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Docs clarification

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neilotoole 2024-01-29 00:20:51 -07:00
parent 293206ebb5
commit 0cec859ada
1 changed files with 10 additions and 9 deletions
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19
libsq/files/internal/downloader/cache.go
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@ -300,14 +300,15 @@ func (c *cache) newResponseCacher(ctx context.Context, resp *http.Response) (*re
var _ io.ReadCloser = (*responseCacher)(nil)
// responseCacher is an io.ReadCloser that wraps an [http.Response.Body],
// appending bytes read via Read to a staging cache file. When Read receives
// [io.EOF] from the wrapped response body, the staging cache is promoted and
// replaces the main cache. If an error occurs during Read, the staging cache is
// discarded, and the main cache is left untouched. If an error occurs during
// cache promotion (which happens on receipt of io.EOF from resp.Body), the
// promotion error, not [io.EOF], is returned by Read. Thus, a consumer of
// responseCacher will not receive [io.EOF] unless the cache is successfully
// promoted.
// appending bytes read via Read to a staging cache file, and then returning
// those same bytes to the caller. It is conceptually similar to [io.TeeReader].
// When Read receives [io.EOF] from the wrapped response body, the staging cache
// is promoted and replaces the main cache. If an error occurs during Read, the
// staging cache is discarded, and the main cache is left untouched. If an error
// occurs during cache promotion (which happens on receipt of [io.EOF] from
// resp.Body), the promotion error, not [io.EOF], is returned by Read. Thus, a
// consumer of responseCacher will not receive [io.EOF] unless the cache is
// successfully promoted.
type responseCacher struct {
body io.ReadCloser
closeErr *error
@ -383,7 +384,7 @@ func (r *responseCacher) cacheAppend(p []byte, n int) error {
return errz.Wrap(err, "failed to append http response body bytes to staging cache")
}
// cachePromote is invoked by Read when it receives io.EOF from the wrapped
// cachePromote is invoked by [Read] when it receives [io.EOF] from the wrapped
// response body. It promotes the staging cache to main, and on success returns
// nil. If an error occurs during promotion, the staging cache is discarded, and
// the promotion error is returned.