From 8b13479806453d65c4e4a09e1080cafd75326dd4 Mon Sep 17 00:00:00 2001
From: Florian Fischer <florian.fl.fischer@fau.de>
Date: Fri, 19 Feb 2021 21:54:06 +0100
Subject: [PATCH] [Actor] use AlarmFuture for Actor::waitUntilIdle if IO is
enabled
Using an AlarmFuture blocks the Fiber executing Actor::waitUntilIdle,
freeing its current worker and thus preventing life-locks.
Where all workers are sleeping except one.
Which executes the Actor::waitUntilIdle Fiber causing a starvation of
the actual Actor.
---
emper/Actor.hpp | 34 ++++++++++++++++++++++----------
tests/AlarmActorTest.cpp | 2 +-
tests/SimpleActorTest.cpp | 2 +-
tests/UnblockOnMainActorTest.cpp | 2 +-
4 files changed, 27 insertions(+), 13 deletions(-)
diff --git a/emper/Actor.hpp b/emper/Actor.hpp
index f2b1d57b..3b95c0d6 100644
--- a/emper/Actor.hpp
+++ b/emper/Actor.hpp
@@ -8,6 +8,7 @@
#include "CallerEnvironment.hpp"
#include "Fiber.hpp"
#include "UnboundedBlockingMpscQueue.hpp"
+#include "io/Future.hpp"
template <typename T>
class Actor {
@@ -77,17 +78,30 @@ class Actor {
auto pendingMailboxItems() -> size_t { return queue.size(); }
auto waitUntilIdle(long timeout) -> bool {
- const auto start = std::chrono::steady_clock::now();
- const auto deadline = start + std::chrono::milliseconds(timeout);
- while (!(queue.size() == 0 && state.load(std::memory_order_acquire) == Retrieving)) {
- // TODO: The suppressed linter error below may be a false positive
- // reported by clang-tidy.
- // NOLINTNEXTLINE(modernize-use-nullptr)
- if (std::chrono::steady_clock::now() > deadline) {
- return false;
+ if constexpr (emper::IO) {
+ for (; timeout > 0; --timeout) {
+ emper::io::AlarmFuture::Timespec ts = {.tv_sec = 1, .tv_nsec = 0};
+ emper::io::AlarmFuture alarm(ts);
+ alarm.submitAndWait();
+ if (queue.size() == 0 && state.load(std::memory_order_acquire) == Retrieving) {
+ return true;
+ }
}
- }
- return true;
+ return false;
+ } else {
+ const auto start = std::chrono::steady_clock::now();
+ const auto deadline = start + std::chrono::seconds(timeout);
+ while (!(queue.size() == 0 && state.load(std::memory_order_acquire) == Retrieving)) {
+ // TODO: The suppressed linter error below may be a false positive
+ // reported by clang-tidy.
+ // NOLINTNEXTLINE(modernize-use-nullptr)
+ if (std::chrono::steady_clock::now() > deadline) {
+ return false;
+ }
+ }
+
+ return true;
+ }
}
};
diff --git a/tests/AlarmActorTest.cpp b/tests/AlarmActorTest.cpp
index a0f962b6..31c9c46a 100644
--- a/tests/AlarmActorTest.cpp
+++ b/tests/AlarmActorTest.cpp
@@ -61,7 +61,7 @@ auto main(int argc, char* argv[]) -> int {
cps.wait();
// Wait for the actor to become idle.
- bool actorIdle = alarmActor.waitUntilIdle(60 * 1000);
+ bool actorIdle = alarmActor.waitUntilIdle(60);
if (!actorIdle) {
std::cerr << "FAILURE: Actor did not went idle";
exit(EXIT_FAILURE);
diff --git a/tests/SimpleActorTest.cpp b/tests/SimpleActorTest.cpp
index 3415863c..76b4cfe3 100644
--- a/tests/SimpleActorTest.cpp
+++ b/tests/SimpleActorTest.cpp
@@ -63,7 +63,7 @@ static void mainFiber(void* runtime_ptr) {
cps.wait();
// Wait for the actor to become idle.
- bool actorIdle = sumActor.waitUntilIdle(60 * 1000);
+ bool actorIdle = sumActor.waitUntilIdle(60);
if (!actorIdle) {
std::cerr << "FAILURE: Actor did not went idle";
exit(EXIT_FAILURE);
diff --git a/tests/UnblockOnMainActorTest.cpp b/tests/UnblockOnMainActorTest.cpp
index 020db28f..6ae3883f 100644
--- a/tests/UnblockOnMainActorTest.cpp
+++ b/tests/UnblockOnMainActorTest.cpp
@@ -76,7 +76,7 @@ auto main(int argc, char* argv[]) -> int {
cps.wait();
// Wait for the actor to become idle.
- bool actorIdle = alarmActor.waitUntilIdle(60 * 1000);
+ bool actorIdle = alarmActor.waitUntilIdle(60);
if (!actorIdle) {
std::cerr << "FAILURE: Actor did not went idle";
quit = true;
--
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