refactor: Use boost::scoped_connection in signal/slot, also prefer range-based loop instead of std::transform

Author: ken2812221

src/rpc/server.cpp

@@ -500,11 +500,7 @@ UniValue CRPCTable::execute(const JSONRPCRequest &request) const
 std::vector<std::string> CRPCTable::listCommands() const
 {
     std::vector<std::string> commandList;
-    typedef std::map<std::string, const CRPCCommand*> commandMap;
-
-    std::transform( mapCommands.begin(), mapCommands.end(),
-                   std::back_inserter(commandList),
-                   boost::bind(&commandMap::value_type::first,_1) );
+    for (const auto& i : mapCommands) commandList.emplace_back(i.first);
     return commandList;
 }
 

src/validation.cpp

@@ -2368,14 +2368,11 @@ class ConnectTrace {
 private:
     std::vector<PerBlockConnectTrace> blocksConnected;
     CTxMemPool &pool;
+    boost::signals2::scoped_connection m_connNotifyEntryRemoved;
 
 public:
     explicit ConnectTrace(CTxMemPool &_pool) : blocksConnected(1), pool(_pool) {
-        pool.NotifyEntryRemoved.connect(boost::bind(&ConnectTrace::NotifyEntryRemoved, this, _1, _2));
-    }
-
-    ~ConnectTrace() {
-        pool.NotifyEntryRemoved.disconnect(boost::bind(&ConnectTrace::NotifyEntryRemoved, this, _1, _2));
+        m_connNotifyEntryRemoved = pool.NotifyEntryRemoved.connect(boost::bind(&ConnectTrace::NotifyEntryRemoved, this, _1, _2));
     }
 
     void BlockConnected(CBlockIndex* pindex, std::shared_ptr<const CBlock> pblock) {

src/validationinterface.cpp

@@ -17,6 +17,18 @@
 
 #include <boost/signals2/signal.hpp>
 
+struct ValidationInterfaceConnections {
+    boost::signals2::scoped_connection UpdatedBlockTip;
+    boost::signals2::scoped_connection TransactionAddedToMempool;
+    boost::signals2::scoped_connection BlockConnected;
+    boost::signals2::scoped_connection BlockDisconnected;
+    boost::signals2::scoped_connection TransactionRemovedFromMempool;
+    boost::signals2::scoped_connection ChainStateFlushed;
+    boost::signals2::scoped_connection Broadcast;
+    boost::signals2::scoped_connection BlockChecked;
+    boost::signals2::scoped_connection NewPoWValidBlock;
+};
+
 struct MainSignalsInstance {
     boost::signals2::signal<void (const CBlockIndex *, const CBlockIndex *, bool fInitialDownload)> UpdatedBlockTip;
     boost::signals2::signal<void (const CTransactionRef &)> TransactionAddedToMempool;
@@ -32,12 +44,18 @@ struct MainSignalsInstance {
     // but must ensure all callbacks happen in-order, so we end up creating
     // our own queue here :(
     SingleThreadedSchedulerClient m_schedulerClient;
+    std::unordered_map<CValidationInterface*, ValidationInterfaceConnections> m_connMainSignals;
 
     explicit MainSignalsInstance(CScheduler *pscheduler) : m_schedulerClient(pscheduler) {}
 };
 
 static CMainSignals g_signals;
 
+// This map has to a separate global instead of a member of MainSignalsInstance,
+// because RegisterWithMempoolSignals is currently called before RegisterBackgroundSignalScheduler,
+// so MainSignalsInstance hasn't been created yet.
+static std::unordered_map<CTxMemPool*, boost::signals2::scoped_connection> g_connNotifyEntryRemoved;
+
 void CMainSignals::RegisterBackgroundSignalScheduler(CScheduler& scheduler) {
     assert(!m_internals);
     m_internals.reset(new MainSignalsInstance(&scheduler));
@@ -59,11 +77,11 @@ size_t CMainSignals::CallbacksPending() {
 }
 
 void CMainSignals::RegisterWithMempoolSignals(CTxMemPool& pool) {
-    pool.NotifyEntryRemoved.connect(boost::bind(&CMainSignals::MempoolEntryRemoved, this, _1, _2));
+    g_connNotifyEntryRemoved.emplace(&pool, pool.NotifyEntryRemoved.connect(boost::bind(&CMainSignals::MempoolEntryRemoved, this, _1, _2)));
 }
 
 void CMainSignals::UnregisterWithMempoolSignals(CTxMemPool& pool) {
-    pool.NotifyEntryRemoved.disconnect(boost::bind(&CMainSignals::MempoolEntryRemoved, this, _1, _2));
+    g_connNotifyEntryRemoved.erase(&pool);
 }
 
 CMainSignals& GetMainSignals()
@@ -72,42 +90,27 @@ CMainSignals& GetMainSignals()
 }
 
 void RegisterValidationInterface(CValidationInterface* pwalletIn) {
-    g_signals.m_internals->UpdatedBlockTip.connect(boost::bind(&CValidationInterface::UpdatedBlockTip, pwalletIn, _1, _2, _3));
-    g_signals.m_internals->TransactionAddedToMempool.connect(boost::bind(&CValidationInterface::TransactionAddedToMempool, pwalletIn, _1));
-    g_signals.m_internals->BlockConnected.connect(boost::bind(&CValidationInterface::BlockConnected, pwalletIn, _1, _2, _3));
-    g_signals.m_internals->BlockDisconnected.connect(boost::bind(&CValidationInterface::BlockDisconnected, pwalletIn, _1));
-    g_signals.m_internals->TransactionRemovedFromMempool.connect(boost::bind(&CValidationInterface::TransactionRemovedFromMempool, pwalletIn, _1));
-    g_signals.m_internals->ChainStateFlushed.connect(boost::bind(&CValidationInterface::ChainStateFlushed, pwalletIn, _1));
-    g_signals.m_internals->Broadcast.connect(boost::bind(&CValidationInterface::ResendWalletTransactions, pwalletIn, _1, _2));
-    g_signals.m_internals->BlockChecked.connect(boost::bind(&CValidationInterface::BlockChecked, pwalletIn, _1, _2));
-    g_signals.m_internals->NewPoWValidBlock.connect(boost::bind(&CValidationInterface::NewPoWValidBlock, pwalletIn, _1, _2));
+    ValidationInterfaceConnections& conns = g_signals.m_internals->m_connMainSignals[pwalletIn];
+    conns.UpdatedBlockTip = g_signals.m_internals->UpdatedBlockTip.connect(boost::bind(&CValidationInterface::UpdatedBlockTip, pwalletIn, _1, _2, _3));
+    conns.TransactionAddedToMempool = g_signals.m_internals->TransactionAddedToMempool.connect(boost::bind(&CValidationInterface::TransactionAddedToMempool, pwalletIn, _1));
+    conns.BlockConnected = g_signals.m_internals->BlockConnected.connect(boost::bind(&CValidationInterface::BlockConnected, pwalletIn, _1, _2, _3));
+    conns.BlockDisconnected = g_signals.m_internals->BlockDisconnected.connect(boost::bind(&CValidationInterface::BlockDisconnected, pwalletIn, _1));
+    conns.TransactionRemovedFromMempool = g_signals.m_internals->TransactionRemovedFromMempool.connect(boost::bind(&CValidationInterface::TransactionRemovedFromMempool, pwalletIn, _1));
+    conns.ChainStateFlushed = g_signals.m_internals->ChainStateFlushed.connect(boost::bind(&CValidationInterface::ChainStateFlushed, pwalletIn, _1));
+    conns.Broadcast = g_signals.m_internals->Broadcast.connect(boost::bind(&CValidationInterface::ResendWalletTransactions, pwalletIn, _1, _2));
+    conns.BlockChecked = g_signals.m_internals->BlockChecked.connect(boost::bind(&CValidationInterface::BlockChecked, pwalletIn, _1, _2));
+    conns.NewPoWValidBlock = g_signals.m_internals->NewPoWValidBlock.connect(boost::bind(&CValidationInterface::NewPoWValidBlock, pwalletIn, _1, _2));
 }
 
 void UnregisterValidationInterface(CValidationInterface* pwalletIn) {
-    g_signals.m_internals->BlockChecked.disconnect(boost::bind(&CValidationInterface::BlockChecked, pwalletIn, _1, _2));
-    g_signals.m_internals->Broadcast.disconnect(boost::bind(&CValidationInterface::ResendWalletTransactions, pwalletIn, _1, _2));
-    g_signals.m_internals->ChainStateFlushed.disconnect(boost::bind(&CValidationInterface::ChainStateFlushed, pwalletIn, _1));
-    g_signals.m_internals->TransactionAddedToMempool.disconnect(boost::bind(&CValidationInterface::TransactionAddedToMempool, pwalletIn, _1));
-    g_signals.m_internals->BlockConnected.disconnect(boost::bind(&CValidationInterface::BlockConnected, pwalletIn, _1, _2, _3));
-    g_signals.m_internals->BlockDisconnected.disconnect(boost::bind(&CValidationInterface::BlockDisconnected, pwalletIn, _1));
-    g_signals.m_internals->TransactionRemovedFromMempool.disconnect(boost::bind(&CValidationInterface::TransactionRemovedFromMempool, pwalletIn, _1));
-    g_signals.m_internals->UpdatedBlockTip.disconnect(boost::bind(&CValidationInterface::UpdatedBlockTip, pwalletIn, _1, _2, _3));
-    g_signals.m_internals->NewPoWValidBlock.disconnect(boost::bind(&CValidationInterface::NewPoWValidBlock, pwalletIn, _1, _2));
+    g_signals.m_internals->m_connMainSignals.erase(pwalletIn);
 }
 
 void UnregisterAllValidationInterfaces() {
     if (!g_signals.m_internals) {
         return;
     }
-    g_signals.m_internals->BlockChecked.disconnect_all_slots();
-    g_signals.m_internals->Broadcast.disconnect_all_slots();
-    g_signals.m_internals->ChainStateFlushed.disconnect_all_slots();
-    g_signals.m_internals->TransactionAddedToMempool.disconnect_all_slots();
-    g_signals.m_internals->BlockConnected.disconnect_all_slots();
-    g_signals.m_internals->BlockDisconnected.disconnect_all_slots();
-    g_signals.m_internals->TransactionRemovedFromMempool.disconnect_all_slots();
-    g_signals.m_internals->UpdatedBlockTip.disconnect_all_slots();
-    g_signals.m_internals->NewPoWValidBlock.disconnect_all_slots();
+    g_signals.m_internals->m_connMainSignals.clear();
 }
 
 void CallFunctionInValidationInterfaceQueue(std::function<void ()> func) {