48 lines
1.2 KiB
Go
48 lines
1.2 KiB
Go
// Copyright 2019 PingCAP, 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 common
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import (
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"sync"
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)
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// OnceError is an error value which will can be assigned once.
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//
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// The zero value is ready for use.
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type OnceError struct {
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lock sync.Mutex
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err error
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}
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// Set assigns an error to this instance, if `e != nil`.
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//
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// If this method is called multiple times, only the first call is effective.
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func (oe *OnceError) Set(e error) {
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if e != nil {
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oe.lock.Lock()
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if oe.err == nil {
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oe.err = e
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}
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oe.lock.Unlock()
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}
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}
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// Get returns the first error value stored in this instance.
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func (oe *OnceError) Get() error {
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oe.lock.Lock()
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defer oe.lock.Unlock()
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return oe.err
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}
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