chain: refactor spending.

lib/blockchain/chain.js

@@ -624,15 +624,14 @@ Chain.prototype.verifyInputs = co(function* verifyInputs(block, prev, state) {
   var sigops = 0;
   var jobs = [];
   var ret = new VerifyResult();
-  var i, view, tx, valid;
+  var view = new CoinView();
+  var i, tx, valid;
 
   if (this.options.spv)
-    return new CoinView();
+    return view;
 
   if (this.isGenesis(block))
-    return new CoinView();
-
-  view = yield this.db.getCoinView(block);
+    return view;
 
   // Check all transactions
   for (i = 0; i < block.txs.length; i++) {
@@ -640,13 +639,15 @@ Chain.prototype.verifyInputs = co(function* verifyInputs(block, prev, state) {
 
     // Ensure tx is not double spending an output.
     if (i > 0) {
-      if (!view.fillCoins(tx)) {
+      if (!(yield view.hasInputs(this.db, tx))) {
         assert(!historical, 'BUG: Spent inputs in historical data!');
         throw new VerifyError(block,
           'invalid',
           'bad-txns-inputs-missingorspent',
           100);
       }
+
+      view.spendCoins(tx);
     }
 
     // Skip everything if we're

lib/blockchain/chaindb.js

@@ -1768,23 +1768,18 @@ ChainDB.prototype.disconnectBlock = co(function* disconnectBlock(block) {
       }
     }
 
-    // Add all of the coins we are about to
-    // remove. This is to ensure they appear
-    // in the view array below.
-    view.addTX(tx);
-
     for (j = 0; j < tx.outputs.length; j++) {
       output = tx.outputs[j];
 
       if (output.script.isUnspendable())
         continue;
 
-      // Spend added coin.
-      view.spend(hash, j);
-
       this.pending.spend(output);
     }
 
+    // Remove any created coins.
+    view.removeTX(tx);
+
     // Remove from transaction index.
     this.unindexTX(tx);
   }

lib/blockchain/coinview.js

@@ -6,6 +6,8 @@
 
 'use strict';
 
+var assert = require('assert');
+var co = require('../utils/co');
 var Coins = require('./coins');
 var UndoCoins = require('./undocoins');
 
@@ -32,6 +34,7 @@ function CoinView(coins) {
 
 CoinView.prototype.add = function add(coins) {
   this.coins[coins.hash] = coins;
+  return coins;
 };
 
 /**
@@ -40,7 +43,18 @@ CoinView.prototype.add = function add(coins) {
  */
 
 CoinView.prototype.addTX = function addTX(tx) {
-  this.add(Coins.fromTX(tx));
+  return this.add(Coins.fromTX(tx));
+};
+
+/**
+ * Remove a tx from the collection.
+ * @param {TX} tx
+ */
+
+CoinView.prototype.removeTX = function removeTX(tx) {
+  var coins = this.addTX(tx);
+  coins.outputs.length = 0;
+  return coins;
 };
 
 /**
@@ -93,12 +107,12 @@ CoinView.prototype.spend = function spend(hash, index) {
   var entry, undo;
 
   if (!coins)
-    return;
+    return null;
 
   entry = coins.spend(index);
 
   if (!entry)
-    return;
+    return null;
 
   this.undo.push(entry);
 
@@ -113,23 +127,66 @@ CoinView.prototype.spend = function spend(hash, index) {
 };
 
 /**
- * Fill transaction(s) with coins.
+ * Retrieve coins from database.
  * @param {TX} tx
- * @returns {Boolean} True if all inputs were filled.
+ * @returns {Promise}
  */
 
-CoinView.prototype.fillCoins = function fillCoins(tx) {
+CoinView.prototype.getCoins = co(function* getCoins(db, hash) {
+  var coins = this.coins[hash];
+
+  if (!coins) {
+    coins = yield db.getCoins(hash);
+
+    if (!coins)
+      return;
+
+    this.coins[hash] = coins;
+  }
+
+  return coins;
+});
+
+/**
+ * Test whether all inputs are available.
+ * @param {ChainDB} db
+ * @param {TX} tx
+ * @returns {Boolean} True if all inputs are available.
+ */
+
+CoinView.prototype.hasInputs = co(function* hasInputs(db, tx) {
+  var i, input, prevout, coins;
+
+  for (i = 0; i < tx.inputs.length; i++) {
+    input = tx.inputs[i];
+    prevout = input.prevout;
+    coins = yield this.getCoins(db, prevout.hash);
+
+    if (!coins)
+      return false;
+
+    if (!coins.has(prevout.index))
+      return false;
+  }
+
+  return true;
+});
+
+/**
+ * Spend coins for transaction.
+ * @param {TX} tx
+ * @throws on missing coin
+ */
+
+CoinView.prototype.spendCoins = function spendCoins(tx) {
   var i, input, prevout;
 
   for (i = 0; i < tx.inputs.length; i++) {
     input = tx.inputs[i];
     prevout = input.prevout;
     input.coin = this.spend(prevout.hash, prevout.index);
-    if (!input.coin)
-      return false;
+    assert(input.coin, 'Not all coins available.');
   }
-
-  return true;
 };
 
 /**