Merge pull request #1187 from MetaMask/i1118-IncreaseGasBuffer

I1118 increase gas buffer

3 files changed, 35 insertions, 5 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d07154bdf..603a92df5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@
 
 - Add personal_sign method support.
 - Add ability to customize gas and gasPrice on the transaction approval screen.
+- Increase default gas buffer to 1.5x estimated gas value.
 
 ## 3.3.0 2017-2-20
 
diff --git a/app/scripts/lib/tx-utils.js b/app/scripts/lib/tx-utils.js
index 19a2d430e..f5051eb8f 100644
--- a/app/scripts/lib/tx-utils.js
+++ b/app/scripts/lib/tx-utils.js
@@ -55,7 +55,7 @@ module.exports = class txProviderUtils {
     // try adding an additional gas buffer to our estimation for safety
     const estimatedGasBn = new BN(ethUtil.stripHexPrefix(txData.estimatedGas), 16)
     const blockGasLimitBn = new BN(ethUtil.stripHexPrefix(blockGasLimitHex), 16)
-    const estimationWithBuffer = new BN(this.addGasBuffer(estimatedGasBn), 16)
+    const estimationWithBuffer = new BN(this.addGasBuffer(estimatedGasBn, blockGasLimitHex), 16)
     // added gas buffer is too high
     if (estimationWithBuffer.gt(blockGasLimitBn)) {
       txParams.gas = txData.estimatedGas
@@ -68,11 +68,14 @@ module.exports = class txProviderUtils {
     return
   }
 
-  addGasBuffer (gas) {
-    const gasBuffer = new BN('100000', 10)
+  addGasBuffer (gas, blockGasLimitHex) {
+    const blockGasLimitBn = new BN(ethUtil.stripHexPrefix(blockGasLimitHex), 16)
     const bnGas = new BN(ethUtil.stripHexPrefix(gas), 16)
-    const correct = bnGas.add(gasBuffer)
-    return ethUtil.addHexPrefix(correct.toString(16))
+    const bufferedGas = bnGas.muln(1.5)
+
+    if (bnGas.gt(blockGasLimitBn)) return gas
+    if (bufferedGas.lt(blockGasLimitBn)) return ethUtil.addHexPrefix(bufferedGas.toString(16))
+    return ethUtil.addHexPrefix(blockGasLimitBn.toString(16))
   }
 
   fillInTxParams (txParams, cb) {
diff --git a/test/unit/tx-utils-test.js b/test/unit/tx-utils-test.js
new file mode 100644
index 000000000..65233e1d9
--- /dev/null
+++ b/test/unit/tx-utils-test.js
@@ -0,0 +1,26 @@
+const assert = require('assert')
+const ethUtil = require('ethereumjs-util')
+const BN = ethUtil.BN
+
+const TxUtils = require('../../app/scripts/lib/tx-utils')
+
+
+describe('txUtils', function() {
+  let txUtils
+
+  before(function() {
+    txUtils = new TxUtils()
+  })
+
+  describe('addGasBuffer', function() {
+    it('multiplies by 1.5', function() {
+      const input = '0x123fad'
+      const output = txUtils.addGasBuffer(input, '0x3d4c52') //0x3d4c52 is 4mil for dummy gas limit
+
+      const inputBn = new BN(ethUtil.stripHexPrefix(input), 'hex')
+      const outputBn = new BN(ethUtil.stripHexPrefix(output), 'hex')
+      const expectedBn = inputBn.muln(1.5)
+      assert(outputBn.eq(expectedBn), 'returns 1.5 the input value')
+    })
+  })
+})