Preparing to fix #1812 - Moving locking code to a module

This moves the locking code out of Puppet::Util into a
separate module, to make the code cleaner.

Signed-off-by: Luke Kanies <luke@madstop.com>

2 files changed, 51 insertions, 2 deletions

diff --git a/lib/puppet/util/file_locking.rb b/lib/puppet/util/file_locking.rb
new file mode 100644
index 000000000..80a0b2b0c
--- /dev/null
+++ b/lib/puppet/util/file_locking.rb
@@ -0,0 +1,47 @@
+require 'puppet/util'
+
+module Puppet::Util::FileLocking
+    module_function
+
+    # Create a shared lock for reading
+    def readlock(file)
+        Puppet::Util.sync(file).synchronize(Sync::SH) do
+            File.open(file) { |f|
+                f.lock_shared { |lf| yield lf }
+            }
+        end
+    end
+
+    # Create an exclusive lock for writing, and do the writing in a
+    # tmp file.
+    def writelock(file, mode = nil)
+        unless FileTest.directory?(File.dirname(file))
+            raise Puppet::DevError, "Cannot create %s; directory %s does not exist" % [file, File.dirname(file)]
+        end
+        tmpfile = file + ".tmp"
+
+        unless mode
+            begin
+                mode = File.stat(file).mode
+            rescue
+                mode = 0600
+            end
+        end
+
+        Puppet::Util.sync(file).synchronize(Sync::EX) do
+            File.open(file, "w", mode) do |rf|
+                rf.lock_exclusive do |lrf|
+                    File.open(tmpfile, "w", mode) do |tf|
+                        yield tf
+                    end
+                    begin
+                        File.rename(tmpfile, file)
+                    rescue => detail
+                        File.unlink(tmpfile) if File.exist?(tmpfile)
+                        raise Puppet::Error, "Could not rename %s to %s: %s; file %s was unchanged" % [file, tmpfile, Thread.current.object_id, detail, file]
+                    end
+                end
+            end
+        end
+    end
+end
diff --git a/lib/puppet/util/storage.rb b/lib/puppet/util/storage.rb
index dc4e9cd71..01c411181 100644
--- a/lib/puppet/util/storage.rb
+++ b/lib/puppet/util/storage.rb
@@ -1,6 +1,8 @@
 require 'yaml'
 require 'sync'
 
+require 'puppet/util/file_locking'
+
 # a class for storing state
 class Puppet::Util::Storage
     include Singleton
@@ -59,7 +61,7 @@ class Puppet::Util::Storage
             return
         end
         Puppet::Util.benchmark(:debug, "Loaded state") do
-            Puppet::Util.readlock(Puppet[:statefile]) do |file|
+            Puppet::Util::FileLocking.readlock(Puppet[:statefile]) do |file|
                 begin
                     @@state = YAML.load(file)
                 rescue => detail
@@ -97,7 +99,7 @@ class Puppet::Util::Storage
         end
 
         Puppet::Util.benchmark(:debug, "Stored state") do
-            Puppet::Util.writelock(Puppet[:statefile], 0660) do |file|
+            Puppet::Util::FileLocking.writelock(Puppet[:statefile], 0660) do |file|
                 file.print YAML.dump(@@state)
             end
         end