fix: start retrying immediately, stop after 10 attempts

PR-URL: #217
Credit: @nlf
Close: #217
Reviewed-by: @isaacs, @wraithgar

graceful-fs.js

@@ -114,14 +114,13 @@ function patch (fs) {
 
     return go$readFile(path, options, cb)
 
-    function go$readFile (path, options, cb) {
+    function go$readFile (path, options, cb, attempts = 0) {
       return fs$readFile(path, options, function (err) {
         if (err && (err.code === 'EMFILE' || err.code === 'ENFILE'))
-          enqueue([go$readFile, [path, options, cb]])
+          enqueue([go$readFile, [path, options, cb], attempts + 1, err])
         else {
           if (typeof cb === 'function')
             cb.apply(this, arguments)
-          retry()
         }
       })
     }
@@ -135,14 +134,13 @@ function patch (fs) {
 
     return go$writeFile(path, data, options, cb)
 
-    function go$writeFile (path, data, options, cb) {
+    function go$writeFile (path, data, options, cb, attempts = 0) {
       return fs$writeFile(path, data, options, function (err) {
         if (err && (err.code === 'EMFILE' || err.code === 'ENFILE'))
-          enqueue([go$writeFile, [path, data, options, cb]])
+          enqueue([go$writeFile, [path, data, options, cb], attempts + 1, err])
         else {
           if (typeof cb === 'function')
             cb.apply(this, arguments)
-          retry()
         }
       })
     }
@@ -157,14 +155,13 @@ function patch (fs) {
 
     return go$appendFile(path, data, options, cb)
 
-    function go$appendFile (path, data, options, cb) {
+    function go$appendFile (path, data, options, cb, attempts = 0) {
       return fs$appendFile(path, data, options, function (err) {
         if (err && (err.code === 'EMFILE' || err.code === 'ENFILE'))
-          enqueue([go$appendFile, [path, data, options, cb]])
+          enqueue([go$appendFile, [path, data, options, cb], attempts + 1, err])
         else {
           if (typeof cb === 'function')
             cb.apply(this, arguments)
-          retry()
         }
       })
     }
@@ -180,14 +177,13 @@ function patch (fs) {
     }
     return go$copyFile(src, dest, flags, cb)
 
-    function go$copyFile (src, dest, flags, cb) {
+    function go$copyFile (src, dest, flags, cb, attempts = 0) {
       return fs$copyFile(src, dest, flags, function (err) {
         if (err && (err.code === 'EMFILE' || err.code === 'ENFILE'))
-          enqueue([go$copyFile, [src, dest, flags, cb]])
+          enqueue([go$copyFile, [src, dest, flags, cb], attempts + 1, err])
         else {
           if (typeof cb === 'function')
             cb.apply(this, arguments)
-          retry()
         }
       })
     }
@@ -201,10 +197,10 @@ function patch (fs) {
 
     return go$readdir(path, options, cb)
 
-    function go$readdir (path, options, cb) {
+    function go$readdir (path, options, cb, attempts = 0) {
       return fs$readdir(path, options, function (err, files) {
         if (err && (err.code === 'EMFILE' || err.code === 'ENFILE'))
-          enqueue([go$readdir, [path, options, cb]])
+          enqueue([go$readdir, [path, options, cb], attempts + 1, err])
         else {
           if (files && files.sort)
             files.sort()
@@ -338,14 +334,13 @@ function patch (fs) {
 
     return go$open(path, flags, mode, cb)
 
-    function go$open (path, flags, mode, cb) {
+    function go$open (path, flags, mode, cb, attempts = 0) {
       return fs$open(path, flags, mode, function (err, fd) {
         if (err && (err.code === 'EMFILE' || err.code === 'ENFILE'))
-          enqueue([go$open, [path, flags, mode, cb]])
+          enqueue([go$open, [path, flags, mode, cb], attempts + 1, err])
         else {
           if (typeof cb === 'function')
             cb.apply(this, arguments)
-          retry()
         }
       })
     }
@@ -357,12 +352,24 @@ function patch (fs) {
 function enqueue (elem) {
   debug('ENQUEUE', elem[0].name, elem[1])
   fs[gracefulQueue].push(elem)
+  retry()
 }
 
 function retry () {
+  if (fs[gracefulQueue].length === 0)
+    return
+
   var elem = fs[gracefulQueue].shift()
   if (elem) {
-    debug('RETRY', elem[0].name, elem[1])
-    elem[0].apply(null, elem[1])
+    const [fn, args, attempts, err] = elem
+    if (attempts < 10) {
+      debug('RETRY', fn.name, args, `ATTEMPT #${attempts}`)
+      fn.call(null, ...args, attempts)
+    } else {
+      const cb = args.pop()
+      if (typeof cb === 'function')
+        cb.call(null, err)
+    }
   }
+  setImmediate(retry)
 }

test/readdir-sort.js

@@ -1,7 +1,7 @@
 var fs = require("fs")
 
 var readdir = fs.readdir
-fs.readdir = function(path, cb) {
+fs.readdir = function(path, options, cb) {
   process.nextTick(function() {
     cb(null, ["b", "z", "a"])
   })

test/retry.js

@@ -0,0 +1,23 @@
+'use strict'
+
+var importFresh = require('import-fresh')
+var path = require('path')
+var realFs = require('fs')
+var test = require('tap').test
+
+var EMFILE = Object.assign(new Error('FAKE EMFILE'), { code: 'EMFILE' })
+
+test('retries 10 times before erroring', function (t) {
+  var attempts = 0
+  realFs.readFile = function (path, options, cb) {
+    ++attempts
+    process.nextTick(cb, EMFILE)
+  }
+  var fs = importFresh(path.dirname(__dirname))
+
+  fs.readFile('literally anything', function (err) {
+    t.equal(err.code, 'EMFILE', 'eventually got the EMFILE')
+    t.equal(attempts, 10, 'tried 10 times')
+    t.done()
+  })
+})