Merge pull request #12 from sanchaz/add_fee_per_byte

Add feePerByte for fee calculation options
bitpay · Nov 30, 2018 · df618e7 · df618e7
2 parents 9cb4217 + 66aedc2
commit df618e7
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Showing 2 changed files with 98 additions and 3 deletions.
diff --git a/lib/transaction/transaction.js b/lib/transaction/transaction.js
@@ -80,6 +80,9 @@ Transaction.NLOCKTIME_MAX_VALUE = 4294967295;
 // Value used for fee estimation (satoshis per kilobyte)
 Transaction.FEE_PER_KB = 100000;
 
+// Value used for fee estimation (satoshis per byte)
+Transaction.FEE_PER_BYTE = 1;
+
 // Safe upper bound for change address script size in bytes
 Transaction.CHANGE_OUTPUT_MAX_SIZE = 20 + 4 + 34 + 4;
 Transaction.MAXIMUM_EXTRA_SIZE = 4 + 9 + 9 + 4;
@@ -665,6 +668,7 @@ Transaction.prototype.fee = function(amount) {
  * Manually set the fee per KB for this transaction. Beware that this resets all the signatures
  * for inputs (in further versions, SIGHASH_SINGLE or SIGHASH_NONE signatures will not
  * be reset).
+ * Takes priority over fee per Byte, for backwards compatibility
  *
  * @param {number} amount satoshis per KB to be sent
  * @return {Transaction} this, for chaining
@@ -676,6 +680,22 @@ Transaction.prototype.feePerKb = function(amount) {
   return this;
 };
 
+/**
+ * Manually set the fee per Byte for this transaction. Beware that this resets all the signatures
+ * for inputs (in further versions, SIGHASH_SINGLE or SIGHASH_NONE signatures will not
+ * be reset).
+ * fee per Byte will be ignored if fee per KB is set
+ *
+ * @param {number} amount satoshis per Byte to be sent
+ * @return {Transaction} this, for chaining
+ */
+Transaction.prototype.feePerByte = function(amount) {
+  $.checkArgument(_.isNumber(amount), 'amount must be a number');
+  this._feePerByte = amount;
+  this._updateChangeOutput();
+  return this;
+};
+
 /* Output management */
 
 /**
@@ -888,7 +908,11 @@ Transaction.prototype.getFee = function() {
 Transaction.prototype._estimateFee = function() {
   var estimatedSize = this._estimateSize();
   var available = this._getUnspentValue();
-  return Transaction._estimateFee(estimatedSize, available, this._feePerKb);
+  if (this._feePerByte && !this._feePerKb) {
+    return Transaction._estimateFeePerByte(estimatedSize, available, this._feePerByte);
+  } else {
+    return Transaction._estimateFeePerKb(estimatedSize, available, this._feePerKb);
+  }
 };
 
 Transaction.prototype._getUnspentValue = function() {
@@ -901,14 +925,22 @@ Transaction.prototype._clearSignatures = function() {
   });
 };
 
-Transaction._estimateFee = function(size, amountAvailable, feePerKb) {
+Transaction._estimateFeePerKb = function(size, amountAvailable, feePerKb) {
   var fee = Math.ceil(size / 1000) * (feePerKb || Transaction.FEE_PER_KB);
   if (amountAvailable > fee) {
     size += Transaction.CHANGE_OUTPUT_MAX_SIZE;
   }
   return Math.ceil(size / 1000) * (feePerKb || Transaction.FEE_PER_KB);
 };
 
+Transaction._estimateFeePerByte = function(size, amountAvailable, feePerByte) {
+  var fee = size * (feePerByte || Transaction.FEE_PER_BYTE);
+  if (amountAvailable > fee) {
+    size += Transaction.CHANGE_OUTPUT_MAX_SIZE;
+  }
+  return size * (feePerByte || Transaction.FEE_PER_BYTE);
+};
+
 Transaction.prototype._estimateSize = function() {
   var result = Transaction.MAXIMUM_EXTRA_SIZE;
   _.each(this.inputs, function(input) {

diff --git a/test/transaction/transaction.js b/test/transaction/transaction.js
@@ -29,7 +29,7 @@ describe('Transaction', function() {
   });
 
   it('should parse the version as a signed integer', function() {
-    var transaction = Transaction('ffffffff0000ffffffff')
+    var transaction = Transaction('ffffffff0000ffffffff');
     transaction.version.should.equal(-1);
     transaction.nLockTime.should.equal(0xffffffff);
   });
@@ -390,6 +390,69 @@ describe('Transaction', function() {
       transaction.outputs.length.should.equal(2);
       transaction.outputs[1].satoshis.should.equal(34000);
     });
+    it('fee per byte (low fee) can be set up manually', function() {
+      var inputs = _.map(_.range(10), function(i) {
+        var utxo = _.clone(simpleUtxoWith100000Satoshis);
+        utxo.outputIndex = i;
+        return utxo;
+      });
+      var transaction = new Transaction()
+        .from(inputs)
+        .to(toAddress, 950000)
+        .feePerByte(1)
+        .change(changeAddress)
+        .sign(privateKey);
+      transaction._estimateSize().should.be.within(1000, 1999);
+      transaction.outputs.length.should.equal(2);
+      transaction.outputs[1].satoshis.should.be.within(48001, 49000); 
+    });
+    it('fee per byte (high fee) can be set up manually', function() {
+      var inputs = _.map(_.range(10), function(i) {
+        var utxo = _.clone(simpleUtxoWith100000Satoshis);
+        utxo.outputIndex = i;
+        return utxo;
+      });
+      var transaction = new Transaction()
+        .from(inputs)
+        .to(toAddress, 950000)
+        .feePerByte(2)
+        .change(changeAddress)
+        .sign(privateKey);
+      transaction._estimateSize().should.be.within(1000, 1999);
+      transaction.outputs.length.should.equal(2);
+      transaction.outputs[1].satoshis.should.be.within(46002, 48000); 
+    });
+    it('fee per byte can be set up manually', function() {
+      var inputs = _.map(_.range(10), function(i) {
+        var utxo = _.clone(simpleUtxoWith100000Satoshis);
+        utxo.outputIndex = i;
+        return utxo;
+      });
+      var transaction = new Transaction()
+        .from(inputs)
+        .to(toAddress, 950000)
+        .feePerByte(13)
+        .change(changeAddress)
+        .sign(privateKey);
+      transaction._estimateSize().should.be.within(1000, 1999);
+      transaction.outputs.length.should.equal(2);
+      transaction.outputs[1].satoshis.should.be.within(24013, 37000); 
+    });
+    it('fee per byte not enough for change', function() {
+      var inputs = _.map(_.range(10), function(i) {
+        var utxo = _.clone(simpleUtxoWith100000Satoshis);
+        utxo.outputIndex = i;
+        return utxo;
+      });
+      var transaction = new Transaction()
+        .from(inputs)
+        .to(toAddress, 999999)
+        .feePerByte(1)
+        .change(changeAddress)
+        .sign(privateKey);
+      transaction._estimateSize().should.be.within(1000, 1999);
+      transaction.outputs.length.should.equal(1);
+    });
     it('if satoshis are invalid', function() {
       var transaction = new Transaction()
         .from(simpleUtxoWith100000Satoshis)