class

Sync::Exclusive(T)

Inherits Sync::Lockable / Reference / Object

Safely share a value T across fibers and execution contexts using a Mutex, so only one critical section can access the value at any time.

For example:

require "sync/exclusive"

class Queue
  @@running : Sync::Exclusive.new([] of Queue)

  def self.on_started(queue)
    @@running.lock(&.push(queue))
  end

  def self.on_stopped(queue)
    @@running.lock(&.delete(queue))
  end

  def self.each(&)
    @@running.lock do |list|
      list.each { |queue| yield queue }
    end
  end
end

Consider an Exclusive(T) if your workload mostly needs to own the value, and most, if not all, critical sections need to mutate the inner state of the value for example.

Constructors

new(value : T, type : Type = :checked)

Source

Instance methods

get

Locks the mutex and returns the value. Unlocks before returning.

Always acquires the lock, so reading the value is synchronized in relation with the other methods. However, safely accessing the returned value entirely depends on the safety of T.

Prefer #lock(&.dup) or #lock(&.clone) to get a shallow or deep copy of the value instead.

WARNING: Breaks the mutual exclusion guarantee since the returned value outlives the lock, the value can be accessed concurrently to the synchronized methods.

Source

lock

Locks the mutex and yields the value. The lock is released before returning.

The value is owned for the duration of the block, and can be safely mutated.

WARNING: The value musn't be retained and accessed after the block has returned.

Source

replace

Locks the mutex, yields the value and eventually replaces the value with the one returned by the block. The lock is released before returning.

The current value is now owned: it can be safely retained and mutated even after the block returned.

WARNING: The new value musn't be retained and accessed after the block has returned.

Source

set(value : T) : Nil

Locks the mutex and sets the value. Unlocks the mutex before returning.

Always acquires and releases the lock, so writing the value is always synchronized with the other methods.

Source

unsafe_get

Returns the value without any synchronization.

WARNING: Breaks the mutual exclusion constraint! Should only be called after acquiring the lock.

Source

unsafe_set(value : T) : T

Sets the value without any synchronization.

WARNING: Breaks the mutual exclusion constraint! Should only be called after acquiring the lock.

Source