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https://github.com/sigmasternchen/php-doc-en
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removing the others git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@78562 c90b9560-bf6c-de11-be94-00142212c4b1
377 lines
12 KiB
XML
Executable file
377 lines
12 KiB
XML
Executable file
<!-- D O N O T E D I T T H I S F I L E ! ! !
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it is still here for historical reasons only
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(as translators may need to check old revision diffs)
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if you want to change things documented in this file
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you should now edit the files found under en/reference
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instead -->
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<?xml version="1.0" encoding="iso-8859-1"?>
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<!-- $Revision: 1.16 $ -->
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<reference id="ref.shmop">
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<title>Shared Memory Functions</title>
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<titleabbrev>shmop</titleabbrev>
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<partintro>
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<para>
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Shmop is an easy to use set of functions that allows php to read,
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write, create and delete UNIX shared memory segments. The functions
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will not work on windows, as it does not support shared memory. To
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use shmop you will need to compile php with the --enable-shmop parameter
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in your configure line.
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</para>
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<note>
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<simpara>
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This module is experimental. API and others are subject to be
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changed without notice.
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</simpara>
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<simpara>
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In PHP 4.0.3, there functions were prefixed by <literal>shm</literal>
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rather than <literal>shmop</literal>.
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<!-- TODO: do the old shm_* funcs still work, i.e. are they still
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aliased? -->
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</simpara>
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</note>
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<para>
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<example>
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<title>Shared Memory Operations Overview</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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// Create 100 byte shared memory block with system id if 0xff3
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$shm_id = shmop_open(0xff3, "c", 0644, 100);
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if(!$shm_id) {
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echo "Couldn't create shared memory segment\n";
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}
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// Get shared memory block's size
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$shm_size = shmop_size($shm_id);
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echo "SHM Block Size: ".$shm_size. " has been created.\n";
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// Lets write a test string into shared memory
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$shm_bytes_written = shmop_write($shm_id, "my shared memory block", 0);
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if($shm_bytes_written != strlen("my shared memory block")) {
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echo "Couldn't write the entire length of data\n";
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}
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// Now lets read the string back
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$my_string = shmop_read($shm_id, 0, $shm_size);
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if(!$my_string) {
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echo "Couldn't read from shared memory block\n";
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}
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echo "The data inside shared memory was: ".$my_string."\n";
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//Now lets delete the block and close the shared memory segment
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if(!shmop_delete($shm_id)) {
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echo "Couldn't mark shared memory block for deletion.";
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}
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shmop_close($shm_id);
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?>
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]]>
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</programlisting>
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</example>
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</para>
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</partintro>
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<refentry id="function.shmop-open">
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<refnamediv>
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<refname>shmop_open</refname>
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<refpurpose>Create or open shared memory block</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<methodsynopsis>
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<type>int</type><methodname>shmop_open</methodname>
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<methodparam><type>int</type><parameter>key</parameter></methodparam>
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<methodparam><type>string</type><parameter>flags</parameter></methodparam>
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<methodparam><type>int</type><parameter>mode</parameter></methodparam>
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<methodparam><type>int</type><parameter>size</parameter></methodparam>
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</methodsynopsis>
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<para>
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<function>shmop_open</function> can create or open a shared memory block.
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</para>
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<para>
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<function>shmop_open</function> takes 4 parameters: key, which is the
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system's id for the shared memory block, this parameter can be passed
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as a decimal or hex. The second parameter are the flags that you can use:
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<itemizedlist>
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<listitem>
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<simpara>
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"a" for access (sets SHM_RDONLY for shmat)
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use this flag when you need to open an existing shared memory segment for read only
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</simpara>
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</listitem>
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<listitem>
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<simpara>
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"c" for create (sets IPC_CREATE)
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use this flag when you need to create a new shared memory segment or if a
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segment with the same key exists, try to open it for read and write
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</simpara>
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</listitem>
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<listitem>
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<simpara>
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"w" for read & write access
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use this flag when you need to read and write to a shared memory segment, use this flag
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in most cases.
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</simpara>
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</listitem>
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<listitem>
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<simpara>
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"n" create a new memory segment (sets IPC_CREATE|IPC_EXCL)
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use this flag when you want to create a new shared memory segment but if one
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already exists with the same flag, fail. This is useful for security purposes, using this you
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can prevent race condition exploits.
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</simpara>
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</listitem>
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</itemizedlist>
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The third parameter is the mode, which are the permissions that you
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wish to assign to your memory segment, those are the same as permission
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for a file. Permissions need to be passed in octal form ex. 0644.
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The last parameter is size of the shared memory block you wish to create
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in bytes.
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<note><simpara>
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Note: the 3rd and 4th should be entered as 0 if you are opening an
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existing memory segment. On success <function>shmop_open</function> will
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return an id that you can use to access the shared memory segment
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you've created.
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</simpara></note>
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</para>
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<para>
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<example>
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<title>Create a new shared memory block</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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$shm_id = shmop_open(0x0fff, "c", 0644, 100);
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?>
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]]>
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</programlisting>
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</example>
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</para>
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<para>
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This example opened a shared memory block with a system id of 0x0fff.
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</para>
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</refsect1>
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</refentry>
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<refentry id="function.shmop-read">
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<refnamediv>
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<refname>shmop_read</refname>
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<refpurpose>Read data from shared memory block</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<methodsynopsis>
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<type>string</type><methodname>shmop_read</methodname>
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<methodparam><type>int</type><parameter>shmid</parameter></methodparam>
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<methodparam><type>int</type><parameter>start</parameter></methodparam>
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<methodparam><type>int</type><parameter>count</parameter></methodparam>
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</methodsynopsis>
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<para>
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<function>shmop_read</function> will read a string from shared memory block.
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</para>
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<para>
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<function>shmop_read</function> takes 3 parameters: shmid, which is the shared
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memory block identifier created by <function>shmop_open</function>, offset from
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which to start reading and count on the number of bytes to read.
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</para>
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<para>
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<example>
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<title>Reading shared memory block</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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$shm_data = shmop_read($shm_id, 0, 50);
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?>
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]]>
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</programlisting>
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</example>
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</para>
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<para>
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This example will read 50 bytes from shared memory block and place the data
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inside <literal>$shm_data</literal>.
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</para>
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</refsect1>
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</refentry>
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<refentry id="function.shmop-write">
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<refnamediv>
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<refname>shmop_write</refname>
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<refpurpose>Write data into shared memory block</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<methodsynopsis>
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<type>int</type><methodname>shmop_write</methodname>
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<methodparam><type>int</type><parameter>shmid</parameter></methodparam>
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<methodparam><type>string</type><parameter>data</parameter></methodparam>
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<methodparam><type>int</type><parameter>offset</parameter></methodparam>
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</methodsynopsis>
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<para>
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<function>shmop_write</function> will write a string into shared memory block.
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</para>
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<para>
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<function>shmop_write</function> takes 3 parameters: shmid, which is the
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shared memory block identifier created by <function>shmop_open</function>,
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data, a string that you want to write into shared memory block and offset,
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which specifies where to start writing data inside the shared memory segment.
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</para>
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<para>
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<example>
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<title>Writing to shared memory block</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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$shm_bytes_written = shmop_write($shm_id, $my_string, 0);
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?>
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]]>
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</programlisting>
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</example>
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</para>
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<para>
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This example will write data inside <literal>$my_string</literal> into
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shared memory block, <literal>$shm_bytes_written</literal> will contain
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the number of bytes written.
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</para>
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</refsect1>
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</refentry>
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<refentry id="function.shmop-size">
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<refnamediv>
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<refname>shmop_size</refname>
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<refpurpose>Get size of shared memory block</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<methodsynopsis>
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<type>int</type><methodname>shmop_size</methodname>
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<methodparam><type>int</type><parameter>shmid</parameter></methodparam>
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</methodsynopsis>
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<para>
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<function>shmop_size</function> is used to get the size, in bytes of the
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shared memory block.
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</para>
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<para>
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<function>shmop_size</function> takes the shmid, which is the shared memory
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block identifier created by <function>shmop_open</function>, the function
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will return and int, which represents the number of bytes the shared memory
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block occupies.
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</para>
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<para>
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<example>
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<title>Getting the size of the shared memory block</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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$shm_size = shmop_size($shm_id);
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?>
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]]>
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</programlisting>
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</example>
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</para>
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<para>
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This example will put the size of shared memory block identified by
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<literal>$shm_id</literal> into <literal>$shm_size</literal>.
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</para>
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</refsect1>
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</refentry>
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<refentry id="function.shmop-delete">
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<refnamediv>
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<refname>shmop_delete</refname>
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<refpurpose>Delete shared memory block</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<methodsynopsis>
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<type>int</type><methodname>shmop_delete</methodname>
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<methodparam><type>int</type><parameter>shmid</parameter></methodparam>
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</methodsynopsis>
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<para>
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<function>shmop_delete</function> is used to delete a shared memory block.
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</para>
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<para>
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<function>shmop_delete</function> takes the shmid, which is the shared memory
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block identifier created by <function>shmop_open</function>. On success 1 is
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returned, on failure 0 is returned.
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</para>
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<para>
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<example>
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<title>Deleting shared memory block</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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shmop_delete($shm_id);
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?>
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]]>
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</programlisting>
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</example>
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</para>
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<para>
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This example will delete shared memory block identified by
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<literal>$shm_id</literal>.
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</para>
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</refsect1>
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</refentry>
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<refentry id="function.shmop-close">
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<refnamediv>
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<refname>shmop_close</refname>
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<refpurpose>Close shared memory block</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<methodsynopsis>
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<type>int</type><methodname>shmop_close</methodname>
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<methodparam><type>int</type><parameter>shmid</parameter></methodparam>
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</methodsynopsis>
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<para>
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<function>shmop_close</function> is used to close a shared memory block.
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</para>
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<para>
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<function>shmop_close</function> takes the shmid, which is the shared memory
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block identifier created by <function>shmop_open</function>.
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</para>
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<para>
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<example>
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<title>Closing shared memory block</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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shmop_close($shm_id);
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?>
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]]>
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</programlisting>
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</example>
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</para>
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<para>
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This example will close shared memory block identified by <literal>$shm_id</literal>.
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</para>
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</refsect1>
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</refentry>
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</reference>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:t
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sgml-shorttag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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indent-tabs-mode:nil
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sgml-parent-document:nil
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sgml-default-dtd-file:"../../manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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vim600: syn=xml fen fdm=syntax fdl=2 si
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vim: et tw=78 syn=sgml
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vi: ts=1 sw=1
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-->
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