boost_1_45_0/libs/iostreams/doc/concepts/blocking.html - nest-learning-thermostat/5.0/boost - Git at Google

 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
 <HTML>
 <HEAD>
     <TITLE>Blocking</TITLE>
     <LINK REL="stylesheet" HREF="../../../../boost.css">
     <LINK REL="stylesheet" HREF="../theme/iostreams.css">
 </HEAD>
 <BODY>

 <!-- Begin Banner -->

     <H1 CLASS="title">Blocking</H1>
     <HR CLASS="banner">

 <!-- End Banner -->

 <H2>Description</H2>

 <P>
     A <A HREF="device.html">Device</A> is Blocking if a <CODE>read</CODE> request never produces fewer characters than requested except at end-of-stream, and if a <CODE>write</CODE> request never consumes fewer characters than requested under any circumstances. All Devices currently provided with the Iostreams library are Blocking. Limited support for non-Blocking Devices has been provided as a foundation for future more comprehensive support of <A HREF='../guide/asynchronous.html'>asynchronous and non-blocking i/o</A>.
 </P>

 <P>
     The Blocking concept does not apply to filters. Instead, filters are required to be <SPAN CLASS='term'>blocking-preserving</SPAN>, which means that
 </P>
 <UL>
     <LI>
         a <CODE>read</CODE> request never produces fewer characters than requested unless end-of-stream has been reached or unless a <CODE>read</CODE> request to a downsteam Source produces fewer characters than requested, and
     </LI>
     <LI>
         a <CODE>write</CODE> request never consumes fewer characters than requested unless a <CODE>write</CODE> request to a downsteam Sink consumes fewer characters than requested.
     </LI>
 </UL>

 <P>
     Unlike other Iostreams library concepts, Blocking is not associated with any <A HREF='../guide/traits.html#category_tags'>category tag</A>. In the future, a <CODE>non_blocking_tag</CODE> may be introduced.
 </P>

 <H2>Refinement of</H2>

 <P><A HREF="device.html">Device</A>.</P>

 <A NAME="types"></A>
 <H2>Associated Types</H2>

 <P>Same as <A HREF="device.html">Device</A>.</P>

 <A NAME="expressions"></A>
 <H2>Valid Expressions / Semantics</H2>

 <P>Valid expressions are the same as <A HREF="device.html">Device</A>. The additional semantic requirements are described informally above.</P>

 <!-- Begin Footer -->

 <HR>
 <P CLASS="copyright">Revised 02 Feb 2008</P>

 <P CLASS="copyright">&copy; Copyright 2008 <a href="http://www.coderage.com/" target="_top">CodeRage, LLC</a><br/>&copy; Copyright 2004-2007 <a href="http://www.coderage.com/turkanis/" target="_top">Jonathan Turkanis</a></P>
 <P CLASS="copyright">
     Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at <A HREF="http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</A>)
 </P>

 <!-- End Footer -->

 </BODY>
	<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
	<HTML>
	<HEAD>
	<TITLE>Blocking</TITLE>
	<LINK REL="stylesheet" HREF="../../../../boost.css">
	<LINK REL="stylesheet" HREF="../theme/iostreams.css">
	</HEAD>
	<BODY>

	<!-- Begin Banner -->

	<H1 CLASS="title">Blocking</H1>
	<HR CLASS="banner">

	<!-- End Banner -->

	<H2>Description</H2>

	<P>
	A <A HREF="device.html">Device</A> is Blocking if a <CODE>read</CODE> request never produces fewer characters than requested except at end-of-stream, and if a <CODE>write</CODE> request never consumes fewer characters than requested under any circumstances. All Devices currently provided with the Iostreams library are Blocking. Limited support for non-Blocking Devices has been provided as a foundation for future more comprehensive support of <A HREF='../guide/asynchronous.html'>asynchronous and non-blocking i/o</A>.
	</P>

	<P>
	The Blocking concept does not apply to filters. Instead, filters are required to be <SPAN CLASS='term'>blocking-preserving</SPAN>, which means that
	</P>
	<UL>
	<LI>
	a <CODE>read</CODE> request never produces fewer characters than requested unless end-of-stream has been reached or unless a <CODE>read</CODE> request to a downsteam Source produces fewer characters than requested, and
	</LI>
	<LI>
	a <CODE>write</CODE> request never consumes fewer characters than requested unless a <CODE>write</CODE> request to a downsteam Sink consumes fewer characters than requested.
	</LI>
	</UL>

	<P>
	Unlike other Iostreams library concepts, Blocking is not associated with any <A HREF='../guide/traits.html#category_tags'>category tag</A>. In the future, a <CODE>non_blocking_tag</CODE> may be introduced.
	</P>

	<H2>Refinement of</H2>

	<P><A HREF="device.html">Device</A>.</P>

	<A NAME="types"></A>
	<H2>Associated Types</H2>

	<P>Same as <A HREF="device.html">Device</A>.</P>

	<A NAME="expressions"></A>
	<H2>Valid Expressions / Semantics</H2>

	<P>Valid expressions are the same as <A HREF="device.html">Device</A>. The additional semantic requirements are described informally above.</P>

	<!-- Begin Footer -->

	<HR>
	<P CLASS="copyright">Revised 02 Feb 2008</P>

	<P CLASS="copyright">© Copyright 2008 <a href="http://www.coderage.com/" target="_top">CodeRage, LLC</a><br/>© Copyright 2004-2007 <a href="http://www.coderage.com/turkanis/" target="_top">Jonathan Turkanis</a></P>
	<P CLASS="copyright">
	Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at <A HREF="http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</A>)
	</P>

	<!-- End Footer -->

	</BODY>