simple coin views.

lib/bcoin/chain.js

@@ -310,7 +310,7 @@ Chain.prototype._preload = function _preload(callback) {
     if (!unlock)
       return;
 
-    self.db.save(entry, null, true, function(err) {
+    self.db.save(entry, null, null, true, function(err) {
       if (err) {
         stream.destroy();
         locker.destroy();
@@ -451,11 +451,11 @@ Chain.prototype._verifyContext = function _verifyContext(block, prev, callback)
       if (err)
         return callback(err);
 
-      self._checkInputs(block, prev, state, function(err) {
+      self._checkInputs(block, prev, state, function(err, view) {
         if (err)
           return callback(err);
 
-        return callback();
+        return callback(null, view);
       });
     });
   });
@@ -838,7 +838,7 @@ Chain.prototype._checkInputs = function _checkInputs(block, prev, state, callbac
     historical = true;
   }
 
-  this.db.fillBlock(block, function(err) {
+  this.db.getCoinView(block, function(err, view) {
     var ret = {};
     var sigops = 0;
 
@@ -849,6 +849,7 @@ Chain.prototype._checkInputs = function _checkInputs(block, prev, state, callbac
     utils.forEachSerial(block.txs, function(tx, next) {
       // Ensure tx is not double spending an output.
       if (!tx.isCoinbase()) {
+        view.fill(tx);
         if (!tx.hasCoins()) {
           assert(!historical, 'BUG: Spent inputs in historical data!');
           return next(new VerifyError(block,
@@ -890,6 +891,8 @@ Chain.prototype._checkInputs = function _checkInputs(block, prev, state, callbac
           }
         }
 
+        view.add(tx.toCoins());
+
         return next();
       });
     }, function(err) {
@@ -922,7 +925,7 @@ Chain.prototype._checkInputs = function _checkInputs(block, prev, state, callbac
             100));
         }
 
-        return callback();
+        return callback(null, view);
       });
     });
   });
@@ -1141,7 +1144,7 @@ Chain.prototype.connect = function connect(entry, callback) {
 
       assert(prev);
 
-      self._verifyContext(block, prev, function(err) {
+      self._verifyContext(block, prev, function(err, view) {
         if (err) {
           if (err.type === 'VerifyError') {
             self.invalid[entry.hash] = true;
@@ -1155,7 +1158,7 @@ Chain.prototype.connect = function connect(entry, callback) {
           return callback(err);
         }
 
-        self.db.connect(entry, block, function(err) {
+        self.db.connect(entry, block, view, function(err) {
           if (err)
             return callback(err);
 
@@ -1196,7 +1199,7 @@ Chain.prototype._setBestChain = function _setBestChain(entry, block, prev, callb
     // Do "contextual" verification on our block
     // now that we're certain its previous
     // block is in the chain.
-    self._verifyContext(block, prev, function(err) {
+    self._verifyContext(block, prev, function(err, view) {
       if (err) {
         // Couldn't verify block.
         // Revert the height.
@@ -1216,7 +1219,7 @@ Chain.prototype._setBestChain = function _setBestChain(entry, block, prev, callb
       }
 
       // Save block and connect inputs.
-      self.db.save(entry, block, true, function(err) {
+      self.db.save(entry, block, view, true, function(err) {
         if (err)
           return callback(err);
 
@@ -1564,7 +1567,7 @@ Chain.prototype.add = function add(block, callback, force) {
         // our tip's. Add the block but do _not_
         // connect the inputs.
         if (entry.chainwork.cmp(self.tip.chainwork) <= 0) {
-          return self.db.save(entry, block, false, function(err) {
+          return self.db.save(entry, block, null, false, function(err) {
             if (err)
               return done(err);
 

lib/bcoin/chaindb.js

@@ -93,8 +93,8 @@ function ChainDB(chain, options) {
   // Average number of outputs per tx: 2.2
   // Average size of outputs per tx: 74b
   // Average number of txs: 2300
-  // Key size: 68b (* 2)
+  // Key size: 66b (* 2)
-  this.coinWindow = ((165 * 1024 + 5000 * 9) + (5000 * 68 * 2)) * 5;
+  this.coinWindow = ((165 * 1024 + 2300 * 4) + (2300 * 66 * 2)) * 5;
 
   this.coinCache = new NullCache(this.coinWindow);
   this.cacheHash = new bcoin.lru(this.cacheWindow, 1);
@@ -160,7 +160,7 @@ ChainDB.prototype._init = function _init() {
       block = bcoin.block.fromRaw(self.network.genesisBlock, 'hex');
       block.setHeight(0);
 
-      self.save(genesis, block, true, finish);
+      self.save(genesis, block, null, true, finish);
     });
   });
 };
@@ -423,7 +423,7 @@ ChainDB.prototype.get = function get(hash, callback) {
  * @param {Function} callback
  */
 
-ChainDB.prototype.save = function save(entry, block, connect, callback) {
+ChainDB.prototype.save = function save(entry, block, view, connect, callback) {
   var batch, hash, height;
 
   callback = utils.ensure(callback);
@@ -443,7 +443,7 @@ ChainDB.prototype.save = function save(entry, block, connect, callback) {
   this.cacheHash.set(entry.hash, entry);
 
   if (!connect) {
-    return this.saveBlock(block, batch, false, function(err) {
+    return this.saveBlock(block, view, batch, false, function(err) {
       if (err)
         return callback(err);
       return batch.write(callback);
@@ -458,7 +458,7 @@ ChainDB.prototype.save = function save(entry, block, connect, callback) {
 
   this.emit('add entry', entry);
 
-  this.saveBlock(block, batch, true, function(err) {
+  this.saveBlock(block, view, batch, true, function(err) {
     if (err)
       return callback(err);
     return batch.write(callback);
@@ -492,7 +492,7 @@ ChainDB.prototype.getTip = function getTip(callback) {
  * @param {Function} callback - Returns [Error, {@link ChainEntry}].
  */
 
-ChainDB.prototype.connect = function connect(entry, block, callback) {
+ChainDB.prototype.connect = function connect(entry, block, view, callback) {
   var batch = this.db.batch();
   var hash = new Buffer(entry.hash, 'hex');
 
@@ -505,7 +505,7 @@ ChainDB.prototype.connect = function connect(entry, block, callback) {
 
   this.emit('add entry', entry);
 
-  this.connectBlock(block, batch, function(err) {
+  this.connectBlock(block, view, batch, function(err) {
     if (err)
       return callback(err);
 
@@ -527,24 +527,24 @@ ChainDB.prototype.disconnect = function disconnect(block, callback) {
   var self = this;
   var batch;
 
-  this._ensureEntry(block, function(err, entry) {
+  batch = this.db.batch();
+
+  batch.del('n/' + entry.prevBlock);
+  batch.del('H/' + pad32(entry.height));
+  batch.put('R', new Buffer(entry.prevBlock, 'hex'));
+
+  this.cacheHeight.remove(entry.height);
+
+  this.emit('remove entry', entry);
+
+  this.getBlock(entry.hash, function(err, block) {
     if (err)
       return callback(err);
 
-    if (!entry)
+    if (!block)
-      return callback(new Error('Entry not found.'));
+      return callback(new Error('Block not found.'));
 
-    batch = self.db.batch();
+    self.disconnectBlock(block, batch, function(err) {
-
-    batch.del('n/' + entry.prevBlock);
-    batch.del('H/' + pad32(entry.height));
-    batch.put('R', new Buffer(entry.prevBlock, 'hex'));
-
-    self.cacheHeight.remove(entry.height);
-
-    self.emit('remove entry', entry);
-
-    self.disconnectBlock(entry.hash, batch, function(err) {
       if (err)
         return callback(err);
 
@@ -557,12 +557,6 @@ ChainDB.prototype.disconnect = function disconnect(block, callback) {
   });
 };
 
-ChainDB.prototype._ensureEntry = function _ensureEntry(block, callback) {
-  if (block instanceof bcoin.chainentry)
-    return callback(null, block);
-  return this.get(block, callback);
-};
-
 /**
  * Get the _next_ block hash (does not work by height).
  * @param {Hash} hash
@@ -701,7 +695,7 @@ ChainDB.prototype.has = function has(height, callback) {
  * @param {Function} callback - Returns [Error, {@link Block}].
  */
 
-ChainDB.prototype.saveBlock = function saveBlock(block, batch, connect, callback) {
+ChainDB.prototype.saveBlock = function saveBlock(block, view, batch, connect, callback) {
   if (this.options.spv)
     return utils.nextTick(callback);
 
@@ -710,7 +704,7 @@ ChainDB.prototype.saveBlock = function saveBlock(block, batch, connect, callback
   if (!connect)
     return utils.nextTick(callback);
 
-  this.connectBlock(block, batch, callback);
+  this.connectBlock(block, view, batch, callback);
 };
 
 /**
@@ -724,10 +718,7 @@ ChainDB.prototype.saveBlock = function saveBlock(block, batch, connect, callback
 ChainDB.prototype.removeBlock = function removeBlock(hash, batch, callback) {
   var self = this;
 
-  if (this.options.spv)
+  this.getBlock(hash, function(err, block) {
-    return utils.nextTick(callback);
-
-  this._ensureHistory(hash, function(err, block) {
     if (err)
       return callback(err);
 
@@ -736,6 +727,9 @@ ChainDB.prototype.removeBlock = function removeBlock(hash, batch, callback) {
 
     batch.del('b/' + block.hash('hex'));
 
+    if (self.options.spv)
+      return callback(null, block);
+
     self.disconnectBlock(block, batch, callback);
   });
 };
@@ -747,13 +741,13 @@ ChainDB.prototype.removeBlock = function removeBlock(hash, batch, callback) {
  * @param {Function} callback - Returns [Error, {@link Block}].
  */
 
-ChainDB.prototype.connectBlock = function connectBlock(block, batch, callback) {
+ChainDB.prototype.connectBlock = function connectBlock(block, view, batch, callback) {
   var self = this;
   var undo = new BufferWriter();
-  var i, j, tx, input, output, key, addresses, address, hash, coin;
+  var i, j, tx, input, output, key, addresses, address, hash, coins, raw;
 
   if (this.options.spv) {
-    self.emit('add block', block);
+    this.emit('add block', block);
     return utils.nextTick(callback);
   }
 
@@ -761,81 +755,76 @@ ChainDB.prototype.connectBlock = function connectBlock(block, batch, callback) {
   if (this.chain.isGenesis(block))
     return utils.nextTick(callback);
 
-  this._ensureBlock(block, function(err, block) {
+  for (i = 0; i < block.txs.length; i++) {
-    if (err)
+    tx = block.txs[i];
-      return callback(err);
+    hash = tx.hash('hex');
 
-    if (!block)
+    if (this.options.indexTX) {
-      return callback();
+      batch.put('t/' + hash, tx.toExtended());
-
+      if (this.options.indexAddress) {
-    for (i = 0; i < block.txs.length; i++) {
+        addresses = tx.getHashes();
-      tx = block.txs[i];
+        for (j = 0; j < addresses.length; j++) {
-      hash = tx.hash('hex');
+          address = addresses[j];
-
+          batch.put('T/' + address + '/' + hash, DUMMY);
-      if (self.options.indexTX) {
-        batch.put('t/' + hash, tx.toExtended());
-        if (self.options.indexAddress) {
-          addresses = tx.getHashes();
-          for (j = 0; j < addresses.length; j++) {
-            address = addresses[j];
-            batch.put('T/' + address + '/' + hash, DUMMY);
-          }
         }
       }
-
-      for (j = 0; j < tx.inputs.length; j++) {
-        input = tx.inputs[j];
-        key = input.prevout.hash + '/' + input.prevout.index;
-
-        if (tx.isCoinbase())
-          break;
-
-        assert(input.coin);
-
-        if (self.options.indexAddress) {
-          address = input.getHash();
-          if (address)
-            batch.del('C/' + address + '/' + key);
-        }
-
-        batch.del('c/' + key);
-
-        Framer.coin(input.coin, false, undo);
-
-        self.coinCache.remove(key);
-      }
-
-      for (j = 0; j < tx.outputs.length; j++) {
-        output = tx.outputs[j];
-        key = hash + '/' + j;
-
-        if (output.script.isUnspendable())
-          continue;
-
-        coin = bcoin.coin.fromTX(tx, j).toRaw();
-
-        if (self.options.indexAddress) {
-          address = output.getHash();
-          if (address)
-            batch.put('C/' + address + '/' + key, DUMMY);
-        }
-
-        batch.put('c/' + key, coin);
-
-        self.coinCache.set(key, coin);
-      }
     }
 
-    if (undo.written > 0)
+    for (j = 0; j < tx.inputs.length; j++) {
-      batch.put('u/' + block.hash('hex'), undo.render());
+      input = tx.inputs[j];
+      key = input.prevout.hash + '/' + input.prevout.index;
 
-    self.emit('add block', block);
+      if (tx.isCoinbase())
+        break;
 
-    self._pruneBlock(block, batch, function(err) {
+      assert(input.coin);
-      if (err)
+
-        return callback(err);
+      if (this.options.indexAddress) {
-      return callback(null, block);
+        address = input.getHash();
-    });
+        if (address)
+          batch.del('C/' + address + '/' + key);
+      }
+
+      Framer.coin(input.coin, false, undo);
+    }
+
+    for (j = 0; j < tx.outputs.length; j++) {
+      output = tx.outputs[j];
+
+      if (output.script.isUnspendable())
+        continue;
+
+      if (this.options.indexAddress) {
+        address = output.getHash();
+        if (address)
+          batch.put('C/' + address + '/' + key, DUMMY);
+      }
+    }
+  }
+
+  view = view.toArray();
+
+  for (i = 0; i < view.length; i++) {
+    coins = view[i];
+    if (coins.count() === 0) {
+      batch.del('c/' + coins.hash);
+      this.coinCache.remove(coins.hash);
+    } else {
+      raw = coins.toRaw();
+      batch.put('c/' + coins.hash, raw);
+      this.coinCache.set(coins.hash, raw);
+    }
+  }
+
+  if (undo.written > 0)
+    batch.put('u/' + block.hash('hex'), undo.render());
+
+  this.emit('add block', block);
+
+  this._pruneBlock(block, batch, function(err) {
+    if (err)
+      return callback(err);
+    return callback(null, block);
   });
 };
 
@@ -848,18 +837,15 @@ ChainDB.prototype.connectBlock = function connectBlock(block, batch, callback) {
 
 ChainDB.prototype.disconnectBlock = function disconnectBlock(block, batch, callback) {
   var self = this;
-  var i, j, tx, input, output, key, addresses, address, hash, coin;
+  var i, j, tx, input, output, key, addresses, address, hash, view, coins, raw;
 
   if (this.options.spv)
     return utils.nextTick(callback);
 
-  this._ensureHistory(block, function(err, block) {
+  this.getUndoView(block, function(err, view) {
     if (err)
       return callback(err);
 
-    if (!block)
-      return callback(new Error('Block not found.'));
-
     for (i = block.txs.length - 1; i >= 0; i--) {
       tx = block.txs[i];
       hash = tx.hash('hex');
@@ -889,14 +875,10 @@ ChainDB.prototype.disconnectBlock = function disconnectBlock(block, batch, callb
           if (address)
             batch.put('C/' + address + '/' + key, DUMMY);
         }
-
-        coin = input.coin.toRaw();
-
-        batch.put('c/' + key, coin);
-
-        self.coinCache.set(key, coin);
       }
 
+      view.add(tx.toCoins());
+
       for (j = 0; j < tx.outputs.length; j++) {
         output = tx.outputs[j];
         key = hash + '/' + j;
@@ -910,9 +892,21 @@ ChainDB.prototype.disconnectBlock = function disconnectBlock(block, batch, callb
             batch.del('C/' + address + '/' + key);
         }
 
-        batch.del('c/' + key);
+        view.spend(hash, j);
+      }
+    }
 
-        self.coinCache.remove(key);
+    view = view.toArray();
+
+    for (i = 0; i < view.length; i++) {
+      coins = view[i];
+      if (coins.count() === 0) {
+        batch.del('c/' + coins.hash);
+        self.coinCache.remove(coins.hash);
+      } else {
+        raw = coins.toRaw();
+        batch.put('c/' + coins.hash, raw);
+        self.coinCache.set(coins.hash, raw);
       }
     }
 
@@ -933,16 +927,6 @@ ChainDB.prototype.disconnectBlock = function disconnectBlock(block, batch, callb
 ChainDB.prototype.fillCoins = function fillCoins(tx, callback) {
   var self = this;
 
-  if (Array.isArray(tx)) {
-    return utils.forEachSerial(tx, function(tx, next) {
-      self.fillCoins(tx, next);
-    }, function(err) {
-      if (err)
-        return callback(err);
-      return callback(null, tx);
-    });
-  }
-
   if (tx.isCoinbase())
     return utils.asyncify(callback)(null, tx);
 
@@ -975,16 +959,6 @@ ChainDB.prototype.fillCoins = function fillCoins(tx, callback) {
 ChainDB.prototype.fillHistory = function fillHistory(tx, callback) {
   var self = this;
 
-  if (Array.isArray(tx)) {
-    return utils.forEachSerial(tx, function(tx, next) {
-      self.fillHistory(tx, next);
-    }, function(err) {
-      if (err)
-        return callback(err);
-      return callback(null, tx);
-    });
-  }
-
   if (tx.isCoinbase())
     return utils.asyncify(callback)(null, tx);
 
@@ -1017,28 +991,54 @@ ChainDB.prototype.fillHistory = function fillHistory(tx, callback) {
 
 ChainDB.prototype.getCoin = function getCoin(hash, index, callback) {
   var self = this;
-  var key = hash + '/' + index;
+  var coins = this.coinCache.get(hash);
-  var coin;
 
-  coin = this.coinCache.get(key);
+  if (coins) {
-  if (coin) {
     callback = utils.asyncify(callback);
+
+    if (raw)
+      return callback(null, coins);
+
     try {
-      coin = bcoin.coin.fromRaw(coin);
+      coins = bcoin.coins.parseCoin(coins, hash, index);
-      coin.hash = hash;
-      coin.index = index;
     } catch (e) {
       return callback(e);
     }
-    return callback(null, coin);
+
+    return callback(null, coins);
   }
 
-  this.db.fetch('c/' + key, function(data) {
+  this.db.fetch('c/' + hash, function(data) {
-    var coin = bcoin.coin.fromRaw(data);
+    self.coinCache.set(hash, data);
-    coin.hash = hash;
+    return bcoin.coins.parseCoin(data, hash, index);
-    coin.index = index;
+  }, callback);
-    self.coinCache.set(key, data);
+};
-    return coin;
+
+/**
+ * Get coins (unspents only).
+ * @param {Hash} hash
+ * @param {Function} callback - Returns [Error, {@link Coins}].
+ */
+
+ChainDB.prototype.getCoins = function getCoins(hash, callback) {
+  var self = this;
+  var coins = this.coinCache.get(hash);
+
+  if (coins) {
+    callback = utils.asyncify(callback);
+
+    try {
+      coins = bcoin.coins.fromRaw(coins, hash);
+    } catch (e) {
+      return callback(e);
+    }
+
+    return callback(null, coins);
+  }
+
+  this.db.fetch('c/' + hash, function(data) {
+    self.coinCache.set(hash, data);
+    return bcoin.coins.fromRaw(data, hash);
   }, callback);
 };
 
@@ -1096,27 +1096,32 @@ ChainDB.prototype.getCoinsByAddress = function getCoinsByAddress(addresses, call
 
   utils.forEachSerial(addresses, function(address, next) {
     address = bcoin.address.getHash(address);
+
     if (!address)
       return next();
-    self.db.lookup({
+
+    self.db.iterate({
       gte: 'C/' + address,
       lte: 'C/' + address + '~',
       transform: function(key) {
         key = key.split('/');
-        return 'c/' + key[2] + '/' + key[3];
+        return [key[2], +key[3]];
-      },
-      parse: function(data, key) {
-        var coin = bcoin.coin.fromRaw(data);
-        var hash = key.split('/');
-        coin.hash = hash[1];
-        coin.index = +hash[2];
-        return coin;
       }
-    }, function(err, coin) {
+    }, function(err, keys) {
       if (err)
         return next(err);
-      coins = coins.concat(coin);
+
-      next();
+      utils.forEachSerial(keys, function(key, next) {
+        self.getCoin(key[0], key[1], function(err, coin) {
+          if (err)
+            return callback(err);
+
+          if (coin)
+            coins.push(coin);
+
+          return next();
+        });
+      }, next);
     });
   }, function(err) {
     if (err)
@@ -1217,76 +1222,40 @@ ChainDB.prototype.getFullBlock = function getFullBlock(hash, callback) {
     if (!block)
       return callback();
 
-    return self.fillHistoryBlock(block, callback);
+    return self.getUndoView(block, function(err, view) {
+      if (err)
+        return callback(err);
+
+      return callback(null, block);
+    });
   });
 };
 
-ChainDB.prototype._ensureBlock = function _ensureBlock(hash, callback) {
-  var self = this;
-
-  if (hash instanceof bcoin.block)
-    return utils.asyncify(callback)(null, hash);
-
-  return this.getBlock(hash, function(err, block) {
-    if (err)
-      return callback(err);
-
-    if (!block)
-      return callback();
-
-    return self.fillBlock(block, callback);
-  });
-};
-
-ChainDB.prototype._ensureHistory = function _ensureHistory(hash, callback) {
-  if (hash instanceof bcoin.block)
-    return utils.asyncify(callback)(null, hash);
-
-  return this.getFullBlock(hash, callback);
-};
-
 /**
  * Fill a block with coins (unspent only).
  * @param {Block} block
  * @param {Function} callback - Returns [Error, {@link Block}].
  */
 
-ChainDB.prototype.fillBlock = function fillBlock(block, callback) {
+ChainDB.prototype.getCoinView = function getCoinView(block, callback) {
-  var coins, spent, i, tx, hash, j, input, key;
+  var self = this;
+  var view = new bcoin.coinview();
 
-  return this.fillCoins(block.txs, function(err) {
+  utils.forEachSerial(block.getPrevout(), function(prevout, next) {
+    self.getCoins(prevout, function(err, coins) {
+      if (err)
+        return next(err);
+
+      if (coins)
+        view.add(coins);
+
+      next();
+    });
+  }, function(err) {
     if (err)
       return callback(err);
 
-    coins = {};
+    return callback(null, view);
-    spent = {};
-
-    for (i = 0; i < block.txs.length; i++) {
-      tx = block.txs[i];
-      hash = tx.hash('hex');
-
-      for (j = 0; j < tx.inputs.length; j++) {
-        input = tx.inputs[j];
-        key = input.prevout.hash + '/' + input.prevout.index;
-
-        if (spent[key]) {
-          delete input.coin;
-          continue;
-        }
-
-        spent[key] = true;
-
-        if (!input.coin && coins[key]) {
-          input.coin = coins[key];
-          delete coins[key];
-        }
-      }
-
-      for (j = 0; j < tx.outputs.length; j++)
-        coins[hash + '/' + j] = bcoin.coin.fromTX(tx, j);
-    }
-
-    return callback(null, block);
   });
 };
 
@@ -1317,31 +1286,39 @@ ChainDB.prototype.getUndoCoins = function getUndoCoins(hash, callback) {
  * @param {Function} callback - Returns [Error, {@link Block}].
  */
 
-ChainDB.prototype.fillHistoryBlock = function fillHistoryBlock(block, callback) {
+ChainDB.prototype.getUndoView = function getUndoView(block, callback) {
-  var i, j, k, tx, input;
+  var self = this;
+  var i, j, k, tx, input, coin;
 
-  return this.getUndoCoins(block.hash('hex'), function(err, coins) {
+  return this.getCoinView(block, function(err, view) {
     if (err)
       return callback(err);
 
-    if (!coins)
+    return self.getUndoCoins(block.hash('hex'), function(err, coins) {
-      return callback(null, block);
+      if (err)
+        return callback(err);
 
-    for (i = 0, k = 0; i < block.txs.length; i++) {
+      if (!coins)
-      tx = block.txs[i];
+        return callback(null, view);
 
-      if (tx.isCoinbase())
+      for (i = 0, k = 0; i < block.txs.length; i++) {
-        continue;
+        tx = block.txs[i];
 
-      for (j = 0; j < tx.inputs.length; j++) {
+        if (tx.isCoinbase())
-        input = tx.inputs[j];
+          continue;
-        input.coin = coins[k++];
+
-        input.coin.hash = input.prevout.hash;
+        for (j = 0; j < tx.inputs.length; j++) {
-        input.coin.index = input.prevout.index;
+          input = tx.inputs[j];
+          coin = coins[k++];
+          coin.hash = input.prevout.hash;
+          coin.index = input.prevout.index;
+          input.coin = coin;
+          view.addCoin(coin);
+        }
       }
-    }
 
-    return callback(null, block);
+      return callback(null, view);
+    });
   });
 };
 
@@ -1395,32 +1372,13 @@ ChainDB.prototype.isUnspentTX = function isUnspentTX(hash, callback) {
  */
 
 ChainDB.prototype.isSpentTX = function isSpentTX(hash, callback) {
-  var iter;
-
   if (hash.hash)
     hash = hash.hash('hex');
 
-  iter = this.db.iterator({
+  this.getCoins(hash, function(err, coins) {
-    gte: 'c/' + hash,
+    if (err)
-    lte: 'c/' + hash + '~',
+      return callback(err);
-    keys: true,
+    return callback(null, !coins);
-    values: false,
-    fillCache: false,
-    keyAsBuffer: false
-  });
-
-  iter.next(function(err, key, value) {
-    if (err) {
-      return iter.end(function() {
-        callback(err);
-      });
-    }
-
-    iter.end(function(err) {
-      if (err)
-        return callback(err);
-      return callback(null, key === undefined);
-    });
   });
 };