Drop upgrade-cancel callback registration for a generic "resumeable"

Instead of passing a StartShutdown reference all the way up from
txdb, give ShowProgress a "resumeable" boolean, which is used to
inform the user if the action will be resumed, but cancel is always
allowed by just calling StartShutdown().

src/qt/splashscreen.cpp

@@ -142,8 +142,8 @@ SplashScreen::~SplashScreen()
 bool SplashScreen::eventFilter(QObject * obj, QEvent * ev) {
     if (ev->type() == QEvent::KeyPress) {
         QKeyEvent *keyEvent = static_cast<QKeyEvent *>(ev);
-        if(keyEvent->text()[0] == 'q' && breakAction != nullptr) {
-            breakAction();
+        if(keyEvent->text()[0] == 'q') {
+            StartShutdown();
         }
     }
     return QObject::eventFilter(obj, ev);
@@ -170,27 +170,18 @@ static void InitMessage(SplashScreen *splash, const std::string &message)
         Q_ARG(QColor, QColor(55,55,55)));
 }
 
-static void ShowProgress(SplashScreen *splash, const std::string &title, int nProgress)
+static void ShowProgress(SplashScreen *splash, const std::string &title, int nProgress, bool resume_possible)
 {
-    InitMessage(splash, title + strprintf("%d", nProgress) + "%");
-}
-
-void SplashScreen::setBreakAction(const std::function<void(void)> &action)
-{
-    breakAction = action;
-}
-
-static void SetProgressBreakAction(SplashScreen *splash, const std::function<void(void)> &action)
-{
-    QMetaObject::invokeMethod(splash, "setBreakAction",
-        Qt::QueuedConnection,
-        Q_ARG(std::function<void(void)>, action));
+    InitMessage(splash, title + std::string("\n") +
+            (resume_possible ? _("(press q to shutdown and continue later)")
+                                : _("press q to shutdown")) +
+            strprintf("\n%d", nProgress) + "%");
 }
 
 #ifdef ENABLE_WALLET
 void SplashScreen::ConnectWallet(CWallet* wallet)
 {
-    wallet->ShowProgress.connect(boost::bind(ShowProgress, this, _1, _2));
+    wallet->ShowProgress.connect(boost::bind(ShowProgress, this, _1, _2, false));
     connectedWallets.push_back(wallet);
 }
 #endif
@@ -199,8 +190,7 @@ void SplashScreen::subscribeToCoreSignals()
 {
     // Connect signals to client
     uiInterface.InitMessage.connect(boost::bind(InitMessage, this, _1));
-    uiInterface.ShowProgress.connect(boost::bind(ShowProgress, this, _1, _2));
-    uiInterface.SetProgressBreakAction.connect(boost::bind(SetProgressBreakAction, this, _1));
+    uiInterface.ShowProgress.connect(boost::bind(ShowProgress, this, _1, _2, _3));
 #ifdef ENABLE_WALLET
     uiInterface.LoadWallet.connect(boost::bind(&SplashScreen::ConnectWallet, this, _1));
 #endif
@@ -210,10 +200,10 @@ void SplashScreen::unsubscribeFromCoreSignals()
 {
     // Disconnect signals from client
     uiInterface.InitMessage.disconnect(boost::bind(InitMessage, this, _1));
-    uiInterface.ShowProgress.disconnect(boost::bind(ShowProgress, this, _1, _2));
+    uiInterface.ShowProgress.disconnect(boost::bind(ShowProgress, this, _1, _2, _3));
 #ifdef ENABLE_WALLET
     for (CWallet* const & pwallet : connectedWallets) {
-        pwallet->ShowProgress.disconnect(boost::bind(ShowProgress, this, _1, _2));
+        pwallet->ShowProgress.disconnect(boost::bind(ShowProgress, this, _1, _2, false));
     }
 #endif
 }

src/qt/splashscreen.h

@@ -36,8 +36,6 @@ public Q_SLOTS:
     /** Show message and progress */
     void showMessage(const QString &message, int alignment, const QColor &color);
 
-    /** Sets the break action */
-    void setBreakAction(const std::function<void(void)> &action);
 protected:
     bool eventFilter(QObject * obj, QEvent * ev);
 
@@ -55,8 +53,6 @@ private:
     int curAlignment;
 
     QList<CWallet*> connectedWallets;
-
-    std::function<void(void)> breakAction;
 };
 
 #endif // BITCOIN_QT_SPLASHSCREEN_H

src/txdb.cpp

@@ -371,9 +371,9 @@ bool CCoinsViewDB::Upgrade() {
     int64_t count = 0;
     LogPrintf("Upgrading utxo-set database...\n");
     LogPrintf("[0%%]...");
+    uiInterface.ShowProgress(_("Upgrading UTXO database"), 0, true);
     size_t batch_size = 1 << 24;
     CDBBatch batch(db);
-    uiInterface.SetProgressBreakAction(StartShutdown);
     int reportDone = 0;
     std::pair<unsigned char, uint256> key;
     std::pair<unsigned char, uint256> prev_key = {DB_COINS, uint256()};
@@ -386,7 +386,7 @@ bool CCoinsViewDB::Upgrade() {
             if (count++ % 256 == 0) {
                 uint32_t high = 0x100 * *key.second.begin() + *(key.second.begin() + 1);
                 int percentageDone = (int)(high * 100.0 / 65536.0 + 0.5);
-                uiInterface.ShowProgress(_("Upgrading UTXO database") + "\n"+ _("(press q to shutdown and continue later)") + "\n", percentageDone);
+                uiInterface.ShowProgress(_("Upgrading UTXO database"), percentageDone, true);
                 if (reportDone < percentageDone/10) {
                     // report max. every 10% step
                     LogPrintf("[%d%%]...", percentageDone);
@@ -420,7 +420,7 @@ bool CCoinsViewDB::Upgrade() {
     }
     db.WriteBatch(batch);
     db.CompactRange({DB_COINS, uint256()}, key);
-    uiInterface.SetProgressBreakAction(std::function<void(void)>());
+    uiInterface.ShowProgress("", 100, false);
     LogPrintf("[%s].\n", ShutdownRequested() ? "CANCELLED" : "DONE");
     return !ShutdownRequested();
 }

src/ui_interface.h

@@ -94,11 +94,11 @@ public:
     /** A wallet has been loaded. */
     boost::signals2::signal<void (CWallet* wallet)> LoadWallet;
 
-    /** Show progress e.g. for verifychain */
-    boost::signals2::signal<void (const std::string &title, int nProgress)> ShowProgress;
-
-    /** Set progress break action (possible "cancel button" triggers that action) */
-    boost::signals2::signal<void (std::function<void(void)> action)> SetProgressBreakAction;
+    /**
+     * Show progress e.g. for verifychain.
+     * resume_possible indicates shutting down now will result in the current progress action resuming upon restart.
+     */
+    boost::signals2::signal<void (const std::string &title, int nProgress, bool resume_possible)> ShowProgress;
 
     /** New block has been accepted */
     boost::signals2::signal<void (bool, const CBlockIndex *)> NotifyBlockTip;

src/validation.cpp

@@ -3563,12 +3563,12 @@ bool LoadChainTip(const CChainParams& chainparams)
 
 CVerifyDB::CVerifyDB()
 {
-    uiInterface.ShowProgress(_("Verifying blocks..."), 0);
+    uiInterface.ShowProgress(_("Verifying blocks..."), 0, false);
 }
 
 CVerifyDB::~CVerifyDB()
 {
-    uiInterface.ShowProgress("", 100);
+    uiInterface.ShowProgress("", 100, false);
 }
 
 bool CVerifyDB::VerifyDB(const CChainParams& chainparams, CCoinsView *coinsview, int nCheckLevel, int nCheckDepth)
@@ -3598,7 +3598,7 @@ bool CVerifyDB::VerifyDB(const CChainParams& chainparams, CCoinsView *coinsview,
             LogPrintf("[%d%%]...", percentageDone);
             reportDone = percentageDone/10;
         }
-        uiInterface.ShowProgress(_("Verifying blocks..."), percentageDone);
+        uiInterface.ShowProgress(_("Verifying blocks..."), percentageDone, false);
         if (pindex->nHeight < chainActive.Height()-nCheckDepth)
             break;
         if (fPruneMode && !(pindex->nStatus & BLOCK_HAVE_DATA)) {
@@ -3649,7 +3649,7 @@ bool CVerifyDB::VerifyDB(const CChainParams& chainparams, CCoinsView *coinsview,
         CBlockIndex *pindex = pindexState;
         while (pindex != chainActive.Tip()) {
             boost::this_thread::interruption_point();
-            uiInterface.ShowProgress(_("Verifying blocks..."), std::max(1, std::min(99, 100 - (int)(((double)(chainActive.Height() - pindex->nHeight)) / (double)nCheckDepth * 50))));
+            uiInterface.ShowProgress(_("Verifying blocks..."), std::max(1, std::min(99, 100 - (int)(((double)(chainActive.Height() - pindex->nHeight)) / (double)nCheckDepth * 50))), false);
             pindex = chainActive.Next(pindex);
             CBlock block;
             if (!ReadBlockFromDisk(block, pindex, chainparams.GetConsensus()))
@@ -3696,7 +3696,7 @@ bool ReplayBlocks(const CChainParams& params, CCoinsView* view)
     if (hashHeads.empty()) return true; // We're already in a consistent state.
     if (hashHeads.size() != 2) return error("ReplayBlocks(): unknown inconsistent state");
 
-    uiInterface.ShowProgress(_("Replaying blocks..."), 0);
+    uiInterface.ShowProgress(_("Replaying blocks..."), 0, false);
     LogPrintf("Replaying blocks\n");
 
     const CBlockIndex* pindexOld = nullptr;  // Old tip during the interrupted flush.
@@ -3747,7 +3747,7 @@ bool ReplayBlocks(const CChainParams& params, CCoinsView* view)
 
     cache.SetBestBlock(pindexNew->GetBlockHash());
     cache.Flush();
-    uiInterface.ShowProgress("", 100);
+    uiInterface.ShowProgress("", 100, false);
     return true;
 }