[Downloader::Git] Completed cache support

- ensure that cache git repos are clean
- added cache size limit

lib/cocoapods/config.rb

@@ -14,6 +14,7 @@ module Pod
     attr_accessor :clean, :verbose, :silent
     attr_accessor :generate_docs, :doc_install, :force_doc
     attr_accessor :integrate_targets
+    attr_accessor :git_cache_size
 
     alias_method :clean?,             :clean
     alias_method :verbose?,           :verbose
@@ -27,6 +28,7 @@ module Pod
       @repos_dir = Pathname.new(File.expand_path("~/.cocoapods"))
       @verbose = @silent = @force_doc = false
       @clean = @generate_docs = @doc_install = @integrate_targets = true
+      @git_cache_size = 200
     end
 
     def project_root

lib/cocoapods/downloader/git.rb

@@ -6,10 +6,12 @@ require 'digest/sha1'
 module Pod
   class Downloader
     class Git < Downloader
+      include Config::Mixin
       executable :git
 
       def download
         prepare_cache
+        puts '->'.green << ' Cloning git repo' if config.verbose?
         if options[:tag]
           download_tag
         elsif options[:commit]
@@ -17,33 +19,71 @@ module Pod
         else
           download_head
         end
+        removed_cached_repos_if_needed
       end
 
       def prepare_cache
-        # TODO:clean oldest repos if the cache becomes too big
-        if cache_path.exist?
-          #TODO: check remote and reset hard
-          Dir.chdir(cache_path) { git "pull" }
-        else
-          FileUtils.mkdir_p cache_path
+        return if config.git_cache_size == 0
+        if is_cache_valid?
+          puts '->'.green << " Updating cache git repo (#{cache_path})" if config.verbose?
           Dir.chdir(cache_path) do
-            git "clone '#{url}' ."
+            git "reset --hard HEAD"
+            git "clean -d -x -f"
+            git "pull"
+          end
+        else
+          puts '->'.green << " Creating cache git repo (#{cache_path})" if config.verbose?
+          cache_path.rmtree if cache_path.exist?
+          cache_path.mkpath
+          git "clone '#{url}' #{cache_path}"
+        end
+      end
+
+      def removed_cached_repos_if_needed
+        Dir.chdir(caches_dir) do
+          repos = Pathname.new(caches_dir).children.select { |c| c.directory? }.sort_by(&:ctime)
+          while caches_size >= config.git_cache_size && !repos.empty?
+            dir = repos.shift
+            puts '->'.yellow << " Removing git cache for `#{origin_url(dir)}'" if config.verbose?
+            dir.rmtree
           end
         end
       end
 
       def cache_path
-        @cache_path ||= Pathname.new "/var/tmp/CocoaPods/Git/#{Digest::SHA1.hexdigest(url.to_s)}/"
+        @cache_path ||= caches_dir + "#{Digest::SHA1.hexdigest(url.to_s)}"
+      end
+
+      def is_cache_valid?
+        cache_path.exist? && origin_url(cache_path) == url
+      end
+
+      def origin_url(dir)
+        Dir.chdir(dir) { `git config remote.origin.url`.chomp }
+      end
+
+      def caches_dir
+        Pathname.new "/var/tmp/CocoaPods/Git"
+      end
+
+      def clone_url
+        # git_cache_size disables the cache
+        config.git_cache_size == 0 ? url : cache_path
+      end
+
+      def caches_size
+        # expressed in Mb
+        `du -cm`.split("\n").last.to_i
       end
 
       def download_head
-        git "clone '#{cache_path}' '#{target_path}'"
+        git "clone '#{clone_url}' '#{target_path}'"
       end
 
       def download_tag
         Dir.chdir(target_path) do
           git "init"
-          git "remote add origin '#{cache_path}'"
+          git "remote add origin '#{clone_url}'"
           git "fetch origin tags/#{options[:tag]}"
           git "reset --hard FETCH_HEAD"
           git "checkout -b activated-pod-commit"
@@ -51,7 +91,7 @@ module Pod
       end
 
       def download_commit
-        git "clone '#{cache_path}' '#{target_path}'"
+        git "clone '#{clone_url}' '#{target_path}'"
 
         Dir.chdir(target_path) do
           git "checkout -b activated-pod-commit #{options[:commit]}"

spec/spec_helper.rb

@@ -53,6 +53,7 @@ end
 config = Pod::Config.instance
 config.silent = true
 config.repos_dir = SpecHelper.tmp_repos_path
+config.git_cache_size = 0
 
 require 'tmpdir'