implement local cache for mercurial remote repositories

git-svn-id: http://redmine.rubyforge.org/svn/branches/nbc@1908 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/models/repository/mercurial.rb

@@ -21,6 +21,15 @@ class Repository::Mercurial < Repository
   attr_protected :root_url
   validates_presence_of :url
 
+  def init_cache
+    return unless dir = repositories_cache_directory
+    # we need to use a cache only if repository isn't local and dir exists
+    if url[/^(|https?|ssh):\/\//]
+      update_attribute(:cache_path, dir + project.identifier)
+      update_attribute(:cache, true)
+    end
+  end
+
   def scm_adapter
     Redmine::Scm::Adapters::MercurialAdapter
   end
@@ -53,6 +62,8 @@ class Repository::Mercurial < Repository
   end
 
   def fetch_changesets
+    create_or_sync_cache if cache
+
     scm_info = scm.info
     if scm_info
       # latest revision found in database