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@Grezvany13
Created November 17, 2015 23:12
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<?php
/**
* SnowFlake ID Generator
* Based on Twitter Snowflake to generate unique ID across multiple
* datacenters and databases without having duplicates.
*
*
* SnowFlake Layout
*
* 1 sign bit -- 0 is positive, 1 is negative
* 41 bits -- milliseconds since epoch
* 5 bits -- datacenter ID
* 5 bits -- machine ID
* 12 bits -- sequence number
*
* Total 64 bit integer/string
*/
class SnowFlake {
/**
* Offset from Unix Epoch
* Unix Epoch : January 1 1970 00:00:00 GMT
* Epoch Offset : January 1 2000 00:00:00 GMT
*/
CONST EPOCH_OFFSET = 9466848000000;
/**
* @var mixed
*/
private $datacenter_id;
/**
* @var mixed
*/
private $machine_id;
/**
* @var null|int
*/
private $lastTime = null;
/**
* @var int
*/
private $sequence = 1;
/**
* Constructor to set required paremeters
*
* @param mixed $datacenter_id Unique ID for datacenter (if multiple locations are used)
* @param mixed $machine_id Unique ID for machine (if multiple machines are used)
*/
public function __construct($datacenter_id, $machine_id)
{
$this->datacenter_id = $datacenter_id;
$this->machine_id = $machine_id;
}
/**
* Generate an unique ID based on SnowFlake
*
* @return string Unique ID
*/
public function generateID() {
$sign = 0; // default 0
$time = (int)($this->getUnixTimestamp() - self::EPOCH_OFFSET);
$sequence = $this->getNextSequence($time);
$this->lastTime = $time;
$id = ($sign << 1) | ($time << 41) | ($this->datacenter_id << 5) | ($this->machine_id << 5) | ($sequence << 12) ;
return (string)$id;
}
/**
* Get UNIX timestamp in microseconds
*
* @return int Timestamp in microseconds
*/
private function getUnixTimestamp()
{
return floor(microtime(true) * 1000);
}
/**
* Get the next sequence number if $time
* was already used
*
* @param int $time (micro)timestamp from EPOCH_OFFSET
* @return int Sequence number
*/
private function getNextSequence($time)
{
if($time === $this->lastTime) {
return ++$this->sequence;
}
return $this->sequence;
}
}
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