github.com/kcburge/terraform@v0.11.12-beta1/svchost/auth/cache.go (about)

     1  package auth
     2  
     3  import (
     4  	"github.com/hashicorp/terraform/svchost"
     5  )
     6  
     7  // CachingCredentialsSource creates a new credentials source that wraps another
     8  // and caches its results in memory, on a per-hostname basis.
     9  //
    10  // No means is provided for expiration of cached credentials, so a caching
    11  // credentials source should have a limited lifetime (one Terraform operation,
    12  // for example) to ensure that time-limited credentials don't expire before
    13  // their cache entries do.
    14  func CachingCredentialsSource(source CredentialsSource) CredentialsSource {
    15  	return &cachingCredentialsSource{
    16  		source: source,
    17  		cache:  map[svchost.Hostname]HostCredentials{},
    18  	}
    19  }
    20  
    21  type cachingCredentialsSource struct {
    22  	source CredentialsSource
    23  	cache  map[svchost.Hostname]HostCredentials
    24  }
    25  
    26  // ForHost passes the given hostname on to the wrapped credentials source and
    27  // caches the result to return for future requests with the same hostname.
    28  //
    29  // Both credentials and non-credentials (nil) responses are cached.
    30  //
    31  // No cache entry is created if the wrapped source returns an error, to allow
    32  // the caller to retry the failing operation.
    33  func (s *cachingCredentialsSource) ForHost(host svchost.Hostname) (HostCredentials, error) {
    34  	if cache, cached := s.cache[host]; cached {
    35  		return cache, nil
    36  	}
    37  
    38  	result, err := s.source.ForHost(host)
    39  	if err != nil {
    40  		return result, err
    41  	}
    42  
    43  	s.cache[host] = result
    44  	return result, nil
    45  }