%%%------------------------------------------------------------------- %%% File : ibrowse.erl %%% Author : Chandrashekhar Mullaparthi %%% Description : Load balancer process for HTTP client connections. %%% %%% Created : 11 Oct 2003 by Chandrashekhar Mullaparthi %%%------------------------------------------------------------------- %% @author Chandrashekhar Mullaparthi %% @copyright 2005-2009 Chandrashekhar Mullaparthi %% @version 1.5.0 %% @doc The ibrowse application implements an HTTP 1.1 client. This %% module implements the API of the HTTP client. There is one named %% process called 'ibrowse' which assists in load balancing and maintaining configuration. There is one load balancing process per unique webserver. There is %% one process to handle one TCP connection to a webserver %% (implemented in the module ibrowse_http_client). Multiple connections to a %% webserver are setup based on the settings for each webserver. The %% ibrowse process also determines which connection to pipeline a %% certain request on. The functions to call are send_req/3, %% send_req/4, send_req/5, send_req/6. %% %%

Here are a few sample invocations.

%% %% %% ibrowse:send_req("http://intranet/messenger/", [], get). %%

%% %% ibrowse:send_req("http://www.google.com/", [], get, [], %% [{proxy_user, "XXXXX"}, %% {proxy_password, "XXXXX"}, %% {proxy_host, "proxy"}, %% {proxy_port, 8080}], 1000). %%

%% %%ibrowse:send_req("http://www.erlang.org/download/otp_src_R10B-3.tar.gz", [], get, [], %% [{proxy_user, "XXXXX"}, %% {proxy_password, "XXXXX"}, %% {proxy_host, "proxy"}, %% {proxy_port, 8080}, %% {save_response_to_file, true}], 1000). %%

%% %% ibrowse:send_req("http://www.erlang.org", [], head). %% %%

%% ibrowse:send_req("http://www.sun.com", [], options). %% %%

%% ibrowse:send_req("http://www.bbc.co.uk", [], trace). %% %%

%% ibrowse:send_req("http://www.google.com", [], get, [], %% [{stream_to, self()}]). %% %% %%

A driver exists which implements URL encoding in C, but the %% speed achieved using only erlang has been good enough, so the %% driver isn't actually used.

-module(ibrowse). -vsn('$Id: ibrowse.erl,v 1.8 2009/07/01 22:43:19 chandrusf Exp $ '). -behaviour(gen_server). %%-------------------------------------------------------------------- %% Include files %%-------------------------------------------------------------------- %%-------------------------------------------------------------------- %% External exports -export([start_link/0, start/0, stop/0]). %% gen_server callbacks -export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]). %% API interface -export([ rescan_config/0, rescan_config/1, get_config_value/1, get_config_value/2, spawn_worker_process/2, spawn_link_worker_process/2, stop_worker_process/1, send_req/3, send_req/4, send_req/5, send_req/6, send_req_direct/4, send_req_direct/5, send_req_direct/6, send_req_direct/7, stream_next/1, set_max_sessions/3, set_max_pipeline_size/3, set_dest/3, trace_on/0, trace_off/0, trace_on/2, trace_off/2, all_trace_off/0, show_dest_status/2 ]). -ifdef(debug). -compile(export_all). -endif. -import(ibrowse_lib, [ parse_url/1, get_value/3, do_trace/2 ]). -record(state, {trace = false}). -include("ibrowse.hrl"). -include_lib("stdlib/include/ms_transform.hrl"). -define(DEF_MAX_SESSIONS,10). -define(DEF_MAX_PIPELINE_SIZE,10). %%==================================================================== %% External functions %%==================================================================== %%-------------------------------------------------------------------- %% Function: start_link/0 %% Description: Starts the server %%-------------------------------------------------------------------- %% @doc Starts the ibrowse process linked to the calling process. Usually invoked by the supervisor ibrowse_sup %% @spec start_link() -> {ok, pid()} start_link() -> gen_server:start_link({local, ?MODULE}, ?MODULE, [], []). %% @doc Starts the ibrowse process without linking. Useful when testing using the shell start() -> gen_server:start({local, ?MODULE}, ?MODULE, [], [{debug, []}]). %% @doc Stop the ibrowse process. Useful when testing using the shell. stop() -> catch gen_server:call(ibrowse, stop). %% @doc This is the basic function to send a HTTP request. %% The Status return value indicates the HTTP status code returned by the webserver %% @spec send_req(Url::string(), Headers::headerList(), Method::method()) -> response() %% headerList() = [{header(), value()}] %% header() = atom() | string() %% value() = term() %% method() = get | post | head | options | put | delete | trace | mkcol | propfind | proppatch | lock | unlock | move | copy %% Status = string() %% ResponseHeaders = [respHeader()] %% respHeader() = {headerName(), headerValue()} %% headerName() = string() %% headerValue() = string() %% response() = {ok, Status, ResponseHeaders, ResponseBody} | {ibrowse_req_id, req_id() } | {error, Reason} %% req_id = term() %% ResponseBody = string() | {file, Filename} %% Reason = term() send_req(Url, Headers, Method) -> send_req(Url, Headers, Method, [], []). %% @doc Same as send_req/3. %% If a list is specified for the body it has to be a flat list. The body can also be a fun/0 or a fun/1.
%% If fun/0, the connection handling process will repeatdely call the fun until it returns an error or eof. 
Fun() = {ok, Data} | eof

%% If fun/1, the connection handling process will repeatedly call the fun with the supplied state until it returns an error or eof. 
Fun(State) = {ok, Data} | {ok, Data, NewState} | eof
%% @spec send_req(Url, Headers, Method::method(), Body::body()) -> response() %% body() = [] | string() | binary() | fun_arity_0() | {fun_arity_1(), initial_state()} %% initial_state() = term() send_req(Url, Headers, Method, Body) -> send_req(Url, Headers, Method, Body, []). %% @doc Same as send_req/4. %% For a description of SSL Options, look in the ssl manpage. If the %% HTTP Version to use is not specified, the default is 1.1. %%
%%

The host_header option is useful in the case where ibrowse is %% connecting to a component such as stunnel which then sets up a %% secure connection to a webserver. In this case, the URL supplied to %% ibrowse must have the stunnel host/port details, but that won't %% make sense to the destination webserver. This option can then be %% used to specify what should go in the Host header in %% the request.

%%
    %%
  • When both the options save_response_to_file and stream_to %% are specified, the former takes precedence.
    • %% %%
  • For the save_response_to_file option, the response body is saved to %% file only if the status code is in the 200-299 range. If not, the response body is returned %% as a string.
    • %%
  • Whenever an error occurs in the processing of a request, ibrowse will return as much %% information as it has, such as HTTP Status Code and HTTP Headers. When this happens, the response %% is of the form {error, {Reason, {stat_code, StatusCode}, HTTP_headers}}
    • %% %%
  • The inactivity_timeout option is useful when %% dealing with large response bodies and/or slow links. In these %% cases, it might be hard to estimate how long a request will take to %% complete. In such cases, the client might want to timeout if no %% data has been received on the link for a certain time interval.
    • %% %%
  • %% The connect_timeout option is to specify how long the %% client process should wait for connection establishment. This is %% useful in scenarios where connections to servers are usually setup %% very fast, but responses might take much longer compared to %% connection setup. In such cases, it is better for the calling %% process to timeout faster if there is a problem (DNS lookup %% delays/failures, network routing issues, etc). The total timeout %% value specified for the request will enforced. To illustrate using %% an example: %% %% ibrowse:send_req("http://www.example.com/cgi-bin/request", [], get, [], [{connect_timeout, 100}], 1000). %% %% In the above invocation, if the connection isn't established within %% 100 milliseconds, the request will fail with %% {error, conn_failed}.
    %% If connection setup succeeds, the total time allowed for the %% request to complete will be 1000 milliseconds minus the time taken %% for connection setup. %%
    • %%
%% %% @spec send_req(Url::string(), Headers::headerList(), Method::method(), Body::body(), Options::optionList()) -> response() %% optionList() = [option()] %% option() = {max_sessions, integer()} | %% {response_format,response_format()}| %% {stream_chunk_size, integer()} | %% {max_pipeline_size, integer()} | %% {trace, boolean()} | %% {is_ssl, boolean()} | %% {ssl_options, [SSLOpt]} | %% {pool_name, atom()} | %% {proxy_host, string()} | %% {proxy_port, integer()} | %% {proxy_user, string()} | %% {proxy_password, string()} | %% {use_absolute_uri, boolean()} | %% {basic_auth, {username(), password()}} | %% {cookie, string()} | %% {content_length, integer()} | %% {content_type, string()} | %% {save_response_to_file, srtf()} | %% {stream_to, process()} | %% {http_vsn, {MajorVsn, MinorVsn}} | %% {host_header, string()} | %% {inactivity_timeout, integer()} | %% {connect_timeout, integer()} | %% {transfer_encoding, {chunked, ChunkSize}} %% %% process() = pid() | atom() %% username() = string() %% password() = string() %% SSLOpt = term() %% ChunkSize = integer() %% srtf() = boolean() | filename() %% filename() = string() %% response_format() = list | binary send_req(Url, Headers, Method, Body, Options) -> send_req(Url, Headers, Method, Body, Options, 30000). %% @doc Same as send_req/5. %% All timeout values are in milliseconds. %% @spec send_req(Url, Headers::headerList(), Method::method(), Body::body(), Options::optionList(), Timeout) -> response() %% Timeout = integer() | infinity send_req(Url, Headers, Method, Body, Options, Timeout) -> case catch parse_url(Url) of #url{host = Host, port = Port, protocol = Protocol} = Parsed_url -> Lb_pid = case ets:lookup(ibrowse_lb, {Host, Port}) of [] -> get_lb_pid(Parsed_url); [#lb_pid{pid = Lb_pid_1}] -> Lb_pid_1 end, Max_sessions = get_max_sessions(Host, Port, Options), Max_pipeline_size = get_max_pipeline_size(Host, Port, Options), Options_1 = merge_options(Host, Port, Options), {SSLOptions, IsSSL} = case (Protocol == https) orelse get_value(is_ssl, Options_1, false) of false -> {[], false}; true -> {get_value(ssl_options, Options_1, []), true} end, case ibrowse_lb:spawn_connection(Lb_pid, Parsed_url, Max_sessions, Max_pipeline_size, {SSLOptions, IsSSL}) of {ok, Conn_Pid} -> do_send_req(Conn_Pid, Parsed_url, Headers, Method, Body, Options_1, Timeout); Err -> Err end; Err -> {error, {url_parsing_failed, Err}} end. merge_options(Host, Port, Options) -> Config_options = get_config_value({options, Host, Port}, []), lists:foldl( fun({Key, Val}, Acc) -> case lists:keysearch(Key, 1, Options) of false -> [{Key, Val} | Acc]; _ -> Acc end end, Options, Config_options). get_lb_pid(Url) -> gen_server:call(?MODULE, {get_lb_pid, Url}). get_max_sessions(Host, Port, Options) -> get_value(max_sessions, Options, get_config_value({max_sessions, Host, Port}, ?DEF_MAX_SESSIONS)). get_max_pipeline_size(Host, Port, Options) -> get_value(max_pipeline_size, Options, get_config_value({max_pipeline_size, Host, Port}, ?DEF_MAX_PIPELINE_SIZE)). %% @doc Deprecated. Use set_max_sessions/3 and set_max_pipeline_size/3 %% for achieving the same effect. set_dest(Host, Port, [{max_sessions, Max} | T]) -> set_max_sessions(Host, Port, Max), set_dest(Host, Port, T); set_dest(Host, Port, [{max_pipeline_size, Max} | T]) -> set_max_pipeline_size(Host, Port, Max), set_dest(Host, Port, T); set_dest(Host, Port, [{trace, Bool} | T]) when Bool == true; Bool == false -> ibrowse ! {trace, true, Host, Port}, set_dest(Host, Port, T); set_dest(_Host, _Port, [H | _]) -> exit({invalid_option, H}); set_dest(_, _, []) -> ok. %% @doc Set the maximum number of connections allowed to a specific Host:Port. %% @spec set_max_sessions(Host::string(), Port::integer(), Max::integer()) -> ok set_max_sessions(Host, Port, Max) when is_integer(Max), Max > 0 -> gen_server:call(?MODULE, {set_config_value, {max_sessions, Host, Port}, Max}). %% @doc Set the maximum pipeline size for each connection to a specific Host:Port. %% @spec set_max_pipeline_size(Host::string(), Port::integer(), Max::integer()) -> ok set_max_pipeline_size(Host, Port, Max) when is_integer(Max), Max > 0 -> gen_server:call(?MODULE, {set_config_value, {max_pipeline_size, Host, Port}, Max}). do_send_req(Conn_Pid, Parsed_url, Headers, Method, Body, Options, Timeout) -> case catch ibrowse_http_client:send_req(Conn_Pid, Parsed_url, Headers, Method, ensure_bin(Body), Options, Timeout) of {'EXIT', {timeout, _}} -> {error, req_timedout}; {'EXIT', Reason} -> {error, {'EXIT', Reason}}; {ok, St_code, Headers, Body} = Ret when is_binary(Body) -> case get_value(response_format, Options, list) of list -> {ok, St_code, Headers, binary_to_list(Body)}; binary -> Ret end; Ret -> Ret end. ensure_bin(L) when is_list(L) -> list_to_binary(L); ensure_bin(B) when is_binary(B) -> B. %% @doc Creates a HTTP client process to the specified Host:Port which %% is not part of the load balancing pool. This is useful in cases %% where some requests to a webserver might take a long time whereas %% some might take a very short time. To avoid getting these quick %% requests stuck in the pipeline behind time consuming requests, use %% this function to get a handle to a connection process.
%% Note: Calling this function only creates a worker process. No connection %% is setup. The connection attempt is made only when the first %% request is sent via any of the send_req_direct/4,5,6,7 functions.
%% Note: It is the responsibility of the calling process to control %% pipeline size on such connections. %% %% @spec spawn_worker_process(Host::string(), Port::integer()) -> {ok, pid()} spawn_worker_process(Host, Port) -> ibrowse_http_client:start({Host, Port}). %% @doc Same as spawn_worker_process/2 except the the calling process %% is linked to the worker process which is spawned. spawn_link_worker_process(Host, Port) -> ibrowse_http_client:start_link({Host, Port}). %% @doc Terminate a worker process spawned using %% spawn_worker_process/2 or spawn_link_worker_process/2. Requests in %% progress will get the error response 
{error, closing_on_request}
%% @spec stop_worker_process(Conn_pid::pid()) -> ok stop_worker_process(Conn_pid) -> ibrowse_http_client:stop(Conn_pid). %% @doc Same as send_req/3 except that the first argument is the PID %% returned by spawn_worker_process/2 or spawn_link_worker_process/2 send_req_direct(Conn_pid, Url, Headers, Method) -> send_req_direct(Conn_pid, Url, Headers, Method, [], []). %% @doc Same as send_req/4 except that the first argument is the PID %% returned by spawn_worker_process/2 or spawn_link_worker_process/2 send_req_direct(Conn_pid, Url, Headers, Method, Body) -> send_req_direct(Conn_pid, Url, Headers, Method, Body, []). %% @doc Same as send_req/5 except that the first argument is the PID %% returned by spawn_worker_process/2 or spawn_link_worker_process/2 send_req_direct(Conn_pid, Url, Headers, Method, Body, Options) -> send_req_direct(Conn_pid, Url, Headers, Method, Body, Options, 30000). %% @doc Same as send_req/6 except that the first argument is the PID %% returned by spawn_worker_process/2 or spawn_link_worker_process/2 send_req_direct(Conn_pid, Url, Headers, Method, Body, Options, Timeout) -> case catch parse_url(Url) of #url{host = Host, port = Port} = Parsed_url -> Options_1 = merge_options(Host, Port, Options), case do_send_req(Conn_pid, Parsed_url, Headers, Method, Body, Options_1, Timeout) of {error, {'EXIT', {noproc, _}}} -> {error, worker_is_dead}; Ret -> Ret end; Err -> {error, {url_parsing_failed, Err}} end. %% @doc Tell ibrowse to stream the next chunk of data to the %% caller. Should be used in conjunction with the %% stream_to option %% @spec stream_next(Req_id :: req_id()) -> ok | {error, unknown_req_id} stream_next(Req_id) -> case ets:lookup(ibrowse_stream, {req_id_pid, Req_id}) of [] -> {error, unknown_req_id}; [{_, Pid}] -> catch Pid ! {stream_next, Req_id}, ok end. %% @doc Turn tracing on for the ibrowse process trace_on() -> ibrowse ! {trace, true}. %% @doc Turn tracing off for the ibrowse process trace_off() -> ibrowse ! {trace, false}. %% @doc Turn tracing on for all connections to the specified HTTP %% server. Host is whatever is specified as the domain name in the URL %% @spec trace_on(Host, Port) -> ok %% Host = string() %% Port = integer() trace_on(Host, Port) -> ibrowse ! {trace, true, Host, Port}, ok. %% @doc Turn tracing OFF for all connections to the specified HTTP %% server. %% @spec trace_off(Host, Port) -> ok trace_off(Host, Port) -> ibrowse ! {trace, false, Host, Port}, ok. %% @doc Turn Off ALL tracing %% @spec all_trace_off() -> ok all_trace_off() -> ibrowse ! all_trace_off, ok. %% @doc Shows some internal information about load balancing to a %% specified Host:Port. Info about workers spawned using %% spawn_worker_process/2 or spawn_link_worker_process/2 is not %% included. show_dest_status(Host, Port) -> case ets:lookup(ibrowse_lb, {Host, Port}) of [] -> no_active_processes; [#lb_pid{pid = Lb_pid}] -> io:format("Load Balancer Pid : ~p~n", [Lb_pid]), io:format("LB process msg q size : ~p~n", [(catch process_info(Lb_pid, message_queue_len))]), case lists:dropwhile( fun(Tid) -> ets:info(Tid, owner) /= Lb_pid end, ets:all()) of [] -> io:format("Couldn't locate ETS table for ~p~n", [Lb_pid]); [Tid | _] -> First = ets:first(Tid), Last = ets:last(Tid), Size = ets:info(Tid, size), io:format("LB ETS table id : ~p~n", [Tid]), io:format("Num Connections : ~p~n", [Size]), case Size of 0 -> ok; _ -> {First_p_sz, _} = First, {Last_p_sz, _} = Last, io:format("Smallest pipeline : ~1000.p~n", [First_p_sz]), io:format("Largest pipeline : ~1000.p~n", [Last_p_sz]) end end end. %% @doc Clear current configuration for ibrowse and load from the file %% ibrowse.conf in the IBROWSE_EBIN/../priv directory. Current %% configuration is cleared only if the ibrowse.conf file is readable %% using file:consult/1 rescan_config() -> gen_server:call(?MODULE, rescan_config). %% Clear current configuration for ibrowse and load from the specified %% file. Current configuration is cleared only if the specified %% file is readable using file:consult/1 rescan_config(File) when is_list(File) -> gen_server:call(?MODULE, {rescan_config, File}). %%==================================================================== %% Server functions %%==================================================================== %%-------------------------------------------------------------------- %% Function: init/1 %% Description: Initiates the server %% Returns: {ok, State} | %% {ok, State, Timeout} | %% ignore | %% {stop, Reason} %%-------------------------------------------------------------------- init(_) -> process_flag(trap_exit, true), State = #state{}, put(my_trace_flag, State#state.trace), put(ibrowse_trace_token, "ibrowse"), ets:new(ibrowse_lb, [named_table, public, {keypos, 2}]), ets:new(ibrowse_conf, [named_table, protected, {keypos, 2}]), ets:new(ibrowse_stream, [named_table, public]), import_config(), {ok, #state{}}. import_config() -> case code:priv_dir(ibrowse) of {error, _} = Err -> Err; PrivDir -> Filename = filename:join(PrivDir, "ibrowse.conf"), import_config(Filename) end. import_config(Filename) -> case file:consult(Filename) of {ok, Terms} -> ets:delete_all_objects(ibrowse_conf), Fun = fun({dest, Host, Port, MaxSess, MaxPipe, Options}) when is_list(Host), is_integer(Port), is_integer(MaxSess), MaxSess > 0, is_integer(MaxPipe), MaxPipe > 0, is_list(Options) -> I = [{{max_sessions, Host, Port}, MaxSess}, {{max_pipeline_size, Host, Port}, MaxPipe}, {{options, Host, Port}, Options}], lists:foreach( fun({X, Y}) -> ets:insert(ibrowse_conf, #ibrowse_conf{key = X, value = Y}) end, I); ({K, V}) -> ets:insert(ibrowse_conf, #ibrowse_conf{key = K, value = V}); (X) -> io:format("Skipping unrecognised term: ~p~n", [X]) end, lists:foreach(Fun, Terms); Err -> Err end. %% @doc Internal export get_config_value(Key) -> [#ibrowse_conf{value = V}] = ets:lookup(ibrowse_conf, Key), V. %% @doc Internal export get_config_value(Key, DefVal) -> case ets:lookup(ibrowse_conf, Key) of [] -> DefVal; [#ibrowse_conf{value = V}] -> V end. set_config_value(Key, Val) -> ets:insert(ibrowse_conf, #ibrowse_conf{key = Key, value = Val}). %%-------------------------------------------------------------------- %% Function: handle_call/3 %% Description: Handling call messages %% Returns: {reply, Reply, State} | %% {reply, Reply, State, Timeout} | %% {noreply, State} | %% {noreply, State, Timeout} | %% {stop, Reason, Reply, State} | (terminate/2 is called) %% {stop, Reason, State} (terminate/2 is called) %%-------------------------------------------------------------------- handle_call({get_lb_pid, #url{host = Host, port = Port} = Url}, _From, State) -> Pid = do_get_connection(Url, ets:lookup(ibrowse_lb, {Host, Port})), {reply, Pid, State}; handle_call(stop, _From, State) -> do_trace("IBROWSE shutting down~n", []), {stop, normal, ok, State}; handle_call({set_config_value, Key, Val}, _From, State) -> set_config_value(Key, Val), {reply, ok, State}; handle_call(rescan_config, _From, State) -> Ret = (catch import_config()), {reply, Ret, State}; handle_call({rescan_config, File}, _From, State) -> Ret = (catch import_config(File)), {reply, Ret, State}; handle_call(Request, _From, State) -> Reply = {unknown_request, Request}, {reply, Reply, State}. %%-------------------------------------------------------------------- %% Function: handle_cast/2 %% Description: Handling cast messages %% Returns: {noreply, State} | %% {noreply, State, Timeout} | %% {stop, Reason, State} (terminate/2 is called) %%-------------------------------------------------------------------- handle_cast(_Msg, State) -> {noreply, State}. %%-------------------------------------------------------------------- %% Function: handle_info/2 %% Description: Handling all non call/cast messages %% Returns: {noreply, State} | %% {noreply, State, Timeout} | %% {stop, Reason, State} (terminate/2 is called) %%-------------------------------------------------------------------- handle_info(all_trace_off, State) -> Mspec = [{{ibrowse_conf,{trace,'$1','$2'},true},[],[{{'$1','$2'}}]}], Trace_on_dests = ets:select(ibrowse_conf, Mspec), Fun = fun(#lb_pid{host_port = {H, P}, pid = Pid}, _) -> case lists:member({H, P}, Trace_on_dests) of false -> ok; true -> catch Pid ! {trace, false} end; (_, Acc) -> Acc end, ets:foldl(Fun, undefined, ibrowse_lb), ets:select_delete(ibrowse_conf, [{{ibrowse_conf,{trace,'$1','$2'},true},[],['true']}]), {noreply, State}; handle_info({trace, Bool}, State) -> put(my_trace_flag, Bool), {noreply, State}; handle_info({trace, Bool, Host, Port}, State) -> Fun = fun(#lb_pid{host_port = {H, P}, pid = Pid}, _) when H == Host, P == Port -> catch Pid ! {trace, Bool}; (_, Acc) -> Acc end, ets:foldl(Fun, undefined, ibrowse_lb), ets:insert(ibrowse_conf, #ibrowse_conf{key = {trace, Host, Port}, value = Bool}), {noreply, State}; handle_info(_Info, State) -> {noreply, State}. %%-------------------------------------------------------------------- %% Function: terminate/2 %% Description: Shutdown the server %% Returns: any (ignored by gen_server) %%-------------------------------------------------------------------- terminate(_Reason, _State) -> ok. %%-------------------------------------------------------------------- %% Func: code_change/3 %% Purpose: Convert process state when code is changed %% Returns: {ok, NewState} %%-------------------------------------------------------------------- code_change(_OldVsn, State, _Extra) -> {ok, State}. %%-------------------------------------------------------------------- %%% Internal functions %%-------------------------------------------------------------------- do_get_connection(#url{host = Host, port = Port}, []) -> {ok, Pid} = ibrowse_lb:start_link([Host, Port]), ets:insert(ibrowse_lb, #lb_pid{host_port = {Host, Port}, pid = Pid}), Pid; do_get_connection(_Url, [#lb_pid{pid = Pid}]) -> Pid.