terraform/svchost/auth/cache.go

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package auth
import (
"github.com/hashicorp/terraform/svchost"
)
// CachingCredentialsSource creates a new credentials source that wraps another
// and caches its results in memory, on a per-hostname basis.
//
// No means is provided for expiration of cached credentials, so a caching
// credentials source should have a limited lifetime (one Terraform operation,
// for example) to ensure that time-limited credentials don't expire before
// their cache entries do.
func CachingCredentialsSource(source CredentialsSource) CredentialsSource {
return &cachingCredentialsSource{
source: source,
cache: map[svchost.Hostname]HostCredentials{},
}
}
type cachingCredentialsSource struct {
source CredentialsSource
cache map[svchost.Hostname]HostCredentials
}
// ForHost passes the given hostname on to the wrapped credentials source and
// caches the result to return for future requests with the same hostname.
//
// Both credentials and non-credentials (nil) responses are cached.
//
// No cache entry is created if the wrapped source returns an error, to allow
// the caller to retry the failing operation.
func (s *cachingCredentialsSource) ForHost(host svchost.Hostname) (HostCredentials, error) {
if cache, cached := s.cache[host]; cached {
return cache, nil
}
result, err := s.source.ForHost(host)
if err != nil {
return result, err
}
s.cache[host] = result
return result, nil
}
func (s *cachingCredentialsSource) StoreForHost(host svchost.Hostname, credentials HostCredentialsWritable) error {
// We'll delete the cache entry even if the store fails, since that just
// means that the next read will go to the real store and get a chance to
// see which object (old or new) is actually present.
delete(s.cache, host)
return s.source.StoreForHost(host, credentials)
}
func (s *cachingCredentialsSource) ForgetForHost(host svchost.Hostname) error {
// We'll delete the cache entry even if the store fails, since that just
// means that the next read will go to the real store and get a chance to
// see if the object is still present.
delete(s.cache, host)
return s.source.ForgetForHost(host)
}