Support streams in STOMP plugin

This commit introduces the support of an x-stream-offset header
in the SUBSCRIBE frame to start consuming from a specific place
in a stream. The possible values are first, last, next, offset:<offset-value>
(e.g. offset:40000), timestamp:<timestamp-in-seconds> (e.g. timestamp:1619428685).

This commit also propagates the x-stream-offset header in the MESSAGE frame
to know the offset of a the delivered message in the stream.

deps/rabbitmq_stomp/include/rabbit_stomp_headers.hrl

@@ -26,6 +26,7 @@
 -define(HEADER_PASSCODE, "passcode").
 -define(HEADER_PERSISTENT, "persistent").
 -define(HEADER_PREFETCH_COUNT, "prefetch-count").
+-define(HEADER_X_STREAM_OFFSET, "x-stream-offset").
 -define(HEADER_PRIORITY, "priority").
 -define(HEADER_RECEIPT, "receipt").
 -define(HEADER_REDELIVERED, "redelivered").

deps/rabbitmq_stomp/src/rabbit_stomp_frame.erl

@@ -27,6 +27,7 @@
          boolean_header/2, boolean_header/3,
          integer_header/2, integer_header/3,
          binary_header/2, binary_header/3]).
+-export([stream_offset_header/2]).
 -export([serialize/1, serialize/2]).
 
 initial_state() -> none.
@@ -222,6 +223,26 @@ binary_header(F, K) ->
 
 binary_header(F, K, D) -> default_value(binary_header(F, K), D).
 
+stream_offset_header(F, D) ->
+    OffsetPrefix = <<"offset:">>,
+    OffsetPrefixLength = byte_size(OffsetPrefix),
+    TimestampPrefix = <<"timestamp:">>,
+    TimestampPrefixLength = byte_size(TimestampPrefix),
+    case binary_header(F, ?HEADER_X_STREAM_OFFSET, D) of
+        <<"first">> ->
+            {longstr, <<"first">>};
+        <<"last">> ->
+            {longstr, <<"last">>};
+        <<"next">> ->
+            {longstr, <<"next">>};
+        <<OffsetPrefix:OffsetPrefixLength/binary, OffsetValue/binary>> ->
+            {long, binary_to_integer(OffsetValue)};
+        <<TimestampPrefix:TimestampPrefixLength/binary, TimestampValue/binary>> ->
+            {timestamp, binary_to_integer(TimestampValue)};
+        _ ->
+            D
+    end.
+
 serialize(Frame) ->
     serialize(Frame, true).
 

deps/rabbitmq_stomp/src/rabbit_stomp_processor.erl

@@ -685,6 +685,13 @@ do_subscribe(Destination, DestHdr, Frame,
                     {stop, normal, close_connection(State)};
                 error ->
                     ExchangeAndKey = parse_routing(Destination, DfltTopicEx),
+                    StreamOffset = rabbit_stomp_frame:stream_offset_header(Frame, undefined),
+                    Arguments = case StreamOffset of
+                                    undefined ->
+                                        [];
+                                    {Type, Value} ->
+                                        [{<<"x-stream-offset">>, Type, Value}]
+                                end,
                     try
                         amqp_channel:subscribe(Channel,
                                                #'basic.consume'{
@@ -693,7 +700,7 @@ do_subscribe(Destination, DestHdr, Frame,
                                                   no_local     = false,
                                                   no_ack       = (AckMode == auto),
                                                   exclusive    = false,
-                                                  arguments    = []},
+                                                  arguments    = Arguments},
                                                self()),
                         ok = rabbit_routing_util:ensure_binding(
                                Queue, ExchangeAndKey, Channel)

deps/rabbitmq_stomp/src/rabbit_stomp_util.erl

@@ -115,6 +115,8 @@ adhoc_convert_headers(Headers, Existing) ->
                         [{binary_to_list(K), binary_to_list(V)} | Acc];
                     ({K, signedint, V}, Acc) ->
                         [{binary_to_list(K), integer_to_list(V)} | Acc];
+                    ({K, long, V}, Acc) ->
+                        [{binary_to_list(K), integer_to_list(V)} | Acc];
                     (_, Acc) ->
                         Acc
                 end, Existing, Headers).

deps/rabbitmq_stomp/test/frame_SUITE.erl

@@ -38,7 +38,8 @@ all() ->
     header_value_with_cr,
     header_value_with_colon,
     headers_escaping_roundtrip,
-    headers_escaping_roundtrip_without_trailing_lf
+    headers_escaping_roundtrip_without_trailing_lf,
+    stream_offset_header
     ].
 
 parse_simple_frame(_) ->
@@ -162,6 +163,24 @@ header_value_with_colon(_) ->
                                headers     = [{"header", "val:ue"}],
                                body_iolist = []}).
 
+stream_offset_header(_) ->
+    TestCases = [
+        {{"x-stream-offset", "first"}, {longstr, <<"first">>}},
+        {{"x-stream-offset", "last"}, {longstr, <<"last">>}},
+        {{"x-stream-offset", "next"}, {longstr, <<"next">>}},
+        {{"x-stream-offset", "offset:5000"}, {long, 5000}},
+        {{"x-stream-offset", "timestamp:1000"}, {timestamp, 1000}},
+        {{"x-stream-offset", "foo"}, undefined},
+        {{"some-header", "some value"}, undefined}
+    ],
+
+    lists:foreach(fun({Header, Expected}) ->
+        ?assertEqual(
+            Expected,
+            rabbit_stomp_frame:stream_offset_header(#stomp_frame{headers = [Header]}, undefined)
+            )
+    end, TestCases).
+
 test_frame_serialization(Expected, TrailingLF) ->
     {ok, Frame, _} = parse(Expected),
     {ok, Val} = rabbit_stomp_frame:header(Frame, "head\r:\ner"),