From 920959a655028e93409572f44535aaf6c5a398d7 Mon Sep 17 00:00:00 2001
From: David Reiss <dreiss@apache.org>
Date: Wed, 11 Jun 2008 00:56:35 +0000
Subject: [PATCH] Handle crashes/errors in the processor by sending back a
 serialized exception

git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@666407 13f79535-47bb-0310-9956-ffa450edef68
---
 lib/alterl/include/thrift_constants.hrl | 15 ++++++++++++++
 lib/alterl/src/thrift.app.src           | 10 ++++-----
 lib/alterl/src/thrift_processor.erl     | 27 ++++++++++++++++++++++---
 3 files changed, 43 insertions(+), 9 deletions(-)

diff --git a/lib/alterl/include/thrift_constants.hrl b/lib/alterl/include/thrift_constants.hrl
index 19480610..c9b9cd1f 100644
--- a/lib/alterl/include/thrift_constants.hrl
+++ b/lib/alterl/include/thrift_constants.hrl
@@ -23,3 +23,18 @@
 -define(tMessageType_CALL, 1).
 -define(tMessageType_REPLY, 2).
 -define(tMessageType_EXCEPTION, 3).
+
+% TApplicationException
+-define(TApplicationException_Structure,
+        {struct, [{1, string},
+                  {2, i32}]}).
+
+-record('TApplicationException', {message, type}).
+
+-define(TApplicationException_UNKNOWN, 0).
+-define(TApplicationException_UNKNOWN_METHOD, 1).
+-define(TApplicationException_INVALID_MESSAGE_TYPE, 2).
+-define(TApplicationException_WRONG_METHOD_NAME, 3).
+-define(TApplicationException_BAD_SEQUENCE_ID, 4).
+-define(TApplicationException_MISSING_RESULT, 5).
+
diff --git a/lib/alterl/src/thrift.app.src b/lib/alterl/src/thrift.app.src
index 79055ca6..681b3eb3 100644
--- a/lib/alterl/src/thrift.app.src
+++ b/lib/alterl/src/thrift.app.src
@@ -32,12 +32,10 @@
   % configuration parameters similar to those in the config file specified
   % on the command line. can be fetched with gas:get_env
   {env, [
-    {term_width, 110},
-    {force_one_line, false},
-    {omit_fmt, ["thrift ~p:new(~s) = ~s"]},
-    {gen_server_messages, true},
-    {show_pid, true},
-    {lookup, false}                 % DNS
+         % If an error/crash occurs during processing of a function,
+         % should the TApplicationException serialized back to the client
+         % include the erlang backtrace?
+         {exceptions_include_traces, true}
   ]},
 
   % The Module and Args used to start this application.
diff --git a/lib/alterl/src/thrift_processor.erl b/lib/alterl/src/thrift_processor.erl
index fa33d3bc..8cc53c30 100644
--- a/lib/alterl/src/thrift_processor.erl
+++ b/lib/alterl/src/thrift_processor.erl
@@ -55,7 +55,9 @@ handle_function(State = #state{in_protocol = IProto,
         throw:Exception when is_tuple(Exception), size(Exception) > 0 ->
             error_logger:warning_msg("~p threw exception: ~p~n", [Function, Exception]),
             handle_exception(State, Function, Exception),
-            ok % we still want to accept more requests from this client
+            ok;   % we still want to accept more requests from this client
+        error:Error ->
+            ok = handle_error(State, Function, Error)
     end.
 
 handle_success(State = #state{out_protocol = OProto,
@@ -111,9 +113,28 @@ handle_exception(State = #state{out_protocol = OProto,
             ok = send_reply(OProto, Function, ?tMessageType_REPLY, {ReplySpec, ExceptionTuple})
     end.
 
+%%
+% Called when an exception has been explicitly thrown by the service, but it was
+% not one of the exceptions that was defined for the function.
+%%
 handle_unknown_exception(State, Function, Exception) ->
-    io:format("Unknown exception!~n"),
-    ok.
+    handle_error(State, Function, {exception_not_declared_as_thrown,
+                                   Exception}).
+
+handle_error(#state{out_protocol = OProto}, Function, Error) ->
+    Message =
+        case application:get_env(thrift, exceptions_include_traces) of
+            {ok, true} ->
+                lists:flatten(io_lib:format("An error occurred: ~p~n",
+                                            [{Error, erlang:get_stacktrace()}]));
+            _ ->
+                "An unknown handler error occurred."
+        end,
+    Reply = {?TApplicationException_Structure,
+             #'TApplicationException'{
+                message = Message,
+                type = ?TApplicationException_UNKNOWN}},
+    send_reply(OProto, Function, ?tMessageType_EXCEPTION, Reply).
 
 
 send_reply(OProto, Function, ReplyMessageType, Reply) ->
-- 
2.17.1