X-Git-Url: https://git.xandkar.net/?p=dups.git;a=blobdiff_plain;f=dups.ml;h=2521b97261fbc2fa441283aeefc1fb5a78e27c54;hp=b6782b68f9021bdbc81522d75ca236dc029a8a02;hb=b0c3b3f085147e4228cf17a965723feb041b275f;hpb=e09dff7f9b5875b81cf50b33dcf97635518f7c28

diff --git a/dups.ml b/dups.ml
index b6782b6..2521b97 100644
--- a/dups.ml
+++ b/dups.ml
@@ -2,59 +2,420 @@ open Printf
 
 module Array = ArrayLabels
 module List  = ListLabels
-module StrSet= Set.Make(String)
+module StrSet = Set.Make(String)
 module Unix  = UnixLabels
 
+module Metrics : sig
+  type t
+
+  val init
+    : unit -> t
+  val report
+    : t
+    -> wall_time_all:float
+    -> wall_time_group_by_size:float
+    -> wall_time_group_by_head:float
+    -> wall_time_group_by_digest:float
+    -> proc_time_all:float
+    -> proc_time_group_by_size:float
+    -> proc_time_group_by_head:float
+    -> proc_time_group_by_digest:float
+    -> unit
+
+  val file_considered
+    : t -> size:int -> unit
+  val file_ignored
+    : t -> size:int -> unit
+  val file_empty
+    : t -> unit
+  val file_sampled
+    : t -> unit
+  val chunk_read
+    : t -> size:int -> unit
+  val file_unique_size
+    : t -> size:int -> unit
+  val file_unique_sample
+    : t -> size:int -> unit
+  val file_hashed
+    : t -> size:int -> unit
+  val digest
+    : t -> unit
+  val redundant_data
+    : t -> size:int -> unit
+end = struct
+  type t =
+    { considered_files    : int ref
+    ; considered_bytes    : int ref
+    ; empty               : int ref
+    ; ignored_files       : int ref
+    ; ignored_bytes       : int ref
+    ; unique_size_files   : int ref
+    ; unique_size_bytes   : int ref
+    ; unique_sample_files : int ref
+    ; unique_sample_bytes : int ref
+    ; sampled_files       : int ref
+    ; sampled_bytes       : int ref
+    ; hashed_files        : int ref
+    ; hashed_bytes        : int ref
+    ; digests             : int ref
+    ; redundant_data      : int ref
+    }
+
+  let init () =
+    { considered_files    = ref 0
+    ; considered_bytes    = ref 0
+    ; empty               = ref 0
+    ; ignored_files       = ref 0
+    ; ignored_bytes       = ref 0
+    ; unique_size_files   = ref 0
+    ; unique_size_bytes   = ref 0
+    ; sampled_files       = ref 0
+    ; sampled_bytes       = ref 0
+    ; hashed_files        = ref 0
+    ; hashed_bytes        = ref 0
+    ; unique_sample_files = ref 0
+    ; unique_sample_bytes = ref 0
+    ; digests             = ref 0
+    ; redundant_data      = ref 0
+    }
+
+  let add sum addend =
+    sum := !sum + addend
+
+  let file_considered t ~size =
+    incr t.considered_files;
+    add t.considered_bytes size
+
+  let file_ignored {ignored_files; ignored_bytes; _} ~size =
+    incr ignored_files;
+    add ignored_bytes size
+
+  let file_empty t =
+    incr t.empty
+
+  let chunk_read t ~size =
+    add t.sampled_bytes size
+
+  let file_sampled t =
+    incr t.sampled_files
+
+  let file_unique_size t ~size =
+    incr t.unique_size_files;
+    add t.unique_size_bytes size
+
+  let file_unique_sample t ~size =
+    incr t.unique_sample_files;
+    add t.unique_sample_bytes size
+
+  let file_hashed t ~size =
+    incr t.hashed_files;
+    add t.hashed_bytes size
+
+  let digest t =
+    incr t.digests
+
+  let redundant_data t ~size =
+    add t.redundant_data size
+
+  let report
+    t
+    ~wall_time_all
+    ~wall_time_group_by_size
+    ~wall_time_group_by_head
+    ~wall_time_group_by_digest
+    ~proc_time_all
+    ~proc_time_group_by_size
+    ~proc_time_group_by_head
+    ~proc_time_group_by_digest
+  =
+    let b_to_mb b = (float_of_int b) /. 1024. /. 1024. in
+    let b_to_gb b = (b_to_mb b) /. 1024. in
+    eprintf "Total time                   : %.2f wall sec  %.2f proc sec\n%!"
+      wall_time_all
+      proc_time_all;
+    eprintf "Considered                   : %8d files  %6.2f Gb\n%!"
+      !(t.considered_files)
+      (b_to_gb !(t.considered_bytes));
+    eprintf "Sampled                      : %8d files  %6.2f Gb\n%!"
+      !(t.sampled_files)
+      (b_to_gb !(t.sampled_bytes));
+    eprintf "Hashed                       : %8d files  %6.2f Gb  %6.2f wall sec  %6.2f proc sec\n%!"
+      !(t.hashed_files)
+      (b_to_gb !(t.hashed_bytes))
+      wall_time_group_by_digest
+      proc_time_group_by_digest;
+    eprintf "Digests                      : %8d\n%!"
+      !(t.digests);
+    eprintf "Duplicates (Hashed - Digests): %8d files  %6.2f Gb\n%!"
+      (!(t.hashed_files) - !(t.digests))
+      (b_to_gb !(t.redundant_data));
+    eprintf "Skipped due to 0      size   : %8d files\n%!" !(t.empty);
+    eprintf "Skipped due to unique size   : %8d files  %6.2f Gb  %6.2f wall sec  %6.2f proc sec\n%!"
+      !(t.unique_size_files)
+      (b_to_gb !(t.unique_size_bytes))
+      wall_time_group_by_size
+      proc_time_group_by_size;
+    eprintf "Skipped due to unique sample : %8d files  %6.2f Gb  %6.2f wall sec  %6.2f proc sec\n%!"
+      !(t.unique_sample_files)
+      (b_to_gb !(t.unique_sample_bytes))
+      wall_time_group_by_head
+      proc_time_group_by_head;
+    eprintf "Ignored due to regex match   : %8d files  %6.2f Gb\n%!"
+      !(t.ignored_files)
+      (b_to_gb !(t.ignored_bytes))
+end
+
+module M = Metrics
+
 module Stream : sig
   type 'a t
 
   val create : (unit -> 'a option) -> 'a t
 
+  val of_queue : 'a Queue.t -> 'a t
+
   val iter : 'a t -> f:('a -> unit) -> unit
 
+  val bag_map : 'a t -> njobs:int -> f:('a -> 'b) -> ('a * 'b) t
+  (** Parallel map with arbitrarily-reordered elements. *)
+
+  val map : 'a t -> f:('a -> 'b) -> 'b t
+
+  val filter : 'a t -> f:('a -> bool) -> 'a t
+
   val concat : ('a t) list -> 'a t
+
+  val group_by : 'a t -> f:('a -> 'b) -> ('b * int * 'a list) t
 end = struct
   module S = Stream
 
   type 'a t =
-    ('a S.t) list
+    {mutable streams : ('a S.t) list}
+
+  type ('input, 'output) msg_from_vassal =
+    | Ready of int
+    | Result of (int * ('input * 'output))
+    | Exiting of int
+
+  type 'input msg_from_lord =
+    | Job of 'input option
 
   let create f =
-    [S.from (fun _ -> f ())]
+    {streams = [S.from (fun _ -> f ())]}
+
+  let of_queue q =
+    create (fun () ->
+      match Queue.take q with
+      | exception Queue.Empty ->
+          None
+      | x ->
+          Some x
+    )
+
+  let rec next t =
+    match t.streams with
+    | [] ->
+        None
+    | s :: streams ->
+        (match S.next s with
+        | exception Stream.Failure ->
+            t.streams <- streams;
+            next t
+        | x ->
+            Some x
+        )
+
+  let map t ~f =
+    create (fun () ->
+      match next t with
+      | None   -> None
+      | Some x -> Some (f x)
+    )
+
+  let filter t ~f =
+    let rec filter () =
+      match next t with
+      | None ->
+          None
+      | Some x when f x ->
+          Some x
+      | Some _ ->
+          filter ()
+    in
+    create filter
 
   let iter t ~f =
-    List.iter t ~f:(S.iter f)
+    List.iter t.streams ~f:(S.iter f)
 
   let concat ts =
-    List.concat ts
+    {streams = List.concat (List.map ts ~f:(fun {streams} -> streams))}
+
+  let group_by t ~f =
+    let groups_tbl = Hashtbl.create 1_000_000 in
+    let group_update x =
+      let group = f x in
+      let members =
+        match Hashtbl.find_opt groups_tbl group with
+        | None ->
+            (1, [x])
+        | Some (n, xs) ->
+            (succ n, x :: xs)
+      in
+      Hashtbl.replace groups_tbl group members
+    in
+    iter t ~f:group_update;
+    let groups = Queue.create () in
+    Hashtbl.iter
+      (fun name (length, members) -> Queue.add (name, length, members) groups)
+      groups_tbl;
+    of_queue groups
+
+  module Ipc : sig
+    val send : out_channel -> 'a -> unit
+    val recv : in_channel -> 'a
+  end = struct
+    let send oc msg =
+      Marshal.to_channel oc msg [];
+      flush oc
+
+    let recv ic =
+      Marshal.from_channel ic
+  end
+
+  let lord t ~njobs ~vassals ~ic ~ocs =
+    let active_vassals = ref njobs in
+    let results = Queue.create () in
+    let rec loop () =
+      match ((Ipc.recv ic) : ('input, 'output) msg_from_vassal) with
+      | Exiting i ->
+          close_out ocs.(i);
+          decr active_vassals;
+          if !active_vassals = 0 then () else loop ()
+      | Ready i ->
+          Ipc.send ocs.(i) (Job (next t));
+          loop ()
+      | Result (i, result) ->
+          Queue.add result results;
+          Ipc.send ocs.(i) (Job (next t));
+          loop ()
+    in
+    let rec wait = function
+      | [] ->
+          ()
+      | vassals ->
+          let pid, _process_status = Unix.wait () in
+          (* TODO: handle process_status *)
+          wait (List.filter vassals ~f:(fun p -> p <> pid))
+    in
+    loop ();
+    close_in ic;
+    wait vassals;
+    of_queue results
+
+  let vassal i ~f ~vassal_pipe_r ~lord_pipe_w =
+    let ic = Unix.in_channel_of_descr vassal_pipe_r in
+    let oc = Unix.out_channel_of_descr lord_pipe_w in
+    let rec loop () =
+      match (Ipc.recv ic : 'input msg_from_lord) with
+      | Job (Some x) ->
+          Ipc.send oc (Result (i, (x, f x)));
+          loop ()
+      | Job None ->
+          Ipc.send oc (Exiting i)
+    in
+    Ipc.send oc (Ready i);
+    loop ();
+    close_in ic;
+    close_out oc;
+    exit 0
+
+  let bag_map t ~njobs ~f =
+    let lord_pipe_r, lord_pipe_w = Unix.pipe () in
+    let vassal_pipes   = Array.init njobs ~f:(fun _ -> Unix.pipe ()) in
+    let vassal_pipes_r = Array.map vassal_pipes ~f:(fun (r, _) -> r) in
+    let vassal_pipes_w = Array.map vassal_pipes ~f:(fun (_, w) -> w) in
+    let vassals = ref [] in
+    for i=0 to (njobs - 1) do
+      begin match Unix.fork () with
+      | 0 ->
+          Unix.close lord_pipe_r;
+          vassal i ~f ~lord_pipe_w ~vassal_pipe_r:vassal_pipes_r.(i)
+      | pid ->
+          vassals := pid :: !vassals
+      end
+    done;
+    Unix.close lord_pipe_w;
+    lord
+      t
+      ~njobs
+      ~vassals:!vassals
+      ~ic:(Unix.in_channel_of_descr lord_pipe_r)
+      ~ocs:(Array.map vassal_pipes_w ~f:Unix.out_channel_of_descr)
 end
 
 module In_channel : sig
-  val lines : in_channel -> string Stream.t
+  val lines : ?delim_null:bool -> in_channel -> string Stream.t
 end = struct
-  let lines ic =
-    Stream.create (fun () ->
-      match input_line ic with
-      | exception End_of_file ->
-          None
-      | line ->
-          Some line
-    )
+  let read_until_newline ic () =
+    match input_line ic with
+    | exception End_of_file ->
+        None
+    | line ->
+        Some line
+
+  let read_until_null ic =
+    let lexbuf = Lexing.from_channel ic in
+    fun () -> Input_delim.by_null lexbuf
+
+  let lines ?(delim_null=false) ic =
+    let reader =
+      if delim_null then
+        read_until_null ic
+      else
+        read_until_newline ic
+    in
+    Stream.create reader
 end
 
-module Directory_tree : sig
-  val find_files : string -> string Stream.t
+module File : sig
+  type t =
+    { path : string
+    ; size : int
+    }
+
+  val find : string -> t Stream.t
+  (** Find all files in the directory tree, starting from the given root path *)
+
+  val lookup : string Stream.t -> t Stream.t
+  (** Lookup file info for given paths *)
+
+  val head : t -> len:int -> metrics:M.t -> string
+
+  val filter_out_unique_sizes : t Stream.t -> metrics:M.t -> t Stream.t
+  val filter_out_unique_heads : t Stream.t -> len:int -> metrics:M.t -> t Stream.t
 end = struct
-  let find_files root =
+  type t =
+    { path : string
+    ; size : int
+    }
+
+  let lookup paths =
+    Stream.map paths ~f:(fun path ->
+      let {Unix.st_size = size; _} = Unix.lstat path in
+      {path; size}
+    )
+
+  let find root =
     let dirs  = Queue.create () in
     let files = Queue.create () in
     let explore parent =
       Array.iter (Sys.readdir parent) ~f:(fun child ->
         let path = Filename.concat parent child in
-        let {Unix.st_kind = file_kind; _} = Unix.lstat path in
+        let {Unix.st_kind = file_kind; st_size; _} = Unix.lstat path in
         match file_kind with
         | Unix.S_REG ->
-            Queue.add path files
+            let file = {path; size = st_size} in
+            Queue.add file files
         | Unix.S_DIR ->
             Queue.add path dirs
         | Unix.S_CHR
@@ -75,83 +436,227 @@ end = struct
           next ()
     in
     Stream.create next
+
+  let filter_out_singletons files ~group ~handle_singleton =
+    let q = Queue.create () in
+    Stream.iter (Stream.group_by files ~f:group) ~f:(fun group ->
+      let (_, n, members) = group in
+      if n > 1 then
+        List.iter members ~f:(fun m -> Queue.add m q)
+      else
+        handle_singleton group
+    );
+    Stream.of_queue q
+
+  let filter_out_unique_sizes files ~metrics =
+    filter_out_singletons
+      files
+      ~group:(fun {size; _} -> size)
+      ~handle_singleton:(fun (size, _, _) -> M.file_unique_size metrics ~size)
+
+  let head {path; _} ~len ~metrics =
+    M.file_sampled metrics;
+    let buf = Bytes.make len ' ' in
+    let ic = open_in_bin path in
+    let rec read pos len =
+      assert (len >= 0);
+      if len = 0 then
+        ()
+      else begin
+        let chunk_size = input ic buf pos len in
+        M.chunk_read metrics ~size:chunk_size;
+        if chunk_size = 0 then (* EOF *)
+          ()
+        else
+          read (pos + chunk_size) (len - chunk_size)
+      end
+    in
+    read 0 len;
+    close_in ic;
+    Bytes.to_string buf
+
+  let filter_out_unique_heads files ~len ~metrics =
+    filter_out_singletons
+      files
+      ~group:(head ~len ~metrics)
+      ~handle_singleton:(fun (_, _, files) ->
+        let {size; _} = List.hd files in  (* Guaranteed non-empty *)
+        M.file_unique_sample metrics ~size
+      )
 end
 
 type input =
-  | Root_paths of string list
-  | Paths_on_stdin
+  | Stdin
+  | Directories of string list
 
 type output =
   | Stdout
   | Directory of string
 
-let make_input_stream = function
-  | Paths_on_stdin ->
-      In_channel.lines stdin
-  | Root_paths paths ->
-      let paths = StrSet.elements (StrSet.of_list paths) in
-      Stream.concat (List.map paths ~f:Directory_tree.find_files)
+type opt =
+  { input  : input
+  ; output : output
+  ; ignore : string -> bool
+  ; sample : int
+  ; njobs  : int
+  ; delim_null : bool
+  }
+
+let make_input_stream input ignore ~metrics ~delim_null =
+  let input =
+    match input with
+    | Stdin ->
+        File.lookup (In_channel.lines stdin ~delim_null)
+    | Directories paths ->
+        let paths = StrSet.elements (StrSet.of_list paths) in
+        Stream.concat (List.map paths ~f:File.find)
+  in
+  Stream.filter input ~f:(fun {File.path; size} ->
+    M.file_considered metrics ~size;
+    let empty = size = 0 in
+    let ignored = ignore path in
+    if empty then M.file_empty metrics;
+    if ignored then M.file_ignored metrics ~size;
+    (not empty) && (not ignored)
+  )
 
 let make_output_fun = function
   | Stdout ->
-      fun digest n_paths paths ->
-        printf "%s %d\n%!" (Digest.to_hex digest) n_paths;
-        List.iter (StrSet.elements paths) ~f:(printf "    %S\n%!")
+      fun digest n_files files ->
+        printf "%s %d\n%!" (Digest.to_hex digest) n_files;
+        List.iter files ~f:(fun {File.path; _} ->
+          printf "    %S\n%!" path
+        )
   | Directory dir ->
-      fun digest _ paths ->
+      fun digest _ files ->
         let digest = Digest.to_hex digest in
         let dir = Filename.concat dir (String.sub digest 0 2) in
         Unix.mkdir dir ~perm:0o700;
         let oc = open_out (Filename.concat dir digest) in
-        List.iter (StrSet.elements paths) ~f:(fun path ->
+        List.iter files ~f:(fun {File.path; _} ->
           output_string oc (sprintf "%S\n%!" path)
         );
         close_out oc
 
-let main input output =
+let time_wall () =
+  Unix.gettimeofday ()
+
+let time_proc () =
+  Sys.time ()
+
+let main {input; output; ignore; sample = sample_len; njobs; delim_null} =
+  let wt0_all = time_wall () in
+  let pt0_all = time_proc () in
+  let metrics = M.init () in
   let output = make_output_fun  output in
-  let input  = make_input_stream input in
-  let paths_by_digest = Hashtbl.create 1_000_000 in
-  let path_count = ref 0 in
-  let t0 = Sys.time () in
-  Stream.iter input ~f:(fun path ->
-    incr path_count;
-    try
-      let digest = Digest.file path in
-      let count, paths =
-        match Hashtbl.find_opt paths_by_digest digest with
-        | None ->
-            (0, StrSet.empty)
-        | Some (n, paths) ->
-            (n, paths)
+  let input  = make_input_stream input ignore ~metrics ~delim_null in
+  (* TODO: Make a nice(r) abstraction to re-assemble pieces in the pipeline:
+   *
+   * from input           to files_by_size
+   * from files_by_size   to files_by_sample
+   * from files_by_sample to files_by_digest
+   * from files_by_digest to output
+   *
+   * input |> files_by_size |> files_by_sample |> files_by_digest |> output
+   *)
+
+  let files = input in
+
+  let wt0_group_by_size = time_wall () in
+  let pt0_group_by_size = time_proc () in
+  eprintf "[debug] filtering-out files with unique size\n%!";
+  let files = File.filter_out_unique_sizes files ~metrics in
+  let pt1_group_by_size = time_proc () in
+  let wt1_group_by_size = time_wall () in
+
+  let wt0_group_by_sample = wt1_group_by_size in
+  let pt0_group_by_sample = pt1_group_by_size in
+  eprintf "[debug] filtering-out files with unique heads\n%!";
+  let files =
+    if njobs > 1 then begin
+      let q = Queue.create () in
+      files
+        |> Stream.bag_map ~njobs ~f:(File.head ~len:sample_len ~metrics)
+        |> Stream.group_by ~f:snd
+        |> Stream.map ~f:(fun (d, n, pairs) -> (d, n, List.map pairs ~f:fst))
+        |> Stream.filter ~f:(fun (_, n, _) -> n > 1)
+        |> Stream.iter ~f:(fun (_, _, fs) -> List.iter fs ~f:(fun f -> Queue.add f q))
+        ;
+      Stream.of_queue q
+    end else
+      File.filter_out_unique_heads files ~len:sample_len ~metrics
+  in
+  let pt1_group_by_sample = time_proc () in
+  let wt1_group_by_sample = time_wall () in
+
+  let wt0_group_by_digest = wt1_group_by_sample in
+  let pt0_group_by_digest = pt1_group_by_sample in
+  eprintf "[debug] hashing\n%!";
+  let groups =
+    if njobs > 1 then
+      let with_digests =
+        Stream.bag_map files ~njobs ~f:(fun {File.path; _} -> Digest.file path)
       in
-      Hashtbl.replace paths_by_digest digest (count + 1, StrSet.add path paths)
-    with Sys_error e ->
-      eprintf "WARNING: Failed to process %S: %S\n%!" path e
+      Stream.map (Stream.group_by with_digests ~f:snd) ~f:(
+        fun (digest, n, file_digest_pairs) ->
+          let files =
+            List.map file_digest_pairs ~f:(fun (file, _) ->
+              M.file_hashed metrics ~size:file.File.size;
+              file
+            )
+          in
+          (digest, n, files)
+      )
+    else
+      Stream.group_by files ~f:(fun {File.path; size} ->
+        M.file_hashed metrics ~size;
+        Digest.file path
+      )
+  in
+  let pt1_group_by_digest = time_proc () in
+  let wt1_group_by_digest = time_wall () in
+
+  eprintf "[debug] reporting\n%!";
+  Stream.iter groups ~f:(fun (d, n, files) ->
+    M.digest metrics;
+    if n > 1 then begin
+      M.redundant_data metrics ~size:(n * (List.hd files).File.size);
+      output d n files
+    end
   );
-  Hashtbl.iter (fun d (n, ps) -> if n > 1 then output d n ps) paths_by_digest;
-  let t1 = Sys.time () in
-  eprintf "Processed %d files in %f seconds.\n%!" !path_count (t1 -. t0)
 
-let () =
-  let input  = ref Paths_on_stdin in
-  let output = ref Stdout in
-  let assert_file_exists path =
-    if Sys.file_exists path then
-      ()
-    else begin
-      eprintf "File does not exist: %S\n%!" path;
+  let pt1_all = time_proc () in
+  let wt1_all = time_wall () in
+
+  M.report metrics
+    ~wall_time_all:            (wt1_all             -. wt0_all)
+    ~wall_time_group_by_size:  (wt1_group_by_size   -. wt0_group_by_size)
+    ~wall_time_group_by_head:  (wt1_group_by_sample -. wt0_group_by_sample)
+    ~wall_time_group_by_digest:(wt1_group_by_digest -. wt0_group_by_digest)
+    ~proc_time_all:            (pt1_all             -. pt0_all)
+    ~proc_time_group_by_size:  (pt1_group_by_size   -. pt0_group_by_size)
+    ~proc_time_group_by_head:  (pt1_group_by_sample -. pt0_group_by_sample)
+    ~proc_time_group_by_digest:(pt1_group_by_digest -. pt0_group_by_digest)
+
+let get_opt () : opt =
+  let assert_ test x msg =
+    if not (test x) then begin
+      eprintf "%s\n%!" msg;
       exit 1
     end
   in
+  let assert_file_exists path =
+    assert_ Sys.file_exists path (sprintf "File does not exist: %S" path)
+  in
   let assert_file_is_dir path =
-    if Sys.is_directory path then
-      ()
-    else begin
-      eprintf "File is not a directory: %S\n%!" path;
-      exit 1
-    end
+    assert_ Sys.is_directory path (sprintf "File is not a directory: %S" path)
   in
+  let input  = ref Stdin in
+  let output = ref Stdout in
+  let ignore = ref (fun _ -> false) in
+  let sample = ref 512 in
+  let njobs  = ref 6 in
+  let input_delim_null = ref false in
   let spec =
     [ ( "-out"
       , Arg.String (fun path ->
@@ -161,6 +666,30 @@ let () =
         )
       , " Output to this directory instead of stdout."
       )
+    ; ( "-ignore"
+      , Arg.String (fun regexp ->
+          let regexp = Str.regexp regexp in
+          ignore := fun string -> Str.string_match regexp string 0)
+      , " Ignore file paths which match this regexp pattern (see Str module)."
+      )
+    ; ( "-sample"
+      , Arg.Set_int sample
+      , (sprintf " Byte size of file samples to use. Default: %d" !sample)
+      )
+    ; ( "-j"
+      , Arg.Set_int njobs
+      , (sprintf " Number of parallel jobs. Default: %d" !njobs)
+      )
+    ; ( "-0"
+      , Arg.Set input_delim_null
+      , ( sprintf
+            ( " Delimit input paths by null character instead of a newline."
+            ^^" Meaningful only when reading candidate paths from stdin."
+            ^^" Default: %B"
+            )
+            !input_delim_null
+        )
+      )
     ]
   in
   Arg.parse
@@ -169,10 +698,23 @@ let () =
       assert_file_exists path;
       assert_file_is_dir path;
       match !input with
-      | Paths_on_stdin ->
-          input := Root_paths [path]
-      | Root_paths paths ->
-          input := Root_paths (path :: paths)
+      | Stdin ->
+          input := Directories [path]
+      | Directories paths ->
+          input := Directories (path :: paths)
     )
     "";
-  main !input !output
+  assert_
+    (fun x -> x > 0)
+    !sample
+    (sprintf "Sample size cannot be negative: %d" !sample);
+  { input  = !input
+  ; output = !output
+  ; ignore = !ignore
+  ; sample = !sample
+  ; njobs  = !njobs
+  ; delim_null = !input_delim_null
+  }
+
+let () =
+  main (get_opt ())