/*

 Copyright (C) 2015-2016 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 A functor for creating dispatch queue with a unique identifier.

 */

#import <random>

#import <strstream>

#import "CFQueueGenerator.h"

@implementation CFQueueGenerator

{

@private

    // Dispatch queue id.

    uint64_t mnQID;

    // Desired dispatch queue attribute.

    dispatch_queue_attr_t _attribute;

    // Dispatch queue label.

    std::string m_Label;

    // Dispatch queue label plus an attched id.

    std::string m_SQID;

    // A device for random number generation

    std::random_device m_Device;

}

- (instancetype) init

{

    self = [super init];

    if(self)

    {

        // Initialize queue id

        mnQID = 0;

        // Initialize with an empty string

        m_SQID  = "";

        m_Label = "";

        // Default dispatch queue attribute is for a serial queue.

        _attribute = DISPATCH_QUEUE_SERIAL;

    } // if

    return self;

} // init

- (void) setLabel:(nullable const char *)label

{

    if(label != nullptr)

    {

        m_Label = label;

    } // if

} // setLabel

- (nullable const char*) identifier

{

    return m_SQID.c_str();

} // identifier

- (nullable dispatch_queue_t) queue

{

    mnQID = m_Device();

    std::strstream sqid;

    sqid << mnQID;

    if(m_Label.empty())

    {

        m_SQID = sqid.str();

    } // if

    else

    {

        m_SQID  = m_Label + ".";

        m_SQID += sqid.str();

    } // else

    m_SQID += "\0";

    return dispatch_queue_create(m_SQID.c_str(), _attribute);

} // queue

@end