
m.Lock()
// save
m.sets[idx] = cs
// merge sets
set, err := m.opts.Reader.Merge(m.sets...)
if err != nil {
m.Unlock()
return err
}
// set values
m.vals, _ = m.opts.Reader.Values(set)
m.snap = &loader.Snapshot{
ChangeSet: set,
Version: genVer(),
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}
m.Unlock()
// send watch updates
m.update()
}
}
for {
// watch the source
w, err := s.Watch()
if err != nil {
time.Sleep(time.Second)
continue
}
done := make(chan bool)
// the stop watch func
go func() {
select {
case <-done:
case <-m.exit:
}
w.Stop()
}()
// block watch
if err := watch(idx, w); err != nil {
// do something better
time.Sleep(time.Second)
}
// close done chan
close(done)
// if the config is closed exit
select {
case <-m.exit:
return
default:
}
}
}
func (m *memory) loaded() bool {
var loaded bool
m.RLock()
if m.vals != nil {
loaded = true
}
m.RUnlock()
return loaded
}
// reload reads the sets and creates new values
func (m *memory) reload() error {
m.Lock()
// merge sets
set, err := m.opts.Reader.Merge(m.sets...)
if err != nil {
m.Unlock()
return err
}
// set values
m.vals, _ = m.opts.Reader.Values(set)
m.snap = &loader.Snapshot{
ChangeSet: set,
Version: genVer(),
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}
m.Unlock()
// update watchers
m.update()
return nil
}
func (m *memory) update() {
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watchers := make([]*watcher, 0, m.watchers.Len())
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m.RLock()
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for e := m.watchers.Front(); e != nil; e = e.Next() {
watchers = append(watchers, e.Value.(*watcher))
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}
vals := m.vals
snap := m.snap
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m.RUnlock()
for _, w := range watchers {
if w.version >= snap.Version {
continue
}
uv := updateValue{
version: m.snap.Version,
value: vals.Get(w.path...),
}
select {
case <-w.exit:
continue
default:
}
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select {
case w.updates <- uv:
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default:
}
}
}
// Snapshot returns a snapshot of the current loaded config
func (m *memory) Snapshot() (*loader.Snapshot, error) {
if m.loaded() {
m.RLock()
snap := loader.Copy(m.snap)
m.RUnlock()
return snap, nil
}
// not loaded, sync
if err := m.Sync(); err != nil {
return nil, err
}
// make copy
m.RLock()
snap := loader.Copy(m.snap)
m.RUnlock()
return snap, nil
}
// Sync loads all the sources, calls the parser and updates the config
func (m *memory) Sync() error {
//nolint:prealloc
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var sets []*source.ChangeSet
m.Lock()
// read the source
var gerr []string
for _, source := range m.sources {
ch, err := source.Read()
if err != nil {
gerr = append(gerr, err.Error())
continue
}
sets = append(sets, ch)
}
// merge sets
set, err := m.opts.Reader.Merge(sets...)
if err != nil {
m.Unlock()
return err
}
// set values
vals, err := m.opts.Reader.Values(set)
if err != nil {
m.Unlock()
return err
}
m.vals = vals
m.snap = &loader.Snapshot{
ChangeSet: set,
Version: genVer(),
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}
m.Unlock()
// update watchers
m.update()
if len(gerr) > 0 {
return fmt.Errorf("source loading errors: %s", strings.Join(gerr, "\n"))
}
return nil
}
func (m *memory) Close() error {
select {
case <-m.exit:
return nil
default:
close(m.exit)
}
return nil
}
func (m *memory) Get(path ...string) (reader.Value, error) {
if !m.loaded() {
if err := m.Sync(); err != nil {
return nil, err
}
}
m.Lock()
defer m.Unlock()
// did sync actually work?
if m.vals != nil {
return m.vals.Get(path...), nil
}
// assuming vals is nil
// create new vals
ch := m.snap.ChangeSet
// we are truly screwed, trying to load in a hacked way
v, err := m.opts.Reader.Values(ch)
if err != nil {
return nil, err
}
// lets set it just because
m.vals = v
if m.vals != nil {
return m.vals.Get(path...), nil
}
// ok we're going hardcore now
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return nil, errors.New("no values")
}
func (m *memory) Load(sources ...source.Source) error {
var gerrors []string
for _, source := range sources {
set, err := source.Read()
if err != nil {
gerrors = append(gerrors,
fmt.Sprintf("error loading source %s: %v",
source,
err))
// continue processing
continue
}
m.Lock()
m.sources = append(m.sources, source)
m.sets = append(m.sets, set)
idx := len(m.sets) - 1
m.Unlock()
go m.watch(idx, source)
}
if err := m.reload(); err != nil {
gerrors = append(gerrors, err.Error())
}
// Return errors
if len(gerrors) != 0 {
return errors.New(strings.Join(gerrors, "\n"))
}
return nil
}
func (m *memory) Watch(path ...string) (loader.Watcher, error) {
value, err := m.Get(path...)
if err != nil {
return nil, err
}
m.Lock()
w := &watcher{
exit: make(chan bool),
path: path,
value: value,
reader: m.opts.Reader,
updates: make(chan updateValue, 1),
version: m.snap.Version,
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}
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e := m.watchers.PushBack(w)
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m.Unlock()
go func() {
<-w.exit
m.Lock()
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m.watchers.Remove(e)
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m.Unlock()
}()
return w, nil
}
func (m *memory) String() string {
return "memory"
}
func (w *watcher) Next() (*loader.Snapshot, error) {
update := func(v reader.Value) *loader.Snapshot {
w.value = v
cs := &source.ChangeSet{
Data: v.Bytes(),
Format: w.reader.String(),
Source: "memory",
Timestamp: time.Now(),
}
cs.Checksum = cs.Sum()
return &loader.Snapshot{
ChangeSet: cs,
Version: w.version,
}
}
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for {
select {
case <-w.exit:
return nil, errors.New("watcher stopped")
case uv := <-w.updates:
if uv.version <= w.version {
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continue
}
v := uv.value
w.version = uv.version
if bytes.Equal(w.value.Bytes(), v.Bytes()) {
continue
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}
return update(v), nil
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}
}
}
func (w *watcher) Stop() error {
select {
case <-w.exit:
default:
close(w.exit)
close(w.updates)
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}
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return nil
}
func genVer() string {
return fmt.Sprintf("%d", time.Now().UnixNano())
}
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func NewLoader(opts ...loader.Option) loader.Loader {
options := loader.Options{
Reader: json.NewReader(),
}
for _, o := range opts {
o(&options)
}
m := &memory{
exit: make(chan bool),
opts: options,
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watchers: list.New(),
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sources: options.Source,
}
m.sets = make([]*source.ChangeSet, len(options.Source))
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for i, s := range options.Source {
m.sets[i] = &source.ChangeSet{Source: s.String()}
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go m.watch(i, s)
}
return m
}