boost-react-native-bundle
Version:
Boost library as in https://sourceforge.net/projects/boost/files/boost/1.57.0/
95 lines (88 loc) • 5.71 kB
HTML
<html>
<head>
<title>intrusive_ref_counter</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
</head>
<body text="#000000" bgcolor="#ffffff" link="#0000ff" vlink="#0000ff">
<h1><img height="86" alt="boost.png (6897 bytes)" src="../../boost.png"
width="277" align="middle" border="0">basic_intrusive_ref_counter class template</h1>
<p>
<A href="#Introduction">Introduction</A><br>
<A href="#Synopsis">Synopsis</A><br>
<A href="#Members">Members</A><br>
</p>
<h2><a name="Introduction">Introduction</a></h2>
<p>The <STRONG>intrusive_ref_counter</STRONG> class template implements a reference counter for a derived
user's class that is intended to be used with <STRONG><a href="intrusive_ptr.html">intrusive_ptr</a></STRONG>.
The base class has associated <STRONG>intrusive_ptr_add_ref</STRONG> and <STRONG>intrusive_ptr_release</STRONG> functions
which modify the reference counter as needed and destroy the user's object when the counter drops to zero.</p>
<p>The class template is parameterized on <STRONG>DerivedT</STRONG> and <STRONG>CounterPolicyT</STRONG> parameters.
The first parameter is the user's class that derives from <STRONG>intrusive_ref_counter</STRONG>. This type
is needed in order to destroy the object correctly when there are no references to it left.</p>
<p>The second parameter is a policy that defines the nature of the reference counter.
Boost.SmartPtr provides two such policies: <STRONG>thread_unsafe_counter</STRONG> and <STRONG>thread_safe_counter</STRONG>. The former
instructs the <STRONG>intrusive_ref_counter</STRONG> base class to use a counter only suitable for a single-threaded use.
Pointers to a single object that uses this kind of reference counter must not be used in different threads. The latter policy
makes the reference counter thread-safe, unless the target platform doesn't support threading. Since in modern systems support for
threading is common, the default counter policy is <STRONG>thread_safe_counter</STRONG>.</p>
<h2><a name="Synopsis">Synopsis</a></h2>
<pre>namespace boost {
struct thread_unsafe_counter;
struct thread_safe_counter;
template<class DerivedT, class CounterPolicyT = thread_safe_counter>
class intrusive_ref_counter
{
public:
<A href="#constructors" >intrusive_ref_counter</A>() = noexcept;
<A href="#constructors" >intrusive_ref_counter</A>(intrusive_ref_counter const & r) = noexcept;
intrusive_ref_counter & <A href="#assignment" >operator=</A>(intrusive_ref_counter const & r) noexcept;
unsigned int <a href="#use_count" >use_count</a>() const noexcept;
protected:
<A href="#destructor" >~intrusive_ref_counter</A>() = default;
};
}</pre>
<h2><a name="Members">Members</a></h2>
<h3><a name="constructors">constructors</a></h3>
<pre>intrusive_ref_counter();</pre>
<blockquote>
<p><b>Postconditions:</b> <code>use_count() == 0</code>.</p>
<p><b>Throws:</b> nothing.</p>
<P><B>Notes:</B> The pointer to the constructed object is expected to be passed to <STRONG>intrusive_ptr</STRONG>
constructor, assignment operator or <STRONG>reset()</STRONG> method, which would increment the reference counter.</P>
</blockquote>
<pre>intrusive_ref_counter(intrusive_ref_counter const &);</pre>
<blockquote>
<p><b>Postconditions:</b> <code>use_count() == 0</code>.</p>
<p><b>Throws:</b> nothing.</p>
<P><B>Notes:</B> The pointer to the constructed object is expected to be passed to <STRONG>intrusive_ptr</STRONG>
constructor, assignment operator or <STRONG>reset()</STRONG> method, which would increment the reference counter.</P>
</blockquote>
<h3><a name="destructor">destructor</a></h3>
<pre>~intrusive_ref_counter();</pre>
<BLOCKQUOTE>
<p><b>Throws:</b> nothing.</p>
<P><B>Effects:</B> Destroys the counter object.</P>
<P><B>Notes:</B> The destructor is protected so that the object can only be destroyed through the <STRONG>DerivedT</STRONG> class.</P>
</BLOCKQUOTE>
<H3><a name="assignment">assignment</a></H3>
<pre>intrusive_ref_counter & operator=(intrusive_ref_counter const & r) noexcept;</pre>
<BLOCKQUOTE>
<P><B>Effects:</B> Does nothing, reference counter is not modified.</P>
<P><B>Returns:</B> <code>*this</code>.</P>
</BLOCKQUOTE>
<H3><a name="use_count">use_count</a></H3>
<pre>unsigned int use_count() const noexcept;</pre>
<BLOCKQUOTE>
<p><b>Returns:</b> The current value of the reference counter.</p>
<p><b>Throws:</b> nothing.</p>
<P><B>Notes:</B> The returned value may not be actual in multi-threaded applications.</P>
</BLOCKQUOTE>
<hr>
<p>$Date$</p>
<p>
<small>Copyright © 2013 Andrey Semashev. Distributed under the Boost Software License, Version
1.0. See accompanying file <A href="../../LICENSE_1_0.txt">LICENSE_1_0.txt</A> or
copy at <A href="http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</A>.</small></p>
</body>
</html>