Add chunk buffer

assets/scripts/lib/travis/chunk_buffer.coffee

@@ -0,0 +1,43 @@
+Travis.ChunkBuffer = Em.ArrayProxy.extend
+  timeout: 15000
+  start: 0
+  next: 0
+
+  init: ->
+    @_super.apply this, arguments
+
+    if @get('content.length')
+      @get('queue.content').pushObjects @get('content').toArray()
+
+  arrangedContent: (->
+    []
+  ).property('content')
+
+  queue: (->
+    Em.ArrayProxy.create(Em.SortableMixin,
+      content: []
+      sortProperties: ['number']
+      sortAscending: true
+    )
+  ).property()
+
+  contentArrayDidChange: (array, index, removedCount, addedCount) ->
+    console.log 'content array did change'
+    @_super.apply this, arguments
+
+    if addedCount
+      queue   = @get('queue.content')
+      queue.pushObjects array.slice(index, index + addedCount)
+      @check()
+
+  check: ->
+    queue = @get('queue')
+    next  = @get('next')
+
+    arrangedContent = @get('arrangedContent')
+
+    while queue.get('firstObject.number') == next
+      arrangedContent.pushObject queue.shiftObject().get('content')
+      next += 1
+
+    @set('next', next)

assets/scripts/spec/unit/chunk_buffer_spec.coffee

@@ -0,0 +1,52 @@
+createChunk = (number, content) ->
+  Em.Object.create(number: number, content: content)
+
+describe 'Travis.ChunkBuffer', ->
+  it 'waits for parts to be in order before revealing them', ->
+    content = []
+    buffer = Travis.ChunkBuffer.create(content: content)
+
+    content.pushObject createChunk(2, "baz")
+    content.pushObject createChunk(1, "bar")
+
+    expect(buffer.get('length')).toEqual(0)
+
+    content.pushObject createChunk(0, "foo")
+
+    expect(buffer.get('length')).toEqual(3)
+
+    expect(buffer.toArray()).toEqual(['foo', 'bar', 'baz'])
+
+  it 'ignores a part if it fails to be delivered within timeout', ->
+    expect 4
+
+    content = []
+    buffer = Travis.ChunkBuffer.create(content: content, timeout: 10)
+
+    content.pushObject createChunk(2, "baz")
+
+    expect(buffer.get('length')).toEqual(0)
+
+    content.pushObject createChunk(0, "foo")
+
+    expect(buffer.get('length')).toEqual(1)
+
+    stop()
+    setTimeout( (->
+      expect(buffer.get('length')).toEqual(2)
+      expect(buffer.toArray()).toEqual(['foo', 'bar', 'baz'])
+    ), 20)
+
+  it 'works correctly when parts are passed as content', ->
+    content = [createChunk(1, 'bar')]
+
+    buffer = Travis.ChunkBuffer.create(content: content)
+
+    expect(buffer.get('length')).toEqual(0)
+
+    content.pushObject createChunk(0, "foo")
+
+    expect(buffer.get('length')).toEqual(2)
+    expect(buffer.toArray()).toEqual(['foo', 'bar'])
+
+