From 8a39407e8c69e4d6df586d3bb73efd05d05ee3c5 Mon Sep 17 00:00:00 2001
From: klaus spanderen <klaus@spanderen.de>
Date: Fri, 6 Oct 2023 21:43:44 +0200
Subject: [PATCH 1/3] avoid potential double notifications

---
 ql/patterns/observable.cpp | 25 +++++++++++++------------
 ql/patterns/observable.hpp |  4 ++--
 2 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/ql/patterns/observable.cpp b/ql/patterns/observable.cpp
index 39a7de18100..3e5eaf5a0d6 100644
--- a/ql/patterns/observable.cpp
+++ b/ql/patterns/observable.cpp
@@ -161,9 +161,8 @@ namespace QuantLib {
 
         if (ObservableSettings::instance().updatesDeferred()) {
             std::lock_guard<std::mutex> sLock(ObservableSettings::instance().mutex_);
-            if (ObservableSettings::instance().updatesDeferred()) {
+            if (ObservableSettings::instance().updatesDeferred())
                 ObservableSettings::instance().unregisterDeferredObserver(observerProxy);
-            }
         }
 
         if (disconnect) {
@@ -173,18 +172,20 @@ namespace QuantLib {
 
     void Observable::notifyObservers() {
         if (ObservableSettings::instance().updatesEnabled()) {
-            return (*sig_)();
+            sig_->operator()();
         }
+        else {
+            bool updatesEnabled = false;
+            {
+                std::lock_guard<std::mutex> sLock(ObservableSettings::instance().mutex_);
+                updatesEnabled = ObservableSettings::instance().updatesEnabled();
+
+                if (ObservableSettings::instance().updatesDeferred())
+                    ObservableSettings::instance().registerDeferredObservers(observers_);
+            }
 
-        std::lock_guard<std::mutex> sLock(ObservableSettings::instance().mutex_);
-        if (ObservableSettings::instance().updatesEnabled()) {
-            return (*sig_)();
-        }
-        else if (ObservableSettings::instance().updatesDeferred()) {
-            std::lock_guard<std::recursive_mutex> lock(mutex_);
-            // if updates are only deferred, flag this for later notification
-            // these are held centrally by the settings singleton
-            ObservableSettings::instance().registerDeferredObservers(observers_);
+            if (updatesEnabled)
+                sig_->operator()();
         }
     }
 
diff --git a/ql/patterns/observable.hpp b/ql/patterns/observable.hpp
index 35ead03ee70..13d7dbc7fc9 100644
--- a/ql/patterns/observable.hpp
+++ b/ql/patterns/observable.hpp
@@ -401,7 +401,7 @@ namespace QuantLib {
       public:
         void disableUpdates(bool deferred=false) {
             std::lock_guard<std::mutex> lock(mutex_);
-            updatesType_ = (deferred) ? UpdatesDeferred : 0;
+            updatesType_ = (deferred) ? UpdatesDeferred : UpdatesDisabled;
         }
         void enableUpdates();
 
@@ -420,7 +420,7 @@ namespace QuantLib {
         set_type deferredObservers_;
         mutable std::mutex mutex_;
 
-        enum UpdateType { UpdatesEnabled = 1, UpdatesDeferred = 2} ;
+        enum UpdateType { UpdatesDisabled = 0, UpdatesEnabled = 1, UpdatesDeferred = 2} ;
         std::atomic<int> updatesType_;
     };
 

From 32b0cbb41ce1cc64610c35d2c741f1a5cda1b019 Mon Sep 17 00:00:00 2001
From: klaus spanderen <klaus@spanderen.de>
Date: Fri, 6 Oct 2023 21:58:51 +0200
Subject: [PATCH 2/3] secure observer list

---
 ql/patterns/observable.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/ql/patterns/observable.cpp b/ql/patterns/observable.cpp
index 3e5eaf5a0d6..996b8a05063 100644
--- a/ql/patterns/observable.cpp
+++ b/ql/patterns/observable.cpp
@@ -180,8 +180,10 @@ namespace QuantLib {
                 std::lock_guard<std::mutex> sLock(ObservableSettings::instance().mutex_);
                 updatesEnabled = ObservableSettings::instance().updatesEnabled();
 
-                if (ObservableSettings::instance().updatesDeferred())
+                if (ObservableSettings::instance().updatesDeferred()) {
+                    std::lock_guard<std::recursive_mutex> lock(mutex_);
                     ObservableSettings::instance().registerDeferredObservers(observers_);
+                }
             }
 
             if (updatesEnabled)

From c7a31049ce7298aa1061ab58d42d4bb06526fa21 Mon Sep 17 00:00:00 2001
From: klaus spanderen <klaus@spanderen.de>
Date: Fri, 6 Oct 2023 23:43:02 +0200
Subject: [PATCH 3/3] avoid includes

---
 ql/patterns/observable.hpp | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/ql/patterns/observable.hpp b/ql/patterns/observable.hpp
index 13d7dbc7fc9..f7536c76964 100644
--- a/ql/patterns/observable.hpp
+++ b/ql/patterns/observable.hpp
@@ -262,7 +262,9 @@ namespace QuantLib {
 
 #else
 
+#ifndef QL_USE_STD_SHARED_PTR
 #include <boost/smart_ptr/owner_less.hpp>
+#endif
 #include <atomic>
 #include <mutex>
 #include <set>
@@ -410,9 +412,15 @@ namespace QuantLib {
       private:
         ObservableSettings() : updatesType_(UpdatesEnabled) {}
 
+#if defined(QL_USE_STD_SHARED_PTR)
+        typedef std::set<ext::weak_ptr<Observer::Proxy>,
+                         std::owner_less<ext::weak_ptr<Observer::Proxy> > >
+            set_type;
+#else
         typedef std::set<ext::weak_ptr<Observer::Proxy>,
                          boost::owner_less<ext::weak_ptr<Observer::Proxy> > >
             set_type;
+#endif
 
         void registerDeferredObservers(const Observable::set_type& observers);
         void unregisterDeferredObserver(const ext::shared_ptr<Observer::Proxy>& proxy);