c21a0ca39f
Currently all registry implementations live in a single package, which makes it bit harder to maintain. The different registry implementations do not follow the same coding style and naming conventions, which makes the code harder to read. Breakup the registry package into smaller packages based on the registry implementation. Refactor the registry packages to follow a similar coding style and naming convention. This patch does not introduce any changes in behavior.
118 lines
2.6 KiB
Go
118 lines
2.6 KiB
Go
/*
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Copyright 2014 Google Inc. All rights reserved.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package minion
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import (
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"sync"
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"sync/atomic"
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"time"
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)
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type Clock interface {
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Now() time.Time
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}
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type SystemClock struct{}
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func (SystemClock) Now() time.Time {
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return time.Now()
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}
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type CachingRegistry struct {
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delegate Registry
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ttl time.Duration
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minions []string
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lastUpdate int64
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lock sync.RWMutex
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clock Clock
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}
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func NewCachingRegistry(delegate Registry, ttl time.Duration) (Registry, error) {
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list, err := delegate.List()
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if err != nil {
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return nil, err
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}
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return &CachingRegistry{
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delegate: delegate,
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ttl: ttl,
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minions: list,
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lastUpdate: time.Now().Unix(),
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clock: SystemClock{},
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}, nil
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}
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func (r *CachingRegistry) Contains(minion string) (bool, error) {
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if r.expired() {
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if err := r.refresh(false); err != nil {
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return false, err
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}
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}
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// block updates in the middle of a contains.
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r.lock.RLock()
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defer r.lock.RUnlock()
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for _, name := range r.minions {
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if name == minion {
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return true, nil
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}
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}
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return false, nil
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}
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func (r *CachingRegistry) Delete(minion string) error {
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if err := r.delegate.Delete(minion); err != nil {
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return err
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}
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return r.refresh(true)
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}
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func (r *CachingRegistry) Insert(minion string) error {
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if err := r.delegate.Insert(minion); err != nil {
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return err
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}
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return r.refresh(true)
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}
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func (r *CachingRegistry) List() ([]string, error) {
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if r.expired() {
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if err := r.refresh(false); err != nil {
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return r.minions, err
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}
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}
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return r.minions, nil
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}
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func (r *CachingRegistry) expired() bool {
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var unix int64
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atomic.SwapInt64(&unix, r.lastUpdate)
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return r.clock.Now().Sub(time.Unix(r.lastUpdate, 0)) > r.ttl
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}
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// refresh updates the current store. It double checks expired under lock with the assumption
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// of optimistic concurrency with the other functions.
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func (r *CachingRegistry) refresh(force bool) error {
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r.lock.Lock()
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defer r.lock.Unlock()
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if force || r.expired() {
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var err error
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r.minions, err = r.delegate.List()
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time := r.clock.Now()
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atomic.SwapInt64(&r.lastUpdate, time.Unix())
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return err
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}
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return nil
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}
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