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Check if all callbacks match a signature on ConsumerDispatcher

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This commit is contained in:
Matias Fontanini
2017-06-10 17:55:17 -07:00
parent 4369b75695
commit bb5fb490ce
1 changed files with 38 additions and 6 deletions
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44
include/cppkafka/utils/consumer_dispatcher.h
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@@ -102,6 +102,12 @@ public:
*/
void stop();
private:
// Define the types we need for each type of callback
using OnMessageArgs = std::tuple<Message>;
using OnErrorArgs = std::tuple<Error>;
using OnEofArgs = std::tuple<EndOfFile, TopicPartition>;
using OnTimeoutArgs = std::tuple<Timeout>;
static void handle_error(Error error);
static void handle_eof(EndOfFile, const TopicPartition& topic_partition);
static void handle_timeout(Timeout);
@@ -189,20 +195,46 @@ private:
return find_functor<type>(functors...);
}
// Check that a given functor matches at least one of the expected signatures
template <typename Functor>
void check_callback_matches(const Functor& functor) {
static_assert(
!std::is_same<type_not_found,
typename find_type<OnMessageArgs, Functor>::type>::value ||
!std::is_same<type_not_found,
typename find_type<OnEofArgs, Functor>::type>::value ||
!std::is_same<type_not_found,
typename find_type<OnTimeoutArgs, Functor>::type>::value ||
!std::is_same<type_not_found,
typename find_type<OnErrorArgs, Functor>::type>::value,
"Callback doesn't match any of the expected signatures"
);
}
// Base case for recursion
void check_callbacks_match() {
}
// Check that all given functors match at least one of the expected signatures
template <typename Functor, typename... Functors>
void check_callbacks_match(const Functor& functor, const Functors&... functors) {
check_callback_matches(functor);
check_callbacks_match(functors...);
}
Consumer& consumer_;
bool running_;
};
template <typename... Args>
void ConsumerDispatcher::run(const Args&... args) {
// Define the types we need for each type of callback
using OnMessageArgs = std::tuple<Message>;
using OnErrorArgs = std::tuple<Error>;
using OnEofArgs = std::tuple<EndOfFile, TopicPartition>;
using OnTimeoutArgs = std::tuple<Timeout>;
using self = ConsumerDispatcher;
// Make sure all callbacks match one of the signatures. Otherwise users could provide
// bogus callbacks that would never be executed
check_callbacks_match(args...);
// This one is required
const auto& on_message = find_callable_functor<OnMessageArgs>(args...);