php-doc-en/reference/sync/syncsemaphore/construct.xml
2014-07-07 14:48:52 +00:00

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<?xml version="1.0" encoding="utf-8"?>
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<refentry xml:id="syncsemaphore.construct" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
<refnamediv>
<refname>SyncSemaphore::__construct</refname>
<refpurpose>Constructs a new SyncSemaphore object</refpurpose>
</refnamediv>
<refsect1 role="description">
&reftitle.description;
<methodsynopsis>
<modifier>public</modifier> <methodname>SyncSemaphore::__construct</methodname>
<methodparam choice="opt"><type>string</type><parameter>name</parameter></methodparam>
<methodparam choice="opt"><type>integer</type><parameter>initialval</parameter></methodparam>
<methodparam choice="opt"><type>bool</type><parameter>autounlock</parameter></methodparam>
</methodsynopsis>
<para>
Constructs a named or unnamed semaphore.
</para>
</refsect1>
<refsect1 role="parameters">
&reftitle.parameters;
<variablelist>
<varlistentry>
<term><parameter>name</parameter></term>
<listitem>
<para>
The name of the semaphore if this is a named semaphore object.
</para>
<note>
<para>
If the name already exists, it must be able to be opened by the current user
that the process is running as or an exception will be thrown with a meaningless
error message.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>initialval</parameter></term>
<listitem>
<para>
The initial value of the semaphore. This is the number of locks that may be obtained.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>autounlock</parameter></term>
<listitem>
<para>
Specifies whether or not to automatically unlock the semaphore at the
conclusion of the PHP script.
</para>
<warning>
<para>
If an object is: A named semaphore with an autounlock of FALSE, the object is
locked, and the PHP script concludes before the object is unlocked, then the
underlying semaphore will end up in an inconsistent state.
</para>
</warning>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 role="returnvalues">
&reftitle.returnvalues;
<para>
The new SyncSemaphore object. An exception is thrown if the semaphore cannot
be created or opened.
</para>
</refsect1>
<refsect1 role="examples">
&reftitle.examples;
<example>
<title><function>SyncSemaphore::__construct</function> example</title>
<programlisting role="php">
<![CDATA[
<?php
$semaphore = new SyncSemaphore("LimitedResource_2clients", 2);
if (!$semaphore->lock(3000))
{
echo "Unable to lock semaphore.";
exit();
}
/* ... */
$semaphore->unlock();
?>
]]>
</programlisting>
</example>
</refsect1>
<refsect1 role="seealso">
&reftitle.seealso;
<simplelist>
<member><methodname>SyncSemaphore::lock</methodname></member>
<member><methodname>SyncSemaphore::unlock</methodname></member>
</simplelist>
</refsect1>
</refentry>
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