Finally implement the "sticky" chain node

src/hz.erl

@@ -582,7 +582,7 @@ next_nonce(AccountID) ->
 %       {ok, #{"reason" := Reason}}              -> {error, Reason};
 %       Error                                    -> Error
 %   end.
-    case request(["/v3/accounts/", AccountID]) of
+    case request_sticky(["/v3/accounts/", AccountID]) of
         {ok, #{"nonce"  := Nonce}}               -> {ok, Nonce + 1};
         {ok, #{"reason" := "Account not found"}} -> {ok, 1};
         {ok, #{"reason" := Reason}}              -> {error, Reason};
@@ -729,7 +729,7 @@ tx_info(ID) ->
 
 post_tx(Data) when is_binary(Data) ->
     JSON = zj:binary_encode(#{tx => Data}),
-    request("/v3/transactions", JSON);
+    request_sticky("/v3/transactions", JSON);
 post_tx(Data) when is_list(Data) ->
     post_tx(list_to_binary(Data)).
 
@@ -841,6 +841,14 @@ status_chainends() ->
     request("/v3/status/chain-ends").
 
 
+request_sticky(Path) ->
+    hz_man:request_sticky(unicode:characters_to_list(Path)).
+
+
+request_sticky(Path, Payload) ->
+    hz_man:request_sticky(unicode:characters_to_list(Path), Payload).
+
+
 request(Path) ->
     hz_man:request(unicode:characters_to_list(Path)).
 

src/hz_man.erl

@@ -21,7 +21,7 @@
          timeout/0,     timeout/1]).
 
 %% The whole point of this module:
--export([request/1, request/2]).
+-export([request_sticky/1, request_sticky/2,request/1, request/2]).
 
 %% gen_server goo
 -export([start_link/0]).
@@ -94,6 +94,25 @@ timeout(Value) when 0 < Value, Value =< 120000 ->
     gen_server:cast(?MODULE, {timeout, Value}).
 
 
+-spec request_sticky(Path) -> {ok, Value} | {error, Reason}
+    when Path   :: unicode:charlist(),
+         Value  :: map(),
+         Reason :: hz:chain_error().
+
+request_sticky(Path) ->
+    gen_server:call(?MODULE, {request_sticky, {get, Path}}, infinity).
+
+
+-spec request_sticky(Path, Data) -> {ok, Value} | {error, Reason}
+    when Path   :: unicode:charlist(),
+         Data   :: unicode:charlist(),
+         Value  :: map(),
+         Reason :: hz:chain_error().
+
+request_sticky(Path, Data) ->
+    gen_server:call(?MODULE, {request_sticky, {post, Path, Data}}, infinity).
+
+
 -spec request(Path) -> {ok, Value} | {error, Reason}
     when Path   :: unicode:charlist(),
          Value  :: map(),
@@ -145,6 +164,9 @@ init(none) ->
 handle_call({request, Request}, From, State) ->
     NewState = do_request(Request, From, State),
     {noreply, NewState};
+handle_call({request_sticky, Request}, From, State) ->
+    NewState = do_request_sticky(Request, From, State),
+    {noreply, NewState};
 handle_call(tls, _, State = #s{tls = TLS}) ->
     {reply, TLS, State};
 handle_call(chain_nodes, _, State = #s{chain_nodes = {Wait, Used}}) ->
@@ -160,10 +182,9 @@ handle_call(Unexpected, From, State) ->
 handle_cast({tls, Boolean}, State) ->
     NewState = do_tls(Boolean, State),
     {noreply, NewState};
-handle_cast({chain_nodes, []}, State) ->
-    {noreply, State#s{chain_nodes = {[], []}}};
-handle_cast({chain_nodes, ToUse}, State) ->
-    {noreply, State#s{chain_nodes = {ToUse, []}}};
+handle_cast({chain_nodes, List}, State) ->
+    NewState = do_chain_nodes(List, State),
+    {noreply, NewState};
 handle_cast({timeout, Value}, State) ->
     {noreply, State#s{timeout = Value}};
 handle_cast(Unexpected, State) ->
@@ -218,6 +239,14 @@ terminate(_, _) ->
 
 %%% Doer Functions
 
+do_chain_nodes([], State) ->
+    State#s{sticky = none, chain_nodes = {[], []}};
+do_chain_nodes(List = [Sticky], State) ->
+    State#s{sticky = Sticky, chain_nodes = {List, []}};
+do_chain_nodes([Sticky | List], State) ->
+    State#s{sticky = Sticky, chain_nodes = {List, []}}.
+
+
 do_tls(true, State) ->
     ok = ssl:start(),
     State#s{tls = true};
@@ -227,17 +256,21 @@ do_tls(_, State) ->
     State.
 
 
-do_request(_, From, State = #s{chain_nodes = {[], []}}) ->
+do_request_sticky(_, From, State = #s{sticky = none}) ->
     ok = gen_server:reply(From, {error, no_nodes}),
     State;
-do_request(Request,
+do_request_sticky(Request,
                   From,
-           State = #s{tls         = false,
+                  State = #s{tls       = TLS,
                              fetchers  = Fetchers,
-                      chain_nodes = {[Node | Rest], Used},
+                             sticky    = Node,
                              timeout   = Timeout}) ->
     Now = erlang:system_time(nanosecond),
-    Fetcher = fun() -> hz_fetcher:connect(Node, Request, From, Timeout) end,
+    Fetcher =
+        case TLS of
+            true  -> fun() -> hz_fetcher:slowly_connect(Node, Request, From, Timeout) end;
+            false -> fun() -> hz_fetcher:connect(Node, Request, From, Timeout) end
+        end,
     {PID, Mon} = spawn_monitor(Fetcher),
     New = #fetcher{pid  = PID,
                    mon  = Mon,
@@ -245,15 +278,24 @@ do_request(Request,
                    node = Node,
                    from = From,
                    req  = Request},
-    State#s{fetchers = [New | Fetchers], chain_nodes = {Rest, [Node | Used]}};
+    State#s{fetchers = [New | Fetchers]}.
+
+
+do_request(_, From, State = #s{chain_nodes = {[], []}}) ->
+    ok = gen_server:reply(From, {error, no_nodes}),
+    State;
 do_request(Request,
            From,
-           State = #s{tls         = true,
+           State = #s{tls         = TLS,
                       fetchers    = Fetchers,
                       chain_nodes = {[Node | Rest], Used},
                       timeout     = Timeout}) ->
     Now = erlang:system_time(nanosecond),
-    Fetcher = fun() -> hz_fetcher:slowly_connect(Node, Request, From, Timeout) end,
+    Fetcher =
+        case TLS of
+            true  -> fun() -> hz_fetcher:slowly_connect(Node, Request, From, Timeout) end;
+            false -> fun() -> hz_fetcher:connect(Node, Request, From, Timeout) end
+        end,
     {PID, Mon} = spawn_monitor(Fetcher),
     New = #fetcher{pid  = PID,
                    mon  = Mon,