Simple class for SHMOP implementation.
# Warning #
You can write/read only one direction. If you try read and write at the same time you get corrupt data. (Its works like STD in/out)
If you need bi-directional communication create 2 instance of shmop class.
Don't try attach more than one readers or writers for some shmid, you get corrupt data. This class use kludged spinlocks for improve speed, and not real atomic operations. You can add semaphore with flock, but it very slow. (~x3)
Benchmark:
Reads per sec: 6316 Data size per sec: 6.17 gb
<?php
$blockSize = 1024 * 1024 * 100;
$data = random_bytes($blockSize);
try
{
$shm = new SHMOP('shmopwriter.php', 'c', 644, $blockSize);
while(1)
{
if(!$shm->canWrite())
continue;
$shm->write($data);
}
$shm->close();
} catch (Exception $e) {
echo 'Error: ', $e->getMessage(), PHP_EOL;
exit;
}
$blockSize = 1024 * 1024 * 100;
$shm = new SHMOP('shmopwriter.php', 'c', 644, $blockSize);
$readsMT = 0;
$readsPS = 0;
while(!$shm->eof())
{
$times = microtime(true);
if(($data = $shm->read()) === false)
continue;
$readsPS++;
$readsMT += round(((microtime(true) - $times ) * 1000), 3);
if($readsMT > 1000)
{
echo 'Reads per sec: ', $readsPS, ' Data size per sec: ', convert($blockSize * $readsPS), PHP_EOL;
$readsPS = 0;
$readsMT = 0;
}
}
function convert($size)
{
$unit=array('b','kb','mb','gb','tb','pb');
return @round($size/pow(1024,($i=floor(log($size,1024)))),2).' '.$unit[$i];
}
class SHMOP
{
private $shmId;
private $shmHeaderSize;
private $shmHeaderOffset;
private $shmBlockSize;
private $shmMaxBlockSize;
function __construct(string $pathname, string $flags, int $mode, int $size)
{
$this->shmHeaderSize = strlen($size);
$this->shmHeaderOffset = $this->shmHeaderSize + 1;
$this->shmMaxBlockSize = $size;
$this->shmBlockSize = $size + $this->shmHeaderOffset + 1;
$this->shmId = shmop_open(ftok($pathname, 's'), $flags, $mode, $this->shmBlockSize);
if(!$this->shmId)
throw new Exception('shmop_open error');
}
function __destruct()
{
if(!$this->shmId)
return;
$this->close();
}
public function read()
{
if(shmop_read($this->shmId, 0, 1) === "\0")
return false;
$dataSize = (int)shmop_read($this->shmId, 1, $this->shmHeaderSize);
$data = shmop_read($this->shmId, $this->shmHeaderOffset, $dataSize);
shmop_write($this->shmId, "\0", 0);
return $data;
}
public function write(string $data)
{
if(shmop_read($this->shmId, 0, 1) !== "\0")
return false;
$dataSize = strlen($data);
if($dataSize < 1)
throw new Exception('dataSize < 1');
if($dataSize > $this->shmMaxBlockSize)
throw new Exception('dataSize > shmMaxBlockSize: '. $this->shmMaxBlockSize);
$dataSize .= "\0";
shmop_write($this->shmId, $dataSize, 1);
shmop_write($this->shmId, $data, $this->shmHeaderOffset);
shmop_write($this->shmId, "\1", 0);
return true;
}
public function eof()
{
return (shmop_read($this->shmId, 0, 1) === "\2") ? true : false;
}
public function sendeof()
{
if(shmop_read($this->shmId, 0, 1) !== "\0")
return false;
shmop_write($this->shmId, "\2", 0);
return true;
}
public function canWrite()
{
return (shmop_read($this->shmId, 0, 1) === "\0") ? true : false;
}
public function close()
{
return @shmop_close($this->shmId);
}
private function delete()
{
$del = @shmop_delete($this->shmId);
if($del === false)
return false;
return @shmop_close($this->shmId);
}
}
?>