Module Linebuf

module Linebuf: sig .. end
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.

type t 
The type of a line buffer.
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
val create : ?pos:Int64.t ->
?close_on_eof:bool ->
?null_hack:[ `Off | `Retry | `Retry_then_fail ] ->
?eprint_nulls:bool ->
?follow_deletes:bool ->
?signal_on_truncate_or_delete:bool -> string -> t
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 close : t -> unit
Closes the line buffer (and the underlying file).
val is_closed : t -> bool
Returns whether or not the line buffer is closed
val try_read : t -> string option
Tries to read a line from the file. If no more lines are available, returns None.
val try_read_lnum : t -> (lnum * string) option
try_read_lnum is like try_read except also provides the line number of the read line.
val try_read_lnum_verbose : t -> result
Like try_read, except that it returns more verbose errors
val read : t -> string
Calls try_read every 0.01 seconds and returns when a line is available.
val tail : t -> unit
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 unsafe_tail : t -> unit
Same as tail except it may return before a new line is available on the file i.e. it (usually) doesn't block. Note that this does interact with files in a fairly naive way, so there's no guarantee that it absolutely doesn't block.

Note that when this functions is called, the next line that's read may be a partial line. After that first line, only full lines will be read.

val name : t -> string
val reset : t -> unit
reopens the file and seeks to the beginning. Also recovers the ability to get line numbers if tail has been called