github.com/stffabi/git-lfs@v2.3.5-0.20180214015214-8eeaa8d88902+incompatible/config/os_fetcher.go (about)

     1  package config
     2  
     3  import (
     4  	"os"
     5  	"sync"
     6  )
     7  
     8  // OsFetcher is an implementation of the Fetcher type for communicating with
     9  // the system's environment.
    10  //
    11  // It is safe to use across multiple goroutines.
    12  type OsFetcher struct {
    13  	// vmu guards read/write access to vals
    14  	vmu sync.Mutex
    15  	// vals maintains a local cache of the system's enviornment variables
    16  	// for fast repeat lookups of a given key.
    17  	vals map[string]*string
    18  }
    19  
    20  // NewOsFetcher returns a new *OsFetcher.
    21  func NewOsFetcher() *OsFetcher {
    22  	return &OsFetcher{
    23  		vals: make(map[string]*string),
    24  	}
    25  }
    26  
    27  // Get returns the value associated with the given key as stored in the local
    28  // cache, or in the operating system's environment variables.
    29  //
    30  // If there was a cache-hit, the value will be returned from the cache, skipping
    31  // a check against os.Getenv. Otherwise, the value will be fetched from the
    32  // system, stored in the cache, and then returned. If no value was present in
    33  // the cache or in the system, an empty string will be returned.
    34  //
    35  // Get is safe to call across multiple goroutines.
    36  func (o *OsFetcher) Get(key string) (val string, ok bool) {
    37  	o.vmu.Lock()
    38  	defer o.vmu.Unlock()
    39  
    40  	if i, ok := o.vals[key]; ok {
    41  		if i == nil {
    42  			return "", false
    43  		}
    44  		return *i, true
    45  	}
    46  
    47  	v, ok := os.LookupEnv(key)
    48  	if ok {
    49  		o.vals[key] = &v
    50  	} else {
    51  		o.vals[key] = nil
    52  	}
    53  
    54  	return v, ok
    55  }
    56  
    57  // GetAll implements the `config.Fetcher.GetAll` method by returning, at most, a
    58  // 1-ary set containing the result of `config.OsFetcher.Get()`.
    59  func (o *OsFetcher) GetAll(key string) []string {
    60  	if v, ok := o.Get(key); ok {
    61  		return []string{v}
    62  	}
    63  	return make([]string, 0)
    64  }
    65  
    66  func (o *OsFetcher) All() map[string][]string {
    67  	return nil
    68  }