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path: root/src/rabbit_framing_channel.erl
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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_framing_channel).
-include("rabbit.hrl").

-export([start_link/3, process/2, shutdown/1]).

%% internal
-export([mainloop/3]).

%%--------------------------------------------------------------------

start_link(Parent, ChannelPid, Protocol) ->
    {ok, proc_lib:spawn_link(
           fun () -> mainloop(Parent, ChannelPid, Protocol) end)}.

process(Pid, Frame) ->
    Pid ! {frame, Frame},
    ok.

shutdown(Pid) ->
    Pid ! terminate,
    ok.

%%--------------------------------------------------------------------

read_frame(ChannelPid) ->
    receive
        {frame, Frame}         -> Frame;
        terminate              -> rabbit_channel:shutdown(ChannelPid),
                                  read_frame(ChannelPid);
        Msg                    -> exit({unexpected_message, Msg})
    end.

mainloop(Parent, ChannelPid, Protocol) ->
    case read_frame(ChannelPid) of
        {method, MethodName, FieldsBin} ->
            Method = Protocol:decode_method_fields(MethodName, FieldsBin),
            case Protocol:method_has_content(MethodName) of
                true  -> {ClassId, _MethodId} = Protocol:method_id(MethodName),
                         case collect_content(ChannelPid, ClassId, Protocol) of
                             {ok, Content} ->
                                 rabbit_channel:do(ChannelPid, Method, Content),
                                 ?MODULE:mainloop(Parent, ChannelPid, Protocol);
                             {error, Reason} ->
                                 channel_exit(Parent, Reason, MethodName)
                         end;
                false -> rabbit_channel:do(ChannelPid, Method),
                         ?MODULE:mainloop(Parent, ChannelPid, Protocol)
            end;
        _ ->
            channel_exit(Parent, {unexpected_frame,
                                  "expected method frame, "
                                  "got non method frame instead",
                                  []}, none)
    end.

collect_content(ChannelPid, ClassId, Protocol) ->
    case read_frame(ChannelPid) of
        {content_header, ClassId, 0, BodySize, PropertiesBin} ->
            case collect_content_payload(ChannelPid, BodySize, []) of
                {ok, Payload} -> {ok, #content{
                                    class_id = ClassId,
                                    properties = none,
                                    properties_bin = PropertiesBin,
                                    protocol = Protocol,
                                    payload_fragments_rev = Payload}};
                Error         -> Error
            end;
        {content_header, HeaderClassId, 0, _BodySize, _PropertiesBin} ->
            {error, {unexpected_frame,
                     "expected content header for class ~w, "
                     "got one for class ~w instead",
                     [ClassId, HeaderClassId]}};
        _ ->
            {error, {unexpected_frame,
                     "expected content header for class ~w, "
                     "got non content header frame instead",
                     [ClassId]}}
    end.

collect_content_payload(_ChannelPid, 0, Acc) ->
    {ok, Acc};
collect_content_payload(ChannelPid, RemainingByteCount, Acc) ->
    case read_frame(ChannelPid) of
        {content_body, FragmentBin} ->
            collect_content_payload(ChannelPid,
                                    RemainingByteCount - size(FragmentBin),
                                    [FragmentBin | Acc]);
        _ ->
            {error, {unexpected_frame,
                     "expected content body, "
                     "got non content body frame instead",
                     []}}
    end.

channel_exit(Parent, {ErrorName, ExplanationFormat, Params}, MethodName) ->
    Reason = rabbit_misc:amqp_error(ErrorName, ExplanationFormat, Params,
                                    MethodName),
    Parent ! {channel_exit, self(), Reason}.