[Omake] Re: [CUCS Bug 555] Should we use "sloppy" NFS-safe locking in addition to lockf?

[Jason Hickey]

Looks good to me,

Jason

Aleksey Nogin wrote:
> Jason,
> 
> I am thinking about making the db_file field in the Omake_env.Static.t 
> type (the field that would normally contain an fd for the .omc) into an 
> option - so that if for some reason (such as a non-working lockf or an 
> ro $HOME) we've failed to create the .omc, we can still continue, but 
> without any caching. A partial patch is attached.
> 
> What do you think?
> 
> On 15.03.2006 15:59, Bugzilla - Please Use the Web to Reply wrote:
> 
>> Reply at: http://cvs.cs.cornell.edu:12000/bugzilla/show_bug.cgi?id=555
> 
> 
>> ------- Additional Comments From daniel at peng.dyndns.org  2006-03-15 
>> 18:59 Eastern -------
>> I think the problem is more serious than you suggest.  I can't use 
>> Omake _at
>> all_ because my home directory is mounted over NFS, and locking 
>> fails.  omake
>> gives this totally opaque error when I try to omake metaprl:
>>
>> *** omake error:
>>    File Omake_builtin: line 0, characters 0-0
>>    can't open object: /usr/lib/omake/Pervasives.om
>>
>> strace reveals what's going on:
>>
>> open("/home/dpeng/.omake/cache/usr/lib/omake/Pervasives.omc",
>> O_RDWR|O_CREAT|O_LARGEFILE, 0666) = 4
>> fcntl64(4, F_SETLKW64, {type=F_WRLCK, whence=SEEK_CUR, start=0, 
>> len=1073741823},
>> 0xbffff22c) = -1 ENOLCK (No locks available)
>> write(2, "*** omake error:\n   File Omake_b"..., 114*** omake error:
>>    File Omake_builtin: line 0, characters 0-0
>>    can't open object: /usr/lib/omake/Pervasives.om
>> ) = 114
>> exit_group(123)                         = ?
>>
> 
> 
> 
> ------------------------------------------------------------------------
> 
> Index: src/env/omake_env.ml
> ===================================================================
> --- src/env/omake_env.ml	(revision 8889)
> +++ src/env/omake_env.ml	(working copy)
> @@ -1025,7 +1025,7 @@
>      * A .omc file.
>      *)
>     type t =
> -      { db_file         : Unix.file_descr;
> +      { db_file         : Unix.file_descr option;
>          db_name         : Node.t;
>          db_digest       : string;
>          db_env          : venv;
> @@ -1075,14 +1075,20 @@
>              name
>        in
>        let name = name ^ ".omc" in
> -      let target_name, target_fd =
> -         try Omake_state.lock_cache_file dir name with
> +      let target_fd =
> +         try 
> +            let target_name, target_fd =
> +               Omake_state.lock_cache_file dir name
> +            in
> +               if !debug_db then
> +                  eprintf "@[<v 3>Omake_db.create:@ %a --> %s@]@." pp_print_node source target_name;
> +               Some target_fd
> +         with
>              Unix.Unix_error _
>            | Failure _ ->
> -               raise Not_found
> +               eprintf "@[<v 3>OMake warning: could not create and/or lock a cache file for@ %s@]@." source_name;
> +               None
>        in
> -         if !debug_db then
> -            eprintf "@[<v 3>Omake_db.create:@ %a --> %s@]@." pp_print_node source target_name;
>           { db_file         = target_fd;
>             db_name         = source;
>             db_digest       = digest;
> @@ -1094,25 +1100,26 @@
>     (*
>      * Close the file.
>      *)
> -   let close info =
> -      if !debug_db then
> -         eprintf "Omake_db.close: %a at ." pp_print_node info.db_name;
> -      Unix.close info.db_file
> +   let close = function
> +      { db_file = Some fd } ->
> +         if !debug_db then
> +            eprintf "Omake_db.close: %a at ." pp_print_node info.db_name;
> +         Unix.close fd
> +    | { db_file = None } ->
> +         ()
>  
>     (*
>      * Add the three kinds of entries.
>      *)
>     let add_ir info ir =
> -      let { db_file   = fd;
> -            db_name   = name;
> -            db_digest = digest;
> -            db_env    = venv
> -          } = info
> -      in
> -         if !debug_db then
> -            eprintf "Omake_db.add_ir: %a at ." pp_print_node name;
> -         venv_marshal venv (fun () ->
> -               Lm_db.add fd (Node.absname name) ir_tag Omake_magic.ir_magic digest ir) ()
> +      match info with
> +         { db_file = Some fd; db_name = name; db_digest = digest; db_env = venv } ->
> +            if !debug_db then
> +               eprintf "Omake_db.add_ir: %a at ." pp_print_node name;
> +            venv_marshal venv (fun () ->
> +                  Lm_db.add fd (Node.absname name) ir_tag Omake_magic.ir_magic digest ir) ()
> +       | { db_file = None } ->
> +            ()
>  
>     let add_object info obj =
>        let { db_file   = fd;
> 
> 
> ------------------------------------------------------------------------
> 
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-- 
Jason Hickey                  http://www.cs.caltech.edu/~jyh
Caltech Computer Science      Tel: 626-395-6568 FAX: 626-792-4257