Class: Concurrent::TVar

Inherits:
Synchronization::Object show all
Defined in:
lib/concurrent/tvar.rb

Overview

A ‘TVar` is a transactional variable - a single-element container that is used as part of a transaction - see `Concurrent::atomically`.

## Thread-safe Variable Classes

Each of the thread-safe variable classes is designed to solve a different problem. In general:

  • *Agent:* Shared, mutable variable providing independent, uncoordinated, asynchronous change of individual values. Best used when the value will undergo frequent, complex updates. Suitable when the result of an update does not need to be known immediately.

  • *Atom:* Shared, mutable variable providing independent, uncoordinated, synchronous change of individual values. Best used when the value will undergo frequent reads but only occasional, though complex, updates. Suitable when the result of an update must be known immediately.

  • *AtomicReference:* A simple object reference that can be atomically. Updates are synchronous but fast. Bast used when updates a simple set operations. Not suitable when updates are complex. AtomicBoolean and AtomicFixnum are similar but optimized for the given data type.

  • *Exchanger:* Shared, stateless synchronization point. Used when two or more threads need to exchange data. The threads will pair then block on each other until the exchange is complete.

  • *MVar:* Shared synchronization point. Used when one thread must give a value to another, which must take the value. The threads will block on each other until the exchange is complete.

  • *ThreadLocalVar:* Shared, mutable, isolated variable which holds a different value for each thread which has access. Often used as an instance variable in objects which must maintain different state for different threads.

  • *TVar:* Shared, mutable variables which provide coordinated, synchronous, change of many stated. Used when multiple value must change together, in an all-or-nothing transaction.

Instance Method Summary collapse

Methods inherited from Synchronization::Object

attr_atomic, attr_volatile, ensure_safe_initialization_when_final_fields_are_present, new, safe_initialization!, safe_initialization?, volatile_cas_fields

Constructor Details

#initialize(value) ⇒ TVar

Create a new ‘TVar` with an initial value.



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# File 'lib/concurrent/tvar.rb', line 16

def initialize(value)
  @value = value
  @version = 0
  @lock = Mutex.new
end

Instance Method Details

#value ⇒ Object

Get the value of a ‘TVar`.



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# File 'lib/concurrent/tvar.rb', line 23

def value
  Concurrent::atomically do
    Transaction::current.read(self)
  end
end

#value=(value) ⇒ Object

Set the value of a ‘TVar`.



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# File 'lib/concurrent/tvar.rb', line 30

def value=(value)
  Concurrent::atomically do
    Transaction::current.write(self, value)
  end
end