scheduler: Replace stop(true) with StopWhenDrained()

This helps understanding the code at the call site without having to
look up the name of the argument or the default value.

src/scheduler.cpp

@@ -68,18 +68,6 @@ void CScheduler::serviceQueue()
     newTaskScheduled.notify_one();
 }
 
-void CScheduler::stop(bool drain)
-{
-    {
-        LOCK(newTaskMutex);
-        if (drain)
-            stopWhenEmpty = true;
-        else
-            stopRequested = true;
-    }
-    newTaskScheduled.notify_all();
-}
-
 void CScheduler::schedule(CScheduler::Function f, std::chrono::system_clock::time_point t)
 {
     {

src/scheduler.h

@@ -65,10 +65,18 @@ public:
     // and interrupted using boost::interrupt_thread
     void serviceQueue();
 
-    // Tell any threads running serviceQueue to stop as soon as they're
-    // done servicing whatever task they're currently servicing (drain=false)
-    // or when there is no work left to be done (drain=true)
-    void stop(bool drain=false);
+    /** Tell any threads running serviceQueue to stop as soon as the current task is done */
+    void stop()
+    {
+        WITH_LOCK(newTaskMutex, stopRequested = true);
+        newTaskScheduled.notify_all();
+    }
+    /** Tell any threads running serviceQueue to stop when there is no work left to be done */
+    void StopWhenDrained()
+    {
+        WITH_LOCK(newTaskMutex, stopWhenEmpty = true);
+        newTaskScheduled.notify_all();
+    }
 
     // Returns number of tasks waiting to be serviced,
     // and first and last task times

src/test/scheduler_tests.cpp

@@ -89,7 +89,7 @@ BOOST_AUTO_TEST_CASE(manythreads)
     }
 
     // Drain the task queue then exit threads
-    microTasks.stop(true);
+    microTasks.StopWhenDrained();
     microThreads.join_all(); // ... wait until all the threads are done
 
     int counterSum = 0;
@@ -155,7 +155,7 @@ BOOST_AUTO_TEST_CASE(singlethreadedscheduler_ordered)
     }
 
     // finish up
-    scheduler.stop(true);
+    scheduler.StopWhenDrained();
     threads.join_all();
 
     BOOST_CHECK_EQUAL(counter1, 100);
@@ -186,7 +186,7 @@ BOOST_AUTO_TEST_CASE(mockforward)
     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); }, std::chrono::milliseconds{1});
+    scheduler.scheduleFromNow([&scheduler] { scheduler.stop(); }, std::chrono::milliseconds{1});
     scheduler_thread.join();
 
     // check that the queue only has one job remaining