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Queue

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SizedQueue

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

See Queue for an example of how a SizedQueue works.

Public Class Methods

new click to toggle source

Creates a new Mutex

static VALUE
rb_sized_queue_max_set(VALUE self, VALUE value)
{
    Queue *queue;
    unsigned long new_capacity;
    unsigned long difference;
    Data_Get_Struct(self, Queue, queue);

    new_capacity = NUM2ULONG(value);

    if (new_capacity < 1) {
        rb_raise(rb_eArgError, "value must be positive");
    }

    lock_mutex(&queue->mutex);
    if (queue->capacity && new_capacity > queue->capacity) {
        difference = new_capacity - queue->capacity;
    } else {
        difference = 0;
    }
    queue->capacity = new_capacity;
    for (; difference > 0; --difference) {
        signal_condvar(&queue->space_available);
    }
    unlock_mutex(&queue->mutex);

    return self;
}

Public Instance Methods

clear click to toggle source

Removes all objects from the queue.

static VALUE
rb_queue_clear(VALUE self)
{
    Queue *queue;
    Data_Get_Struct(self, Queue, queue);

    lock_mutex(&queue->mutex);
    clear_list(&queue->values);
    signal_condvar(&queue->space_available);
    unlock_mutex(&queue->mutex);

    return self;
}
empty? click to toggle source

Returns true if the queue is empty.

static VALUE
rb_queue_empty_p(VALUE self)
{
    Queue *queue;
    VALUE result;
    Data_Get_Struct(self, Queue, queue);

    lock_mutex(&queue->mutex);
    result = queue->values.size == 0 ? Qtrue : Qfalse;
    unlock_mutex(&queue->mutex);

    return result;
}
length click to toggle source

Returns the length of the queue.

static VALUE
rb_queue_length(VALUE self)
{
    Queue *queue;
    VALUE result;
    Data_Get_Struct(self, Queue, queue);

    lock_mutex(&queue->mutex);
    result = ULONG2NUM(queue->values.size);
    unlock_mutex(&queue->mutex);

    return result;
}
max click to toggle source

Returns the maximum size of the queue.

static VALUE
rb_sized_queue_max(VALUE self)
{
    Queue *queue;
    VALUE result;
    Data_Get_Struct(self, Queue, queue);

    lock_mutex(&queue->mutex);
    result = ULONG2NUM(queue->capacity);
    unlock_mutex(&queue->mutex);

    return result;
}
max=(size) click to toggle source

Sets the maximum size of the queue.

static VALUE
rb_sized_queue_max_set(VALUE self, VALUE value)
{
    Queue *queue;
    unsigned long new_capacity;
    unsigned long difference;
    Data_Get_Struct(self, Queue, queue);

    new_capacity = NUM2ULONG(value);

    if (new_capacity < 1) {
        rb_raise(rb_eArgError, "value must be positive");
    }

    lock_mutex(&queue->mutex);
    if (queue->capacity && new_capacity > queue->capacity) {
        difference = new_capacity - queue->capacity;
    } else {
        difference = 0;
    }
    queue->capacity = new_capacity;
    for (; difference > 0; --difference) {
        signal_condvar(&queue->space_available);
    }
    unlock_mutex(&queue->mutex);

    return self;
}
num_waiting click to toggle source

Returns the number of threads waiting on the queue.

static VALUE
rb_queue_num_waiting(VALUE self)
{
    Queue *queue;
    VALUE result;
    Data_Get_Struct(self, Queue, queue);

    lock_mutex(&queue->mutex);
    result = ULONG2NUM(queue->value_available.waiting.size +
      queue->space_available.waiting.size);
    unlock_mutex(&queue->mutex);

    return result;
}
pop(*args) click to toggle source

call_seq: pop(non_block=false)

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 an exception is raised.

static VALUE
rb_queue_pop(int argc, VALUE *argv, VALUE self)
{
    Queue *queue;
    int should_block;
    VALUE result;
    Data_Get_Struct(self, Queue, queue);

    if (argc == 0) {
        should_block = 1;
    } else if (argc == 1) {
        should_block = !RTEST(argv[0]);
    } else {
        rb_raise(rb_eArgError, "wrong number of arguments (%d for 1)", argc);
    }

    lock_mutex(&queue->mutex);
    if (!queue->values.entries && !should_block) {
        unlock_mutex(&queue->mutex);
        rb_raise(private_eThreadError, "queue empty");
    }

    while (!queue->values.entries) {
        wait_condvar(&queue->value_available, &queue->mutex);
    }

    result = shift_list(&queue->values);
    if (queue->capacity && queue->values.size < queue->capacity) {
        signal_condvar(&queue->space_available);
    }
    unlock_mutex(&queue->mutex);

    return result;
}
push(obj) click to toggle source

Pushes obj to the queue.

static VALUE
rb_queue_push(VALUE self, VALUE value)
{
    Queue *queue;
    Data_Get_Struct(self, Queue, queue);

    lock_mutex(&queue->mutex);
    while (queue->capacity && queue->values.size >= queue->capacity) {
        wait_condvar(&queue->space_available, &queue->mutex);
    }
    push_list(&queue->values, value);
    signal_condvar(&queue->value_available);
    unlock_mutex(&queue->mutex);

    return self;
}

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