Thumbnail generation in Sidekiq worker

Gemfile

@@ -18,6 +18,7 @@ gem 'fog'
 gem 'simple_form'
 gem 'redcarpet'
 gem 'sidekiq'
+gem 'draper'
 
 # Gems used only for assets and not required
 # in production environments by default.

Gemfile.lock

@@ -70,6 +70,8 @@ GEM
     confstruct (0.2.1)
     connection_pool (0.9.1)
     diff-lcs (1.1.3)
+    draper (0.11.1)
+      activesupport (>= 2.3.10)
     erubis (2.7.0)
     excon (0.9.6)
     execjs (1.3.0)
@@ -288,6 +290,7 @@ DEPENDENCIES
   carrierwave
   coffee-rails
   confstruct
+  draper
   factory_girl_rails
   faker
   fog

app/controllers/api/asciicasts_controller.rb

@@ -5,6 +5,7 @@ class Api::AsciicastsController < ApplicationController
     ac = Asciicast.new(params[:asciicast])
 
     if ac.save
+      SnapshotWorker.perform_async(ac.id)
       render :text => asciicast_url(ac), :status => :created, :location => ac
     else
       render :text => ac.errors.full_messages, :status => 422

app/controllers/asciicasts_controller.rb

@@ -1,7 +1,7 @@
 class AsciicastsController < ApplicationController
   PER_PAGE = 20
 
-  before_filter :load_resource, :only => [:show, :edit, :update, :destroy]
+  before_filter :load_resource, :only => [:edit, :update, :destroy]
   before_filter :ensure_authenticated!, :only => [:edit, :update, :destroy]
   before_filter :ensure_owner!, :only => [:edit, :update, :destroy]
 
@@ -15,6 +15,7 @@ class AsciicastsController < ApplicationController
   end
 
   def show
+    @asciicast = AsciicastDecorator.find(params[:id])
     @title = @asciicast.smart_title
     respond_with @asciicast
   end

app/decorators/application_decorator.rb

@@ -0,0 +1,28 @@
+class ApplicationDecorator < Draper::Base
+  # Lazy Helpers
+  #   PRO: Call Rails helpers without the h. proxy
+  #        ex: number_to_currency(model.price)
+  #   CON: Add a bazillion methods into your decorator's namespace
+  #        and probably sacrifice performance/memory
+  #
+  #   Enable them by uncommenting this line:
+  #   lazy_helpers
+
+  # Shared Decorations
+  #   Consider defining shared methods common to all your models.
+  #
+  #   Example: standardize the formatting of timestamps
+  #
+  #   def formatted_timestamp(time)
+  #     h.content_tag :span, time.strftime("%a %m/%d/%y"),
+  #                   :class => 'timestamp'
+  #   end
+  #
+  #   def created_at
+  #     formatted_timestamp(model.created_at)
+  #   end
+  #
+  #   def updated_at
+  #     formatted_timestamp(model.updated_at)
+  #   end
+end

app/decorators/asciicast_decorator.rb

@@ -0,0 +1,38 @@
+class AsciicastDecorator < ApplicationDecorator
+  decorates :asciicast
+
+  THUMBNAIL_WIDTH = 20
+  THUMBNAIL_HEIGHT = 10
+
+  def thumbnail
+    if @thumbnail.nil?
+      lines = model.snapshot.split("\n")
+
+      top_lines = lines[0...THUMBNAIL_HEIGHT]
+      top_text = prepare_lines(top_lines).join("\n")
+
+      bottom_lines = lines.reverse[0...THUMBNAIL_HEIGHT].reverse
+      bottom_text = prepare_lines(bottom_lines).join("\n")
+
+      if top_text.gsub(/\s+/, '').size > bottom_text.gsub(/\s+/, '').size
+        @thumbnail = top_text
+      else
+        @thumbnail = bottom_text
+      end
+    end
+
+    @thumbnail
+  end
+
+  private
+
+  def prepare_lines(lines)
+    (THUMBNAIL_HEIGHT - lines.size).times { lines << '' }
+
+    lines.map do |line|
+      line = line[0...THUMBNAIL_WIDTH]
+      line << ' ' * (THUMBNAIL_WIDTH - line.size)
+      line
+    end
+  end
+end

app/workers/snapshot_worker.rb

@@ -0,0 +1,85 @@
+require 'tempfile'
+
+class SnapshotWorker
+  include Sidekiq::Worker
+  sidekiq_options :retry => false
+
+  def perform(asciicast_id)
+    begin
+      @asciicast = Asciicast.find(asciicast_id)
+
+      prepare_files
+      convert_to_typescript
+
+      delay = (@asciicast.duration / 2).to_i
+      delay = 30 if delay > 30
+      snapshot = capture_terminal(delay)
+
+      @asciicast.snapshot = snapshot
+      @asciicast.save!
+
+    rescue ActiveRecord::RecordNotFound
+      # oh well...
+
+    ensure
+      cleanup
+    end
+  end
+
+  def prepare_files
+    in_data_file = Tempfile.new('asciiio-data', :encoding => 'ascii-8bit')
+    in_data_file.write(@asciicast.stdout.read)
+    in_data_file.close
+    @in_data_path = in_data_file.path
+
+    in_timing_file = Tempfile.new('asciiio-timing', :encoding => 'ascii-8bit')
+    in_timing_file.write(@asciicast.stdout_timing.read)
+    in_timing_file.close
+    @in_timing_path = in_timing_file.path
+
+    @out_data_path = @in_data_path + '.ts'
+    @out_timing_path = @in_timing_path + '.ts'
+  end
+
+  def convert_to_typescript
+    system "bash -c './script/convert-to-typescript.sh " +
+           "#{@in_data_path} #{@in_timing_path} " +
+           "#{@out_data_path} #{@out_timing_path}'"
+    raise "Can't convert asciicast ##{@asciicast.id} to typescript" if $? != 0
+  end
+
+  def capture_terminal(delay)
+    capture_command =
+      "scriptreplay #{@out_timing_path} #{@out_data_path}; sleep 10"
+
+    command = "bash -c 'ASCIICAST_ID=#{@asciicast.id} " +
+              "COLS=#{@asciicast.terminal_columns} " +
+              "LINES=#{@asciicast.terminal_lines} " +
+              "COMMAND=\"#{capture_command}\" " +
+              "DELAY=#{delay} ./script/capture.sh'"
+
+    lines = []
+    status = nil
+
+    Open3.popen3(command) do |stdin, stdout, stderr, wait_thr|
+      while !stdout.eof?
+        lines << stdout.readline
+      end
+
+      status = wait_thr.value.exitstatus
+    end
+
+    raise "Can't capture output of asciicast ##{@asciicast.id}" if status != 0
+
+    lines.join('')
+  end
+
+  def cleanup
+    FileUtils.rm_f([
+      @in_data_path,
+      @in_timing_path,
+      @out_data_path,
+      @out_timing_path
+    ])
+  end
+end

app/workers/thumbnail_worker.rb

@@ -1,31 +0,0 @@
-require 'tempfile'
-
-class ThumbnailWorker
-  include Sidekiq::Worker
-
-  def perform(asciicast_id)
-    asciicast = Asciicast.find(asciicast_id)
-
-    in_data_file = Tempfile.new('asciiio-data', :encoding => 'ascii-8bit')
-    in_data_file.write(asciicast.stdout.read)
-    in_data_file.close
-    in_data_path = in_data_file.path
-
-    in_timing_file = Tempfile.new('asciiio-timing', :encoding => 'ascii-8bit')
-    in_timing_file.write(asciicast.stdout_timing.read)
-    in_timing_file.close
-    in_timing_path = in_timing_file.path
-
-    out_data_path = in_data_path + '.ts'
-    out_timing_path = in_timing_path + '.ts'
-
-    if system "bash -c './script/convert-to-typescript.sh #{in_data_path} #{in_timing_path} #{out_data_path} #{out_timing_path}'"
-      delay = (asciicast.duration / 2).to_i
-      command = "scriptreplay #{out_timing_path} #{out_data_path}; sleep 10"
-      puts '-' * 80
-      system "bash -c 'ASCIICAST_ID=#{asciicast_id} COLS=#{asciicast.terminal_columns} LINES=#{asciicast.terminal_lines} COMMAND=\"#{command}\" DELAY=#{delay} THUMB_LINES=10 THUMB_COLS=20 ./script/thumbnail.sh'"
-    else
-      puts "failed"
-    end
-  end
-end

config/deploy.rb

@@ -2,6 +2,7 @@ $:.unshift(File.expand_path('./lib', ENV['rvm_path']))
 require "rvm/capistrano"
 require 'bundler/capistrano'
 require 'capistrano_colors'
+require 'sidekiq/capistrano'
 
 set :application, "ascii.io"
 

config/initializers/sidekiq.rb

@@ -0,0 +1,17 @@
+SIDEKIQ_URL = 'redis://localhost:6379'
+SIDEKIQ_NS = 'asciiio-sidekiq'
+
+Sidekiq.configure_server do |config|
+  config.redis = {
+    :url => SIDEKIQ_URL,
+    :namespace => SIDEKIQ_NS
+  }
+end
+
+Sidekiq.configure_client do |config|
+  config.redis = {
+    :url => SIDEKIQ_URL,
+    :namespace => SIDEKIQ_NS,
+    :size => 1
+  }
+end

db/migrate/20120406152447_add_snapshot_to_asciicast.rb

@@ -0,0 +1,6 @@
+class AddSnapshotToAsciicast < ActiveRecord::Migration
+  def change
+    add_column :asciicasts, :snapshot, :text
+
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 20120403165915) do
+ActiveRecord::Schema.define(:version => 20120406152447) do
 
   create_table "asciicasts", :force => true do |t|
     t.integer  "user_id"
@@ -34,10 +34,12 @@ ActiveRecord::Schema.define(:version => 20120403165915) do
     t.text     "description"
     t.boolean  "featured",         :default => false
     t.string   "username"
+    t.text     "snapshot"
   end
 
   add_index "asciicasts", ["created_at"], :name => "index_asciicasts_on_created_at"
   add_index "asciicasts", ["featured"], :name => "index_asciicasts_on_featured"
+  add_index "asciicasts", ["likes_count"], :name => "index_asciicasts_on_likes_count"
   add_index "asciicasts", ["recorded_at"], :name => "index_asciicasts_on_recorded_at"
   add_index "asciicasts", ["user_id"], :name => "index_asciicasts_on_user_id"
   add_index "asciicasts", ["user_token"], :name => "index_asciicasts_on_user_token"
@@ -53,6 +55,17 @@ ActiveRecord::Schema.define(:version => 20120403165915) do
   add_index "comments", ["asciicast_id"], :name => "index_comments_on_asciicast_id"
   add_index "comments", ["user_id"], :name => "index_comments_on_user_id"
 
+  create_table "likes", :force => true do |t|
+    t.integer  "asciicast_id", :null => false
+    t.integer  "user_id",      :null => false
+    t.datetime "created_at",   :null => false
+    t.datetime "updated_at",   :null => false
+  end
+
+  add_index "likes", ["asciicast_id"], :name => "index_likes_on_asciicast_id"
+  add_index "likes", ["user_id", "asciicast_id"], :name => "index_likes_on_user_id_and_asciicast_id"
+  add_index "likes", ["user_id"], :name => "index_likes_on_user_id"
+
   create_table "user_tokens", :force => true do |t|
     t.integer  "user_id",    :null => false
     t.string   "token",      :null => false

script/capture.sh

@@ -2,13 +2,13 @@
 
 # Usage:
 #   ASCIICAST_ID=666 COLS=80 LINES=20 COMMAND="df; df; df; sleep 10"
-#   DELAY=1 THUMB_LINES=5 THUMB_COLS=10 ./tmux-save.sh
+#   DELAY=1 ./tmux-save.sh
 
 set -e
 
-SESSION_NAME=asciiio-thumb-$ASCIICAST_ID
+SESSION_NAME=asciiio-thumb-$ASCIICAST_ID-`date +'%s'`
 
 tmux new -s $SESSION_NAME -d -x $COLS -y $LINES "$COMMAND"
 sleep $DELAY
 tmux capture-pane -t $SESSION_NAME
-tmux save-buffer - | tail -n $THUMB_LINES | ruby -e "ARGF.lines.each { |l| puts l[0...$THUMB_COLS] }"
+tmux save-buffer -

spec/decorators/application_decorator_spec.rb

@@ -0,0 +1,4 @@
+require 'spec_helper'
+
+describe ApplicationDecorator do
+end

spec/decorators/asciicast_decorator_spec.rb

@@ -0,0 +1,5 @@
+require 'spec_helper'
+
+describe AsciicastDecorator do
+  before { ApplicationController.new.set_current_view_context }
+end