class Thread::SizedQueue

This class represents queues of specified size capacity. The push operation may be blocked if the capacity is full.

See Thread::Queue for an example of how a Thread::SizedQueue works.

Public Class Methods

new(max) click to toggle source

Creates a fixed-length queue with a maximum size of max.

static VALUE
rb_szqueue_initialize(VALUE self, VALUE vmax)
{
    long max;
    struct rb_szqueue *sq = szqueue_ptr(self);

    max = NUM2LONG(vmax);
    if (max <= 0) {
        rb_raise(rb_eArgError, "queue size must be positive");
    }

    RB_OBJ_WRITE(self, szqueue_list(sq), ary_buf_new());
    ccan_list_head_init(szqueue_waitq(sq));
    ccan_list_head_init(szqueue_pushq(sq));
    sq->max = max;

    return self;
}

Public Instance Methods

<<(object)

Alias for: push

clear() click to toggle source

Removes all objects from the queue.

static VALUE
rb_szqueue_clear(VALUE self)
{
    struct rb_szqueue *sq = szqueue_ptr(self);

    rb_ary_clear(check_array(self, sq->q.que));
    wakeup_all(szqueue_pushq(sq));
    return self;
}

close click to toggle source

Similar to Thread::Queue#close.

The difference is behavior with waiting enqueuing threads.

If there are waiting enqueuing threads, they are interrupted by raising ClosedQueueError(‘queue closed’).

static VALUE
rb_szqueue_close(VALUE self)
{
    if (!queue_closed_p(self)) {
        struct rb_szqueue *sq = szqueue_ptr(self);

        FL_SET(self, QUEUE_CLOSED);
        wakeup_all(szqueue_waitq(sq));
        wakeup_all(szqueue_pushq(sq));
    }
    return self;
}

deq

Alias for: pop

empty? click to toggle source

Returns true if the queue is empty.

static VALUE
rb_szqueue_empty_p(VALUE self)
{
    struct rb_szqueue *sq = szqueue_ptr(self);

    return RBOOL(queue_length(self, &sq->q) == 0);
}

enq(object, non_block=false, timeout: nil)

Alias for: push

freeze click to toggle source

The queue can’t be frozen, so this method raises an exception:

Thread::Queue.new.freeze # Raises TypeError (cannot freeze #<Thread::Queue:0x...>)

static VALUE
rb_queue_freeze(VALUE self)
{
    rb_raise(rb_eTypeError, "cannot freeze " "%+"PRIsVALUE, self);
    UNREACHABLE_RETURN(self);
}

length click to toggle source

size

Returns the length of the queue.

static VALUE
rb_szqueue_length(VALUE self)
{
    struct rb_szqueue *sq = szqueue_ptr(self);

    return LONG2NUM(queue_length(self, &sq->q));
}

Also aliased as: size

max() click to toggle source

Returns the maximum size of the queue.

static VALUE
rb_szqueue_max_get(VALUE self)
{
    return LONG2NUM(szqueue_ptr(self)->max);
}

max=(number) click to toggle source

Sets the maximum size of the queue to the given number.

static VALUE
rb_szqueue_max_set(VALUE self, VALUE vmax)
{
    long max = NUM2LONG(vmax);
    long diff = 0;
    struct rb_szqueue *sq = szqueue_ptr(self);

    if (max <= 0) {
        rb_raise(rb_eArgError, "queue size must be positive");
    }
    if (max > sq->max) {
        diff = max - sq->max;
    }
    sq->max = max;
    sync_wakeup(szqueue_pushq(sq), diff);
    return vmax;
}

num_waiting() click to toggle source

Returns the number of threads waiting on the queue.

static VALUE
rb_szqueue_num_waiting(VALUE self)
{
    struct rb_szqueue *sq = szqueue_ptr(self);

    return INT2NUM(sq->q.num_waiting + sq->num_waiting_push);
}

pop(non_block=false, timeout: nil) click to toggle source

Retrieves data from the queue.

If the queue is empty, the calling thread is suspended until data is pushed onto the queue. If non_block is true, the thread isn’t suspended, and ThreadError is raised.

If timeout seconds have passed and no data is available nil is returned. If timeout is 0 it returns immediately.

# File thread_sync.rb, line 36
def pop(non_block = false, timeout: nil)
  if non_block && timeout
    raise ArgumentError, "can't set a timeout if non_block is enabled"
  end
  Primitive.rb_szqueue_pop(non_block, timeout)
end

Also aliased as: deq, shift

push(object, non_block=false, timeout: nil) click to toggle source

Pushes object to the queue.

If there is no space left in the queue, waits until space becomes available, unless non_block is true. If non_block is true, the thread isn’t suspended, and ThreadError is raised.

If timeout seconds have passed and no space is available nil is returned. If timeout is 0 it returns immediately. Otherwise it returns self.

# File thread_sync.rb, line 59
def push(object, non_block = false, timeout: nil)
  if non_block && timeout
    raise ArgumentError, "can't set a timeout if non_block is enabled"
  end
  Primitive.rb_szqueue_push(object, non_block, timeout)
end

Also aliased as: enq, <<

shift

Alias for: pop

length

size

Returns the length of the queue.

Alias for: length