Merge #161: Add vsize

3e0db90 Add vsize (Christian Lewe)

Pull request description:

  Useful for computing the fee rate.

ACKs for top commit:
  apoelstra:
    ACK 3e0db90

Tree-SHA512: a4672b6d46d0842affc0391cd3c1fd877ef5c7cac05500be06c612d12fb2d0ca41f491cb56c36d8b2bedf4c7e3012ac7517c6e37ce645c6f42ba08bdce7572c3

Author: apoelstra

src/transaction.rs

@@ -869,6 +869,15 @@ impl Transaction {
         self.scaled_size(1)
     }
 
+    /// Returns the "virtual size" (vsize) of this transaction.
+    ///
+    /// Will be `ceil(weight / 4.0)`.
+    #[inline]
+    pub fn vsize(&self) -> usize {
+        let weight = self.weight();
+        (weight + 4 - 1) / 4
+    }
+
     fn scaled_size(&self, scale_factor: usize) -> usize {
         let witness_flag = self.has_witness();