Ordering bug fix

apps/arweave/src/ar_info.erl

@@ -43,7 +43,8 @@ get_recent() ->
     #{
         %% #{
         %%   "id": <indep_hash>,
-        %%   "received": <received_timestamp>"
+        %%   "received": <received_timestamp>",
+        %%   "height": <height>
         %% }
         <<"blocks">> => get_recent_blocks(),
         %% #{
@@ -56,19 +57,27 @@ get_recent() ->
     }.
 
 %% @doc Return the the most recent blocks in reverse chronological order.
+%% 
+%% There are a few list reversals that happen here:
+%% 1. get_block_anchors returns the blocks in reverse chronological order (latest block first)
+%% 2. [Element | Acc] reverses the list into chronological order (latest block last)
+%% 3. The final lists:reverse puts the list back into reverse chronological order
+%%    (latest block first)
 get_recent_blocks() ->
     Anchors = lists:sublist(ar_node:get_block_anchors(), ?CHECKPOINT_DEPTH),
-    CutOff = length(Anchors) - ?RECENT_BLOCKS_WITHOUT_TIMESTAMP,
-    lists:foldl(
+    Blocks = lists:foldl(
         fun(H, Acc) ->
+            B = ar_block_cache:get(block_cache, H),
             [#{
                 <<"id">> => ar_util:encode(H),
-                <<"received">> => get_block_timestamp(H, length(Acc), CutOff)
+                <<"received">> => get_block_timestamp(B, length(Acc)),
+                <<"height">> => B#block.height
             } | Acc]
         end,
         [],
         Anchors
-    ).
+    ),
+    lists:reverse(Blocks).
 
 %% @doc Return the the most recent forks in reverse chronological order.
 get_recent_forks() ->
@@ -93,12 +102,10 @@ get_recent_forks() ->
             )
     end.
 
-get_block_timestamp(H, Depth, CutOff) when Depth >= CutOff ->
+get_block_timestamp(B, Depth)
+        when Depth < ?RECENT_BLOCKS_WITHOUT_TIMESTAMP orelse
+            B#block.receive_timestamp =:= undefined ->
     <<"pending">>;
-get_block_timestamp(H, _Depth, _Cutoff) ->
-    B = ar_block_cache:get(block_cache, H),
-    case B#block.receive_timestamp of
-        undefined -> <<"pending">>;
-        Timestamp -> ar_util:timestamp_to_seconds(Timestamp)
-    end.
+get_block_timestamp(B, _Depth) ->
+    ar_util:timestamp_to_seconds(B#block.receive_timestamp).
 

apps/arweave/test/ar_info_tests.erl

@@ -30,7 +30,8 @@ test_recent_blocks(Type) ->
 	ar_test_node:start_peer(peer1, B0),
 	GenesisBlock = [#{
 		<<"id">> => ar_util:encode(B0#block.indep_hash),
-		<<"received">> => <<"pending">>
+		<<"received">> => <<"pending">>,
+		<<"height">> => 0
 	}],
 	?assertEqual(GenesisBlock, get_recent(ar_test_node:peer_ip(peer1), blocks)),
 
@@ -67,7 +68,9 @@ test_recent_blocks(Type) ->
 						ar_test_node:peer_ip(peer1), Announcement)
 			end
 		end,
-		lists:sublist(PeerBI, TargetHeight)
+		%% Reverse the list so that the peer receives the blocks in the same order they
+		%% were mined.
+		lists:reverse(lists:sublist(PeerBI, TargetHeight))
 	),
 
 	%% Peer1 recent should now have timestamps, but also black out the most recent
@@ -78,30 +81,40 @@ test_recent_blocks(Type) ->
 expected_blocks(Node, BI) ->
 	expected_blocks(Node, BI, false).
 expected_blocks(Node, BI, ForcePending) ->
-	lists:foldl(
+	%% There are a few list reversals that happen here:
+	%% 1. BI has the blocks in reverse chronological order (latest block first)
+	%% 2. [Element | Acc] reverses the list into chronological order (latest block last)
+	%% 3. The final lists:reverse puts the list back into reverse chronological order
+	%%    (latest block first)
+	Blocks = lists:foldl(
 		fun({H, _WeaveSize, _TXRoot}, Acc) ->
 			B = ar_test_node:remote_call(Node, ar_block_cache, get, [block_cache, H]),
 			Timestamp = case ForcePending of
 				true -> <<"pending">>;
 				false ->
-					case length(Acc) > (?CHECKPOINT_DEPTH - ?RECENT_BLOCKS_WITHOUT_TIMESTAMP - 1) of
+					case length(Acc) < ?RECENT_BLOCKS_WITHOUT_TIMESTAMP of
 						true -> <<"pending">>;
 						false -> ar_util:timestamp_to_seconds(B#block.receive_timestamp)
 					end
 				end,
 			[#{
 				<<"id">> => ar_util:encode(H),
-				<<"received">> => Timestamp
+				<<"received">> => Timestamp,
+				<<"height">> => B#block.height
 			} | Acc]
 		end,
 		[],
 		lists:sublist(BI, ?CHECKPOINT_DEPTH)
-	).
+	),
+	lists:reverse(Blocks).
 
 %% -------------------------------------------------------------------------------------------
 %% Recent forks tests
 %% -------------------------------------------------------------------------------------------
 test_get_recent_forks() ->
+	[B0] = ar_weave:init([]),
+	ar_test_node:start(B0),
+
     ForkRootB1 = #block{ height = 1 },
     ForkRootB2= #block{ height = 2 },