Change validator backlog to use tx count and work in chunks.

src/chasers/chaser_validate.cpp

@@ -35,6 +35,15 @@ using namespace system::neutrino;
 using namespace database;
 using namespace std::placeholders;
 
+// In this build we are evaluating an unconfigurable backlog of blocks based
+// on their cumulative tx count. Value loosely approximates 100 full blocks.
+// Since validation is being deferred until download is current, there is no
+// material issue with starving the CPU. The backlog here is filled when the
+// validator is starved, but that should consume the CPU. Splitting download,
+// populate, and validate mitigates thrashing that is otherwise likely on low
+// resource machines. This can be made more dynamic to optimize big machines.
+constexpr auto validation_window = 5'000_size * 100_size;
+
 // TODO: update specialized fault codes, reintegrate neutrino.
 
 // Shared pointer is required to keep the race object alive in bind closure.
@@ -47,7 +56,7 @@ chaser_validate::chaser_validate(full_node& node) NOEXCEPT
     initial_subsidy_(node.config().bitcoin.initial_subsidy()),
     subsidy_interval_(node.config().bitcoin.subsidy_interval_blocks),
     threadpool_(std::max(node.config().node.threads, 1_u32),
-        network::thread_priority::low)
+        network::thread_priority::high)
 {
 }
 
@@ -151,8 +160,6 @@ void chaser_validate::do_checked(height_t height) NOEXCEPT
         do_bump(height);
 }
 
-constexpr auto validation_window = 1'000_size;
-
 void chaser_validate::do_bump(height_t) NOEXCEPT
 {
     BC_ASSERT(stranded());
@@ -166,13 +173,14 @@ void chaser_validate::do_bump(height_t) NOEXCEPT
         const auto link = query.to_candidate(height);
         const auto ec = query.get_block_state(link);
 
-        // TODO: make this more flexible/configurable.
+        // TODO: make currency requirement more flexible/configurable.
+        // TODO: machines with high/fast RAM/SSD can handle much more.
         // Wait until the gap is filled at a current height.
-        if (ec == database::error::unassociated)//// || !is_current(link))
+        if (ec == database::error::unassociated || !is_current(link))
             return;
 
         // complete_block always follows and decrements.
-        ++validation_backlog_;
+        validation_backlog_ += query.get_tx_count(link);
 
         // Causes a reorganization (should have been encountered by headers).
         if (ec == database::error::block_unconfirmable)
@@ -251,7 +259,9 @@ void chaser_validate::complete_block(const code& ec, const header_link& link,
     size_t height) NOEXCEPT
 {
     BC_ASSERT(stranded());
-    --validation_backlog_;
+
+    // Probably cheaper to requery this than to pass it.
+    validation_backlog_ -= archive().get_tx_count(link);
 
     if (ec)
     {
@@ -271,8 +281,8 @@ void chaser_validate::complete_block(const code& ec, const header_link& link,
     if (is_current(link))
         notify(ec, chase::valid, possible_wide_cast<height_t>(height));
 
-    // Prevent stall when window was full.
-    if (validation_backlog_ == sub1(validation_window))
+    // Prevent stall.
+    if (is_zero(validation_backlog_))
         do_bump(height_t{});
 }