Remove the old cache library and cache daemon (#4465)

This PR continues the work started in #4443.

It does the following things:

* Remove the [cache] and [cache_daemon] libraries.
* Clean up and move and the cache trimming logic to [dune_cache].
* Add some tests to make sure the cache trimmer can cope with all versions of the cache.

Signed-off-by: Andrey Mokhov <[email protected]>

bin/cache.ml

@@ -0,0 +1,71 @@
+open Stdune
+open Import
+
+let name = "cache"
+
+(* CR-someday amokhov: Implement other commands supported by Jenga. *)
+
+let man =
+  [ `S "DESCRIPTION"
+  ; `P
+      {|Dune can share build artifacts between workspaces. Currently, the only
+        action supported by this command is `trim`, but we plan to provide more
+        functionality soon. |}
+  ; `S "ACTIONS"
+  ; `P {|$(b,trim) trim the shared cache to free space.|}
+  ; `Blocks Common.help_secs
+  ]
+
+let doc = "Manage the shared cache of build artifacts"
+
+let info = Term.info name ~doc ~man
+
+let trim ~trimmed_size ~size =
+  Log.init_disabled ();
+  let open Result.O in
+  match
+    let+ goal =
+      match (trimmed_size, size) with
+      | Some trimmed_size, None -> Result.Ok trimmed_size
+      | None, Some size ->
+        Result.Ok (Int64.sub (Dune_cache.Trimmer.overhead_size ()) size)
+      | _ -> Result.Error "specify either --size or --trimmed-size"
+    in
+    Dune_cache.Trimmer.trim ~goal
+  with
+  | Error s -> User_error.raise [ Pp.text s ]
+  | Ok { trimmed_bytes } ->
+    User_message.print
+      (User_message.make [ Pp.textf "Freed %Li bytes" trimmed_bytes ])
+
+type mode = Trim
+
+let modes = [ ("trim", Trim) ]
+
+let term =
+  Term.ret
+  @@ let+ mode =
+       Arg.(
+         value
+         & pos 0 (some (enum modes)) None
+         & info [] ~docv:"ACTION"
+             ~doc:
+               (Printf.sprintf "The cache action to perform (%s)"
+                  (Arg.doc_alts_enum modes)))
+     and+ trimmed_size =
+       Arg.(
+         value
+         & opt (some bytes) None
+         & info ~docv:"BYTES" [ "trimmed-size" ]
+             ~doc:"size to trim from the cache")
+     and+ size =
+       Arg.(
+         value
+         & opt (some bytes) None
+         & info ~docv:"BYTES" [ "size" ] ~doc:"size to trim the cache to")
+     in
+     match mode with
+     | Some Trim -> `Ok (trim ~trimmed_size ~size)
+     | None -> `Help (`Pager, Some name)
+
+let command = (term, info)

bin/dune

@@ -6,8 +6,6 @@
   fiber
   stdune
   unix
-  cache_daemon
-  cache
   dune_cache
   dune_cache_storage
   dune_rules

bin/main.ml

@@ -22,7 +22,7 @@ let all : _ Term.Group.t list =
     ; Format_dune_file.command
     ; Compute.command
     ; Upgrade.command
-    ; Caching.command
+    ; Cache.command
     ; Describe.command
     ; Top.command
     ; Ocaml_merlin.command

boot/libs.ml

@@ -13,12 +13,9 @@ let local_libraries =
   ; ("src/dag", Some "Dag", false, None)
   ; ("src/fiber", Some "Fiber", false, None)
   ; ("src/memo", Some "Memo", false, None)
-  ; ("src/dune_util", Some "Dune_util", false, None)
   ; ("src/xdg", Some "Xdg", false, None)
   ; ("src/dune_cache_storage", Some "Dune_cache_storage", false, None)
   ; ("src/dune_cache", Some "Dune_cache", false, None)
-  ; ("src/cache", Some "Cache", false, None)
-  ; ("src/cache_daemon", Some "Cache_daemon", false, None)
   ; ("vendor/re/src", Some "Dune_re", false, None)
   ; ("vendor/opam-file-format/src", None, false, None)
   ; ("otherlibs/dune-glob/src", Some "Dune_glob", false, None)
@@ -27,6 +24,7 @@ let local_libraries =
   ; ("src/chrome_trace", Some "Chrome_trace", false, None)
   ; ("vendor/spawn/src", Some "Spawn", false, None)
   ; ("src/stats", Some "Stats", false, None)
+  ; ("src/dune_util", Some "Dune_util", false, None)
   ; ("src/meta_parser", Some "Dune_meta_parser", false, None)
   ; ("src/section", Some "Dune_section", false, None)
   ; ("vendor/build_path_prefix_map/src", Some "Build_path_prefix_map", false,