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(******************************************************************************
* Core *
* *
* Copyright (C) 2008- Jane Street Holding, LLC *
* Contact: opensource@janestreet.com *
* WWW: http://www.janestreet.com/ocaml *
* *
* *
* This library is free software; you can redistribute it and/or *
* modify it under the terms of the GNU Lesser General Public *
* License as published by the Free Software Foundation; either *
* version 2 of the License, or (at your option) any later version. *
* *
* This library 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 *
* Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public *
* License along with this library; if not, write to the Free Software *
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA *
* *
******************************************************************************)
(** Line-by-line reading of a file. A line buffer allows one to read
one line of a file at a time, blocking until a line is available.
Line buffers are distinct from Pervasives.read_line in that they
"notice" new data arriving in the file more quickly. *)
(** The type of a line buffer. *)
type t
type error_type = Null_retry | Too_many_nulls | Exception of string * exn
type lnum = Known of int | Unknown
type result =
| Success of lnum * string
| Nothing_available
| Error of error_type
| Fatal_error of string * exn
exception File_truncated_or_deleted
(** Open a line buffer from the passed filename. If [close_on_eof] is
set, when [eof] is read, the file will be closed and reopened if
necessary. if [follow_deletes] is set, then when [eof] is read linebuf
will stat the file, and if it has been deleted and recreated it
will open the new file. If [eprint_nulls] is set, then when nulls are found,
a warning message will be printed to stderr. [null_hack] specifies the
behaviour of the linebuf upon reception of null characters in the file (as
seen when tailing files over CIFS).
Null hack options:
`Off: don't check for nulls, just keep going.
`Retry: close and reopen file when nulls are read from the file.
If max_null_retries is reached, then pass the line with nulls.
`Retry_then_fail: the same as retry, except that an exception is raised
once max_null_retries is reached.
*)
val create :
?pos:Int64.t
-> ?close_on_eof:bool
-> ?null_hack:[ `Off | `Retry_then_fail | `Retry ]
-> ?eprint_nulls:bool
-> ?follow_deletes:bool
-> ?signal_on_truncate_or_delete:bool
-> string
-> t
(** Closes the line buffer (and the underlying file). *)
val close : t -> unit
(** Returns whether or not the line buffer is closed *)
val is_closed : t -> bool
(** Tries to read a line from the file. If no more lines are available,
returns [None]. *)
val try_read : t -> string option
(** [try_read_lnum] is like [try_read] except also provides the line number of the
read line. *)
val try_read_lnum : t -> (lnum * string) option
(** Like try_read, except that it returns more verbose errors *)
val try_read_lnum_verbose : t -> result
(** Calls try_read every 0.01 seconds and returns when a line is available. *)
val read : t -> string
(** Seeks to the end of the file and blocks until another line is available -- this new
line is not returned. Successive return values of [try_read_lnum] and
[try_read_lnum] will return [Unknown] as the current line number until
[reset] is called *)
val tail : t -> unit
(** Same as [tail] except it may return before a new line is available on the file
(i.e. it doesn't block). *)
val unsafe_tail : t -> unit
val name : t -> string
(** reopens the file and seeks to the beginning. Also recovers the ability to get line
numbers if [tail] has been called *)
val reset : t -> unit
|
