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-rw-r--r--lib/kernel/src/file_io_server.erl21
1 files changed, 20 insertions, 1 deletions
diff --git a/lib/kernel/src/file_io_server.erl b/lib/kernel/src/file_io_server.erl
index 2b35d2acfb..34d5497a4a 100644
--- a/lib/kernel/src/file_io_server.erl
+++ b/lib/kernel/src/file_io_server.erl
@@ -68,7 +68,8 @@ do_start(Spawn, Owner, FileName, ModeList) ->
erlang:dt_restore_tag(Utag),
%% process_flag(trap_exit, true),
case parse_options(ModeList) of
- {ReadMode, UnicodeMode, Opts} ->
+ {ReadMode, UnicodeMode, Opts0} ->
+ Opts = maybe_add_read_ahead(ReadMode, Opts0),
case raw_file_io:open(FileName, [raw | Opts]) of
{error, Reason} = Error ->
Self ! {Ref, Error},
@@ -158,6 +159,24 @@ valid_enc({utf32,little}) ->
valid_enc(_Other) ->
{error,badarg}.
+%% Add a small read_ahead buffer if the file is opened for reading
+%% only in list mode and no read_ahead is already given.
+maybe_add_read_ahead(binary, Opts) ->
+ Opts;
+maybe_add_read_ahead(list, Opts) ->
+ P = fun(read_ahead) -> true;
+ ({read_ahead,_}) -> true;
+ (append) -> true;
+ (exclusive) -> true;
+ (write) -> true;
+ (_) -> false
+ end,
+ case lists:any(P, Opts) of
+ false ->
+ [{read_ahead, 4096}|Opts];
+ true ->
+ Opts
+ end.
server_loop(#state{mref = Mref} = State) ->
receive