From d17ba0747575ccae873401d3dcc22cc8dd81bfed Mon Sep 17 00:00:00 2001
From: Christopher Jeffrey <chjjeffrey@gmail.com>
Date: Sun, 21 Aug 2016 11:04:47 -0700
Subject: [PATCH] mempool: mem usage estimation.

---
 lib/bcoin/mempool.js | 33 ++++++++++++++++++++++-----------
 1 file changed, 22 insertions(+), 11 deletions(-)

diff --git a/lib/bcoin/mempool.js b/lib/bcoin/mempool.js
index 75805fd6..76f83a51 100644
--- a/lib/bcoin/mempool.js
+++ b/lib/bcoin/mempool.js
@@ -1493,7 +1493,7 @@ Mempool.prototype._removeSpenders = function _removeSpenders(entry) {
 
 Mempool.prototype.memUsage = function memUsage(tx) {
   var mem = 0;
-  var i, input, output;
+  var i, j, input, output, coin, op;
 
   mem += 264; // tx
   mem += 80; // _hash
@@ -1507,13 +1507,19 @@ Mempool.prototype.memUsage = function memUsage(tx) {
     mem += 144; // input
 
     if (input.coin) {
+      coin = input.coin;
       mem += 144; // coin
       mem += 88; // coin hash
       mem += 40; // script
       mem += 80; // script raw buffer
       mem += 32; // script code array
-      mem += input.coin.script.code.length * 40; // opcodes
-      mem += 80; // add a code buffer (assume p2pkh)
+      mem += coin.script.code.length * 40; // opcodes
+
+      for (j = 0; j < coin.script.code.length; j++) {
+        op = coin.script.code[j];
+        if (op.data)
+          mem += 80; // op buffers
+      }
     }
 
     mem += 104; // prevout
@@ -1523,7 +1529,12 @@ Mempool.prototype.memUsage = function memUsage(tx) {
     mem += 80; // script raw buffer
     mem += 32; // script code array
     mem += input.script.code.length * 40; // opcodes
-    mem += 160; // add two code buffers (assume p2pkh)
+
+    for (j = 0; j < input.script.code.length; j++) {
+      op = input.script.code[j];
+      if (op.data)
+        mem += 80; // op buffers
+    }
 
     mem += 96; // witness
     mem += 32; // witness items
@@ -1534,22 +1545,22 @@ Mempool.prototype.memUsage = function memUsage(tx) {
 
   for (i = 0; i < tx.outputs.length; i++) {
     output = tx.outputs[i];
+
     mem += 120; // output
     mem += 40; // script
     mem += 80; // script raw buffer
     mem += 32; // script code array
     mem += output.script.code.length * 40; // opcodes
-    mem += 80; // add a code buffer (assume p2pkh)
+
+    for (j = 0; j < output.script.code.length; j++) {
+      op = output.script.code[j];
+      if (op.data)
+        mem += 80; // op buffers
+    }
   }
 
   mem += 176; // mempool entry
 
-  // Note: normally we could add 176 (88 * 2)
-  // bytes for the spent and tx hash table
-  // entries, but v8 seems to store these
-  // strings off the heap, so it shouldn't
-  // be too much of a problem.
-
   return mem;
 };