fix: Improve performance (#15)

micromatch · Sep 29, 2021 · f50a175 · f50a175
1 parent 6149ec8
commit f50a175
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Showing 5 changed files with 68 additions and 50 deletions.
diff --git a/.eslintrc.json b/.eslintrc.json
@@ -1,7 +1,6 @@
 {
-  "ecmaFeatures": {
-    "modules": true,
-    "experimentalObjectRestSpread": true
+  "parserOptions": {
+    "ecmaVersion": 2020
   },
 
   "env": {

diff --git a/benchmark.js b/benchmark.js
@@ -0,0 +1,23 @@
+'use strict';
+
+if (!global.BigInt) {
+  console.log('Benchmark requirest 10.x or newer.');
+  process.exit(0);
+}
+
+var assert = require('assert');
+var isGlob = require('./');
+
+function runBenchmark(length) {
+  var start = process.hrtime.bigint();
+  ['(', '[', '{', '\\'].forEach(function(char) {
+    isGlob(char.repeat(length));
+    isGlob(char.repeat(length), {strict: false});
+  });
+  return process.hrtime.bigint() - start;
+}
+
+var baseline = runBenchmark(1e6);
+console.log('Benchmark took ' + baseline / global.BigInt(1000000) + ' milliseconds.');
+
+assert.ok(baseline < global.BigInt(1000000000), 'Benchmark goal is less than one second');
diff --git a/index.js b/index.js
@@ -7,11 +7,16 @@
 
 var isExtglob = require('is-extglob');
 var chars = { '{': '}', '(': ')', '[': ']'};
-var strictCheck = function (str) {
+var strictCheck = function(str) {
   if (str[0] === '!') {
     return true;
   }
   var index = 0;
+  var pipeIndex = -2;
+  var closeSquareIndex = -2;
+  var closeCurlyIndex = -2;
+  var closeParenIndex = -2;
+  var backSlashIndex = -2;
   while (index < str.length) {
     if (str[index] === '*') {
       return true;
@@ -21,51 +26,58 @@ var strictCheck = function (str) {
       return true;
     }
 
-    if (str[index] === '[' && str[index + 1] !== ']') {
-      var closeIndex = str.indexOf(']', index);
-      if (closeIndex > index) {
-        var slashIndex = str.indexOf('\\', index);
-        if (slashIndex === -1 || slashIndex > closeIndex) {
+    if (closeSquareIndex !== -1 && str[index] === '[' && str[index + 1] !== ']') {
+      if (closeSquareIndex < index) {
+        closeSquareIndex = str.indexOf(']', index);
+      }
+      if (closeSquareIndex > index) {
+        if (backSlashIndex === -1 || backSlashIndex > closeSquareIndex) {
+          return true;
+        }
+        backSlashIndex = str.indexOf('\\', index);
+        if (backSlashIndex === -1 || backSlashIndex > closeSquareIndex) {
           return true;
         }
       }
     }
 
-    if (str[index] === '{' && str[index + 1] !== '}') {
-      closeIndex = str.indexOf('}', index);
-      if (closeIndex > index) {
-        slashIndex = str.indexOf('\\', index);
-        if (slashIndex === -1 || slashIndex > closeIndex) {
+    if (closeCurlyIndex !== -1 && str[index] === '{' && str[index + 1] !== '}') {
+      closeCurlyIndex = str.indexOf('}', index);
+      if (closeCurlyIndex > index) {
+        backSlashIndex = str.indexOf('\\', index);
+        if (backSlashIndex === -1 || backSlashIndex > closeCurlyIndex) {
           return true;
         }
       }
     }
 
-    if (str[index] === '(' && str[index + 1] === '?' && /[:!=]/.test(str[index + 2]) && str[index + 3] !== ')') {
-      closeIndex = str.indexOf(')', index);
-      if (closeIndex > index) {
-        slashIndex = str.indexOf('\\', index);
-        if (slashIndex === -1 || slashIndex > closeIndex) {
+    if (closeParenIndex !== -1 && str[index] === '(' && str[index + 1] === '?' && /[:!=]/.test(str[index + 2]) && str[index + 3] !== ')') {
+      closeParenIndex = str.indexOf(')', index);
+      if (closeParenIndex > index) {
+        backSlashIndex = str.indexOf('\\', index);
+        if (backSlashIndex === -1 || backSlashIndex > closeParenIndex) {
           return true;
         }
       }
     }
 
-    if (str[index] === '(' && str[index + 1] !== '|') {
-      var pipeIndex = str.indexOf('|', index);
-      if (pipeIndex > index && str[pipeIndex + 1] !== ')') {
-        closeIndex = str.indexOf(')', pipeIndex);
-        if (closeIndex > pipeIndex) {
-          slashIndex = str.indexOf('\\', pipeIndex);
-          if (slashIndex === -1 || slashIndex > closeIndex) {
-           return true;
+    if (pipeIndex !== -1 && str[index] === '(' && str[index + 1] !== '|') {
+      if (pipeIndex < index) {
+        pipeIndex = str.indexOf('|', index);
+      }
+      if (pipeIndex !== -1 && str[pipeIndex + 1] !== ')') {
+        closeParenIndex = str.indexOf(')', pipeIndex);
+        if (closeParenIndex > pipeIndex) {
+          backSlashIndex = str.indexOf('\\', pipeIndex);
+          if (backSlashIndex === -1 || backSlashIndex > closeParenIndex) {
+            return true;
           }
         }
       }
     }
 
     if (str[index] === '\\') {
-      var open = str[index+1];
+      var open = str[index + 1];
       index += 2;
       var close = chars[open];
 
@@ -84,9 +96,9 @@ var strictCheck = function (str) {
     }
   }
   return false;
-}
+};
 
-var relaxedCheck = function (str) {
+var relaxedCheck = function(str) {
   if (str[0] === '!') {
     return true;
   }
@@ -97,7 +109,7 @@ var relaxedCheck = function (str) {
     }
 
     if (str[index] === '\\') {
-      var open = str[index+1];
+      var open = str[index + 1];
       index += 2;
       var close = chars[open];
 
@@ -116,7 +128,7 @@ var relaxedCheck = function (str) {
     }
   }
   return false;
-}
+};
 
 module.exports = function isGlob(str, options) {
   if (typeof str !== 'string' || str === '') {
@@ -135,4 +147,4 @@ module.exports = function isGlob(str, options) {
   }
 
   return check(str);
-}
+};
diff --git a/package.json b/package.json
@@ -22,7 +22,7 @@
     "node": ">=0.10.0"
   },
   "scripts": {
-    "test": "mocha"
+    "test": "mocha && node benchmark.js"
   },
   "dependencies": {
     "is-extglob": "^2.1.1"

diff --git a/test.js b/test.js
@@ -7,7 +7,6 @@
 
 'use strict';
 
-require('mocha');
 var assert = require('assert');
 var isGlob = require('./');
 
@@ -303,20 +302,5 @@ describe('isGlob', function() {
       assert(isGlob('\\*(abc|xyz)/*(abc|xyz)'));
       assert(isGlob('\\+(abc|xyz)/+(abc|xyz)'));
     });
-
-    it('should be performant and not subject to ReDoS/exponential backtracking', function() {
-      if (!String.prototype.repeat) {
-        return;
-      }
-      // These will time out if the algorithm is inefficient.
-      isGlob('('.repeat(1e5));
-      isGlob('('.repeat(1e5), {strict: false});
-      isGlob('['.repeat(1e5));
-      isGlob('['.repeat(1e5), {strict: false});
-      isGlob('{'.repeat(1e5));
-      isGlob('{'.repeat(1e5), {strict: false});
-      isGlob('\\'.repeat(1e5));
-      isGlob('\\'.repeat(1e5), {strict: false});
-    });
   });
 });