Merge bitcoin/bitcoin#32862: rpc: use CScheduler for relocking wallet and remove RPCTimer

fcfd3db563 remove RPCTimerInterface and RPCRunLater (Matthew Zipkin)
8a1765795f use WalletContext scheduler for walletpassphrase callback (Matthew Zipkin)

Pull request description:

  This removes the dependency on libevent for events scheduled by RPC commands, like re-locking a wallet some time after decryption with walletpassphrase. Since walletpassphrase is currently the only RPC that does this, `RPCRunLater`, `RPCTimerInterface` and all related methods are left unused, and deleted in the second commit. Any future RPC that needs to execute a callback in the future can follow the pattern in this PR and just use a scheduler from node or wallet context.

  This is an alternative approach to #32796, described in https://github.com/bitcoin/bitcoin/pull/32796#issuecomment-3014309449

ACKs for top commit:
  fjahr:
    Code Review ACK fcfd3db563
  achow101:
    ACK fcfd3db563
  furszy:
    ACK fcfd3db563

Tree-SHA512: 04f5e9c3f73f598c3d41d6e35bb59c64c7b93b03ad9fce3c40901733147ce7764f41f475fef1527d44af18f722759996a31ca83b48cb52153795d5022fecfd14

src/qt/rpcconsole.cpp

@@ -98,37 +98,6 @@ private:
     interfaces::Node& m_node;
 };
 
-/** Class for handling RPC timers
- * (used for e.g. re-locking the wallet after a timeout)
- */
-class QtRPCTimerBase: public QObject, public RPCTimerBase
-{
-    Q_OBJECT
-public:
-    QtRPCTimerBase(std::function<void()>& _func, int64_t millis):
-        func(_func)
-    {
-        timer.setSingleShot(true);
-        connect(&timer, &QTimer::timeout, [this]{ func(); });
-        timer.start(millis);
-    }
-    ~QtRPCTimerBase() = default;
-private:
-    QTimer timer;
-    std::function<void()> func;
-};
-
-class QtRPCTimerInterface: public RPCTimerInterface
-{
-public:
-    ~QtRPCTimerInterface() = default;
-    const char *Name() override { return "Qt"; }
-    RPCTimerBase* NewTimer(std::function<void()>& func, int64_t millis) override
-    {
-        return new QtRPCTimerBase(func, millis);
-    }
-};
-
 class PeerIdViewDelegate : public QStyledItemDelegate
 {
     Q_OBJECT
@@ -567,12 +536,6 @@ RPCConsole::RPCConsole(interfaces::Node& node, const PlatformStyle *_platformSty
     ui->WalletSelector->setVisible(false);
     ui->WalletSelectorLabel->setVisible(false);
 
-    // Register RPC timer interface
-    rpcTimerInterface = new QtRPCTimerInterface();
-    // avoid accidentally overwriting an existing, non QTThread
-    // based timer interface
-    m_node.rpcSetTimerInterfaceIfUnset(rpcTimerInterface);
-
     setTrafficGraphRange(INITIAL_TRAFFIC_GRAPH_MINS);
     updateDetailWidget();
 
@@ -602,8 +565,6 @@ RPCConsole::~RPCConsole()
     settings.setValue("PeersTabPeerHeaderState", m_peer_widget_header_state);
     settings.setValue("PeersTabBanlistHeaderState", m_banlist_widget_header_state);
 
-    m_node.rpcUnsetTimerInterface(rpcTimerInterface);
-    delete rpcTimerInterface;
     delete ui;
 }
 

src/qt/rpcconsole.h

@@ -20,7 +20,6 @@
 
 class PlatformStyle;
 class RPCExecutor;
-class RPCTimerInterface;
 class WalletModel;
 
 namespace interfaces {
@@ -166,7 +165,6 @@ private:
     QString cmdBeforeBrowsing;
     QList<NodeId> cachedNodeids;
     const PlatformStyle* const platformStyle;
-    RPCTimerInterface *rpcTimerInterface = nullptr;
     QMenu *peersTableContextMenu = nullptr;
     QMenu *banTableContextMenu = nullptr;
     int consoleFontSize = 0;