PHP queue usage examples, php queue examples_PHP tutorial

PHP queue usage examples, php queue examples

The examples in this article describe the use of PHP queues. Share it with everyone for your reference. The specific analysis is as follows:

What is a queue? It is a first-in-first-out linear list. In specific applications, it is usually implemented with a linked list or an array. The queue only allows insertion operations on the back end and deletion operations on the front end.

Under what circumstances will queues be used? Queues will be used when concurrent requests need to ensure the integrity of the transaction. Of course, other better methods are not ruled out. If you know it, why not tell me.

Queue can also be used to reduce the pressure on the database server. We can put non-immediate data into the queue and execute it when the database is idle or after a period of time. For example, for access counters, there is no need to immediately execute the increased Sql. When no queue is used, the sql statement looks like this. Suppose there are 5 people accessing:

update table1 set count=count+1 where id=1
update table1 set count=count+1 where id=1
update table1 set count=count+1 where id=1
update table1 set count=count+1 where id=1
update table1 set count=count+1 where id=1

When using a queue, you can do this:
update table1 set count=count+5 where id=1

Reduce the number of sql requests, thereby reducing the pressure on the server. Of course, this is not necessary for websites that do not have a large number of visits.
The following queue class:

Copy code The code is as follows:

/**
* Queue
*
* @author jaclon
*
*/
class Queue
{
private $_queue = array();
protected $cache = null;
protected $queuecachename;

/**
*Construction method
* @param string $queuename Queue name
*/
function __construct($queuename)
{

$this->cache =& Cache::instance();
$this->queuecachename = 'queue_' . $queuename;

$result = $this->cache->get($this->queuecachename);
if (is_array($result)) {
$this->_queue = $result;
}
}

/**
* Put a unit unit at the end of the queue
* @param mixed $value
*/
function enQueue($value)
{
$this->_queue[] = $value;
$this->cache->set($this->queuecachename, $this->_queue);

return $this;
}

/**
* Remove one or more units at the beginning of the queue
* @param int $num
*/
function sliceQueue($num = 1)
{
if (count($this->_queue) $num = count($this->_queue);
}
$output = array_splice($this->_queue, 0, $num);
$this->cache->set($this->queuecachename, $this->_queue);

return $output;
}

/**
* Remove the unit at the beginning of the queue from the queue
*/
function deQueue()
{
$entry = array_shift($this->_queue);
$this->cache->set($this->queuecachename, $this->_queue);

return $entry;
}

/**
* Return queue length
*/
function size()
{
return count($this->_queue);
}

/**
* Return the first unit in the queue
*/
function peek()
{
return $this->_queue[0];
}

/**
* Return one or more units in the queue
* @param int $num
*/
function peeks($num)
{
if (count($this->_queue) $num = count($this->_queue);
}
return array_slice($this->_queue, 0, $num);
}

/**
* Destroy queue
*/
function destroy()
{
$this->cache->remove($this->queuecachename);
}
}

I hope this article will be helpful to everyone’s PHP programming design.

Whether it is a stack or a queue, let’s give two application examples respectively

In the stack, data is entered first and then output;
In queue, data entered first is output first;
Do you understand this? It’s hard to give an example, it’s very long. Our teacher gave two lectures on stacks and queues
I hope it will be helpful to you.

Summer

Use PHP to implement a two-way queue

Unknown problem

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