Add cap v2 implementation

README.md

@@ -3,8 +3,6 @@
 This gem speeds up asset compilation by skipping the assets:precompile task if none of the assets were changed
 since last release.
 
-Works *only* with Capistrano 3+.
-
 ### Installation
 
 Add this to `Gemfile`:
@@ -24,7 +22,7 @@ And then:
 Add this line to `Capfile`, after `require 'capistrano/rails/assets'`
 
     require 'capistrano/faster_assets'
-    
+
 ### Warning
 
 Please keep in mind, that if you use ERB in your assets, you might run into cases where Capistrano won't recompile assets when needed. For instance, let's say you have a CoffeeScript file like this:

capistrano-faster-assets.gemspec

@@ -11,8 +11,6 @@ Gem::Specification.new do |gem|
   gem.description   = <<-EOF.gsub(/^\s+/, '')
     Speeds up asset compilation by skipping the assets:precompile task if none of the assets were changed since last release.
 
-    Works *only* with Capistrano 3+.
-
     Based on https://coderwall.com/p/aridag
   EOF
   gem.summary       = "Speeds up asset compilation if none of the assets were changed since last release."
@@ -23,6 +21,6 @@ Gem::Specification.new do |gem|
   gem.test_files    = gem.files.grep(%r{^(test|spec|features)/})
   gem.require_paths = ["lib"]
 
-  gem.add_dependency "capistrano", ">= 3.1"
+  gem.add_dependency "capistrano", ">= 2.0"
   gem.add_development_dependency "rake"
 end

lib/capistrano/faster_assets.rb

@@ -1 +1,11 @@
-load File.expand_path("../tasks/faster_assets.rake", __FILE__)
+module Capistrano
+  module FasterAssets
+    DEPENDENCIES = %w(app/assets lib/assets vendor/assets Gemfile.lock config/routes.rb)
+  end
+end
+
+if Gem::Specification.find_by_name('capistrano').version >= Gem::Version.new('3.0.0')
+  load File.expand_path("../tasks/faster_assets.rake", __FILE__)
+else
+  require_relative 'tasks/faster_assets'
+end

lib/capistrano/tasks/faster_assets.rake

@@ -1,8 +1,10 @@
+require "capistrano/faster_assets"
+
 # Original source: https://coderwall.com/p/aridag
 
 
 # set the locations that we will look for changed assets to determine whether to precompile
-set :assets_dependencies, %w(app/assets lib/assets vendor/assets Gemfile.lock config/routes.rb)
+set :assets_dependencies, Capistrano::FasterAssets::DEPENDENCIES
 
 # clear the previous precompile task
 Rake::Task["deploy:assets:precompile"].clear_actions
@@ -17,7 +19,7 @@ namespace :deploy do
         within release_path do
           with rails_env: fetch(:rails_env) do
             begin
-	      # find the most recent release
+              # find the most recent release
               latest_release = capture(:ls, '-xr', releases_path).split[1]
 
               # precompile if this is the first deploy
@@ -29,12 +31,12 @@ namespace :deploy do
               execute(:ls, latest_release_path.join('assets_manifest_backup')) rescue raise(PrecompileRequired)
 
               fetch(:assets_dependencies).each do |dep|
-		release = release_path.join(dep)
-		latest = latest_release_path.join(dep)
-		
-		# skip if both directories/files do not exist
-		next if [release, latest].map{|d| test "[ -e #{d} ]"}.uniq == [false]
-		
+                release = release_path.join(dep)
+                latest = latest_release_path.join(dep)
+
+                # skip if both directories/files do not exist
+                next if [release, latest].map{|d| test "[ -e #{d} ]"}.uniq == [false]
+
                 # execute raises if there is a diff
                 execute(:diff, '-Nqr', release, latest) rescue raise(PrecompileRequired)
               end

lib/capistrano/tasks/faster_assets.rb

@@ -0,0 +1,53 @@
+# Original source: https://coderwall.com/p/aridag
+
+require "capistrano/faster_assets"
+
+Capistrano::Configuration.instance(:must_exist).load do
+  # set the locations that we will look for changed assets to determine whether to precompile
+  _cset(:assets_dependencies) { Capistrano::FasterAssets::DEPENDENCIES }
+  _cset(:assets_manifest_basename) { "assets_manifest" }
+
+  # Alias the base capistrano provided task so that we can still access it
+  alias_task("deploy:assets:force_precompile", "deploy:assets:precompile")
+
+  def first_deploy?
+    previous_release.nil?
+  end
+
+  def previous_release_failed_compilation?
+    previous_manifest_count = capture("ls -1 #{previous_release}/#{assets_manifest_basename}* | wc -l").to_i
+
+    previous_manifest_count < 1
+  end
+
+  def asset_file_diff?
+    assets_dependencies.any? do |dep|
+      previous = "#{previous_release}/#{dep}"
+      latest = "#{release_path}/#{dep}"
+
+      # skip if both directories/files do not exist
+      next if [previous, latest].any? { |path| result = capture("ls -1 #{path} | wc -l"); puts result; result.to_i < 1 }
+
+      # if there are file diffs between the directories/files, return true
+      diff = capture("diff -Nqr #{previous} #{latest} | wc -l")
+      diff.to_i > 0
+    end
+  end
+
+  namespace :deploy do
+    namespace :assets do
+      desc <<-DESC
+        Override capistrano v2's deploy:assets:precompile to add a pre-check
+        for differences in asset files in subsequent relase before invoking
+        the task.
+      DESC
+      task :precompile, roles: lambda { assets_role }, except: { no_release: true } do
+        if !first_deploy? && !previous_release_failed_compilation? && !asset_file_diff?
+          logger.info("Skipping asset precompile, no asset diff found")
+        else
+          force_precompile
+        end
+      end
+    end
+  end
+end