[Libguestfs] [PATCH 1/3] generator: isolate memoized cache in own module

Isolate the logic for the memoized disk cache in a small module, so it can be reused for other tools. Other than refactoring, there should be no behaviour changes. --- generator/Makefile.am | 3 ++ generator/memoized_cache.ml | 62 ++++++++++++++++++++++++ generator/memoized_cache.mli | 29 ++++++++++++ generator/utils.ml | 92 ++++++++++++++++-------------------- 4 files changed, 134 insertions(+), 52 deletions(-) create mode 100644 generator/memoized_cache.ml create mode 100644 generator/memoized_cache.mli diff --git a/generator/Makefile.am b/generator/Makefile.am index 283cf3769..fd854ad03 100644 --- a/generator/Makefile.am +++ b/generator/Makefile.am @@ -85,6 +85,8 @@ sources = \ lua.mli \ main.ml \ main.mli \ + memoized_cache.ml \ + memoized_cache.mli \ OCaml.ml \ OCaml.mli \ optgroups.ml \ @@ -121,6 +123,7 @@ sources = \ # In build dependency order. objects = \ types.cmo \ + memoized_cache.cmo \ utils.cmo \ proc_nr.cmo \ actions_augeas.cmo \ diff --git a/generator/memoized_cache.ml b/generator/memoized_cache.ml new file mode 100644 index 000000000..91493942e --- /dev/null +++ b/generator/memoized_cache.ml @@ -0,0 +1,62 @@ +(* libguestfs + * Copyright (C) 2009-2019 Red Hat Inc. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + *) + +(* Please read generator/README first. *) + +open Std_utils + +open Printf + +type ('a, 'b) t = { + memo : ('a, 'b) Hashtbl.t; + filename : string; + lookup_fn : 'a -> 'b; + batch_size : int; + mutable unsaved_count : int; +} + +let memo_save t = + with_open_out t.filename + (fun chan -> output_value chan t.memo); + t.unsaved_count <- 0 + +let memo_updated t = + t.unsaved_count <- t.unsaved_count + 1; + if t.unsaved_count >= t.batch_size then + memo_save t + +let create ?(version = 1) ?(batch_size = 100) name lookup_fn = + let filename = sprintf "generator/.%s.data.version.%d" name version in + let memo = + try with_open_in filename input_value + with _ -> Hashtbl.create 13 in + { + memo; filename; lookup_fn; batch_size; unsaved_count = 0; + } + +let save t = + if t.unsaved_count > 0 then + memo_save t + +let find t key = + try Hashtbl.find t.memo key + with Not_found -> + let res = t.lookup_fn key in + Hashtbl.add t.memo key res; + memo_updated t; + res diff --git a/generator/memoized_cache.mli b/generator/memoized_cache.mli new file mode 100644 index 000000000..7ad6c7319 --- /dev/null +++ b/generator/memoized_cache.mli @@ -0,0 +1,29 @@ +(* libguestfs + * Copyright (C) 2009-2019 Red Hat Inc. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + *) + +(* Please read generator/README first. *) + +(** A simple memoized cache. *) + +type ('a, 'b) t + +val create : ?version:int -> ?batch_size:int -> string -> ('a -> 'b) -> ('a, 'b) t + +val find : ('a, 'b) t -> 'a -> 'b + +val save : ('a, 'b) t -> unit diff --git a/generator/utils.ml b/generator/utils.ml index 460b61384..dea352afd 100644 --- a/generator/utils.ml +++ b/generator/utils.ml @@ -176,26 +176,44 @@ let html_escape text = type memo_key = int option * bool * bool * string * string (* width, trim, discard, name, longdesc *) type memo_value = string list (* list of lines of POD file *) +let run_pod2text (width, trim, discard, name, longdesc) = + let filename, chan = Filename.open_temp_file "gen" ".tmp" in + fprintf chan "=encoding utf8\n\n"; + fprintf chan "=head1 %s\n\n%s\n" name longdesc; + close_out chan; + let cmd = + match width with + | Some width -> + sprintf "pod2text -w %d %s" width (Filename.quote filename) + | None -> + sprintf "pod2text %s" (Filename.quote filename) in + let chan = open_process_in cmd in + let lines = ref [] in + let rec loop i = + let line = input_line chan in + if i = 1 && discard then (* discard the first line of output *) + loop (i+1) + else ( + let line = if trim then String.triml line else line in + lines := line :: !lines; + loop (i+1) + ) in + let lines : memo_value = try loop 1 with End_of_file -> List.rev !lines in + unlink filename; + (match close_process_in chan with + | WEXITED 0 -> () + | WEXITED i -> + failwithf "pod2text: process exited with non-zero status (%d)" i + | WSIGNALED i | WSTOPPED i -> + failwithf "pod2text: process signalled or stopped by signal %d" i + ); + lines +let pod2text_memo : (memo_key, memo_value) Memoized_cache.t = + Memoized_cache.create ~version:2 "pod2text" run_pod2text -let pod2text_memo_filename = "generator/.pod2text.data.version.2" -let pod2text_memo : (memo_key, memo_value) Hashtbl.t = - try with_open_in pod2text_memo_filename input_value - with _ -> Hashtbl.create 13 -let pod2text_memo_unsaved_count = ref 0 let pod2text_memo_atexit = ref false let pod2text_memo_save () = - with_open_out pod2text_memo_filename - (fun chan -> output_value chan pod2text_memo) -let pod2text_memo_updated () = - if not (!pod2text_memo_atexit) then ( - at_exit pod2text_memo_save; - pod2text_memo_atexit := true; - ); - pod2text_memo_unsaved_count := !pod2text_memo_unsaved_count + 1; - if !pod2text_memo_unsaved_count >= 100 then ( - pod2text_memo_save (); - pod2text_memo_unsaved_count := 0; - ) + Memoized_cache.save pod2text_memo (* Useful if you need the longdesc POD text as plain text. Returns a * list of lines. @@ -205,41 +223,11 @@ let pod2text_memo_updated () = *) let pod2text ?width ?(trim = true) ?(discard = true) name longdesc = let key : memo_key = width, trim, discard, name, longdesc in - try Hashtbl.find pod2text_memo key - with Not_found -> - let filename, chan = Filename.open_temp_file "gen" ".tmp" in - fprintf chan "=encoding utf8\n\n"; - fprintf chan "=head1 %s\n\n%s\n" name longdesc; - close_out chan; - let cmd = - match width with - | Some width -> - sprintf "pod2text -w %d %s" width (Filename.quote filename) - | None -> - sprintf "pod2text %s" (Filename.quote filename) in - let chan = open_process_in cmd in - let lines = ref [] in - let rec loop i = - let line = input_line chan in - if i = 1 && discard then (* discard the first line of output *) - loop (i+1) - else ( - let line = if trim then String.triml line else line in - lines := line :: !lines; - loop (i+1) - ) in - let lines : memo_value = try loop 1 with End_of_file -> List.rev !lines in - unlink filename; - (match close_process_in chan with - | WEXITED 0 -> () - | WEXITED i -> - failwithf "pod2text: process exited with non-zero status (%d)" i - | WSIGNALED i | WSTOPPED i -> - failwithf "pod2text: process signalled or stopped by signal %d" i - ); - Hashtbl.add pod2text_memo key lines; - pod2text_memo_updated (); - lines + if not (!pod2text_memo_atexit) then ( + at_exit pod2text_memo_save; + pod2text_memo_atexit := true; + ); + Memoized_cache.find pod2text_memo key (* Compare two actions (for sorting). *) let action_compare { name = n1 } { name = n2 } = compare n1 n2 -- 2.21.0