class Rinda::TupleEntry

A TupleEntry is a Tuple (i.e. a possible entry in some Tuplespace) together with expiry and cancellation data.

Attributes

expires[RW]

Public Class Methods

new(ary, sec=nil) click to toggle source

Creates a TupleEntry based on ary with an optional renewer or expiry time sec.

A renewer must implement the renew method which returns a Numeric, nil, or true to indicate when the tuple has expired.

# File lib/rinda/tuplespace.rb, line 27
def initialize(ary, sec=nil)
  @cancel = false
  @expires = nil
  @tuple = make_tuple(ary)
  @renewer = nil
  renew(sec)
end

Public Instance Methods

[](key) click to toggle source

Retrieves key from the tuple.

# File lib/rinda/tuplespace.rb, line 111
def [](key)
  @tuple[key]
end

alive?() click to toggle source

A TupleEntry is dead when it is canceled or expired.

# File lib/rinda/tuplespace.rb, line 45
def alive?
  !canceled? && !expired?
end

cancel() click to toggle source

Marks this TupleEntry as canceled.

# File lib/rinda/tuplespace.rb, line 38
def cancel
  @cancel = true
end

canceled?() click to toggle source

Returns the canceled status.

# File lib/rinda/tuplespace.rb, line 58
def canceled?; @cancel; end

expired?() click to toggle source

Has this tuple expired? (true/false).

A tuple has expired when its expiry timer based on the sec argument to initialize runs out.

# File lib/rinda/tuplespace.rb, line 66
def expired?
  return true unless @expires
  return false if @expires > Time.now
  return true if @renewer.nil?
  renew(@renewer)
  return true unless @expires
  return @expires < Time.now
end

fetch(key) click to toggle source

Fetches key from the tuple.

# File lib/rinda/tuplespace.rb, line 118
def fetch(key)
  @tuple.fetch(key)
end

make_expires(sec=nil) click to toggle source

Returns an expiry Time based on sec which can be one of:

Numeric: sec seconds into the future
true: the expiry time is the start of 1970 (i.e. expired)
nil: it is Tue Jan 19 03:14:07 GMT Standard Time 2038 (i.e. when UNIX clocks will die)

# File lib/rinda/tuplespace.rb, line 97
def make_expires(sec=nil)
  case sec
  when Numeric
    Time.now + sec
  when true
    Time.at(1)
  when nil
    Time.at(2**31-1)
  end
end

make_tuple(ary) click to toggle source

Creates a Rinda::Tuple for ary.

# File lib/rinda/tuplespace.rb, line 132
def make_tuple(ary)
  Rinda::Tuple.new(ary)
end

renew(sec_or_renewer) click to toggle source

Reset the expiry time according to sec_or_renewer.

nil: it is set to expire in the far future.
true: it has expired.
Numeric: it will expire in that many seconds.

Otherwise the argument refers to some kind of renewer object which will reset its expiry time.

# File lib/rinda/tuplespace.rb, line 85
def renew(sec_or_renewer)
  sec, @renewer = get_renewer(sec_or_renewer)
  @expires = make_expires(sec)
end

size() click to toggle source

The size of the tuple.

# File lib/rinda/tuplespace.rb, line 125
def size
  @tuple.size
end

value() click to toggle source

Return the object which makes up the tuple itself: the Array or Hash.

# File lib/rinda/tuplespace.rb, line 53
def value; @tuple.value; end

Private Instance Methods

get_renewer(it) click to toggle source

Returns a valid argument to #make_expires and the renewer or nil.

Given true, nil, or Numeric, returns that value and nil (no actual renewer). Otherwise it returns an expiry value from calling it.renew and the renewer.

# File lib/rinda/tuplespace.rb, line 145
def get_renewer(it)
  case it
  when Numeric, true, nil
    return it, nil
  else
    begin
      return it.renew, it
    rescue Exception
      return it, nil
    end
  end
end