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shmop_write

(PHP 4 >= 4.0.4, PHP 5, PHP 7)

shmop_write — Write data into shared memory block

Descrierea

shmop_write ( Shmop $shmop , string $data , int $offset ) : int

shmop_write() will write a string into shared memory block.

Parametri

shmop: The shared memory block identifier created by shmop_open()
data: A string to write into shared memory block
offset: Specifies where to start writing data inside the shared memory segment.

Valorile întoarse

The size of the written data.

Istoricul schimbărilor

Versiune	Descriere
8.0.0	Prior to PHP 8.0.0, `false` was returned on failure.
8.0.0	`shmop` expects a Shmop instance now; previously, a resource was expected.

Exemple

Example #1 Writing to shared memory block


<?php
$shm_bytes_written = shmop_write($shm_id, $my_string, 0);
?>

This example will write data inside $my_string into shared memory block, $shm_bytes_written will contain the number of bytes written.

A se vedea și

shmop_read() - Read data from shared memory block

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User Contributed Notes 2 notes

down

mark at manngo dot net ¶

1 year ago


On thing you might want to do is replace an old string with a shorter one, or to clear out the string altogether.

To replace the string, you can zero-byte pad the string you are writing:

<?php
    //    $shmid is from shmop_open()
    $size = 128;
    $string = 'something';

    //    write
        $string = str_pad(string, $size, "\0");
        shmop_write($shmid, $string, 0);

    //    read
        print rtrim(shmop($shmid,0,0),,"\0");

    //    clear
        $string = str_repeat("\0",$size);
        shmop_write($shmid, $string, 0);
?>

down

radupb at yahoo dot com ¶

3 years ago


I guess pack-unpack are the handy functions for encoding/decoding data as/from a binary string for shmop_write/shmop_read. Example:

$format='LLLLSSCCCC';  //data format for pack
$key=1; 
if( !($shmid=shmop_open($key,'n',0660,30)) )
  die('shmop_open failed.'); 

//my data to encode:
$hd=array('ALIVE1'=>1,'ALIVE2'=>2,'ALIVE3'=>3,'ALIVE4'=>4,
      'CRTPTR'=>5,'CRTSEQ'=>6,
      'CTW'=>7,'LOCK'=>8,'PLAY'=>9,'MISS'=>10
);

$tmp=pack( $format, $hd['ALIVE1'],$hd['ALIVE2'],$hd['ALIVE3'],$hd['ALIVE4'],  $hd['CRTPTR'],$hd['CRTSEQ'],$hd['CTW'],$hd['LOCK'],$hd['PLAY'],$hd['MISS'] );

if( ($w=shmop_write($shmid,$tmp,0))!=24 )
  die('write error $w='.$w);

And reading from some other process:
$key=1; 
if( !($shmid=shmop_open($key,'w',0,0)) )
  die('shmop_open failed.'); 

$formatR='L4ALIVE/SCRTPTR/SCRTSEQ/CCTW/CLOCK/CPLAY/CMISS'; //data format for unpack

$hd=unpack( $formatR, shmop_read( $shmid,0,24) );
echo'hd:<pre>';print_r($hd);echo'</pre>';

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