Class: NFSStore

Inherits:
Object show all
Defined in:
lib/crazy_ivan/vendor/lockfile-1.4.3/samples/nfsstore.rb

Defined Under Namespace

Classes: Error

Constant Summary collapse

HOSTNAME = 
Socket::gethostname

Instance Method Summary collapse

Constructor Details

#initialize(file) ⇒ NFSStore

Returns a new instance of NFSStore.



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# File 'lib/crazy_ivan/vendor/lockfile-1.4.3/samples/nfsstore.rb', line 26

def initialize(file)
  dir = File::dirname(file)
  unless File::directory? dir
    raise NFSStore::Error, format("directory %s does not exist", dir)
  end
  if File::exist? file and not File::readable? file
    raise NFSStore::Error, format("file %s not readable", file)
  end
  @transaction = false
  @filename = file
  @lockfile = Lockfile.new "#{ @filename }.lock",:max_age=>64,:refresh=>8
  @abort = false
end

Instance Method Details

#[](name) ⇒ Object 



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# File 'lib/crazy_ivan/vendor/lockfile-1.4.3/samples/nfsstore.rb', line 45

def [](name)
  in_transaction
  @table[name]
end

#[]=(name, value) ⇒ Object 



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# File 'lib/crazy_ivan/vendor/lockfile-1.4.3/samples/nfsstore.rb', line 59

def []=(name, value)
  in_transaction
  @table[name] = value
end

#abort ⇒ Object 



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# File 'lib/crazy_ivan/vendor/lockfile-1.4.3/samples/nfsstore.rb', line 83

def abort
  in_transaction
  @abort = true
  throw :pstore_abort_transaction
end

#commit ⇒ Object 



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# File 'lib/crazy_ivan/vendor/lockfile-1.4.3/samples/nfsstore.rb', line 78

def commit
  in_transaction
  @abort = false
  throw :pstore_abort_transaction
end

#delete(name) ⇒ Object 



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# File 'lib/crazy_ivan/vendor/lockfile-1.4.3/samples/nfsstore.rb', line 63

def delete(name)
  in_transaction
  @table.delete name
end

#fetch(name, default = NFSStore::Error) ⇒ Object 



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# File 'lib/crazy_ivan/vendor/lockfile-1.4.3/samples/nfsstore.rb', line 49

def fetch(name, default=NFSStore::Error)
  unless @table.key? name
    if default==NFSStore::Error
	raise NFSStore::Error, format("undefined root name `%s'", name)
    else
	default
    end
  end
  self[name]
end

#path ⇒ Object 



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# File 'lib/crazy_ivan/vendor/lockfile-1.4.3/samples/nfsstore.rb', line 75

def path
  @filename
end

#root?(name) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/crazy_ivan/vendor/lockfile-1.4.3/samples/nfsstore.rb', line 71

def root?(name)
  in_transaction
  @table.key? name
end

#roots ⇒ Object 



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# File 'lib/crazy_ivan/vendor/lockfile-1.4.3/samples/nfsstore.rb', line 67

def roots
  in_transaction
  @table.keys
end

#transaction(read_only = false) ⇒ Object

Raises:



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# File 'lib/crazy_ivan/vendor/lockfile-1.4.3/samples/nfsstore.rb', line 110

def transaction(read_only=false)
  raise NFSStore::Error, "nested transaction" if @transaction
  file = nil
  value = nil

@lockfile.lock do
    begin
      @transaction = true
      backup = @filename+"~"
      begin
        file = File::open(@filename, read_only ? "rb" : "rb+")
        orig = true
      rescue Errno::ENOENT
        raise if read_only
        file = File::open(@filename, "wb+")
      end
      #file.flock(read_only ? File::LOCK_SH : File::LOCK_EX)
      uncache file
      file.rewind
      if read_only
        @table = Marshal::load(file)
      elsif orig and (content = file.read) != ""
        @table = Marshal::load(content)
        size = content.size
        md5 = Digest::MD5.digest(content)
        content = nil		# unreference huge data
      else
        @table = {}
      end
      begin
        catch(:pstore_abort_transaction) do
          value = yield(self)
        end
      rescue Exception
        @abort = true
        raise
      ensure
        if !read_only and !@abort
          file.rewind
          content = Marshal::dump(@table)
          if !md5 || size != content.size || md5 != Digest::MD5.digest(content)
            File::copy @filename, backup
            begin
              file.write(content)
              file.truncate(file.pos)
              content = nil		# unreference huge data
            rescue
              File::rename backup, @filename if File::exist?(backup)
              raise
            end
          end
        end
        if @abort and !orig
          File.unlink(@filename)
        end
        @abort = false
      end
    ensure
      @table = nil
      @transaction = false
      file.close if file
    end
end
    value
end

#uncache(file) ⇒ Object

do what we can to invalidate any nfs caching



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# File 'lib/crazy_ivan/vendor/lockfile-1.4.3/samples/nfsstore.rb', line 90

def uncache file 
  begin
    stat = file.stat
    path = file.path
    refresh = "%s.%s.%s.%s" % [path, HOSTNAME, $$, Time.now.to_i % 1024] 
    File.link path, refresh
    file.chmod stat.mode
    File.utime stat.atime, stat.mtime, path
  rescue Exception => e 
    warn e
  ensure
    begin
      File.unlink refresh if File.exist? refresh
    rescue Exception => e
      warn e
    end
  end
end