Edit: /usr/include/boost/asio/strand.hpp (17193B)
//
// strand.hpp
// ~~~~~~~~~~
//
// Copyright (c) 2003-2020 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// 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)
//
#ifndef BOOST_ASIO_STRAND_HPP
#define BOOST_ASIO_STRAND_HPP
#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
#include
#include
#include
#include
#include
#include
namespace boost {
namespace asio {
/// Provides serialised function invocation for any executor type.
template
class strand
{
public:
/// The type of the underlying executor.
typedef Executor inner_executor_type;
/// Default constructor.
/**
* This constructor is only valid if the underlying executor type is default
* constructible.
*/
strand()
: executor_(),
impl_(strand::create_implementation(executor_))
{
}
/// Construct a strand for the specified executor.
template
explicit strand(const Executor1& e,
typename enable_if<
conditional<
!is_same::value,
is_convertible,
false_type
>::type::value
>::type* = 0)
: executor_(e),
impl_(strand::create_implementation(executor_))
{
}
/// Copy constructor.
strand(const strand& other) BOOST_ASIO_NOEXCEPT
: executor_(other.executor_),
impl_(other.impl_)
{
}
/// Converting constructor.
/**
* This constructor is only valid if the @c OtherExecutor type is convertible
* to @c Executor.
*/
template
strand(
const strand& other) BOOST_ASIO_NOEXCEPT
: executor_(other.executor_),
impl_(other.impl_)
{
}
/// Assignment operator.
strand& operator=(const strand& other) BOOST_ASIO_NOEXCEPT
{
executor_ = other.executor_;
impl_ = other.impl_;
return *this;
}
/// Converting assignment operator.
/**
* This assignment operator is only valid if the @c OtherExecutor type is
* convertible to @c Executor.
*/
template
strand& operator=(
const strand& other) BOOST_ASIO_NOEXCEPT
{
executor_ = other.executor_;
impl_ = other.impl_;
return *this;
}
#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
/// Move constructor.
strand(strand&& other) BOOST_ASIO_NOEXCEPT
: executor_(BOOST_ASIO_MOVE_CAST(Executor)(other.executor_)),
impl_(BOOST_ASIO_MOVE_CAST(implementation_type)(other.impl_))
{
}
/// Converting move constructor.
/**
* This constructor is only valid if the @c OtherExecutor type is convertible
* to @c Executor.
*/
template
strand(strand&& other) BOOST_ASIO_NOEXCEPT
: executor_(BOOST_ASIO_MOVE_CAST(OtherExecutor)(other.executor_)),
impl_(BOOST_ASIO_MOVE_CAST(implementation_type)(other.impl_))
{
}
/// Move assignment operator.
strand& operator=(strand&& other) BOOST_ASIO_NOEXCEPT
{
executor_ = BOOST_ASIO_MOVE_CAST(Executor)(other.executor_);
impl_ = BOOST_ASIO_MOVE_CAST(implementation_type)(other.impl_);
return *this;
}
/// Converting move assignment operator.
/**
* This assignment operator is only valid if the @c OtherExecutor type is
* convertible to @c Executor.
*/
template
strand& operator=(strand&& other) BOOST_ASIO_NOEXCEPT
{
executor_ = BOOST_ASIO_MOVE_CAST(OtherExecutor)(other.executor_);
impl_ = BOOST_ASIO_MOVE_CAST(implementation_type)(other.impl_);
return *this;
}
#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
/// Destructor.
~strand() BOOST_ASIO_NOEXCEPT
{
}
/// Obtain the underlying executor.
inner_executor_type get_inner_executor() const BOOST_ASIO_NOEXCEPT
{
return executor_;
}
/// Forward a query to the underlying executor.
/**
* Do not call this function directly. It is intended for use with the
* execution::execute customisation point.
*
* For example:
* @code boost::asio::strand ex = ...;
* if (boost::asio::query(ex, boost::asio::execution::blocking)
* == boost::asio::execution::blocking.never)
* ... @endcode
*/
template
typename enable_if<
can_query::value,
typename query_result::type
>::type query(const Property& p) const
BOOST_ASIO_NOEXCEPT_IF((
is_nothrow_query::value))
{
return boost::asio::query(executor_, p);
}
/// Forward a requirement to the underlying executor.
/**
* Do not call this function directly. It is intended for use with the
* boost::asio::require customisation point.
*
* For example:
* @code boost::asio::strand ex1 = ...;
* auto ex2 = boost::asio::require(ex1,
* boost::asio::execution::blocking.never); @endcode
*/
template
typename enable_if<
can_require::value,
strand::type
>::type>
>::type require(const Property& p) const
BOOST_ASIO_NOEXCEPT_IF((
is_nothrow_require::value))
{
return strand::type
>::type>(boost::asio::require(executor_, p), impl_);
}
/// Forward a preference to the underlying executor.
/**
* Do not call this function directly. It is intended for use with the
* boost::asio::prefer customisation point.
*
* For example:
* @code boost::asio::strand ex1 = ...;
* auto ex2 = boost::asio::prefer(ex1,
* boost::asio::execution::blocking.never); @endcode
*/
template
typename enable_if<
can_prefer::value,
strand::type
>::type>
>::type prefer(const Property& p) const
BOOST_ASIO_NOEXCEPT_IF((
is_nothrow_prefer::value))
{
return strand::type
>::type>(boost::asio::prefer(executor_, p), impl_);
}
#if !defined(BOOST_ASIO_NO_TS_EXECUTORS)
/// Obtain the underlying execution context.
execution_context& context() const BOOST_ASIO_NOEXCEPT
{
return executor_.context();
}
/// Inform the strand that it has some outstanding work to do.
/**
* The strand delegates this call to its underlying executor.
*/
void on_work_started() const BOOST_ASIO_NOEXCEPT
{
executor_.on_work_started();
}
/// Inform the strand that some work is no longer outstanding.
/**
* The strand delegates this call to its underlying executor.
*/
void on_work_finished() const BOOST_ASIO_NOEXCEPT
{
executor_.on_work_finished();
}
#endif // !defined(BOOST_ASIO_NO_TS_EXECUTORS)
/// Request the strand to invoke the given function object.
/**
* Do not call this function directly. It is intended for use with the
* execution::execute customisation point.
*
* For example:
* @code boost::asio::strand ex = ...;
* execution::execute(ex, my_function_object); @endcode
*
* This function is used to ask the strand to execute the given function
* object on its underlying executor. The function object will be executed
* according to the properties of the underlying executor.
*
* @param f The function object to be called. The executor will make
* a copy of the handler object as required. The function signature of the
* function object must be: @code void function(); @endcode
*/
template
typename enable_if<
execution::can_execute::value
>::type execute(BOOST_ASIO_MOVE_ARG(Function) f) const
{
detail::strand_executor_service::execute(impl_,
executor_, BOOST_ASIO_MOVE_CAST(Function)(f));
}
#if !defined(BOOST_ASIO_NO_TS_EXECUTORS)
/// Request the strand to invoke the given function object.
/**
* This function is used to ask the strand to execute the given function
* object on its underlying executor. The function object will be executed
* inside this function if the strand is not otherwise busy and if the
* underlying executor's @c dispatch() function is also able to execute the
* function before returning.
*
* @param f The function object to be called. The executor will make
* a copy of the handler object as required. The function signature of the
* function object must be: @code void function(); @endcode
*
* @param a An allocator that may be used by the executor to allocate the
* internal storage needed for function invocation.
*/
template
void dispatch(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const
{
detail::strand_executor_service::dispatch(impl_,
executor_, BOOST_ASIO_MOVE_CAST(Function)(f), a);
}
/// Request the strand to invoke the given function object.
/**
* This function is used to ask the executor to execute the given function
* object. The function object will never be executed inside this function.
* Instead, it will be scheduled by the underlying executor's defer function.
*
* @param f The function object to be called. The executor will make
* a copy of the handler object as required. The function signature of the
* function object must be: @code void function(); @endcode
*
* @param a An allocator that may be used by the executor to allocate the
* internal storage needed for function invocation.
*/
template
void post(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const
{
detail::strand_executor_service::post(impl_,
executor_, BOOST_ASIO_MOVE_CAST(Function)(f), a);
}
/// Request the strand to invoke the given function object.
/**
* This function is used to ask the executor to execute the given function
* object. The function object will never be executed inside this function.
* Instead, it will be scheduled by the underlying executor's defer function.
*
* @param f The function object to be called. The executor will make
* a copy of the handler object as required. The function signature of the
* function object must be: @code void function(); @endcode
*
* @param a An allocator that may be used by the executor to allocate the
* internal storage needed for function invocation.
*/
template
void defer(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const
{
detail::strand_executor_service::defer(impl_,
executor_, BOOST_ASIO_MOVE_CAST(Function)(f), a);
}
#endif // !defined(BOOST_ASIO_NO_TS_EXECUTORS)
/// Determine whether the strand is running in the current thread.
/**
* @return @c true if the current thread is executing a function that was
* submitted to the strand using post(), dispatch() or defer(). Otherwise
* returns @c false.
*/
bool running_in_this_thread() const BOOST_ASIO_NOEXCEPT
{
return detail::strand_executor_service::running_in_this_thread(impl_);
}
/// Compare two strands for equality.
/**
* Two strands are equal if they refer to the same ordered, non-concurrent
* state.
*/
friend bool operator==(const strand& a, const strand& b) BOOST_ASIO_NOEXCEPT
{
return a.impl_ == b.impl_;
}
/// Compare two strands for inequality.
/**
* Two strands are equal if they refer to the same ordered, non-concurrent
* state.
*/
friend bool operator!=(const strand& a, const strand& b) BOOST_ASIO_NOEXCEPT
{
return a.impl_ != b.impl_;
}
#if defined(GENERATING_DOCUMENTATION)
private:
#endif // defined(GENERATING_DOCUMENTATION)
typedef detail::strand_executor_service::implementation_type
implementation_type;
template
static implementation_type create_implementation(const InnerExecutor& ex,
typename enable_if<
can_query::value
>::type* = 0)
{
return use_service(
boost::asio::query(ex, execution::context)).create_implementation();
}
template
static implementation_type create_implementation(const InnerExecutor& ex,
typename enable_if<
!can_query::value
>::type* = 0)
{
return use_service(
ex.context()).create_implementation();
}
strand(const Executor& ex, const implementation_type& impl)
: executor_(ex),
impl_(impl)
{
}
Executor executor_;
implementation_type impl_;
};
/** @defgroup make_strand boost::asio::make_strand
*
* @brief The boost::asio::make_strand function creates a @ref strand object for
* an executor or execution context.
*/
/*@{*/
/// Create a @ref strand object for an executor.
template
inline strand make_strand(const Executor& ex,
typename enable_if<
is_executor::value || execution::is_executor::value
>::type* = 0)
{
return strand(ex);
}
/// Create a @ref strand object for an execution context.
template
inline strand
make_strand(ExecutionContext& ctx,
typename enable_if<
is_convertible::value
>::type* = 0)
{
return strand(ctx.get_executor());
}
/*@}*/
#if !defined(GENERATING_DOCUMENTATION)
namespace traits {
#if !defined(BOOST_ASIO_HAS_DEDUCED_EQUALITY_COMPARABLE_TRAIT)
template
struct equality_comparable >
{
BOOST_ASIO_STATIC_CONSTEXPR(bool, is_valid = true);
BOOST_ASIO_STATIC_CONSTEXPR(bool, is_noexcept = true);
};
#endif // !defined(BOOST_ASIO_HAS_DEDUCED_EQUALITY_COMPARABLE_TRAIT)
#if !defined(BOOST_ASIO_HAS_DEDUCED_EXECUTE_MEMBER_TRAIT)
template
struct execute_member, Function>
{
BOOST_ASIO_STATIC_CONSTEXPR(bool, is_valid = true);
BOOST_ASIO_STATIC_CONSTEXPR(bool, is_noexcept = false);
typedef void result_type;
};
#endif // !defined(BOOST_ASIO_HAS_DEDUCED_EXECUTE_MEMBER_TRAIT)
#if !defined(BOOST_ASIO_HAS_DEDUCED_QUERY_MEMBER_TRAIT)
template
struct query_member, Property,
typename enable_if<
can_query::value
>::type>
{
BOOST_ASIO_STATIC_CONSTEXPR(bool, is_valid = true);
BOOST_ASIO_STATIC_CONSTEXPR(bool, is_noexcept =
(is_nothrow_query::value));
typedef typename query_result::type result_type;
};
#endif // !defined(BOOST_ASIO_HAS_DEDUCED_QUERY_MEMBER_TRAIT)
#if !defined(BOOST_ASIO_HAS_DEDUCED_REQUIRE_MEMBER_TRAIT)
template
struct require_member, Property,
typename enable_if<
can_require::value
>::type>
{
BOOST_ASIO_STATIC_CONSTEXPR(bool, is_valid = true);
BOOST_ASIO_STATIC_CONSTEXPR(bool, is_noexcept =
(is_nothrow_require::value));
typedef strand::type
>::type> result_type;
};
#endif // !defined(BOOST_ASIO_HAS_DEDUCED_REQUIRE_MEMBER_TRAIT)
#if !defined(BOOST_ASIO_HAS_DEDUCED_PREFER_MEMBER_TRAIT)
template
struct prefer_member, Property,
typename enable_if<
can_prefer::value
>::type>
{
BOOST_ASIO_STATIC_CONSTEXPR(bool, is_valid = true);
BOOST_ASIO_STATIC_CONSTEXPR(bool, is_noexcept =
(is_nothrow_prefer::value));
typedef strand::type
>::type> result_type;
};
#endif // !defined(BOOST_ASIO_HAS_DEDUCED_PREFER_MEMBER_TRAIT)
} // namespace traits
#endif // !defined(GENERATING_DOCUMENTATION)
} // namespace asio
} // namespace boost
#include
// If both io_context.hpp and strand.hpp have been included, automatically
// include the header file needed for the io_context::strand class.
#if !defined(BOOST_ASIO_NO_EXTENSIONS)
# if defined(BOOST_ASIO_IO_CONTEXT_HPP)
# include
# endif // defined(BOOST_ASIO_IO_CONTEXT_HPP)
#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
#endif // BOOST_ASIO_STRAND_HPP