Contents

require 'global_service.rb'
require 'crypt.rb'
require 'ostruct'

class LocalTupleSpaceApp<GlobalService
  provides :localTupleSpace
  MARSHAL=Marshal
  
  MAX_LEND_TIME=2
  
  Lent=Struct.new(:time, :transaction)
  
  def initialize(cluster,options)
    super(cluster,options,:localTupleSpace)
    @dataFile=File.open(File.join(getAppDataPath,"data.bin"),"w+")
    @indexFile=File.open(File.join(getAppDataPath,"index.bin"),"w+")
    @index={}
    @lent={}
    @transactions={}
    @mutex=Mutex.new
  end
  
  def read(ref)
    loadInternal(ref)
  end
  
  def lend(ref,timeout=0.3)
    old=Time.now
    while Time.now-old<timeout
      if @lent[ref]
        @mutex.synchronize do
          if @lent[ref]
            if Time.now-@lent[ref].time>MAX_LEND_TIME
              @transactions.delete(@lent[ref].transaction)
              @lent.delete(ref)
            end
          end  
        end
        sleep(timeout/10) 
      else
        @mutex.synchronize do
          unless @lent[ref]
            thxid=getTransactionID
            @lent[ref]=Lent.new(Time.now,thxid)
            @transactions[thxid]=true
            return loadInternal(ref)
          end
        end
      end
    end
    return nil
  end
  
  def store(ref,object)
    unless @lent.member?(ref)
      unless @index[ref].nil?
        raise "object not lent!"
      end
    end
    @mutex.synchronize do
      storeInternal(ref,object)
      @lent.delete(ref)
    end
    puts "STORED #{ref}:=#{object}"
    true
  end
  
  private
  def storeInternal(ref,object)
    pp "STORING #{ref} #{object}"
    @index[ref]=MARSHAL.dump(object)
  end
  def loadInternal(ref)
    #pp "GETTING #{ref} #{@index[ref]}"
    if @index[ref]
      MARSHAL.load(@index[ref])
      #@index[ref].dup
    else
      nil
    end
  end
  
  # This function shold be called with synchronized mode only !
  def getTransactionID
    begin
      tx=Crypt::digest(rand)
    end while @transactions[tx]
    tx
  end 
    
  
end

Version data entries

1 entries across 1 versions & 1 rubygems

Version	Path
appswarm-0.0.1	apps/local_tuple_space/local_tuple_space.rb