75 lines
3.3 KiB
OCaml
75 lines
3.3 KiB
OCaml
(*****************************************************************************)
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(* *)
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(* Open Source License *)
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(* Copyright (c) 2018 Dynamic Ledger Solutions, Inc. <contact@tezos.com> *)
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(* *)
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(* Permission is hereby granted, free of charge, to any person obtaining a *)
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(* copy of this software and associated documentation files (the "Software"),*)
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(* to deal in the Software without restriction, including without limitation *)
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(* the rights to use, copy, modify, merge, publish, distribute, sublicense, *)
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(* and/or sell copies of the Software, and to permit persons to whom the *)
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(* Software is furnished to do so, subject to the following conditions: *)
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(* *)
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(* The above copyright notice and this permission notice shall be included *)
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(* in all copies or substantial portions of the Software. *)
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(* *)
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(* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR*)
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(* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, *)
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(* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL *)
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(* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER*)
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(* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING *)
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(* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER *)
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(* DEALINGS IN THE SOFTWARE. *)
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(* *)
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(*****************************************************************************)
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open Error_monad
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let create_inner
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lock_command
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?(close_on_exec=true)
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?(unlink_on_exit=false) fn =
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protect begin fun () ->
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Lwt_unix.openfile fn Unix.[O_CREAT ; O_WRONLY; O_TRUNC] 0o644 >>= fun fd ->
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if close_on_exec then Lwt_unix.set_close_on_exec fd ;
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Lwt_unix.lockf fd lock_command 0 >>= fun () ->
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if unlink_on_exit then
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Lwt_main.at_exit (fun () -> Lwt_unix.unlink fn) ;
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let pid_str = string_of_int @@ Unix.getpid () in
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Lwt_unix.write_string fd pid_str 0 (String.length pid_str) >>= fun _ ->
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return_unit
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end
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let create = create_inner Unix.F_TLOCK
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let blocking_create
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?timeout
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?(close_on_exec=true)
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?(unlink_on_exit=false) fn =
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let create () =
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create_inner Unix.F_LOCK ~close_on_exec ~unlink_on_exit fn in
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match timeout with
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| None -> create ()
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| Some duration -> with_timeout (Lwt_unix.sleep duration) (fun _ -> create ())
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let is_locked fn =
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if not @@ Sys.file_exists fn then return_false else
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protect begin fun () ->
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Lwt_unix.openfile fn [Unix.O_RDONLY] 0o644 >>= fun fd ->
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Lwt.finalize (fun () ->
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Lwt.try_bind
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(fun () -> Lwt_unix.(lockf fd F_TEST 0))
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(fun () -> return_false)
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(fun _ -> return_true))
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(fun () -> Lwt_unix.close fd)
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end
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let get_pid fn =
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let open Lwt_io in
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protect begin fun () ->
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with_file ~mode:Input fn begin fun ic ->
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read ic >>= fun content ->
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return (int_of_string content)
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end
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end
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