Add simple synchronization helper to source. Use during install.

When installing cookbooks using infrastructure mode and the same git source is being used for different refs, a race condition can occur where the cached respository is modified while a copy is in progress. To prevent this the source should be locked during install to prevent any unexpected modifications.
sjtindell · Jun 28, 2018 · cfea3f9 · cfea3f9
1 parent adcab2c
commit cfea3f9
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Showing 2 changed files with 34 additions and 21 deletions.
diff --git a/lib/batali/command/install.rb b/lib/batali/command/install.rb
@@ -24,27 +24,29 @@ def execute!
                 units_slice.map do |unit|
                   Thread.new do
                     ui.debug "Starting unit install for: #{unit.name}<#{unit.version}>"
-                    if unit.source.respond_to?(:cache_path)
-                      unit.source.cache_path = cache_directory(
-                        Bogo::Utility.snake(unit.source.class.name.split("::").last)
-                      )
-                    end
-                    asset_path = unit.source.asset
-                    final_path = Utility.join_path(install_path, unit.name)
-                    if infrastructure?
-                      final_path << "-#{unit.version}"
-                    end
-                    begin
-                      FileUtils.cp_r(
-                        Utility.join_path(asset_path, "."),
-                        final_path
-                      )
-                      ui.debug "Completed unit install for: #{unit.name}<#{unit.version}>"
-                    rescue => e
-                      ui.debug "Failed unit install for: #{unit.name}<#{unit.version}> - #{e.class}: #{e}"
-                      raise
-                    ensure
-                      unit.source.clean_asset(asset_path)
+                    unit.source.synchronize do
+                      if unit.source.respond_to?(:cache_path)
+                        unit.source.cache_path = cache_directory(
+                          Bogo::Utility.snake(unit.source.class.name.split("::").last)
+                        )
+                      end
+                      asset_path = unit.source.asset
+                      final_path = Utility.join_path(install_path, unit.name)
+                      if infrastructure?
+                        final_path << "-#{unit.version}"
+                      end
+                      begin
+                        FileUtils.cp_r(
+                          Utility.join_path(asset_path, "."),
+                          final_path
+                        )
+                        ui.debug "Completed unit install for: #{unit.name}<#{unit.version}>"
+                      rescue => e
+                        ui.debug "Failed unit install for: #{unit.name}<#{unit.version}> - #{e.class}: #{e}"
+                        raise
+                      ensure
+                        unit.source.clean_asset(asset_path)
+                      end
                     end
                   end
                 end.map(&:join)

diff --git a/lib/batali/source.rb b/lib/batali/source.rb
@@ -14,10 +14,21 @@ class Source < Utility
     attribute :type, String, :required => true, :default => lambda { self.name } # rubocop:disable Style/RedundantSelf
 
     def initialize(args = {})
+      @lock = Mutex.new
       @cache_path = Utility.clean_path(args.delete(:cache_path))
       super
     end
 
+    # Helper to synchronize access to this source.
+    #
+    # @yield Block to be executed
+    # @return [Object]
+    def synchronize
+      @lock.synchronize do
+        yield
+      end
+    end
+
     # @return [String]
     def unit_version
       raise NotImplementedError.new "Abstract class"