Merge #18289: refactor: Make scheduler methods type safe

fa36f3a29538012a6eb5c3402b3b3c18fd32b230 refactor: move DUMP_BANS_INTERVAL to banman.h (MarcoFalke)
fadafb83cff9a9a340eac1b5a853e2467d5e0ef7 scheduler: Make schedule* methods type safe (MarcoFalke)
fa70ccc6c4e304646b4610228f3975b3a9762643 scheduler: Use C++11 member initialization, add shutdown assert (MarcoFalke)

Pull request description:

  Main benefit is that stuff like `15 * 60 * 1000` is replaced by `minutes{15}`

ACKs for top commit:
  vasild:
    ACK fa36f3a (code review, not tested)
  ajtowns:
    ACK fa36f3a29538012a6eb5c3402b3b3c18fd32b230
  jonatack:
    ACK fa36f3a

Tree-SHA512: f35f1a1d643dfa676bd47474659f6492ed05cca04cdb556064b126f654a6a44a4b93fcaddcdcd41faf81b8f11439c11e5c7ab88685ba2eef12f7188843d17ad8

8 files changed, 43 insertions, 44 deletions

diff --git a/src/banman.h b/src/banman.h
index 8984874914..6bea2e75e9 100644
--- a/src/banman.h
+++ b/src/banman.h
@@ -5,16 +5,19 @@
 #ifndef BITCOIN_BANMAN_H
 #define BITCOIN_BANMAN_H
 
-#include <cstdint>
-#include <memory>
-
 #include <addrdb.h>
 #include <fs.h>
 #include <net_types.h> // For banmap_t
 #include <sync.h>
 
+#include <chrono>
+#include <cstdint>
+#include <memory>
+
 // NOTE: When adjusting this, update rpcnet:setban's help ("24h")
 static constexpr unsigned int DEFAULT_MISBEHAVING_BANTIME = 60 * 60 * 24; // Default 24-hour ban
+// How often to dump addresses to banlist.dat
+static constexpr std::chrono::minutes DUMP_BANS_INTERVAL{15};
 
 class CClientUIInterface;
 class CNetAddr;
diff --git a/src/init.cpp b/src/init.cpp
index 97640b0658..774da8e709 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -86,10 +86,6 @@ static const bool DEFAULT_PROXYRANDOMIZE = true;
 static const bool DEFAULT_REST_ENABLE = false;
 static const bool DEFAULT_STOPAFTERBLOCKIMPORT = false;
 
-// Dump addresses to banlist.dat every 15 minutes (900s)
-static constexpr int DUMP_BANS_INTERVAL = 60 * 15;
-
-
 #ifdef WIN32
 // Win32 LevelDB doesn't use filedescriptors, and the ones used for
 // accessing block files don't count towards the fd_set size limit
@@ -1278,7 +1274,7 @@ bool AppInitMain(NodeContext& node)
     // Gather some entropy once per minute.
     node.scheduler->scheduleEvery([]{
         RandAddPeriodic();
-    }, 60000);
+    }, std::chrono::minutes{1});
 
     GetMainSignals().RegisterBackgroundSignalScheduler(*node.scheduler);
 
@@ -1862,7 +1858,7 @@ bool AppInitMain(NodeContext& node)
     BanMan* banman = node.banman.get();
     node.scheduler->scheduleEvery([banman]{
         banman->DumpBanlist();
-    }, DUMP_BANS_INTERVAL * 1000);
+    }, DUMP_BANS_INTERVAL);
 
     return true;
 }
diff --git a/src/net.cpp b/src/net.cpp
index d156450394..8352c40b98 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -45,8 +45,8 @@ static_assert(MINIUPNPC_API_VERSION >= 10, "miniUPnPc API version >= 10 assumed"
 
 #include <math.h>
 
-// Dump addresses to peers.dat every 15 minutes (900s)
-static constexpr int DUMP_PEERS_INTERVAL = 15 * 60;
+// How often to dump addresses to peers.dat
+static constexpr std::chrono::minutes DUMP_PEERS_INTERVAL{15};
 
 /** Number of DNS seeds to query when the number of connections is low. */
 static constexpr int DNSSEEDS_TO_QUERY_AT_ONCE = 3;
@@ -2343,7 +2343,7 @@ bool CConnman::Start(CScheduler& scheduler, const Options& connOptions)
     threadMessageHandler = std::thread(&TraceThread<std::function<void()> >, "msghand", std::function<void()>(std::bind(&CConnman::ThreadMessageHandler, this)));
 
     // Dump network addresses
-    scheduler.scheduleEvery(std::bind(&CConnman::DumpAddresses, this), DUMP_PEERS_INTERVAL * 1000);
+    scheduler.scheduleEvery([this] { DumpAddresses(); }, DUMP_PEERS_INTERVAL);
 
     return true;
 }
diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index d9b048fd65..9cbc02e55b 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -1127,7 +1127,7 @@ PeerLogicValidation::PeerLogicValidation(CConnman* connmanIn, BanMan* banman, CS
     // combine them in one function and schedule at the quicker (peer-eviction)
     // timer.
     static_assert(EXTRA_PEER_CHECK_INTERVAL < STALE_CHECK_INTERVAL, "peer eviction timer should be less than stale tip check timer");
-    scheduler.scheduleEvery(std::bind(&PeerLogicValidation::CheckForStaleTipAndEvictPeers, this, consensusParams), EXTRA_PEER_CHECK_INTERVAL * 1000);
+    scheduler.scheduleEvery([&] { this->CheckForStaleTipAndEvictPeers(consensusParams); }, std::chrono::seconds{EXTRA_PEER_CHECK_INTERVAL});
 }
 
 /**
diff --git a/src/scheduler.cpp b/src/scheduler.cpp
index 7cb7754fde..4cac5a54e0 100644
--- a/src/scheduler.cpp
+++ b/src/scheduler.cpp
@@ -9,13 +9,14 @@
 #include <assert.h>
 #include <utility>
 
-CScheduler::CScheduler() : nThreadsServicingQueue(0), stopRequested(false), stopWhenEmpty(false)
+CScheduler::CScheduler()
 {
 }
 
 CScheduler::~CScheduler()
 {
     assert(nThreadsServicingQueue == 0);
+    if (stopWhenEmpty) assert(taskQueue.empty());
 }
 
 
@@ -91,11 +92,6 @@ void CScheduler::schedule(CScheduler::Function f, std::chrono::system_clock::tim
     newTaskScheduled.notify_one();
 }
 
-void CScheduler::scheduleFromNow(CScheduler::Function f, int64_t deltaMilliSeconds)
-{
-    schedule(f, std::chrono::system_clock::now() + std::chrono::milliseconds(deltaMilliSeconds));
-}
-
 void CScheduler::MockForward(std::chrono::seconds delta_seconds)
 {
     assert(delta_seconds.count() > 0 && delta_seconds < std::chrono::hours{1});
@@ -118,15 +114,15 @@ void CScheduler::MockForward(std::chrono::seconds delta_seconds)
     newTaskScheduled.notify_one();
 }
 
-static void Repeat(CScheduler* s, CScheduler::Function f, int64_t deltaMilliSeconds)
+static void Repeat(CScheduler& s, CScheduler::Function f, std::chrono::milliseconds delta)
 {
     f();
-    s->scheduleFromNow(std::bind(&Repeat, s, f, deltaMilliSeconds), deltaMilliSeconds);
+    s.scheduleFromNow([=, &s] { Repeat(s, f, delta); }, delta);
 }
 
-void CScheduler::scheduleEvery(CScheduler::Function f, int64_t deltaMilliSeconds)
+void CScheduler::scheduleEvery(CScheduler::Function f, std::chrono::milliseconds delta)
 {
-    scheduleFromNow(std::bind(&Repeat, this, f, deltaMilliSeconds), deltaMilliSeconds);
+    scheduleFromNow([=] { Repeat(*this, f, delta); }, delta);
 }
 
 size_t CScheduler::getQueueInfo(std::chrono::system_clock::time_point &first,
diff --git a/src/scheduler.h b/src/scheduler.h
index 4d5aa3068e..1e64195484 100644
--- a/src/scheduler.h
+++ b/src/scheduler.h
@@ -24,8 +24,8 @@
 // Usage:
 //
 // CScheduler* s = new CScheduler();
-// s->scheduleFromNow(doSomething, 11); // Assuming a: void doSomething() { }
-// s->scheduleFromNow(std::bind(Class::func, this, argument), 3);
+// s->scheduleFromNow(doSomething, std::chrono::milliseconds{11}); // Assuming a: void doSomething() { }
+// s->scheduleFromNow([=] { this->func(argument); }, std::chrono::milliseconds{3});
 // boost::thread* t = new boost::thread(std::bind(CScheduler::serviceQueue, s));
 //
 // ... then at program shutdown, make sure to call stop() to clean up the thread(s) running serviceQueue:
@@ -46,15 +46,19 @@ public:
     // Call func at/after time t
     void schedule(Function f, std::chrono::system_clock::time_point t);
 
-    // Convenience method: call f once deltaMilliSeconds from now
-    void scheduleFromNow(Function f, int64_t deltaMilliSeconds);
+    /** Call f once after the delta has passed */
+    void scheduleFromNow(Function f, std::chrono::milliseconds delta)
+    {
+        schedule(std::move(f), std::chrono::system_clock::now() + delta);
+    }
 
-    // Another convenience method: call f approximately
-    // every deltaMilliSeconds forever, starting deltaMilliSeconds from now.
-    // To be more precise: every time f is finished, it
-    // is rescheduled to run deltaMilliSeconds later. If you
-    // need more accurate scheduling, don't use this method.
-    void scheduleEvery(Function f, int64_t deltaMilliSeconds);
+    /**
+     * Repeat f until the scheduler is stopped. First run is after delta has passed once.
+     *
+     * The timing is not exact: Every time f is finished, it is rescheduled to run again after delta. If you need more
+     * accurate scheduling, don't use this method.
+     */
+    void scheduleEvery(Function f, std::chrono::milliseconds delta);
 
     /**
      * Mock the scheduler to fast forward in time.
@@ -86,9 +90,9 @@ private:
     mutable Mutex newTaskMutex;
     std::condition_variable newTaskScheduled;
     std::multimap<std::chrono::system_clock::time_point, Function> taskQueue GUARDED_BY(newTaskMutex);
-    int nThreadsServicingQueue GUARDED_BY(newTaskMutex);
-    bool stopRequested GUARDED_BY(newTaskMutex);
-    bool stopWhenEmpty GUARDED_BY(newTaskMutex);
+    int nThreadsServicingQueue GUARDED_BY(newTaskMutex){0};
+    bool stopRequested GUARDED_BY(newTaskMutex){false};
+    bool stopWhenEmpty GUARDED_BY(newTaskMutex){false};
     bool shouldStop() const EXCLUSIVE_LOCKS_REQUIRED(newTaskMutex) { return stopRequested || (stopWhenEmpty && taskQueue.empty()); }
 };
 
diff --git a/src/test/scheduler_tests.cpp b/src/test/scheduler_tests.cpp
index caf9be5bd6..801cf8e5d1 100644
--- a/src/test/scheduler_tests.cpp
+++ b/src/test/scheduler_tests.cpp
@@ -168,10 +168,10 @@ BOOST_AUTO_TEST_CASE(mockforward)
     CScheduler::Function dummy = [&counter]{counter++;};
 
     // schedule jobs for 2, 5 & 8 minutes into the future
-    int64_t min_in_milli = 60*1000;
-    scheduler.scheduleFromNow(dummy, 2*min_in_milli);
-    scheduler.scheduleFromNow(dummy, 5*min_in_milli);
-    scheduler.scheduleFromNow(dummy, 8*min_in_milli);
+
+    scheduler.scheduleFromNow(dummy, std::chrono::minutes{2});
+    scheduler.scheduleFromNow(dummy, std::chrono::minutes{5});
+    scheduler.scheduleFromNow(dummy, std::chrono::minutes{8});
 
     // check taskQueue
     std::chrono::system_clock::time_point first, last;
@@ -181,10 +181,10 @@ BOOST_AUTO_TEST_CASE(mockforward)
     std::thread scheduler_thread([&]() { scheduler.serviceQueue(); });
 
     // bump the scheduler forward 5 minutes
-    scheduler.MockForward(std::chrono::seconds(5*60));
+    scheduler.MockForward(std::chrono::minutes{5});
 
     // ensure scheduler has chance to process all tasks queued for before 1 ms from now.
-    scheduler.scheduleFromNow([&scheduler]{ scheduler.stop(false); }, 1);
+    scheduler.scheduleFromNow([&scheduler] { scheduler.stop(false); }, std::chrono::milliseconds{1});
     scheduler_thread.join();
 
     // check that the queue only has one job remaining
diff --git a/src/wallet/load.cpp b/src/wallet/load.cpp
index 071befaebf..3e92c07d64 100644
--- a/src/wallet/load.cpp
+++ b/src/wallet/load.cpp
@@ -88,8 +88,8 @@ void StartWallets(CScheduler& scheduler)
     }
 
     // Schedule periodic wallet flushes and tx rebroadcasts
-    scheduler.scheduleEvery(MaybeCompactWalletDB, 500);
-    scheduler.scheduleEvery(MaybeResendWalletTxs, 1000);
+    scheduler.scheduleEvery(MaybeCompactWalletDB, std::chrono::milliseconds{500});
+    scheduler.scheduleEvery(MaybeResendWalletTxs, std::chrono::milliseconds{1000});
 }
 
 void FlushWallets()