github.com/cloudwego/kitex@v0.9.0/internal/configutil/once.go (about)

     1  /*
     2   * Copyright 2021 CloudWeGo Authors
     3   *
     4   * Licensed under the Apache License, Version 2.0 (the "License");
     5   * you may not use this file except in compliance with the License.
     6   * You may obtain a copy of the License at
     7   *
     8   *     http://www.apache.org/licenses/LICENSE-2.0
     9   *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS,
    12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   * See the License for the specific language governing permissions and
    14   * limitations under the License.
    15   */
    16  
    17  // Package configutil .
    18  package configutil
    19  
    20  import (
    21  	"fmt"
    22  	"runtime"
    23  )
    24  
    25  // OptionOnce is used to ensure an option is only set once.
    26  type OptionOnce struct {
    27  	OptMap map[string]struct{}
    28  }
    29  
    30  // NewOptionOnce creates a new option once instance.
    31  func NewOptionOnce() *OptionOnce {
    32  	return &OptionOnce{
    33  		OptMap: make(map[string]struct{}),
    34  	}
    35  }
    36  
    37  // OnceOrPanic panics if the Option has already been set.
    38  func (o *OptionOnce) OnceOrPanic() {
    39  	if o == nil {
    40  		return
    41  	}
    42  	pc, _, _, _ := runtime.Caller(1)
    43  	name := runtime.FuncForPC(pc).Name()
    44  	if _, ok := o.OptMap[name]; ok {
    45  		panic(fmt.Sprintf("Option %s has already been set", name))
    46  	}
    47  	o.OptMap[name] = struct{}{}
    48  }