use xattr to trace file instead of inode

Gemfile

@@ -3,4 +3,6 @@ source "https://rubygems.org"
 group :test do
   gem 'rspec'
   gem 'stud', "~> 0.0.18"
+  gem 'uuid', "~> 2.3.8"
+  gem 'ffi-xattr', "~> 0.1.2"
 end

lib/filewatch/watch.rb

@@ -2,6 +2,8 @@
 if RbConfig::CONFIG['host_os'] =~ /mswin|mingw|cygwin/
   require "filewatch/winhelper"
 end
+require "ffi-xattr"
+require "uuid"
 
 module FileWatch
   class Watch
@@ -19,6 +21,9 @@ def initialize(opts={})
       @watching = []
       @exclude = []
       @files = Hash.new { |h, k| h[k] = Hash.new }
+
+      @xattr = opts[:xattr] || 'uuid'
+      @uuid = UUID.new if @xattr
     end # def initialize
 
     public
@@ -46,6 +51,22 @@ def inode(path,stat)
       if @iswindows
         fileId = Winhelper.GetWindowsUniqueFileIdentifier(path)
         inode = [fileId, stat.dev_major, stat.dev_minor]
+      elsif @xattr
+        begin
+          xattr = Xattr.new(path)
+
+          fileId = xattr[@xattr]
+
+          if !fileId
+            fileId = @uuid.generate
+
+            xattr[@xattr] = fileId
+          end
+
+          inode = [fileId, stat.dev_major, stat.dev_minor]
+        rescue
+          inode = [stat.ino.to_s, stat.dev_major, stat.dev_minor]
+        end
       else
         inode = [stat.ino.to_s, stat.dev_major, stat.dev_minor]
       end

spec/tail_spec.rb

@@ -1,5 +1,6 @@
 require 'filewatch/tail'
 require 'stud/temporary'
+require 'ffi-xattr'
 
 describe FileWatch::Tail do
 
@@ -21,6 +22,14 @@
     it "reads new lines off the file" do
       expect { |b| subject.subscribe(&b) }.to yield_successive_args([file_path, "line1"], [file_path, "line2"])
     end
+
+    it "file contains xattr 'uuid'" do
+      subject.subscribe {|_,_|  }
+      stat = File::Stat.new(file_path)
+      sincedb_id = subject.sincedb_record_uid(file_path,stat)[0]
+
+      expect(Xattr.new(file_path)['uuid']).to eq(sincedb_id)
+    end
   end
 
   context "when watching a file" do