Style, change estimator::initialize() to derive top block.

include/bitcoin/server/estimator.hpp

@@ -45,9 +45,9 @@ class BCS_API estimator
     /// Pass zero to target next block for confirmation, range:0..1007.
     uint64_t estimate(size_t target, mode mode) const NOEXCEPT;
 
-    /// Populate accumulator.
+    /// Populate accumulator with count blocks up to the top confirmed block.
     bool initialize(std::atomic_bool& cancel, const node::query& query,
-        size_t top, size_t count) NOEXCEPT;
+        size_t count) NOEXCEPT;
 
     /// Update accumulator.
     bool push(const node::query& query) NOEXCEPT;
@@ -60,22 +60,14 @@ class BCS_API estimator
     using rates = database::fee_rates;
     using rate_sets = database::fee_rate_sets;
 
-    /// Bucket count sizing parameters.
+    /// Bucket depth sizing parameters.
     enum horizon : size_t
     {
         small  = 12,
         medium = 48,
         large  = 1008
     };
 
-    /// Estimation confidences.
-    struct confidence
-    {
-        static constexpr double low  = 0.60;
-        static constexpr double mid  = 0.85;
-        static constexpr double high = 0.95;
-    };
-
     /// Bucket count sizing parameters.
     struct sizing
     {
@@ -87,17 +79,25 @@ class BCS_API estimator
         static constexpr size_t count = 283;
     };
 
+    /// Estimation confidences.
+    struct confidence
+    {
+        static constexpr double low = 0.60;
+        static constexpr double mid = 0.85;
+        static constexpr double high = 0.95;
+    };
+
     /// Accumulator (persistent, decay-weighted counters).
     struct accumulator
     {
-        template <size_t Depth>
+        template <size_t Horizon>
         struct bucket
         {
             /// Total scaled txs in bucket.
             std::atomic<size_t> total{};
 
             /// confirmed[n]: scaled txs confirmed in > n blocks.
-            std::array<std::atomic<size_t>, Depth> confirmed;
+            std::array<std::atomic<size_t>, Horizon> confirmed;
         };
 
         /// Current block height of accumulated state.

src/estimator.cpp

@@ -85,10 +85,18 @@ uint64_t estimator::estimate(size_t target, mode mode) const NOEXCEPT
 }
 
 bool estimator::initialize(std::atomic_bool& cancel, const node::query& query,
-    size_t top, size_t count) NOEXCEPT
+    size_t count) NOEXCEPT
 {
+    if (is_zero(count))
+        return true;
+
+    const auto top = query.get_top_confirmed();
+    if (sub1(count) > top)
+        return false;
+
     rate_sets blocks{};
-    return query.get_branch_fees(cancel, blocks, top, count) &&
+    const auto start = top - sub1(count);
+    return query.get_branch_fees(cancel, blocks, start, count) &&
         initialize(blocks);
 }
 
@@ -269,7 +277,7 @@ bool estimator::update(const rates& block, size_t height, bool push) NOEXCEPT
     const auto call = [&](auto& buckets) NOEXCEPT
     {
         // The array count of the buckets element type.
-        const auto depth = buckets.front().confirmed.size();
+        const auto horizon = buckets.front().confirmed.size();
 
         size_t bin{};
         for (const auto count: counts)
@@ -285,7 +293,7 @@ bool estimator::update(const rates& block, size_t height, bool push) NOEXCEPT
             const auto signed_term = push ? scaled : twos_complement(scaled);
 
             bucket.total.fetch_add(signed_term, relaxed);
-            for (auto target = age; target < depth; ++target)
+            for (auto target = age; target < horizon; ++target)
                 bucket.confirmed.at(target).fetch_add(signed_term, relaxed);
         }
     };