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/*
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE_1_0.txt or copy at
* http://www.boost.org/LICENSE_1_0.txt)
*
* (C) Copyright 2007 Anthony Williams
* (C) Copyright 2011-2012 Vicente J. Botet Escriba
* (C) Copyright 2013 Andrey Semashev
*/
/*!
* \file locks/shared_lock.hpp
*
* \brief This header defines a shared lock guard.
*/
#ifndef BOOST_SYNC_LOCKS_SHARED_LOCK_HPP_INCLUDED_
#define BOOST_SYNC_LOCKS_SHARED_LOCK_HPP_INCLUDED_
#include <cstddef>
#include <boost/move/core.hpp>
#include <boost/move/utility.hpp>
#include <boost/core/enable_if.hpp>
#include <boost/core/explicit_operator_bool.hpp>
#include <boost/sync/detail/config.hpp>
#include <boost/sync/detail/time_traits.hpp>
#include <boost/sync/detail/throw_exception.hpp>
#include <boost/sync/detail/system_error.hpp>
#include <boost/sync/exceptions/lock_error.hpp>
#include <boost/sync/locks/lock_options.hpp>
#include <boost/sync/locks/shared_lock_fwd.hpp>
#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
#include <boost/sync/locks/unique_lock_fwd.hpp>
#include <boost/sync/locks/upgrade_lock_fwd.hpp>
#else
// These locks need to be defined for Boost.Move emulation
#include <boost/sync/locks/unique_lock.hpp>
#include <boost/sync/locks/upgrade_lock.hpp>
#endif
#include <boost/sync/detail/header.hpp>
#ifdef BOOST_HAS_PRAGMA_ONCE
#pragma once
#endif
namespace boost {
namespace sync {
/*!
* \brief A shared lock scope guard
*/
template< typename Mutex >
class shared_lock
{
public:
typedef Mutex mutex_type;
private:
mutex_type* m_mutex;
bool m_is_locked;
public:
BOOST_MOVABLE_BUT_NOT_COPYABLE(shared_lock)
public:
shared_lock() BOOST_NOEXCEPT :
m_mutex(NULL), m_is_locked(false)
{
}
explicit shared_lock(mutex_type& m) :
m_mutex(&m), m_is_locked(false)
{
lock();
}
shared_lock(mutex_type& m, adopt_lock_t) BOOST_NOEXCEPT :
m_mutex(&m), m_is_locked(true)
{
}
shared_lock(mutex_type& m, defer_lock_t) BOOST_NOEXCEPT :
m_mutex(&m), m_is_locked(false)
{
}
shared_lock(mutex_type& m, try_to_lock_t) :
m_mutex(&m), m_is_locked(false)
{
try_lock();
}
template< typename Time >
shared_lock(typename enable_if_c< detail::time_traits< Time >::is_specialized, mutex_type& >::type m, Time const& t) :
m_mutex(&m), m_is_locked(false)
{
timed_lock(t);
}
shared_lock(BOOST_RV_REF(shared_lock) that) BOOST_NOEXCEPT :
m_mutex(that.m_mutex), m_is_locked(that.m_is_locked)
{
that.m_mutex = NULL;
that.m_is_locked = false;
}
// Conversion from unique locking
explicit shared_lock(BOOST_RV_REF(unique_lock< mutex_type >) that) :
m_mutex(that.m_mutex), m_is_locked(that.m_is_locked)
{
if (m_is_locked)
m_mutex->unlock_and_lock_shared();
that.release();
}
explicit shared_lock(BOOST_RV_REF(upgrade_lock< mutex_type >) that) :
m_mutex(that.m_mutex), m_is_locked(that.m_is_locked)
{
if (m_is_locked)
m_mutex->unlock_upgrade_and_lock_shared();
that.release();
}
~shared_lock()
{
if (m_is_locked)
m_mutex->unlock_shared();
}
shared_lock& operator= (BOOST_RV_REF(shared_lock) that) BOOST_NOEXCEPT
{
swap((shared_lock&)that);
return *this;
}
shared_lock& operator= (BOOST_RV_REF(unique_lock< mutex_type >) that)
{
shared_lock temp(boost::move(that));
swap(temp);
return *this;
}
shared_lock& operator= (BOOST_RV_REF(upgrade_lock< mutex_type >) that)
{
shared_lock temp(boost::move(that));
swap(temp);
return *this;
}
void lock()
{
if (!m_mutex)
BOOST_SYNC_DETAIL_THROW(lock_error, (detail::system_ns::errc::operation_not_permitted)("boost shared_lock has no mutex"));
if (m_is_locked)
BOOST_SYNC_DETAIL_THROW(lock_error, (detail::system_ns::errc::resource_deadlock_would_occur)("boost shared_lock already owns the mutex"));
m_mutex->lock_shared();
m_is_locked = true;
}
bool try_lock()
{
if (!m_mutex)
BOOST_SYNC_DETAIL_THROW(lock_error, (detail::system_ns::errc::operation_not_permitted)("boost shared_lock has no mutex"));
if (m_is_locked)
BOOST_SYNC_DETAIL_THROW(lock_error, (detail::system_ns::errc::resource_deadlock_would_occur)("boost shared_lock already owns the mutex"));
m_is_locked = m_mutex->try_lock_shared();
return m_is_locked;
}
template< typename Time >
typename enable_if_c< detail::time_traits< Time >::is_specialized, bool >::type timed_lock(Time const& time)
{
if (!m_mutex)
BOOST_SYNC_DETAIL_THROW(lock_error, (detail::system_ns::errc::operation_not_permitted)("boost shared_lock has no mutex"));
if (m_is_locked)
BOOST_SYNC_DETAIL_THROW(lock_error, (detail::system_ns::errc::resource_deadlock_would_occur)("boost shared_lock already owns the mutex"));
m_is_locked = m_mutex->timed_lock_shared(time);
return m_is_locked;
}
template< typename Duration >
typename detail::enable_if_tag< Duration, detail::time_duration_tag, bool >::type try_lock_for(Duration const& rel_time)
{
if (!m_mutex)
BOOST_SYNC_DETAIL_THROW(lock_error, (detail::system_ns::errc::operation_not_permitted)("boost shared_lock has no mutex"));
if (m_is_locked)
BOOST_SYNC_DETAIL_THROW(lock_error, (detail::system_ns::errc::resource_deadlock_would_occur)("boost shared_lock already owns the mutex"));
m_is_locked = m_mutex->try_lock_shared_for(rel_time);
return m_is_locked;
}
template< typename TimePoint >
typename detail::enable_if_tag< TimePoint, detail::time_point_tag, bool >::type try_lock_until(TimePoint const& abs_time)
{
if (!m_mutex)
BOOST_SYNC_DETAIL_THROW(lock_error, (detail::system_ns::errc::operation_not_permitted)("boost shared_lock has no mutex"));
if (m_is_locked)
BOOST_SYNC_DETAIL_THROW(lock_error, (detail::system_ns::errc::resource_deadlock_would_occur)("boost shared_lock already owns the mutex"));
m_is_locked = m_mutex->try_lock_shared_until(abs_time);
return m_is_locked;
}
void unlock()
{
if (!m_mutex)
BOOST_SYNC_DETAIL_THROW(lock_error, (detail::system_ns::errc::operation_not_permitted)("boost shared_lock has no mutex"));
if (!m_is_locked)
BOOST_SYNC_DETAIL_THROW(lock_error, (detail::system_ns::errc::operation_not_permitted)("boost shared_lock doesn't own the mutex"));
m_mutex->unlock_shared();
m_is_locked = false;
}
BOOST_EXPLICIT_OPERATOR_BOOL()
bool operator! () const BOOST_NOEXCEPT
{
return !m_is_locked;
}
bool owns_lock() const BOOST_NOEXCEPT
{
return m_is_locked;
}
mutex_type* mutex() const BOOST_NOEXCEPT
{
return m_mutex;
}
mutex_type* release() BOOST_NOEXCEPT
{
mutex_type* const res = m_mutex;
m_mutex = NULL;
m_is_locked = false;
return res;
}
void swap(shared_lock& that) BOOST_NOEXCEPT
{
mutex_type* const p = m_mutex;
m_mutex = that.m_mutex;
that.m_mutex = p;
const bool f = m_is_locked;
m_is_locked = that.m_is_locked;
that.m_is_locked = f;
}
};
template< typename Mutex >
inline void swap(shared_lock< Mutex >& lhs, shared_lock< Mutex >& rhs) BOOST_NOEXCEPT
{
lhs.swap(rhs);
}
} // namespace sync
} // namespace boost
#include <boost/sync/detail/footer.hpp>
#endif // BOOST_SYNC_LOCKS_SHARED_LOCK_HPP_INCLUDED_
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