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%% The contents of this file are subject to the Mozilla Public License
%% Version 1.1 (the "License"); you may not use this file except in
%% compliance with the License. You may obtain a copy of the License at
%% http://www.mozilla.org/MPL/
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
%% License for the specific language governing rights and limitations
%% under the License.
%%
%% The Original Code is RabbitMQ.
%%
%% The Initial Developers of the Original Code are LShift Ltd,
%% Cohesive Financial Technologies LLC, and Rabbit Technologies Ltd.
%%
%% Portions created before 22-Nov-2008 00:00:00 GMT by LShift Ltd,
%% Cohesive Financial Technologies LLC, or Rabbit Technologies Ltd
%% are Copyright (C) 2007-2008 LShift Ltd, Cohesive Financial
%% Technologies LLC, and Rabbit Technologies Ltd.
%%
%% Portions created by LShift Ltd are Copyright (C) 2007-2010 LShift
%% Ltd. Portions created by Cohesive Financial Technologies LLC are
%% Copyright (C) 2007-2010 Cohesive Financial Technologies
%% LLC. Portions created by Rabbit Technologies Ltd are Copyright
%% (C) 2007-2010 Rabbit Technologies Ltd.
%%
%% All Rights Reserved.
%%
%% Contributor(s): ______________________________________.
%%
-module(rabbit_msg_file).
-export([append/3, read/2, scan/2]).
%%----------------------------------------------------------------------------
-include("rabbit_msg_store.hrl").
-define(INTEGER_SIZE_BYTES, 8).
-define(INTEGER_SIZE_BITS, (8 * ?INTEGER_SIZE_BYTES)).
-define(WRITE_OK_SIZE_BITS, 8).
-define(WRITE_OK_MARKER, 255).
-define(FILE_PACKING_ADJUSTMENT, (1 + ?INTEGER_SIZE_BYTES)).
-define(GUID_SIZE_BYTES, 16).
-define(GUID_SIZE_BITS, (8 * ?GUID_SIZE_BYTES)).
-define(SCAN_BLOCK_SIZE, 4194304). %% 4MB
%%----------------------------------------------------------------------------
-ifdef(use_specs).
-type(io_device() :: any()).
-type(position() :: non_neg_integer()).
-type(msg_size() :: non_neg_integer()).
-type(file_size() :: non_neg_integer()).
-spec(append/3 :: (io_device(), rabbit_guid:guid(), msg()) ->
rabbit_types:ok_or_error2(msg_size(), any())).
-spec(read/2 :: (io_device(), msg_size()) ->
rabbit_types:ok_or_error2({rabbit_guid:guid(), msg()},
any())).
-spec(scan/2 :: (io_device(), file_size()) ->
{'ok', [{rabbit_guid:guid(), msg_size(), position()}],
position()}).
-endif.
%%----------------------------------------------------------------------------
append(FileHdl, Guid, MsgBody)
when is_binary(Guid) andalso size(Guid) =:= ?GUID_SIZE_BYTES ->
MsgBodyBin = term_to_binary(MsgBody),
MsgBodyBinSize = size(MsgBodyBin),
Size = MsgBodyBinSize + ?GUID_SIZE_BYTES,
case file_handle_cache:append(FileHdl,
<<Size:?INTEGER_SIZE_BITS,
Guid:?GUID_SIZE_BYTES/binary,
MsgBodyBin:MsgBodyBinSize/binary,
?WRITE_OK_MARKER:?WRITE_OK_SIZE_BITS>>) of
ok -> {ok, Size + ?FILE_PACKING_ADJUSTMENT};
KO -> KO
end.
read(FileHdl, TotalSize) ->
Size = TotalSize - ?FILE_PACKING_ADJUSTMENT,
BodyBinSize = Size - ?GUID_SIZE_BYTES,
case file_handle_cache:read(FileHdl, TotalSize) of
{ok, <<Size:?INTEGER_SIZE_BITS,
Guid:?GUID_SIZE_BYTES/binary,
MsgBodyBin:BodyBinSize/binary,
?WRITE_OK_MARKER:?WRITE_OK_SIZE_BITS>>} ->
{ok, {Guid, binary_to_term(MsgBodyBin)}};
KO -> KO
end.
scan(FileHdl, FileSize) when FileSize >= 0 ->
scan(FileHdl, FileSize, <<>>, 0, [], 0).
scan(_FileHdl, FileSize, _Data, FileSize, Acc, ScanOffset) ->
{ok, Acc, ScanOffset};
scan(FileHdl, FileSize, Data, ReadOffset, Acc, ScanOffset) ->
Read = lists:min([?SCAN_BLOCK_SIZE, (FileSize - ReadOffset)]),
case file_handle_cache:read(FileHdl, Read) of
{ok, Data1} ->
{Data2, Acc1, ScanOffset1} =
scan(<<Data/binary, Data1/binary>>, Acc, ScanOffset),
ReadOffset1 = ReadOffset + size(Data1),
scan(FileHdl, FileSize, Data2, ReadOffset1, Acc1, ScanOffset1);
_KO ->
{ok, Acc, ScanOffset}
end.
scan(<<>>, Acc, Offset) ->
{<<>>, Acc, Offset};
scan(<<0:?INTEGER_SIZE_BITS, _Rest/binary>>, Acc, Offset) ->
{<<>>, Acc, Offset}; %% Nothing to do other than stop.
scan(<<Size:?INTEGER_SIZE_BITS, GuidAndMsg:Size/binary,
WriteMarker:?WRITE_OK_SIZE_BITS, Rest/binary>>, Acc, Offset) ->
TotalSize = Size + ?FILE_PACKING_ADJUSTMENT,
case WriteMarker of
?WRITE_OK_MARKER ->
%% Here we take option 5 from
%% http://www.erlang.org/cgi-bin/ezmlm-cgi?2:mss:1569 in
%% which we read the Guid as a number, and then convert it
%% back to a binary in order to work around bugs in
%% Erlang's GC.
<<GuidNum:?GUID_SIZE_BITS, _Msg/binary>> =
<<GuidAndMsg:Size/binary>>,
<<Guid:?GUID_SIZE_BYTES/binary>> = <<GuidNum:?GUID_SIZE_BITS>>,
scan(Rest, [{Guid, TotalSize, Offset} | Acc], Offset + TotalSize);
_ ->
scan(Rest, Acc, Offset + TotalSize)
end;
scan(Data, Acc, Offset) ->
{Data, Acc, Offset}.
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