Htaccess    html   Php    javascript   Asp   css    maths  Past Questions  Practice Tests Online

ref.sem function syntax tag tutorial 2013 Donate at flattr Flattr this





Alert! Connect with 10,000 Chating Online. Join Now

Php ref.sem () function

Write your php code

 
<?php ?>

Php Result


Your code below



CIX. Semaphore, Shared Memory and IPC Functions

Introduction

This module provides wrappers for the System V IPC family of functions. It includes semaphores, shared memory and inter-process messaging (IPC).

Semaphores may be used to provide exclusive access to resources on the current machine, or to limit the number of processes that may simultaneously use a resource.

This module provides also shared memory functions using System V shared memory. Shared memory may be used to provide access to global variables. Different httpd-daemons and even other programs (such as Perl, C, ...) are able to access this data to provide a global data-exchange. Remember, that shared memory is NOT safe against simultaneous access. Use semaphores for synchronization.

Table 1. Limits of Shared Memory by the Unix OS

SHMMAXmax size of shared memory, normally 131072 bytes
SHMMINminimum size of shared memory, normally 1 byte
SHMMNI max amount of shared memory segments on a system, normally 100
SHMSEG max amount of shared memory segments per process, normally 6

The messaging functions may be used to send and receive messages to/from other processes. They provide a simple and effective means of exchanging data between processes, without the need for setting up an alternative using Unix domain sockets.

Note: This extension is not available on Windows platforms.

Requirements

No external libraries are needed to build this extension.

Installation

Support for this functions are not enabled by default. To enable System V semaphore support compile PHP with the option --enable-sysvsem. To enable the System V shared memory support compile PHP with the option --enable-sysvshm. To enable the System V messages support compile PHP with the option --enable-sysvmsg.

Runtime Configuration

The behaviour of these functions is affected by settings in php.ini.

Table 2. Semaphore Configuration Options

NameDefaultChangeableChangelog
sysvmsg.value"42"PHP_INI_ALL 
sysvmsg.string"foobar"PHP_INI_ALL 
For further details and definitions of the PHP_INI_* constants, see the Appendix H.

Predefined Constants

The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.

Table 3. System V message constants

ConstantType
MSG_IPC_NOWAITinteger
MSG_NOERRORinteger
MSG_EXCEPTinteger

Table of Contents
ftok --  Convert a pathname and a project identifier to a System V IPC key
msg_get_queue --  Create or attach to a message queue
msg_receive --  Receive a message from a message queue
msg_remove_queue --  Destroy a message queue
msg_send --  Send a message to a message queue
msg_set_queue --  Set information in the message queue data structure
msg_stat_queue --  Returns information from the message queue data structure
sem_acquire -- Acquire a semaphore
sem_get -- Get a semaphore id
sem_release -- Release a semaphore
sem_remove -- Remove a semaphore
shm_attach -- Creates or open a shared memory segment
shm_detach -- Disconnects from shared memory segment
shm_get_var -- Returns a variable from shared memory
shm_put_var --  Inserts or updates a variable in shared memory
shm_remove_var -- Removes a variable from shared memory
shm_remove -- Removes shared memory from Unix systems

Php ref.sem Function syntax tag

ref.sem php code on this is provided for your study purpose, it will guide you to know how create and design a website using php. use it to practice and train your self online



Php ref.sem syntax tutorial

php tutorial guide and code design are for easy learning and programming. The code practice section provided at the top is for practising of this syntax. Use the code section up to practice your php programming online. Learning php is very easy, all you need is to use the examples on this site and practice them to perfect your skills.


Function index

Variables

Expressions

Operators

Control-Structures

Cookies

Array

Date & Time

Directory function

File

Image

Operators

Form data handling

Mathematics operators

Mail

Php Mysql

Network Functions

Strings

php tutorial guides,functions, classes, code examples and tags for creating simple dynamic site to mysql database driven sites
 
 
Htaccess    html   Php    javascript   Asp   css    maths  Past Questions  Practice Tests Online