Extract bucket::available concept which is distinct from ::empty when…

… rate limiting is happening.

nano/core_test/scheduler_buckets.cpp

@@ -110,7 +110,7 @@ TEST (buckets, construction)
 {
 	nano::scheduler::buckets buckets;
 	ASSERT_EQ (0, buckets.size ());
-	ASSERT_TRUE (buckets.empty ());
+	ASSERT_TRUE (buckets.empty () && !buckets.available ()); // Initial state
 	ASSERT_EQ (62, buckets.bucket_count ());
 }
 

nano/node/scheduler/bucket.cpp

@@ -53,6 +53,11 @@ bool nano::scheduler::bucket::empty () const
 	return queue.empty ();
 }
 
+bool nano::scheduler::bucket::available () const
+{
+	return !queue.empty ();
+}
+
 void nano::scheduler::bucket::dump () const
 {
 	for (auto const & item : queue)

nano/node/scheduler/bucket.hpp

@@ -34,6 +34,7 @@ class bucket final
 	void push (uint64_t time, std::shared_ptr<nano::block> block);
 	size_t size () const;
 	bool empty () const;
+	bool available () const;
 	void dump () const;
 };
 } // namespace nano::scheduler

nano/node/scheduler/buckets.cpp

@@ -19,7 +19,7 @@ void nano::scheduler::buckets::next ()
 void nano::scheduler::buckets::seek ()
 {
 	next ();
-	for (std::size_t i = 0, n = buckets_m.size (); (*current)->empty () && i < n; ++i)
+	for (std::size_t i = 0, n = buckets_m.size (); !(*current)->available () && i < n; ++i)
 	{
 		next ();
 	}
@@ -73,10 +73,10 @@ std::size_t nano::scheduler::buckets::index (nano::uint128_t const & balance) co
  */
 void nano::scheduler::buckets::push (uint64_t time, std::shared_ptr<nano::block> block, nano::amount const & priority)
 {
-	auto was_empty = empty ();
+	auto was_available = available ();
 	auto & bucket = buckets_m[index (priority.number ())];
 	bucket->push (time, block);
-	if (was_empty)
+	if (!was_available)
 	{
 		seek ();
 	}
@@ -85,15 +85,15 @@ void nano::scheduler::buckets::push (uint64_t time, std::shared_ptr<nano::block>
 /** Return the highest priority block of the current bucket */
 std::shared_ptr<nano::block> nano::scheduler::buckets::top () const
 {
-	debug_assert (!empty ());
+	debug_assert (available ());
 	auto result = (*current)->top ();
 	return result;
 }
 
 /** Pop the current block from the container and seek to the next block, if it exists */
 void nano::scheduler::buckets::pop ()
 {
-	debug_assert (!empty ());
+	debug_assert (available ());
 	auto & bucket = *current;
 	bucket->pop ();
 	seek ();
@@ -128,6 +128,11 @@ bool nano::scheduler::buckets::empty () const
 	return std::all_of (buckets_m.begin (), buckets_m.end (), [] (auto const & bucket) { return bucket->empty (); });
 }
 
+bool nano::scheduler::buckets::available () const
+{
+	return std::any_of (buckets_m.begin (), buckets_m.end (), [] (auto const & bucket) { return bucket->available (); });
+}
+
 /** Print the state of the class in stderr */
 void nano::scheduler::buckets::dump () const
 {

nano/node/scheduler/buckets.hpp

@@ -52,6 +52,7 @@ class buckets final
 	std::size_t bucket_count () const;
 	std::size_t bucket_size (std::size_t index) const;
 	bool empty () const;
+	bool available () const;
 	void dump () const;
 	std::size_t index (nano::uint128_t const & balance) const;
 

nano/node/scheduler/priority.cpp

@@ -88,7 +88,7 @@ bool nano::scheduler::priority::empty () const
 
 bool nano::scheduler::priority::predicate () const
 {
-	return node.active.vacancy () > 0 && !buckets->empty ();
+	return node.active.vacancy () > 0 && buckets->available ();
 }
 
 void nano::scheduler::priority::run ()