php-doc-en/reference/ev/evchild/construct.xml

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<refentry xml:id="evchild.construct" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
 <refnamediv>
  <refname>EvChild::__construct</refname>
  <refpurpose>Constructs the EvChild watcher object</refpurpose>
 </refnamediv>
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <modifier>public</modifier>
   <methodname>EvChild::__construct</methodname>
   <methodparam>
    <type>int</type>
    <parameter>pid</parameter>
   </methodparam>
   <methodparam>
    <type>bool</type>
    <parameter>trace</parameter>
   </methodparam>
   <methodparam>
    <type>callable</type>
    <parameter>callback</parameter>
   </methodparam>
   <methodparam
   choice="opt">
    <type>mixed</type>
    <parameter>data</parameter>
    <initializer>&null;</initializer>
   </methodparam>
   <methodparam
   choice="opt">
    <type>int</type>
    <parameter>priority</parameter>
    <initializer>0</initializer>
   </methodparam>
  </methodsynopsis>
  <para>
   Constructs the
   <classname>EvChild</classname>
   watcher object.
  </para>
  <para>
   Call the callback when a status change for process ID
   <parameter>pid</parameter>
   (or any
   <emphasis>PID</emphasis>
   if
   <parameter>pid</parameter>
   is
   <constant>0</constant>
   ) has been received(a status change happens when the process terminates or
   is killed, or, when
   <parameter>trace</parameter>
   is &true;, additionally when it is stopped or continued). In other words,
   when the process receives a
   <constant>SIGCHLD</constant>
   ,
   <emphasis>Ev</emphasis>
   will fetch the outstanding exit/wait status for all changed/zombie children
   and call the callback.
  </para>
  <para>
   It is valid to install a child watcher after an
   <classname>EvChild</classname>
   has exited but before the event loop has started its next iteration. For
   example, first one calls
   <literal>fork</literal>
   , then the new child process might exit, and only then an
   <classname>EvChild</classname>
   watcher is installed in the parent for the new
   <emphasis>PID</emphasis>
   .
  </para>
  <para>
   You can access both exit/tracing status and
   <parameter>pid</parameter>
   by using the
   <varname>rstatus</varname>
   and
   <varname>rpid</varname>
   properties of the watcher object.
  </para>
  <para>
   The number of
   <emphasis>PID</emphasis>
   watchers per
   <emphasis>PID</emphasis>
   is unlimited. All of them will be called.
  </para>
  <para>
   The
   <methodname>EvChild::createStopped</methodname>
   method doesn&apos;t start(activate) the newly created watcher.
  </para>
 </refsect1>
 <refsect1 role="parameters">
  &reftitle.parameters;
  <variablelist>
   <varlistentry>
    <term>
     <parameter>pid</parameter>
    </term>
    <listitem>
     <para>
      Wait for status changes of process PID(or any process if PID is
      specified as
      <constant>0</constant>
      ).
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <term>
     <parameter>trace</parameter>
    </term>
    <listitem>
     <para>
      If &false;, only activate the watcher when the process terminates.
      Otherwise(&true;) additionally activate the watcher when the process is
      stopped or continued.
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <term>
     <parameter>callback</parameter>
    </term>
    <listitem>
     <para>
      See
      <link linkend="ev.watcher-callbacks">Watcher callbacks</link>
      .
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <term>
     <parameter>data</parameter>
    </term>
    <listitem>
     <para>
      Custom data associated with the watcher.
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <term>
     <parameter>priority</parameter>
    </term>
    <listitem>
     <para>
      <link linkend="ev.constants.watcher-pri">Watcher priority</link>
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>
 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns EvChild object on success.
  </para>
 </refsect1>
 <refsect1 role="seealso">
  &reftitle.seealso;
  <simplelist>
   <member>
    <methodname>EvLoop::child</methodname>
   </member>
  </simplelist>
 </refsect1>
</refentry>
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