6 files changed, 32 insertions, 0 deletions
diff --git a/src/init.cpp b/src/init.cpp
index 94bba6820e..12f29a4ca8 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -215,6 +215,19 @@ void Shutdown()
         fFeeEstimatesInitialized = false;
     }
 
+    // FlushStateToDisk generates a SetBestChain callback, which we should avoid missing
+    FlushStateToDisk();
+
+    // After there are no more peers/RPC left to give us new data which may generate
+    // CValidationInterface callbacks, flush them...
+    GetMainSignals().FlushBackgroundCallbacks();
+
+    // Any future callbacks will be dropped. This should absolutely be safe - if
+    // missing a callback results in an unrecoverable situation, unclean shutdown
+    // would too. The only reason to do the above flushes is to let the wallet catch
+    // up with our current chain to avoid any strange pruning edge cases and make
+    // next startup faster by avoiding rescan.
+
     {
         LOCK(cs_main);
         if (pcoinsTip != NULL) {
diff --git a/src/scheduler.cpp b/src/scheduler.cpp
index a76a87e10a..35bf0da4be 100644
--- a/src/scheduler.cpp
+++ b/src/scheduler.cpp
@@ -191,3 +191,12 @@ void SingleThreadedSchedulerClient::AddToProcessQueue(std::function<void (void)>
     }
     MaybeScheduleProcessQueue();
 }
+
+void SingleThreadedSchedulerClient::EmptyQueue() {
+    bool should_continue = true;
+    while (should_continue) {
+        ProcessQueue();
+        LOCK(m_cs_callbacks_pending);
+        should_continue = !m_callbacks_pending.empty();
+    }
+}
diff --git a/src/scheduler.h b/src/scheduler.h
index 82036afdf0..6a079f7749 100644
--- a/src/scheduler.h
+++ b/src/scheduler.h
@@ -101,6 +101,9 @@ private:
 public:
     SingleThreadedSchedulerClient(CScheduler *pschedulerIn) : m_pscheduler(pschedulerIn) {}
     void AddToProcessQueue(std::function<void (void)> func);
+
+    // Processes all remaining queue members on the calling thread, blocking until queue is empty
+    void EmptyQueue();
 };
 
 #endif
diff --git a/src/test/test_bitcoin.cpp b/src/test/test_bitcoin.cpp
index e6a8cc779d..3ba81ed17b 100644
--- a/src/test/test_bitcoin.cpp
+++ b/src/test/test_bitcoin.cpp
@@ -94,6 +94,7 @@ TestingSetup::~TestingSetup()
         UnregisterNodeSignals(GetNodeSignals());
         threadGroup.interrupt_all();
         threadGroup.join_all();
+        GetMainSignals().FlushBackgroundCallbacks();
         GetMainSignals().UnregisterBackgroundSignalScheduler();
         UnloadBlockIndex();
         delete pcoinsTip;
diff --git a/src/validationinterface.cpp b/src/validationinterface.cpp
index 8edc7c398d..bf20d606f8 100644
--- a/src/validationinterface.cpp
+++ b/src/validationinterface.cpp
@@ -44,6 +44,10 @@ void CMainSignals::UnregisterBackgroundSignalScheduler() {
     m_internals.reset(nullptr);
 }
 
+void CMainSignals::FlushBackgroundCallbacks() {
+    m_internals->m_schedulerClient.EmptyQueue();
+}
+
 CMainSignals& GetMainSignals()
 {
     return g_signals;
diff --git a/src/validationinterface.h b/src/validationinterface.h
index fbfe273b10..568da66df2 100644
--- a/src/validationinterface.h
+++ b/src/validationinterface.h
@@ -79,6 +79,8 @@ public:
     void RegisterBackgroundSignalScheduler(CScheduler& scheduler);
     /** Unregister a CScheduler to give callbacks which should run in the background - these callbacks will now be dropped! */
     void UnregisterBackgroundSignalScheduler();
+    /** Call any remaining callbacks on the calling thread */
+    void FlushBackgroundCallbacks();
 
     void UpdatedBlockTip(const CBlockIndex *, const CBlockIndex *, bool fInitialDownload);
     void TransactionAddedToMempool(const CTransactionRef &);