Add block/tx virtual_size as (ceiling_divide(weight(),4)).

Author: evoskuil

include/bitcoin/system/chain/block.hpp

@@ -100,6 +100,7 @@ class BC_API block
     size_t segregated() const NOEXCEPT;
     size_t serialized_size(bool witness) const NOEXCEPT;
     size_t signature_operations(bool bip16, bool bip141) const NOEXCEPT;
+    size_t virtual_size() const NOEXCEPT;
 
     /// Computed malleation properties.
     bool is_malleable() const NOEXCEPT;

include/bitcoin/system/chain/transaction.hpp

@@ -111,6 +111,7 @@ class BC_API transaction
     bool is_segregated() const NOEXCEPT;
     hash_digest hash(bool witness) const NOEXCEPT;
     size_t serialized_size(bool witness) const NOEXCEPT;
+    size_t virtual_size() const NOEXCEPT;
 
     /// Cache setters/getters, not thread safe.
     /// -----------------------------------------------------------------------

src/chain/block.cpp

@@ -481,6 +481,12 @@ size_t block::weight() const NOEXCEPT
         ceilinged_multiply(total_size_contribution, serialized_size(true)));
 }
 
+size_t block::virtual_size() const NOEXCEPT
+{
+    constexpr auto scale = base_size_contribution + total_size_contribution;
+    return ceilinged_divide(weight(), scale);
+}
+
 bool block::is_overweight() const NOEXCEPT
 {
     return weight() > max_block_weight;

src/chain/transaction.cpp

@@ -563,12 +563,18 @@ bool transaction::is_segregated() const NOEXCEPT
 
 size_t transaction::weight() const NOEXCEPT
 {
-    // Block weight is 3 * base size * + 1 * total size [bip141].
+    // Transaction weight is 3 * base size * + 1 * total size [bip141].
     return ceilinged_add(
         ceilinged_multiply(base_size_contribution, serialized_size(false)),
         ceilinged_multiply(total_size_contribution, serialized_size(true)));
 }
 
+size_t transaction::virtual_size() const NOEXCEPT
+{
+    constexpr auto scale = base_size_contribution + total_size_contribution;
+    return ceilinged_divide(weight(), scale);
+}
+
 bool transaction::is_overweight() const NOEXCEPT
 {
     return weight() > max_block_weight;