From a780df5e7f0e5fe2a5c4acc13685a13d9b918d4f Mon Sep 17 00:00:00 2001
From: Florian Fischer <florian.fl.fischer@fau.de>
Date: Sat, 6 Feb 2021 14:21:26 +0100
Subject: [PATCH] [IO] add FutureError and throw it when wait is called on a
Future with callback
The wait() call on a Future with callback currently will never return
therefore calling wait() is disallowed.
---
emper/io/Future.cpp | 4 ++++
emper/io/Future.hpp | 12 ++++++++++++
2 files changed, 16 insertions(+)
diff --git a/emper/io/Future.cpp b/emper/io/Future.cpp
index 8d59a3d6..50870da1 100644
--- a/emper/io/Future.cpp
+++ b/emper/io/Future.cpp
@@ -44,6 +44,10 @@ template PartialCompletableFuture::CompletionType
PartialCompletableFuture::tryComplete<CallerEnvironment::ANYWHERE>(int32_t res);
auto Future::wait() -> int32_t {
+ if (unlikely(callback)) {
+ throw FutureError("Futures with registered callback must not be awaited");
+ }
+
LOGD("Waiting on " << this);
sem.wait();
diff --git a/emper/io/Future.hpp b/emper/io/Future.hpp
index f21de80b..91f157a1 100644
--- a/emper/io/Future.hpp
+++ b/emper/io/Future.hpp
@@ -11,6 +11,8 @@
#include <cstdlib> // for abort
#include <functional>
#include <ostream> // for operator<<, ostream, basic_ost...
+#include <stdexcept>
+#include <string>
#include "BinaryPrivateSemaphore.hpp" // for BPS
#include "CallerEnvironment.hpp" // for CallerEnvironment, ANYWHERE
@@ -25,6 +27,11 @@ struct io_uring_sqe;
namespace emper::io {
class Stats;
+class FutureError : public std::logic_error {
+ friend class Future;
+ FutureError(const std::string& what) : std::logic_error(what) {}
+};
+
/*
* @brief Future representing an IO request which can be awaited
*/
@@ -115,6 +122,11 @@ class Future : public Logger<LogSubsystem::IO> {
: op(op), fd(fd), buf(buf), len(len), offsetOrFlags(offsetOrFlags){};
public:
+ // Clang-tidy warns about the exception possibly thrown by
+ // ~Future -> cancel -> wait
+ // But this exception will never be thrown because wait() throws an exception
+ // only if callback is set and if callback is set ~Future does not call cancel.
+ // NOLINTNEXTLINE(bugprone-exception-escape)
virtual ~Future() {
if (isForgotten() || callback) {
return;
--
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