From 0c645c88164bc29c64aaa1861b73aaaae443e075 Mon Sep 17 00:00:00 2001
From: Tor Brede Vekterli <vekterli@yahooinc.com>
Date: Thu, 17 Feb 2022 12:45:53 +0000
Subject: Make finished-polling outside of lock thread safe

---
 fnet/src/vespa/fnet/transport_thread.cpp | 10 +++++-----
 fnet/src/vespa/fnet/transport_thread.h   |  6 +++++-
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/fnet/src/vespa/fnet/transport_thread.cpp b/fnet/src/vespa/fnet/transport_thread.cpp
index 53f8fea40cd..1d55ac3b327 100644
--- a/fnet/src/vespa/fnet/transport_thread.cpp
+++ b/fnet/src/vespa/fnet/transport_thread.cpp
@@ -236,7 +236,7 @@ FNET_TransportThread::~FNET_TransportThread()
     {
         std::lock_guard<std::mutex> guard(_shutdownLock);
     }
-    if (_started.load() && !_finished) {
+    if (_started.load() && !is_finished()) {
         LOG(error, "Transport: delete called on active object!");
     } else {
         std::lock_guard guard(_pseudo_thread);
@@ -380,11 +380,11 @@ FNET_TransportThread::ShutDown(bool waitFinished)
 void
 FNET_TransportThread::WaitFinished()
 {
-    if (_finished)
+    if (is_finished())
         return;
 
     std::unique_lock<std::mutex> guard(_shutdownLock);
-    while (!_finished)
+    while (!is_finished())
         _shutdownCond.wait(guard);
 }
 
@@ -501,7 +501,7 @@ FNET_TransportThread::EventLoopIteration() {
 
     if (!IsShutDown())
         return true;
-    if (_finished)
+    if (is_finished())
         return false;
 
     endEventLoop();
@@ -557,7 +557,7 @@ FNET_TransportThread::endEventLoop() {
 
     {
         std::lock_guard<std::mutex> guard(_shutdownLock);
-        _finished = true;
+        _finished.store(true, std::memory_order_relaxed);
         _shutdownCond.notify_all();
     }
 
diff --git a/fnet/src/vespa/fnet/transport_thread.h b/fnet/src/vespa/fnet/transport_thread.h
index cf1f68a8b39..dfdcf4e1970 100644
--- a/fnet/src/vespa/fnet/transport_thread.h
+++ b/fnet/src/vespa/fnet/transport_thread.h
@@ -50,7 +50,7 @@ private:
     std::recursive_mutex     _pseudo_thread;  // used after transport thread has shut down
     std::atomic<bool>        _started;        // event loop started ?
     std::atomic<bool>        _shutdown;       // should stop event loop ?
-    bool                     _finished;       // event loop stopped ?
+    std::atomic<bool>        _finished;       // event loop stopped ?
 
     /**
      * Add an IOComponent to the list of components. This operation is
@@ -173,6 +173,10 @@ private:
         return _shutdown.load(std::memory_order_relaxed);
     }
 
+    [[nodiscard]] bool is_finished() const noexcept {
+        return _finished.load(std::memory_order_relaxed);
+    }
+
 public:
     FNET_TransportThread(const FNET_TransportThread &) = delete;
     FNET_TransportThread &operator=(const FNET_TransportThread &) = delete;
-- 
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