mirror of https://github.com/dapr/kit.git
99 lines
2.4 KiB
Go
99 lines
2.4 KiB
Go
/*
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Copyright 2023 The Dapr Authors
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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 context
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import (
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"context"
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"sync"
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)
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// Pool is a pool of contexts whereby the callee context is only cancelled when
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// all callers in the pool are done. Contexts added after the pool is created
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// are also tracked, but will be ignored if the pool is already cancelled.
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type Pool struct {
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context.Context
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closed chan struct{}
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pool []<-chan struct{}
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lock sync.RWMutex
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}
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// NewPool creates a new context pool with the given contexts. The returned
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// context is cancelled when all contexts in the pool are done. Added contexts
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// are ignored if the pool is already cancelled or if all current contexts in
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// the pool are done.
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func NewPool(ctx ...context.Context) *Pool {
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callee, cancel := context.WithCancel(context.Background())
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p := &Pool{
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Context: callee,
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pool: make([]<-chan struct{}, 0, len(ctx)),
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closed: make(chan struct{}),
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}
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for i := range ctx {
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select {
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case <-ctx[i].Done():
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default:
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p.pool = append(p.pool, ctx[i].Done())
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}
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}
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p.lock.RLock()
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go func() {
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defer cancel()
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defer p.lock.RUnlock()
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for i := 0; i < len(p.pool); i++ {
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ch := p.pool[i]
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p.lock.RUnlock()
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select {
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case <-ch:
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case <-p.closed:
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}
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p.lock.RLock()
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}
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}()
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return p
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}
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// Add adds a context to the pool. The context is ignored if the pool is
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// already cancelled or if all current contexts in the pool are done.
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func (p *Pool) Add(ctx context.Context) *Pool {
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p.lock.Lock()
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defer p.lock.Unlock()
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select {
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case <-p.Done():
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case <-p.closed:
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default:
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p.pool = append(p.pool, ctx.Done())
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}
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return p
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}
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// Cancel cancels the pool. Removes all contexts from the pool.
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func (p *Pool) Cancel() {
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p.lock.Lock()
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defer p.lock.Unlock()
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if p.pool != nil {
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close(p.closed)
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p.pool = nil
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}
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}
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// Size returns the number of contexts in the pool.
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func (p *Pool) Size() int {
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p.lock.RLock()
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defer p.lock.RUnlock()
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return len(p.pool)
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}
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