c9e9ae555f
* Add license headers & NOTICE * generated protobuf --------- Co-authored-by: github-actions <41898282+github-actions[bot]@users.noreply.github.com>
78 lines
1.7 KiB
Go
78 lines
1.7 KiB
Go
// Copyright 2023 LiveKit, Inc.
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//
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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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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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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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package rpc
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import (
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"context"
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"sync"
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)
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type raceResult[T any] struct {
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i int
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val *T
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err error
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}
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type Race[T any] struct {
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ctx context.Context
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cancel context.CancelFunc
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nextIndex int
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resultLock sync.Mutex
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result *raceResult[T]
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}
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// NewRace creates a race to yield the result from one or more candidate
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// functions
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func NewRace[T any](ctx context.Context) *Race[T] {
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ctx, cancel := context.WithCancel(ctx)
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return &Race[T]{
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ctx: ctx,
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cancel: cancel,
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}
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}
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// Go adds a candidate function to the race by running it in a new goroutine
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func (r *Race[T]) Go(fn func(ctx context.Context) (*T, error)) {
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i := r.nextIndex
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r.nextIndex++
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go func() {
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val, err := fn(r.ctx)
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r.resultLock.Lock()
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if r.result == nil {
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r.result = &raceResult[T]{i, val, err}
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}
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r.resultLock.Unlock()
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r.cancel()
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}()
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}
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// Wait awaits the first complete function and returns the index and results
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// or -1 if the context is cancelled before any candidate finishes.
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func (r *Race[T]) Wait() (int, *T, error) {
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<-r.ctx.Done()
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r.resultLock.Lock()
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res := r.result
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r.resultLock.Unlock()
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if res != nil {
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return res.i, res.val, res.err
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}
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return -1, nil, r.ctx.Err()
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}
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