use loader-fs-cache as the caching engine

Author: viankakrisna

index.js

@@ -1,93 +1,40 @@
 var eslint = require("eslint")
 var assign = require("object-assign")
 var loaderUtils = require("loader-utils")
-var crypto = require("crypto")
-var fs = require("fs")
-var findCacheDir = require("find-cache-dir")
 var objectHash = require("object-hash")
-var os = require("os")
+var pkg = require("./package.json")
+var createCache = require("loader-fs-cache")
+var cache = createCache("eslint-loader")
 
 var engines = {}
-var rules = {}
-var cache = null
-var cachePath = null
 
 /**
- * linter
+ * printLinterOutput
  *
- * @param {String|Buffer} input JavaScript string
+ * @param {Object} eslint.executeOnText return value
  * @param {Object} config eslint configuration
  * @param {Object} webpack webpack instance
  * @return {void}
  */
-function lint(input, config, webpack) {
-  var resourcePath = webpack.resourcePath
-  var cwd = process.cwd()
-
-  // remove cwd from resource path in case webpack has been started from project
-  // root, to allow having relative paths in .eslintignore
-  if (resourcePath.indexOf(cwd) === 0) {
-    resourcePath = resourcePath.substr(cwd.length + 1)
-  }
-
-  // get engine
-  var configHash = objectHash(config)
-  var engine = engines[configHash]
-  var rulesHash = rules[configHash]
-
-  var res
-  // If cache is enable and the data are the same as in the cache, just
-  // use them
-  if (config.cache) {
-    // just get rules hash once per engine for performance reasons
-    if (!rulesHash) {
-      rulesHash = objectHash(engine.getConfigForFile(resourcePath))
-      rules[configHash] = rulesHash
-    }
-    var inputMD5 = crypto.createHash("md5").update(input).digest("hex")
-    if (
-      cache[resourcePath] &&
-      cache[resourcePath].hash === inputMD5 &&
-      cache[resourcePath].rules === rulesHash
-    ) {
-      res = cache[resourcePath].res
-    }
-  }
-
-  // Re-lint the text if the cache off or miss
-  if (!res) {
-    res = engine.executeOnText(input, resourcePath, true)
-
-    // Save new results in the cache
-    if (config.cache) {
-      cache[resourcePath] = {
-        hash: inputMD5,
-        rules: rulesHash,
-        res: res,
-      }
-      fs.writeFileSync(cachePath, JSON.stringify(cache))
-    }
-  }
-
-  // executeOnText ensure we will have res.results[0] only
-
+function printLinterOutput(res, config, webpack) {
   // skip ignored file warning
-  if (!(
-    res.warningCount === 1 &&
-    res.results[0].messages[0] &&
-    res.results[0].messages[0].message &&
-    res.results[0].messages[0].message.indexOf("ignore") > 1
-  )) {
+  if (
+    !(res.warningCount === 1 &&
+      res.results[0].messages[0] &&
+      res.results[0].messages[0].message &&
+      res.results[0].messages[0].message.indexOf("ignore") > 1)
+  ) {
     // quiet filter done now
     // eslint allow rules to be specified in the input between comments
     // so we can found warnings defined in the input itself
     if (res.warningCount && config.quiet) {
       res.warningCount = 0
       res.results[0].warningCount = 0
-      res.results[0].messages = res.results[0].messages
-        .filter(function(message) {
-          return message.severity !== 1
-        })
+      res.results[0].messages = res.results[0].messages.filter(function(
+        message
+      ) {
+        return message.severity !== 1
+      })
     }
 
     // if enabled, use eslint auto-fixing where possible
@@ -128,19 +75,21 @@ function lint(input, config, webpack) {
       if (emitter) {
         emitter(messages)
         if (config.failOnError && res.errorCount) {
-          throw new Error("Module failed because of a eslint error.\n"
-            + messages)
+          throw new Error(
+            "Module failed because of a eslint error.\n" + messages
+          )
         }
         else if (config.failOnWarning && res.warningCount) {
-          throw new Error("Module failed because of a eslint warning.\n"
-            + messages)
+          throw new Error(
+            "Module failed because of a eslint warning.\n" + messages
+          )
         }
       }
       else {
         throw new Error(
           "Your module system doesn't support emitWarning. " +
-          "Update available? \n" +
-          messages
+            "Update available? \n" +
+            messages
         )
       }
     }
@@ -155,45 +104,72 @@ function lint(input, config, webpack) {
  * @return {void}
  */
 module.exports = function(input, map) {
+  var webpack = this
   var config = assign(
     // loader defaults
     {
       formatter: require("eslint/lib/formatters/stylish"),
+      cacheIdentifier: JSON.stringify({
+        "eslint-loader": pkg.version,
+        eslint: eslint.version,
+      }),
     },
     // user defaults
     this.options.eslint || {},
     // loader query string
     loaderUtils.getOptions(this)
   )
-  this.cacheable()
+
+  var cacheDirectory = config.cacheDirectory
+  var cacheIdentifier = config.cacheIdentifier
+
+  delete config.cacheDirectory
+  delete config.cacheIdentifier
 
   // Create the engine only once per config
   var configHash = objectHash(config)
   if (!engines[configHash]) {
     engines[configHash] = new eslint.CLIEngine(config)
   }
 
-  // Read the cached information only once and if enable
-  if (cache === null) {
-    if (config.cache) {
-      var thunk = findCacheDir({
-        name: "eslint-loader",
-        thunk: true,
-        create: true,
-      })
-      cachePath = thunk("data.json") || os.tmpdir() + "/data.json"
-      try {
-        cache = require(cachePath)
-      }
-      catch (e) {
-        cache = {}
+  this.cacheable()
+
+  var resourcePath = webpack.resourcePath
+  var cwd = process.cwd()
+
+  // remove cwd from resource path in case webpack has been started from project
+  // root, to allow having relative paths in .eslintignore
+  if (resourcePath.indexOf(cwd) === 0) {
+    resourcePath = resourcePath.substr(cwd.length + 1)
+  }
+
+  var engine = engines[configHash]
+  // return early if cached
+  if (config.cache) {
+    var callback = this.async()
+    return cache(
+      {
+        directory: cacheDirectory,
+        identifier: cacheIdentifier,
+        options: config,
+        source: input,
+        transform: function() {
+          return lint(engine, input, resourcePath)
+        },
+      },
+      function(err, res) {
+        if (err) {
+          return callback(err)
+        }
+        printLinterOutput(res || {}, config, webpack)
+        return callback(null, input, map)
       }
-    }
-    else {
-      cache = false
-    }
+    )
   }
+  printLinterOutput(lint(engine, input, resourcePath), config, this)
+  this.callback(input, map)
+}
 
-  lint(input, config, this)
-  this.callback(null, input, map)
+function lint(engine, input, resourcePath) {
+  return engine.executeOnText(input, resourcePath, true)
 }

package.json

@@ -20,9 +20,11 @@
   },
   "dependencies": {
     "find-cache-dir": "^0.1.1",
+    "loader-fs-cache": "^1.0.0",
     "loader-utils": "^1.0.2",
     "object-assign": "^4.0.1",
-    "object-hash": "^1.1.4"
+    "object-hash": "^1.1.4",
+    "rimraf": "^2.6.1"
   },
   "devDependencies": {
     "ava": "^0.17.0",