AMQP 1.0, AMQP 0-9-1: dynamically adjust client connection socket buffer size

deps/rabbit/include/rabbit_amqp_reader.hrl

@@ -59,7 +59,10 @@
          buf :: list(),
          buf_len :: non_neg_integer(),
          tracked_channels = maps:new() :: #{channel_number() => Session :: pid()},
-         stats_timer :: rabbit_event:state()
+         stats_timer :: rabbit_event:state(),
+         %% dynamic buffer
+         dynamic_buffer_size = 128,
+         dynamic_buffer_moving_average = 0.0
         }).
 
 -type state() :: #v1{}.

deps/rabbit/src/rabbit_amqp_reader.erl

@@ -111,9 +111,10 @@ recvloop(Deb, State0 = #v1{recv_len = RecvLen,
 mainloop(Deb, State = #v1{sock = Sock, buf = Buf, buf_len = BufLen}) ->
     case rabbit_net:recv(Sock) of
         {data, Data} ->
-            recvloop(Deb, State#v1{buf = [Data | Buf],
-                                   buf_len = BufLen + size(Data),
-                                   pending_recv = false});
+            State1 = maybe_resize_buffer(State, Data),
+            recvloop(Deb, State1#v1{buf = [Data | Buf],
+                                    buf_len = BufLen + size(Data),
+                                    pending_recv = false});
         closed when State#v1.connection_state =:= closed ->
             ok;
         closed ->
@@ -130,6 +131,37 @@ mainloop(Deb, State = #v1{sock = Sock, buf = Buf, buf_len = BufLen}) ->
             end
     end.
 
+maybe_resize_buffer(State=#v1{sock=Sock, dynamic_buffer_size=BufferSize0,
+        dynamic_buffer_moving_average=MovingAvg0}, Data) ->
+    LowDynamicBuffer = 128,
+    HighDynamicBuffer = 131072,
+    DataLen = byte_size(Data),
+    MovingAvg = (MovingAvg0 * 7 + DataLen) / 8,
+    if
+        BufferSize0 < HighDynamicBuffer andalso MovingAvg > BufferSize0 * 0.9 ->
+            BufferSize = min(BufferSize0 * 2, HighDynamicBuffer),
+            case rabbit_net:setopts(Sock, [{buffer, BufferSize}]) of
+                ok -> State#v1{
+                    dynamic_buffer_size=BufferSize,
+                    dynamic_buffer_moving_average=MovingAvg
+                };
+                {error, Reason} ->
+                    throw({inet_error, Reason})
+            end;
+        BufferSize0 > LowDynamicBuffer andalso MovingAvg < BufferSize0 * 0.4 ->
+            BufferSize = max(BufferSize0 div 2, LowDynamicBuffer),
+            case rabbit_net:setopts(Sock, [{buffer, BufferSize}]) of
+                ok -> State#v1{
+                    dynamic_buffer_size=BufferSize,
+                    dynamic_buffer_moving_average=MovingAvg
+                };
+                {error, Reason} ->
+                    throw({inet_error, Reason})
+            end;
+        true ->
+            State#v1{dynamic_buffer_moving_average=MovingAvg}
+    end.
+
 -spec handle_other(any(), state()) -> state() | stop.
 handle_other(emit_stats, State) ->
     emit_stats(State);

deps/rabbit/src/rabbit_networking.erl

@@ -32,7 +32,7 @@
          close_connection/2, close_connections/2, close_all_connections/1,
          close_all_user_connections/2,
          force_connection_event_refresh/1, force_non_amqp_connection_event_refresh/1,
-         handshake/2, tcp_host/1,
+         handshake/2, handshake/3, tcp_host/1,
          ranch_ref/1, ranch_ref/2, ranch_ref_of_protocol/1,
          listener_of_protocol/1, stop_ranch_listener_of_protocol/1,
          list_local_connections_of_protocol/1]).
@@ -551,6 +551,9 @@ failed_to_recv_proxy_header(Ref, Error) ->
     exit({shutdown, failed_to_recv_proxy_header}).
 
 handshake(Ref, ProxyProtocolEnabled) ->
+    handshake(Ref, ProxyProtocolEnabled, static_buffer).
+
+handshake(Ref, ProxyProtocolEnabled, BufferStrategy) ->
     case ProxyProtocolEnabled of
         true ->
             case ranch:recv_proxy_header(Ref, 3000) of
@@ -560,23 +563,29 @@ handshake(Ref, ProxyProtocolEnabled) ->
                     failed_to_recv_proxy_header(Ref, Error);
                 {ok, ProxyInfo} ->
                     {ok, Sock} = ranch:handshake(Ref),
-                    ok = tune_buffer_size(Sock),
+                    ok = tune_buffer_size(Sock, BufferStrategy),
                     {ok, {rabbit_proxy_socket, Sock, ProxyInfo}}
             end;
         false ->
             {ok, Sock} = ranch:handshake(Ref),
-            ok = tune_buffer_size(Sock),
+            ok = tune_buffer_size(Sock, BufferStrategy),
             {ok, Sock}
     end.
 
-tune_buffer_size(Sock) ->
-    case tune_buffer_size1(Sock) of
+tune_buffer_size(Sock, dynamic_buffer) ->
+    case rabbit_net:setopts(Sock, [{buffer, 128}]) of
+        ok         -> ok;
+        {error, _} -> rabbit_net:fast_close(Sock),
+                      exit(normal)
+    end;
+tune_buffer_size(Sock, static_buffer) ->
+    case tune_buffer_size_static(Sock) of
         ok         -> ok;
         {error, _} -> rabbit_net:fast_close(Sock),
                       exit(normal)
     end.
 
-tune_buffer_size1(Sock) ->
+tune_buffer_size_static(Sock) ->
     case rabbit_net:getopts(Sock, [sndbuf, recbuf, buffer]) of
         {ok, BufSizes} -> BufSz = lists:max([Sz || {_Opt, Sz} <- BufSizes]),
                           rabbit_net:setopts(Sock, [{buffer, BufSz}]);

deps/rabbit/src/rabbit_reader.erl

@@ -99,7 +99,11 @@
           %% throttling state, for both
           %% credit- and resource-driven flow control
           throttle,
-          proxy_socket}).
+          proxy_socket,
+          %% dynamic buffer
+          dynamic_buffer_size = 128,
+          dynamic_buffer_moving_average = 0.0
+}).
 
 -record(throttle, {
   %% never | timestamp()
@@ -155,7 +159,8 @@ shutdown(Pid, Explanation) ->
 init(Parent, HelperSups, Ref) ->
     ?LG_PROCESS_TYPE(reader),
     {ok, Sock} = rabbit_networking:handshake(Ref,
-        application:get_env(rabbit, proxy_protocol, false)),
+        application:get_env(rabbit, proxy_protocol, false),
+        dynamic_buffer),
     Deb = sys:debug_options([]),
     start_connection(Parent, HelperSups, Ref, Deb, Sock).
 
@@ -512,8 +517,9 @@ mainloop(Deb, Buf, BufLen, State = #v1{sock = Sock,
     end,
     case Recv of
         {data, Data} ->
+            State1 = maybe_resize_buffer(State, Data),
             recvloop(Deb, [Data | Buf], BufLen + size(Data),
-                     State#v1{pending_recv = false});
+                     State1#v1{pending_recv = false});
         closed when State#v1.connection_state =:= closed ->
             State;
         closed when CS =:= pre_init andalso Buf =:= [] ->
@@ -536,6 +542,37 @@ mainloop(Deb, Buf, BufLen, State = #v1{sock = Sock,
             end
     end.
 
+maybe_resize_buffer(State=#v1{sock=Sock, dynamic_buffer_size=BufferSize0,
+        dynamic_buffer_moving_average=MovingAvg0}, Data) ->
+    LowDynamicBuffer = 128,
+    HighDynamicBuffer = 131072,
+    DataLen = byte_size(Data),
+    MovingAvg = (MovingAvg0 * 7 + DataLen) / 8,
+    if
+        BufferSize0 < HighDynamicBuffer andalso MovingAvg > BufferSize0 * 0.9 ->
+            BufferSize = min(BufferSize0 * 2, HighDynamicBuffer),
+            case rabbit_net:setopts(Sock, [{buffer, BufferSize}]) of
+                ok -> State#v1{
+                    dynamic_buffer_size=BufferSize,
+                    dynamic_buffer_moving_average=MovingAvg
+                };
+                Error ->
+                    stop(Error, State)
+            end;
+        BufferSize0 > LowDynamicBuffer andalso MovingAvg < BufferSize0 * 0.4 ->
+            BufferSize = max(BufferSize0 div 2, LowDynamicBuffer),
+            case rabbit_net:setopts(Sock, [{buffer, BufferSize}]) of
+                ok -> State#v1{
+                    dynamic_buffer_size=BufferSize,
+                    dynamic_buffer_moving_average=MovingAvg
+                };
+                Error ->
+                    stop(Error, State)
+            end;
+        true ->
+            State#v1{dynamic_buffer_moving_average=MovingAvg}
+    end.
+
 -spec stop(_, #v1{}) -> no_return().
 stop(tcp_healthcheck, State) ->
     %% The connection was closed before any packet was received. It's