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%%

%% Licensed to the Apache Software Foundation (ASF) under one

%% or more contributor license agreements. See the NOTICE file

%% distributed with this work for additional information

%% regarding copyright ownership. The ASF licenses this file

%% to you under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0

%%

%% Unless required by applicable law or agreed to in writing,

%% software distributed under the License is distributed on an

%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

%% KIND, either express or implied. See the License for the

%% specific language governing permissions and limitations

%% under the License.

%%

-module(thrift_framed_transport).

-behaviour(gen_server).

-behaviour(thrift_transport).

%% API

-export([new/1]).

%% gen_server callbacks

-export([init/1, handle_call/3, handle_cast/2, handle_info/2,

         terminate/2, code_change/3]).

%% thrift_transport callbacks

-export([write/2, read/2, flush/1, close/1]).

-record(framed_transport, {wrapped, % a thrift_transport

                           read_buffer, % iolist()

                           write_buffer % iolist()

                          }).

%%====================================================================

%% API

%%====================================================================

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

%% Function: start_link() -> {ok,Pid} | ignore | {error,Error}

%% Description: Starts the server

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

new(WrappedTransport) ->

    case gen_server:start_link(?MODULE, [WrappedTransport], []) of

        {ok, Pid} ->

            thrift_transport:new(?MODULE, Pid);

        Else ->

            Else

    end.

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

%% Function: write(Transport, Data) -> ok

%%

%% Data = iolist()

%%

%% Description: Writes data into the buffer

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

write(Transport, Data) ->

    gen_server:call(Transport, {write, Data}).

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

%% Function: flush(Transport) -> ok

%%

%% Description: Flushes the buffer through to the wrapped transport

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

flush(Transport) ->

    gen_server:call(Transport, flush).

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

%% Function: close(Transport) -> ok

%%

%% Description: Closes the transport and the wrapped transport

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

close(Transport) ->

    gen_server:cast(Transport, close).

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

%% Function: Read(Transport, Len) -> {ok, Data}

%%

%% Data = binary()

%%

%% Description: Reads data through from the wrapped transoprt

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

read(Transport, Len) when is_integer(Len) ->

    gen_server:call(Transport, {read, Len}).

%%====================================================================

%% gen_server callbacks

%%====================================================================

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

%% Function: init(Args) -> {ok, State} |

%%                         {ok, State, Timeout} |

%%                         ignore               |

%%                         {stop, Reason}

%% Description: Initiates the server

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

init([Wrapped]) ->

    {ok, #framed_transport{wrapped = Wrapped,

                           read_buffer = [],

                           write_buffer = []}}.

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

%% Function: %% handle_call(Request, From, State) -> {reply, Reply, State} |

%%                                      {reply, Reply, State, Timeout} |

%%                                      {noreply, State} |

%%                                      {noreply, State, Timeout} |

%%                                      {stop, Reason, Reply, State} |

%%                                      {stop, Reason, State}

%% Description: Handling call messages

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

handle_call({write, Data}, _From, State = #framed_transport{write_buffer = WBuf}) ->

    {reply, ok, State#framed_transport{write_buffer = [WBuf, Data]}};

handle_call({read, Len}, _From, State = #framed_transport{wrapped = Wrapped,

                                                          read_buffer = RBuf}) ->

    {RBuf1, RBuf1Size} =

        %% if the read buffer is empty, read another frame

        %% otherwise, just read from what's left in the buffer

        case iolist_size(RBuf) of

                %% read the frame length

                {ok, <<FrameLen:32/integer-signed-big, _/binary>>} =

                    thrift_transport:read(Wrapped, 4),

                %% then read the data

                {ok, Bin} =

                    thrift_transport:read(Wrapped, FrameLen),

                {Bin, erlang:byte_size(Bin)};

            Sz ->

                {RBuf, Sz}

        end,

    %% pull off Give bytes, return them to the user, leave the rest in the buffer

    Give = min(RBuf1Size, Len),

    <<Data:Give/binary, RBuf2/binary>> = iolist_to_binary(RBuf1),

    Response = {ok, Data},

    State1 = State#framed_transport{read_buffer=RBuf2},

    {reply, Response, State1};

handle_call(flush, _From, State) ->

    {Response, State1} = do_flush(State),

    {reply, Response, State1}.

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

%% Function: handle_cast(Msg, State) -> {noreply, State} |

%%                                      {noreply, State, Timeout} |

%%                                      {stop, Reason, State}

%% Description: Handling cast messages

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

handle_cast(close, State) ->

    {_, State1} = do_flush(State),

    %% Wrapped is closed by terminate/2

    %%  error_logger:info_msg("thrift_framed_transport ~p: closing", [self()]),

    {stop, normal, State};

handle_cast(Msg, State=#framed_transport{}) ->

    {noreply, State}.

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

%% Function: handle_info(Info, State) -> {noreply, State} |

%%                                       {noreply, State, Timeout} |

%%                                       {stop, Reason, State}

%% Description: Handling all non call/cast messages

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

handle_info(_Info, State) ->

    {noreply, State}.

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

%% Function: terminate(Reason, State) -> void()

%% Description: This function is called by a gen_server when it is about to

%% terminate. It should be the opposite of Module:init/1 and do any necessary

%% cleaning up. When it returns, the gen_server terminates with Reason.

%% The return value is ignored.

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

terminate(_Reason, State = #framed_transport{wrapped=Wrapped}) ->

    thrift_transport:close(Wrapped),

    ok.

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

%% Func: code_change(OldVsn, State, Extra) -> {ok, NewState}

%% Description: Convert process state when code is changed

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

code_change(_OldVsn, State, _Extra) ->

    {ok, State}.

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

%%% Internal functions

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

do_flush(State = #framed_transport{write_buffer = Buffer,

                                   wrapped = Wrapped}) ->

    FrameLen = iolist_size(Buffer),

    Data     = [<<FrameLen:32/integer-signed-big>>, Buffer],

    Response = thrift_transport:write(Wrapped, Data),

    thrift_transport:flush(Wrapped),

    State1 = State#framed_transport{write_buffer = []},

    {Response, State1}.

min(A,B) when A<B -> A;

min(_,B)          -> B.