publish: Remove expired cache entries when '--ttl' is used.

* guix/scripts/publish.scm (narinfo-files): New procedure.
(render-narinfo/cached)[delete-file]: New procedure.  Add call to
'maybe-remove-expired-cache-entries'.
* doc/guix.texi (Invoking guix publish): Document the interation between
--cache and --ttl.

1 files changed, 6 insertions, 0 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index bbb2ba732d..f2eba59d9c 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -6600,6 +6600,9 @@ The ``baking'' process is performed by worker threads.  By default, one
 thread per CPU core is created, but this can be customized.  See
 @option{--workers} below.
 
+When @option{--ttl} is used, cached entries are automatically deleted
+when they have expired.
+
 @item --workers=@var{N}
 When @option{--cache} is used, request the allocation of @var{N} worker
 threads to ``bake'' archives.
@@ -6614,6 +6617,9 @@ This allows the user's Guix to keep substitute information in cache for
 guarantee that the store items it provides will indeed remain available
 for as long as @var{ttl}.
 
+Additionally, when @option{--cache} is used, cached entries that have
+not been accessed for @var{ttl} may be deleted.
+
 @item --nar-path=@var{path}
 Use @var{path} as the prefix for the URLs of ``nar'' files
 (@pxref{Invoking guix archive, normalized archives}).