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class LimitedQueue

A queue which limits the number of items that can be enqueued.

Signature
public

Since stable-v1.

Definitions

def initialize(limit = 1, full: Notification.new, **options)

Create a new limited queue.

Signature
parameter　limit　Integer

The maximum number of items that can be enqueued.

parameter　full　Notification

The notification to use for signaling when the queue is full.

Implementation

 
def initialize(limit = 1, full: Notification.new, **options)
	super(**options)
	
	@limit = limit
	@full = full
end

attr :limit

Signature
attribute　Integer

The maximum number of items that can be enqueued.

def limited?

Signature
returns　Boolean

Whether trying to enqueue an item would block.

Implementation

 
def limited?
	@items.size >= @limit
end

def <<(item)

Add an item to the queue.

If the queue is full, this method will block until there is space available.

Signature
parameter　item　Object

The item to add to the queue.

Implementation

 
def <<(item)
	while limited?
		@full.wait
	end
	
	super
end

def enqueue(*items)

Add multiple items to the queue.

If the queue is full, this method will block until there is space available.

Signature
parameter　items　Array

The items to add to the queue.

Implementation

 
def enqueue(*items)
	while !items.empty?
		while limited?
			@full.wait
		end
		
		available = @limit - @items.size
		@items.concat(items.shift(available))
		
		@available.signal unless self.empty?
	end
end

def dequeue

Remove and return the next item from the queue.

If the queue is empty, this method will block until an item is available.

Signature
returns　Object

The next item in the queue.

Implementation

 
def dequeue
	item = super
	
	@full.signal
	
	return item
end

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