github.com/aaabigfish/gopkg@v1.1.0/cache/asynccache/atomic_error.go (about)

     1  // Copyright 2021 ByteDance Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  // Copyright (c) 2016 Uber Technologies, Inc.
    16  //
    17  // Permission is hereby granted, free of charge, to any person obtaining a copy
    18  // of this software and associated documentation files (the "Software"), to deal
    19  // in the Software without restriction, including without limitation the rights
    20  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    21  // copies of the Software, and to permit persons to whom the Software is
    22  // furnished to do so, subject to the following conditions:
    23  //
    24  // The above copyright notice and this permission notice shall be included in
    25  // all copies or substantial portions of the Software.
    26  //
    27  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    28  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    29  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    30  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    31  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    32  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    33  // THE SOFTWARE.
    34  
    35  package asynccache
    36  
    37  import "sync/atomic"
    38  
    39  // Error is an atomic type-safe wrapper around Value for errors
    40  type Error struct{ v atomic.Value }
    41  
    42  // errorHolder is non-nil holder for error object.
    43  // atomic.Value panics on saving nil object, so err object needs to be
    44  // wrapped with valid object first.
    45  type errorHolder struct{ err error }
    46  
    47  // Load atomically loads the wrapped error
    48  func (e *Error) Load() error {
    49  	v := e.v.Load()
    50  	if v == nil {
    51  		return nil
    52  	}
    53  
    54  	eh := v.(errorHolder)
    55  	return eh.err
    56  }
    57  
    58  // Store atomically stores error.
    59  // NOTE: a holder object is allocated on each Store call.
    60  func (e *Error) Store(err error) {
    61  	e.v.Store(errorHolder{err: err})
    62  }