Don't create duplicate buffers if a path is opened twice concurrently

spec/project-spec.coffee

@@ -1,4 +1,5 @@
 temp = require('temp').track()
+TextBuffer = require('text-buffer')
 Project = require '../src/project'
 fs = require 'fs-plus'
 path = require 'path'
@@ -326,7 +327,8 @@ describe "Project", ->
           expect(newBufferHandler).toHaveBeenCalledWith(editor.buffer)
 
   describe ".bufferForPath(path)", ->
-    [buffer] = []
+    buffer = null
+
     beforeEach ->
       waitsForPromise ->
         atom.project.bufferForPath("a").then (o) ->
@@ -346,6 +348,23 @@ describe "Project", ->
           atom.project.bufferForPath("b").then (anotherBuffer) ->
             expect(anotherBuffer).not.toBe buffer
 
+        waitsForPromise ->
+          Promise.all([
+            atom.project.bufferForPath('c'),
+            atom.project.bufferForPath('c')
+          ]).then ([buffer1, buffer2]) ->
+            expect(buffer1).toBe(buffer2)
+
+      it "retries loading the buffer if it previously failed", ->
+        waitsForPromise shouldReject: true, ->
+          spyOn(TextBuffer, 'load').andCallFake ->
+            Promise.reject(new Error('Could not open file'))
+          atom.project.bufferForPath('b')
+
+        waitsForPromise shouldReject: false, ->
+          TextBuffer.load.andCallThrough()
+          atom.project.bufferForPath('b')
+
       it "creates a new buffer if the previous buffer was destroyed", ->
         buffer.release()
 

src/project.coffee

@@ -27,6 +27,7 @@ class Project extends Model
     @defaultDirectoryProvider = new DefaultDirectoryProvider()
     @repositoryPromisesByPath = new Map()
     @repositoryProviders = [new GitRepositoryProvider(this, config)]
+    @loadPromisesByPath = {}
     @consumeServices(packageManager)
 
   destroyed: ->
@@ -42,6 +43,7 @@ class Project extends Model
     buffer?.destroy() for buffer in @buffers
     @buffers = []
     @setPaths([])
+    @loadPromisesByPath = {}
     @consumeServices(packageManager)
 
   destroyUnretainedBuffers: ->
@@ -381,13 +383,19 @@ class Project extends Model
   buildBuffer: (absoluteFilePath) ->
     params = {shouldDestroyOnFileDelete: @shouldDestroyBufferOnFileDelete}
     if absoluteFilePath?
-      promise = TextBuffer.load(absoluteFilePath, params)
+      promise =
+        @loadPromisesByPath[absoluteFilePath] ?=
+        TextBuffer.load(absoluteFilePath, params).catch (error) =>
+          delete @loadPromisesByPath[absoluteFilePath]
+          throw error
     else
       promise = Promise.resolve(new TextBuffer(params))
     promise.then (buffer) =>
+      delete @loadPromisesByPath[absoluteFilePath]
       @addBuffer(buffer)
       buffer
 
+
   addBuffer: (buffer, options={}) ->
     @addBufferAtIndex(buffer, @buffers.length, options)