scheduler: switch from boost to std

Changes from boost::chrono to std::chrono, boost::condition_var to
std::condition_var, boost::mutex to sync.h Mutex, and reverselock.h to
sync.h REVERSE_LOCK. Also adds threadsafety annotations to CScheduler
members.

Author: ajtowns

src/rpc/misc.cpp

@@ -393,7 +393,7 @@ static UniValue mockscheduler(const JSONRPCRequest& request)
     // protect against null pointer dereference
     CHECK_NONFATAL(g_rpc_node);
     CHECK_NONFATAL(g_rpc_node->scheduler);
-    g_rpc_node->scheduler->MockForward(boost::chrono::seconds(delta_seconds));
+    g_rpc_node->scheduler->MockForward(std::chrono::seconds(delta_seconds));
 
     return NullUniValue;
 }

src/scheduler.cpp

@@ -5,7 +5,6 @@
 #include <scheduler.h>
 
 #include <random.h>
-#include <reverselock.h>
 
 #include <assert.h>
 #include <utility>
@@ -20,18 +19,9 @@ CScheduler::~CScheduler()
 }
 
 
-#if BOOST_VERSION < 105000
-static boost::system_time toPosixTime(const boost::chrono::system_clock::time_point& t)
-{
-    // Creating the posix_time using from_time_t loses sub-second precision. So rather than exporting the time_point to time_t,
-    // start with a posix_time at the epoch (0) and add the milliseconds that have passed since then.
-    return boost::posix_time::from_time_t(0) + boost::posix_time::milliseconds(boost::chrono::duration_cast<boost::chrono::milliseconds>(t.time_since_epoch()).count());
-}
-#endif
-
 void CScheduler::serviceQueue()
 {
-    boost::unique_lock<boost::mutex> lock(newTaskMutex);
+    WAIT_LOCK(newTaskMutex, lock);
     ++nThreadsServicingQueue;
 
     // newTaskMutex is locked throughout this loop EXCEPT
@@ -40,7 +30,7 @@ void CScheduler::serviceQueue()
     while (!shouldStop()) {
         try {
             if (!shouldStop() && taskQueue.empty()) {
-                reverse_lock<boost::unique_lock<boost::mutex> > rlock(lock);
+                REVERSE_LOCK(lock);
             }
             while (!shouldStop() && taskQueue.empty()) {
                 // Wait until there is something to do.
@@ -50,21 +40,13 @@ void CScheduler::serviceQueue()
             // Wait until either there is a new task, or until
             // the time of the first item on the queue:
 
-// wait_until needs boost 1.50 or later; older versions have timed_wait:
-#if BOOST_VERSION < 105000
-            while (!shouldStop() && !taskQueue.empty() &&
-                   newTaskScheduled.timed_wait(lock, toPosixTime(taskQueue.begin()->first))) {
-                // Keep waiting until timeout
-            }
-#else
-            // Some boost versions have a conflicting overload of wait_until that returns void.
-            // Explicitly use a template here to avoid hitting that overload.
             while (!shouldStop() && !taskQueue.empty()) {
-                boost::chrono::system_clock::time_point timeToWaitFor = taskQueue.begin()->first;
-                if (newTaskScheduled.wait_until<>(lock, timeToWaitFor) == boost::cv_status::timeout)
+                std::chrono::system_clock::time_point timeToWaitFor = taskQueue.begin()->first;
+                if (newTaskScheduled.wait_until(lock, timeToWaitFor) == std::cv_status::timeout) {
                     break; // Exit loop after timeout, it means we reached the time of the event
+                }
             }
-#endif
+
             // If there are multiple threads, the queue can empty while we're waiting (another
             // thread may service the task we were waiting on).
             if (shouldStop() || taskQueue.empty())
@@ -76,7 +58,7 @@ void CScheduler::serviceQueue()
             {
                 // Unlock before calling f, so it can reschedule itself or another task
                 // without deadlocking:
-                reverse_lock<boost::unique_lock<boost::mutex> > rlock(lock);
+                REVERSE_LOCK(lock);
                 f();
             }
         } catch (...) {
@@ -91,7 +73,7 @@ void CScheduler::serviceQueue()
 void CScheduler::stop(bool drain)
 {
     {
-        boost::unique_lock<boost::mutex> lock(newTaskMutex);
+        LOCK(newTaskMutex);
         if (drain)
             stopWhenEmpty = true;
         else
@@ -100,29 +82,29 @@ void CScheduler::stop(bool drain)
     newTaskScheduled.notify_all();
 }
 
-void CScheduler::schedule(CScheduler::Function f, boost::chrono::system_clock::time_point t)
+void CScheduler::schedule(CScheduler::Function f, std::chrono::system_clock::time_point t)
 {
     {
-        boost::unique_lock<boost::mutex> lock(newTaskMutex);
+        LOCK(newTaskMutex);
         taskQueue.insert(std::make_pair(t, f));
     }
     newTaskScheduled.notify_one();
 }
 
 void CScheduler::scheduleFromNow(CScheduler::Function f, int64_t deltaMilliSeconds)
 {
-    schedule(f, boost::chrono::system_clock::now() + boost::chrono::milliseconds(deltaMilliSeconds));
+    schedule(f, std::chrono::system_clock::now() + std::chrono::milliseconds(deltaMilliSeconds));
 }
 
-void CScheduler::MockForward(boost::chrono::seconds delta_seconds)
+void CScheduler::MockForward(std::chrono::seconds delta_seconds)
 {
-    assert(delta_seconds.count() > 0 && delta_seconds < boost::chrono::hours{1});
+    assert(delta_seconds.count() > 0 && delta_seconds < std::chrono::hours{1});
 
     {
-        boost::unique_lock<boost::mutex> lock(newTaskMutex);
+        LOCK(newTaskMutex);
 
         // use temp_queue to maintain updated schedule
-        std::multimap<boost::chrono::system_clock::time_point, Function> temp_queue;
+        std::multimap<std::chrono::system_clock::time_point, Function> temp_queue;
 
         for (const auto& element : taskQueue) {
             temp_queue.emplace_hint(temp_queue.cend(), element.first - delta_seconds, element.second);
@@ -147,10 +129,10 @@ void CScheduler::scheduleEvery(CScheduler::Function f, int64_t deltaMilliSeconds
     scheduleFromNow(std::bind(&Repeat, this, f, deltaMilliSeconds), deltaMilliSeconds);
 }
 
-size_t CScheduler::getQueueInfo(boost::chrono::system_clock::time_point &first,
-                             boost::chrono::system_clock::time_point &last) const
+size_t CScheduler::getQueueInfo(std::chrono::system_clock::time_point &first,
+                             std::chrono::system_clock::time_point &last) const
 {
-    boost::unique_lock<boost::mutex> lock(newTaskMutex);
+    LOCK(newTaskMutex);
     size_t result = taskQueue.size();
     if (!taskQueue.empty()) {
         first = taskQueue.begin()->first;
@@ -160,7 +142,7 @@ size_t CScheduler::getQueueInfo(boost::chrono::system_clock::time_point &first,
 }
 
 bool CScheduler::AreThreadsServicingQueue() const {
-    boost::unique_lock<boost::mutex> lock(newTaskMutex);
+    LOCK(newTaskMutex);
     return nThreadsServicingQueue;
 }
 
@@ -174,7 +156,7 @@ void SingleThreadedSchedulerClient::MaybeScheduleProcessQueue() {
         if (m_are_callbacks_running) return;
         if (m_callbacks_pending.empty()) return;
     }
-    m_pscheduler->schedule(std::bind(&SingleThreadedSchedulerClient::ProcessQueue, this));
+    m_pscheduler->schedule(std::bind(&SingleThreadedSchedulerClient::ProcessQueue, this), std::chrono::system_clock::now());
 }
 
 void SingleThreadedSchedulerClient::ProcessQueue() {

src/scheduler.h

@@ -7,11 +7,12 @@
 
 //
 // NOTE:
-// boost::thread / boost::chrono should be ported to std::thread / std::chrono
+// boost::thread should be ported to std::thread
 // when we support C++11.
 //
-#include <boost/chrono/chrono.hpp>
-#include <boost/thread.hpp>
+#include <condition_variable>
+#include <functional>
+#include <list>
 #include <map>
 
 #include <sync.h>
@@ -27,8 +28,8 @@
 // s->scheduleFromNow(std::bind(Class::func, this, argument), 3);
 // boost::thread* t = new boost::thread(std::bind(CScheduler::serviceQueue, s));
 //
-// ... then at program shutdown, clean up the thread running serviceQueue:
-// t->interrupt();
+// ... then at program shutdown, make sure to call stop() to clean up the thread(s) running serviceQueue:
+// s->stop();
 // t->join();
 // delete t;
 // delete s; // Must be done after thread is interrupted/joined.
@@ -43,7 +44,7 @@ class CScheduler
     typedef std::function<void()> Function;
 
     // Call func at/after time t
-    void schedule(Function f, boost::chrono::system_clock::time_point t=boost::chrono::system_clock::now());
+    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);
@@ -60,7 +61,7 @@ class CScheduler
      * Iterates through items on taskQueue and reschedules them
      * to be delta_seconds sooner.
      */
-    void MockForward(boost::chrono::seconds delta_seconds);
+    void MockForward(std::chrono::seconds delta_seconds);
 
     // To keep things as simple as possible, there is no unschedule.
 
@@ -75,20 +76,20 @@ class CScheduler
 
     // Returns number of tasks waiting to be serviced,
     // and first and last task times
-    size_t getQueueInfo(boost::chrono::system_clock::time_point &first,
-                        boost::chrono::system_clock::time_point &last) const;
+    size_t getQueueInfo(std::chrono::system_clock::time_point &first,
+                        std::chrono::system_clock::time_point &last) const;
 
     // Returns true if there are threads actively running in serviceQueue()
     bool AreThreadsServicingQueue() const;
 
 private:
-    std::multimap<boost::chrono::system_clock::time_point, Function> taskQueue;
-    boost::condition_variable newTaskScheduled;
-    mutable boost::mutex newTaskMutex;
-    int nThreadsServicingQueue;
-    bool stopRequested;
-    bool stopWhenEmpty;
-    bool shouldStop() const { return stopRequested || (stopWhenEmpty && taskQueue.empty()); }
+    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);
+    bool shouldStop() const EXCLUSIVE_LOCKS_REQUIRED(newTaskMutex) { return stopRequested || (stopWhenEmpty && taskQueue.empty()); }
 };
 
 /**

src/test/scheduler_tests.cpp

@@ -11,13 +11,13 @@
 
 BOOST_AUTO_TEST_SUITE(scheduler_tests)
 
-static void microTask(CScheduler& s, boost::mutex& mutex, int& counter, int delta, boost::chrono::system_clock::time_point rescheduleTime)
+static void microTask(CScheduler& s, boost::mutex& mutex, int& counter, int delta, std::chrono::system_clock::time_point rescheduleTime)
 {
     {
         boost::unique_lock<boost::mutex> lock(mutex);
         counter += delta;
     }
-    boost::chrono::system_clock::time_point noTime = boost::chrono::system_clock::time_point::min();
+    std::chrono::system_clock::time_point noTime = std::chrono::system_clock::time_point::min();
     if (rescheduleTime != noTime) {
         CScheduler::Function f = std::bind(&microTask, std::ref(s), std::ref(mutex), std::ref(counter), -delta + 1, noTime);
         s.schedule(f, rescheduleTime);
@@ -45,15 +45,15 @@ BOOST_AUTO_TEST_CASE(manythreads)
     auto randomMsec = [](FastRandomContext& rc) -> int { return -11 + (int)rc.randrange(1012); }; // [-11, 1000]
     auto randomDelta = [](FastRandomContext& rc) -> int { return -1000 + (int)rc.randrange(2001); }; // [-1000, 1000]
 
-    boost::chrono::system_clock::time_point start = boost::chrono::system_clock::now();
-    boost::chrono::system_clock::time_point now = start;
-    boost::chrono::system_clock::time_point first, last;
+    std::chrono::system_clock::time_point start = std::chrono::system_clock::now();
+    std::chrono::system_clock::time_point now = start;
+    std::chrono::system_clock::time_point first, last;
     size_t nTasks = microTasks.getQueueInfo(first, last);
     BOOST_CHECK(nTasks == 0);
 
     for (int i = 0; i < 100; ++i) {
-        boost::chrono::system_clock::time_point t = now + boost::chrono::microseconds(randomMsec(rng));
-        boost::chrono::system_clock::time_point tReschedule = now + boost::chrono::microseconds(500 + randomMsec(rng));
+        std::chrono::system_clock::time_point t = now + std::chrono::microseconds(randomMsec(rng));
+        std::chrono::system_clock::time_point tReschedule = now + std::chrono::microseconds(500 + randomMsec(rng));
         int whichCounter = zeroToNine(rng);
         CScheduler::Function f = std::bind(&microTask, std::ref(microTasks),
                                              std::ref(counterMutex[whichCounter]), std::ref(counter[whichCounter]),
@@ -71,14 +71,14 @@ BOOST_AUTO_TEST_CASE(manythreads)
         microThreads.create_thread(std::bind(&CScheduler::serviceQueue, &microTasks));
 
     UninterruptibleSleep(std::chrono::microseconds{600});
-    now = boost::chrono::system_clock::now();
+    now = std::chrono::system_clock::now();
 
     // More threads and more tasks:
     for (int i = 0; i < 5; i++)
         microThreads.create_thread(std::bind(&CScheduler::serviceQueue, &microTasks));
     for (int i = 0; i < 100; i++) {
-        boost::chrono::system_clock::time_point t = now + boost::chrono::microseconds(randomMsec(rng));
-        boost::chrono::system_clock::time_point tReschedule = now + boost::chrono::microseconds(500 + randomMsec(rng));
+        std::chrono::system_clock::time_point t = now + std::chrono::microseconds(randomMsec(rng));
+        std::chrono::system_clock::time_point tReschedule = now + std::chrono::microseconds(500 + randomMsec(rng));
         int whichCounter = zeroToNine(rng);
         CScheduler::Function f = std::bind(&microTask, std::ref(microTasks),
                                              std::ref(counterMutex[whichCounter]), std::ref(counter[whichCounter]),
@@ -157,14 +157,14 @@ BOOST_AUTO_TEST_CASE(mockforward)
     scheduler.scheduleFromNow(dummy, 8*min_in_milli);
 
     // check taskQueue
-    boost::chrono::system_clock::time_point first, last;
+    std::chrono::system_clock::time_point first, last;
     size_t num_tasks = scheduler.getQueueInfo(first, last);
     BOOST_CHECK_EQUAL(num_tasks, 3ul);
 
     std::thread scheduler_thread([&]() { scheduler.serviceQueue(); });
 
     // bump the scheduler forward 5 minutes
-    scheduler.MockForward(boost::chrono::seconds(5*60));
+    scheduler.MockForward(std::chrono::seconds(5*60));
 
     // ensure scheduler has chance to process all tasks queued for before 1 ms from now.
     scheduler.scheduleFromNow([&scheduler]{ scheduler.stop(false); }, 1);
@@ -178,8 +178,8 @@ BOOST_AUTO_TEST_CASE(mockforward)
     BOOST_CHECK_EQUAL(counter, 2);
 
     // check that the time of the remaining job has been updated
-    boost::chrono::system_clock::time_point now = boost::chrono::system_clock::now();
-    int delta = boost::chrono::duration_cast<boost::chrono::seconds>(first - now).count();
+    std::chrono::system_clock::time_point now = std::chrono::system_clock::now();
+    int delta = std::chrono::duration_cast<std::chrono::seconds>(first - now).count();
     // should be between 2 & 3 minutes from now
     BOOST_CHECK(delta > 2*60 && delta < 3*60);
 }

test/lint/lint-includes.sh

@@ -53,7 +53,6 @@ EXPECTED_BOOST_INCLUDES=(
     boost/algorithm/string/classification.hpp
     boost/algorithm/string/replace.hpp
     boost/algorithm/string/split.hpp
-    boost/chrono/chrono.hpp
     boost/date_time/posix_time/posix_time.hpp
     boost/filesystem.hpp
     boost/filesystem/fstream.hpp