From fb300c26ec10e6daff44ea7660842c72dccd467e Mon Sep 17 00:00:00 2001
From: Martin Acosta <tinchoz49@gmail.com>
Date: Tue, 16 Jun 2020 13:07:02 -0300
Subject: [PATCH] Fixed crash on random concurrent requests

---
 index.js     | 62 ++++++++++++++++++++++++++++------------------------
 package.json |  6 ++---
 test.js      | 51 ++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 86 insertions(+), 33 deletions(-)

diff --git a/index.js b/index.js
index 57518b8..5b2edee 100644
--- a/index.js
+++ b/index.js
@@ -152,7 +152,7 @@ WriteRequest.prototype.onwrite = function (err, e) {
   }
 
   if (!err) {
-    this.file.updateSize(e.currentTarget.length, this.truncating)
+    this.file.updateSize(e.currentTarget.length)
   }
 
   if (this.truncating) {
@@ -166,6 +166,7 @@ WriteRequest.prototype.onwrite = function (err, e) {
 
 WriteRequest.prototype.truncate = function () {
   this.truncating = true
+  this.file.truncate()
   this.writer.truncate(this.req.offset)
 }
 
@@ -176,21 +177,23 @@ WriteRequest.prototype.lock = function () {
 }
 
 WriteRequest.prototype.run = function (req) {
-  var file = this.file
+  this.file.getWritableFile((err, file) => {
+    if (err) return req.callback(err)
 
-  this.req = req
-  if (!this.writer || this.writer.length !== file.size) return this.makeWriter()
+    this.req = req
+    if (!this.writer || this.writer.length !== file.size) return this.makeWriter()
 
-  const end = req.offset + req.size
-  if (end > file.size && !this.lock()) return
+    const end = req.offset + req.size
+    if (end > file.size && !this.lock()) return
 
-  if (req.offset > this.writer.length) {
-    if (req.offset > file.size) return this.truncate()
-    return this.makeWriter()
-  }
+    if (req.offset > this.writer.length) {
+      if (req.offset > file.size) return this.truncate()
+      return this.makeWriter()
+    }
 
-  this.writer.seek(req.offset)
-  this.writer.write(new Blob([req.data], TYPE))
+    this.writer.seek(req.offset)
+    this.writer.write(new Blob([req.data], TYPE))
+  })
 }
 
 function Mutex () {
@@ -246,12 +249,6 @@ ReadRequest.prototype.onread = function (err, buf) {
   const req = this.req
 
   if (err && this.retry) {
-    if (err.name === 'NotReadableError') {
-      this.file.clearFile()
-      this.run(req)
-      return
-    }
-
     this.retry = false
     if (this.lock(this)) {
       this.file.clearFile()
@@ -289,44 +286,53 @@ class EntryFile {
     this._lock = mutexify()
     this._file = null
     this._size = 0
-  }
-
-  get locked () {
-    return this._lock.locked
+    this._truncated = false
   }
 
   get size () {
     return this._size
   }
 
-  updateSize (size, truncating = false) {
-    if (truncating || size > this._size) {
+  updateSize (size) {
+    if (!this._truncated) {
       this._size = size
     }
 
     this.clearFile()
   }
 
+  truncate () {
+    this._truncated = true
+  }
+
   clearFile () {
     this._file = null
   }
 
   get (cb) {
-    if (this._file) {
-      cb(null, this._file)
-      return
+    if (this._file && !this._truncated) {
+      return cb(null, this._file)
     }
 
     this._lock(release => {
-      if (this._file) {
+      if (this._file && !this._truncated) {
         return release(cb, null, this._file)
       }
 
       this._entry.file(file => {
+        this._truncated = false
         this._file = file
         this._size = file.size
         release(cb, null, file)
       }, err => release(cb, err))
     })
   }
+
+  getWritableFile (cb) {
+    if (!this._truncated) {
+      return cb(null, this)
+    }
+
+    this.get(cb)
+  }
 }
diff --git a/package.json b/package.json
index f4ed100..e95089d 100644
--- a/package.json
+++ b/package.json
@@ -8,17 +8,17 @@
     "random-access-storage": "^1.3.0"
   },
   "devDependencies": {
-    "@dxos/browser-runner": "1.0.0-beta.6",
+    "@dxos/browser-runner": "^1.0.0-beta.9",
     "random-access-test": "^1.0.0",
     "standard": "^11.0.1",
     "tap-finished": "0.0.1",
-    "tape": "^5.0.0"
+    "tape": "^5.0.1"
   },
   "scripts": {
     "test": "browser-runner test.js",
     "posttest": "npm run lint",
     "lint": "standard",
-    "bench": "browser-runner bench.js"
+    "bench": "browser-runner bench.js --timeout 0"
   },
   "repository": {
     "type": "git",
diff --git a/test.js b/test.js
index 04dabb7..f1d67b8 100644
--- a/test.js
+++ b/test.js
@@ -1,10 +1,57 @@
-const test = require('random-access-test')
+const test = require('tape')
+const randomAccessTest = require('random-access-test')
 const racf = require('./')
 
 const createStorage = (root) => (file, opts) => racf(`${root}/${file}`, opts)
 
 const storage = createStorage('tests-' + Math.random())
 
-test(function (name, options, callback) {
+randomAccessTest(function (name, options, callback) {
   callback(storage(name, options))
 }, {})
+
+test('write/read concurrent requests', async t => {
+  const st = storage('random')
+
+  const rand = (min, max) => Math.floor(Math.random() * max) + min
+
+  const read = (...args) => new Promise((resolve, reject) => {
+    st.read(...args, (err) => {
+      if (err) return reject(err)
+      resolve()
+    })
+  })
+
+  const write = (...args) => new Promise((resolve, reject) => {
+    st.write(...args, (err) => {
+      if (err) return reject(err)
+      resolve()
+    })
+  })
+
+  try {
+    await new Promise(resolve => st.open(() => resolve()))
+
+    const buf = Buffer.alloc(1)
+
+    await Promise.all([...Array(1000).keys()].map(from => {
+      return write(from, buf)
+    }))
+
+    await Promise.all([...Array(1000).keys()].map(() => {
+      const row = rand(0, 2)
+      const from = rand(0, 1000)
+      const to = 1
+
+      if (row === 0) {
+        return read(from, to)
+      }
+      return write(from, buf)
+    }))
+
+    t.pass('should work ok with random concurrent request')
+    t.end()
+  } catch (err) {
+    t.end(err)
+  }
+})