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hookable.go
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hookable.go
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/*
* Copyright 2021 CloudWeGo Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package lbcache
import (
"sync"
"github.com/cloudwego/kitex/pkg/discovery"
"github.com/cloudwego/kitex/pkg/loadbalance"
)
// intercept the rebalancer and call hooks
// wrap the loadbalance.Rebalancer and execute registered hooks
type hookableRebalancer struct {
inner loadbalance.Rebalancer
rebalanceL sync.Mutex
rebalanceIndex int
rebalanceHooks map[int]func(*discovery.Change)
deleteL sync.Mutex
deleteIndex int
deleteHooks map[int]func(*discovery.Change)
}
var (
_ loadbalance.Rebalancer = (*hookableRebalancer)(nil)
_ Hookable = (*hookableRebalancer)(nil)
)
func newHookRebalancer(inner loadbalance.Rebalancer) *hookableRebalancer {
return &hookableRebalancer{
inner: inner,
rebalanceHooks: map[int]func(*discovery.Change){},
deleteHooks: map[int]func(*discovery.Change){},
}
}
func (b *hookableRebalancer) Rebalance(ch discovery.Change) {
b.rebalanceL.Lock()
for _, h := range b.rebalanceHooks {
h(&ch)
}
b.rebalanceL.Unlock()
b.inner.Rebalance(ch)
}
func (b *hookableRebalancer) Delete(ch discovery.Change) {
b.deleteL.Lock()
for _, h := range b.deleteHooks {
h(&ch)
}
b.deleteL.Unlock()
b.inner.Delete(ch)
}
func (b *hookableRebalancer) RegisterRebalanceHook(f func(ch *discovery.Change)) int {
b.rebalanceL.Lock()
defer b.rebalanceL.Unlock()
index := b.rebalanceIndex
b.rebalanceIndex++
b.rebalanceHooks[index] = f
return index
}
func (b *hookableRebalancer) DeregisterRebalanceHook(index int) {
b.rebalanceL.Lock()
defer b.rebalanceL.Unlock()
delete(b.rebalanceHooks, index)
}
func (b *hookableRebalancer) RegisterDeleteHook(f func(ch *discovery.Change)) int {
b.deleteL.Lock()
defer b.deleteL.Unlock()
index := b.deleteIndex
b.deleteIndex++
b.deleteHooks[index] = f
return index
}
func (b *hookableRebalancer) DeregisterDeleteHook(index int) {
b.deleteL.Lock()
defer b.deleteL.Unlock()
delete(b.deleteHooks, index)
}
type noopHookRebalancer struct{}
var _ Hookable = (*noopHookRebalancer)(nil)
func (noopHookRebalancer) RegisterRebalanceHook(func(ch *discovery.Change)) int { return 0 }
func (noopHookRebalancer) RegisterDeleteHook(func(ch *discovery.Change)) int { return 0 }
func (noopHookRebalancer) DeregisterRebalanceHook(index int) {}
func (noopHookRebalancer) DeregisterDeleteHook(index int) {}