Separate loks so the same lock is not used for multiple things.

2 files changed, 11 insertions, 17 deletions

diff --git a/fnet/src/vespa/fnet/transport_thread.cpp b/fnet/src/vespa/fnet/transport_thread.cpp
index 41906a7550d..9758cff21e4 100644
--- a/fnet/src/vespa/fnet/transport_thread.cpp
+++ b/fnet/src/vespa/fnet/transport_thread.cpp
@@ -116,7 +116,7 @@ FNET_TransportThread::PostEvent(FNET_ControlPacket *cpacket,
 {
     size_t qLen;
     {
-        std::unique_lock<std::mutex> guard(_lock);
+        std::unique_lock<std::mutex> guard(_qLock);
         if (IsShutDown()) {
             guard.unlock();
             SafeDiscardEvent(cpacket, context);
@@ -217,6 +217,7 @@ FNET_TransportThread::FNET_TransportThread(FNET_Transport &owner_in)
       _selector(),
       _queue(),
       _myQueue(),
+      _qLock(),
       _lock(),
       _cond(),
       _pseudo_thread(),
@@ -234,7 +235,7 @@ FNET_TransportThread::~FNET_TransportThread()
     {
         std::lock_guard<std::mutex> guard(_lock);
     }
-    if (_started && !_finished) {
+    if (_started.load(std::memory_order_relaxed) && !_finished) {
         LOG(error, "Transport: delete called on active object!");
     } else {
         std::lock_guard guard(_pseudo_thread);
@@ -354,7 +355,7 @@ FNET_TransportThread::ShutDown(bool waitFinished)
 {
     bool wasEmpty = false;
     {
-        std::lock_guard<std::mutex> guard(_lock);
+        std::lock_guard<std::mutex> guard(_qLock);
         if (!IsShutDown()) {
             _shutdown.store(true, std::memory_order_relaxed);
             wasEmpty  = _queue.IsEmpty_NoLock();
@@ -385,15 +386,7 @@ FNET_TransportThread::WaitFinished()
 bool
 FNET_TransportThread::InitEventLoop()
 {
-    bool wasStarted;
-    {
-        std::lock_guard<std::mutex> guard(_lock);
-        wasStarted = _started;
-        if (!_started) {
-            _started = true;
-        }
-    }
-    if (wasStarted) {
+    if (_started.exchange(true)) {
         LOG(error, "Transport: InitEventLoop: object already active!");
         return false;
     }
@@ -405,7 +398,7 @@ void
 FNET_TransportThread::handle_wakeup_events()
 {
     {
-        std::lock_guard<std::mutex> guard(_lock);
+        std::lock_guard<std::mutex> guard(_qLock);
         _queue.FlushPackets_NoLock(&_myQueue);
     }
 
@@ -523,7 +516,7 @@ void
 FNET_TransportThread::endEventLoop() {
     // flush event queue
     {
-        std::lock_guard<std::mutex> guard(_lock);
+        std::lock_guard<std::mutex> guard(_qLock);
         _queue.FlushPackets_NoLock(&_myQueue);
     }
 
diff --git a/fnet/src/vespa/fnet/transport_thread.h b/fnet/src/vespa/fnet/transport_thread.h
index 83332fb4cc8..aa03c8d300e 100644
--- a/fnet/src/vespa/fnet/transport_thread.h
+++ b/fnet/src/vespa/fnet/transport_thread.h
@@ -43,10 +43,11 @@ private:
     Selector                 _selector;       // I/O event generator
     FNET_PacketQueue_NoLock  _queue;          // outer event queue
     FNET_PacketQueue_NoLock  _myQueue;        // inner event queue
-    std::mutex               _lock;           // used for synchronization
-    std::condition_variable  _cond;           // used for synchronization
+    std::mutex               _qLock;          // protects the Q
+    std::mutex               _lock;           // used for synchronization during shutdown
+    std::condition_variable  _cond;           // used for synchronization during shutdown
     std::recursive_mutex     _pseudo_thread;  // used after transport thread has shut down
-    bool                     _started;        // event loop started ?
+    std::atomic<bool>        _started;        // event loop started ?
     std::atomic<bool>        _shutdown;       // should stop event loop ?
     bool                     _finished;       // event loop stopped ?
     bool                     _waitFinished;   // someone is waiting for _finished