pht\Queue::front
(PECL pht >= 0.0.1)
pht\Queue::front — Returns the first value from a queue
Description
This method will remove a value from the front of the queue (in constant time). Attempting to return the front value from an empty queue will result in an Error exception.
Due to the fact that all values in a pht\Queue are serialised, extracting a value from the queue will require it to be deserialised. This can incur a noticeable performance hit if the inspection of the queue's front value is performed within a loop.
Examples
Example #1 Retrieving the front value of a queue
<?php
use pht\Queue;
$queue = new Queue();
$queue->push(1);
var_dump($queue->front());
The above example will output:
int(1)
Example #2 Retrieving the front value in a loop (bad example - don't do this)
<?php
use pht\Queue;
$queue = new Queue();
$queue->push(array_fill(0, 2000, 0));
for ($i = 0; $i < count($queue->front()); ++$i); // quadratic runtime
Example #3 Retrieving the front value in a loop (good example)
<?php
use pht\Queue;
$queue = new Queue();
$queue->push(array_fill(0, 2000, 0));
$front = $queue->front(); // create a separate variable
for ($i = 0; $i < count($front); ++$i); // linear runtime
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Document created the 30/01/2003, last modified the 26/10/2018
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References
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