ecency-mobile/ios/Pods/boost-for-react-native/boost/asio/io_service.hpp

773 lines
28 KiB
C++

//
// io_service.hpp
// ~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2016 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_IO_SERVICE_HPP
#define BOOST_ASIO_IO_SERVICE_HPP
#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
#include <boost/asio/detail/config.hpp>
#include <cstddef>
#include <stdexcept>
#include <typeinfo>
#include <boost/asio/async_result.hpp>
#include <boost/asio/detail/noncopyable.hpp>
#include <boost/asio/detail/wrapped_handler.hpp>
#include <boost/system/error_code.hpp>
#if defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
# include <boost/asio/detail/winsock_init.hpp>
#elif defined(__sun) || defined(__QNX__) || defined(__hpux) || defined(_AIX) \
|| defined(__osf__)
# include <boost/asio/detail/signal_init.hpp>
#endif
#include <boost/asio/detail/push_options.hpp>
namespace boost {
namespace asio {
class io_service;
template <typename Service> Service& use_service(io_service& ios);
template <typename Service> void add_service(io_service& ios, Service* svc);
template <typename Service> bool has_service(io_service& ios);
namespace detail {
#if defined(BOOST_ASIO_HAS_IOCP)
typedef class win_iocp_io_service io_service_impl;
class win_iocp_overlapped_ptr;
#else
typedef class task_io_service io_service_impl;
#endif
class service_registry;
} // namespace detail
/// Provides core I/O functionality.
/**
* The io_service class provides the core I/O functionality for users of the
* asynchronous I/O objects, including:
*
* @li boost::asio::ip::tcp::socket
* @li boost::asio::ip::tcp::acceptor
* @li boost::asio::ip::udp::socket
* @li boost::asio::deadline_timer.
*
* The io_service class also includes facilities intended for developers of
* custom asynchronous services.
*
* @par Thread Safety
* @e Distinct @e objects: Safe.@n
* @e Shared @e objects: Safe, with the specific exceptions of the reset() and
* notify_fork() functions. Calling reset() while there are unfinished run(),
* run_one(), poll() or poll_one() calls results in undefined behaviour. The
* notify_fork() function should not be called while any io_service function,
* or any function on an I/O object that is associated with the io_service, is
* being called in another thread.
*
* @par Concepts:
* Dispatcher.
*
* @par Synchronous and asynchronous operations
*
* Synchronous operations on I/O objects implicitly run the io_service object
* for an individual operation. The io_service functions run(), run_one(),
* poll() or poll_one() must be called for the io_service to perform
* asynchronous operations on behalf of a C++ program. Notification that an
* asynchronous operation has completed is delivered by invocation of the
* associated handler. Handlers are invoked only by a thread that is currently
* calling any overload of run(), run_one(), poll() or poll_one() for the
* io_service.
*
* @par Effect of exceptions thrown from handlers
*
* If an exception is thrown from a handler, the exception is allowed to
* propagate through the throwing thread's invocation of run(), run_one(),
* poll() or poll_one(). No other threads that are calling any of these
* functions are affected. It is then the responsibility of the application to
* catch the exception.
*
* After the exception has been caught, the run(), run_one(), poll() or
* poll_one() call may be restarted @em without the need for an intervening
* call to reset(). This allows the thread to rejoin the io_service object's
* thread pool without impacting any other threads in the pool.
*
* For example:
*
* @code
* boost::asio::io_service io_service;
* ...
* for (;;)
* {
* try
* {
* io_service.run();
* break; // run() exited normally
* }
* catch (my_exception& e)
* {
* // Deal with exception as appropriate.
* }
* }
* @endcode
*
* @par Stopping the io_service from running out of work
*
* Some applications may need to prevent an io_service object's run() call from
* returning when there is no more work to do. For example, the io_service may
* be being run in a background thread that is launched prior to the
* application's asynchronous operations. The run() call may be kept running by
* creating an object of type boost::asio::io_service::work:
*
* @code boost::asio::io_service io_service;
* boost::asio::io_service::work work(io_service);
* ... @endcode
*
* To effect a shutdown, the application will then need to call the io_service
* object's stop() member function. This will cause the io_service run() call
* to return as soon as possible, abandoning unfinished operations and without
* permitting ready handlers to be dispatched.
*
* Alternatively, if the application requires that all operations and handlers
* be allowed to finish normally, the work object may be explicitly destroyed.
*
* @code boost::asio::io_service io_service;
* auto_ptr<boost::asio::io_service::work> work(
* new boost::asio::io_service::work(io_service));
* ...
* work.reset(); // Allow run() to exit. @endcode
*
* @par The io_service class and I/O services
*
* Class io_service implements an extensible, type-safe, polymorphic set of I/O
* services, indexed by service type. An object of class io_service must be
* initialised before I/O objects such as sockets, resolvers and timers can be
* used. These I/O objects are distinguished by having constructors that accept
* an @c io_service& parameter.
*
* I/O services exist to manage the logical interface to the operating system on
* behalf of the I/O objects. In particular, there are resources that are shared
* across a class of I/O objects. For example, timers may be implemented in
* terms of a single timer queue. The I/O services manage these shared
* resources.
*
* Access to the services of an io_service is via three function templates,
* use_service(), add_service() and has_service().
*
* In a call to @c use_service<Service>(), the type argument chooses a service,
* making available all members of the named type. If @c Service is not present
* in an io_service, an object of type @c Service is created and added to the
* io_service. A C++ program can check if an io_service implements a
* particular service with the function template @c has_service<Service>().
*
* Service objects may be explicitly added to an io_service using the function
* template @c add_service<Service>(). If the @c Service is already present, the
* service_already_exists exception is thrown. If the owner of the service is
* not the same object as the io_service parameter, the invalid_service_owner
* exception is thrown.
*
* Once a service reference is obtained from an io_service object by calling
* use_service(), that reference remains usable as long as the owning io_service
* object exists.
*
* All I/O service implementations have io_service::service as a public base
* class. Custom I/O services may be implemented by deriving from this class and
* then added to an io_service using the facilities described above.
*/
class io_service
: private noncopyable
{
private:
typedef detail::io_service_impl impl_type;
#if defined(BOOST_ASIO_HAS_IOCP)
friend class detail::win_iocp_overlapped_ptr;
#endif
public:
class work;
friend class work;
class id;
class service;
class strand;
/// Constructor.
BOOST_ASIO_DECL io_service();
/// Constructor.
/**
* Construct with a hint about the required level of concurrency.
*
* @param concurrency_hint A suggestion to the implementation on how many
* threads it should allow to run simultaneously.
*/
BOOST_ASIO_DECL explicit io_service(std::size_t concurrency_hint);
/// Destructor.
/**
* On destruction, the io_service performs the following sequence of
* operations:
*
* @li For each service object @c svc in the io_service set, in reverse order
* of the beginning of service object lifetime, performs
* @c svc->shutdown_service().
*
* @li Uninvoked handler objects that were scheduled for deferred invocation
* on the io_service, or any associated strand, are destroyed.
*
* @li For each service object @c svc in the io_service set, in reverse order
* of the beginning of service object lifetime, performs
* <tt>delete static_cast<io_service::service*>(svc)</tt>.
*
* @note The destruction sequence described above permits programs to
* simplify their resource management by using @c shared_ptr<>. Where an
* object's lifetime is tied to the lifetime of a connection (or some other
* sequence of asynchronous operations), a @c shared_ptr to the object would
* be bound into the handlers for all asynchronous operations associated with
* it. This works as follows:
*
* @li When a single connection ends, all associated asynchronous operations
* complete. The corresponding handler objects are destroyed, and all
* @c shared_ptr references to the objects are destroyed.
*
* @li To shut down the whole program, the io_service function stop() is
* called to terminate any run() calls as soon as possible. The io_service
* destructor defined above destroys all handlers, causing all @c shared_ptr
* references to all connection objects to be destroyed.
*/
BOOST_ASIO_DECL ~io_service();
/// Run the io_service object's event processing loop.
/**
* The run() function blocks until all work has finished and there are no
* more handlers to be dispatched, or until the io_service has been stopped.
*
* Multiple threads may call the run() function to set up a pool of threads
* from which the io_service may execute handlers. All threads that are
* waiting in the pool are equivalent and the io_service may choose any one
* of them to invoke a handler.
*
* A normal exit from the run() function implies that the io_service object
* is stopped (the stopped() function returns @c true). Subsequent calls to
* run(), run_one(), poll() or poll_one() will return immediately unless there
* is a prior call to reset().
*
* @return The number of handlers that were executed.
*
* @throws boost::system::system_error Thrown on failure.
*
* @note The run() function must not be called from a thread that is currently
* calling one of run(), run_one(), poll() or poll_one() on the same
* io_service object.
*
* The poll() function may also be used to dispatch ready handlers, but
* without blocking.
*/
BOOST_ASIO_DECL std::size_t run();
/// Run the io_service object's event processing loop.
/**
* The run() function blocks until all work has finished and there are no
* more handlers to be dispatched, or until the io_service has been stopped.
*
* Multiple threads may call the run() function to set up a pool of threads
* from which the io_service may execute handlers. All threads that are
* waiting in the pool are equivalent and the io_service may choose any one
* of them to invoke a handler.
*
* A normal exit from the run() function implies that the io_service object
* is stopped (the stopped() function returns @c true). Subsequent calls to
* run(), run_one(), poll() or poll_one() will return immediately unless there
* is a prior call to reset().
*
* @param ec Set to indicate what error occurred, if any.
*
* @return The number of handlers that were executed.
*
* @note The run() function must not be called from a thread that is currently
* calling one of run(), run_one(), poll() or poll_one() on the same
* io_service object.
*
* The poll() function may also be used to dispatch ready handlers, but
* without blocking.
*/
BOOST_ASIO_DECL std::size_t run(boost::system::error_code& ec);
/// Run the io_service object's event processing loop to execute at most one
/// handler.
/**
* The run_one() function blocks until one handler has been dispatched, or
* until the io_service has been stopped.
*
* @return The number of handlers that were executed. A zero return value
* implies that the io_service object is stopped (the stopped() function
* returns @c true). Subsequent calls to run(), run_one(), poll() or
* poll_one() will return immediately unless there is a prior call to
* reset().
*
* @throws boost::system::system_error Thrown on failure.
*/
BOOST_ASIO_DECL std::size_t run_one();
/// Run the io_service object's event processing loop to execute at most one
/// handler.
/**
* The run_one() function blocks until one handler has been dispatched, or
* until the io_service has been stopped.
*
* @return The number of handlers that were executed. A zero return value
* implies that the io_service object is stopped (the stopped() function
* returns @c true). Subsequent calls to run(), run_one(), poll() or
* poll_one() will return immediately unless there is a prior call to
* reset().
*
* @return The number of handlers that were executed.
*/
BOOST_ASIO_DECL std::size_t run_one(boost::system::error_code& ec);
/// Run the io_service object's event processing loop to execute ready
/// handlers.
/**
* The poll() function runs handlers that are ready to run, without blocking,
* until the io_service has been stopped or there are no more ready handlers.
*
* @return The number of handlers that were executed.
*
* @throws boost::system::system_error Thrown on failure.
*/
BOOST_ASIO_DECL std::size_t poll();
/// Run the io_service object's event processing loop to execute ready
/// handlers.
/**
* The poll() function runs handlers that are ready to run, without blocking,
* until the io_service has been stopped or there are no more ready handlers.
*
* @param ec Set to indicate what error occurred, if any.
*
* @return The number of handlers that were executed.
*/
BOOST_ASIO_DECL std::size_t poll(boost::system::error_code& ec);
/// Run the io_service object's event processing loop to execute one ready
/// handler.
/**
* The poll_one() function runs at most one handler that is ready to run,
* without blocking.
*
* @return The number of handlers that were executed.
*
* @throws boost::system::system_error Thrown on failure.
*/
BOOST_ASIO_DECL std::size_t poll_one();
/// Run the io_service object's event processing loop to execute one ready
/// handler.
/**
* The poll_one() function runs at most one handler that is ready to run,
* without blocking.
*
* @param ec Set to indicate what error occurred, if any.
*
* @return The number of handlers that were executed.
*/
BOOST_ASIO_DECL std::size_t poll_one(boost::system::error_code& ec);
/// Stop the io_service object's event processing loop.
/**
* This function does not block, but instead simply signals the io_service to
* stop. All invocations of its run() or run_one() member functions should
* return as soon as possible. Subsequent calls to run(), run_one(), poll()
* or poll_one() will return immediately until reset() is called.
*/
BOOST_ASIO_DECL void stop();
/// Determine whether the io_service object has been stopped.
/**
* This function is used to determine whether an io_service object has been
* stopped, either through an explicit call to stop(), or due to running out
* of work. When an io_service object is stopped, calls to run(), run_one(),
* poll() or poll_one() will return immediately without invoking any
* handlers.
*
* @return @c true if the io_service object is stopped, otherwise @c false.
*/
BOOST_ASIO_DECL bool stopped() const;
/// Reset the io_service in preparation for a subsequent run() invocation.
/**
* This function must be called prior to any second or later set of
* invocations of the run(), run_one(), poll() or poll_one() functions when a
* previous invocation of these functions returned due to the io_service
* being stopped or running out of work. After a call to reset(), the
* io_service object's stopped() function will return @c false.
*
* This function must not be called while there are any unfinished calls to
* the run(), run_one(), poll() or poll_one() functions.
*/
BOOST_ASIO_DECL void reset();
/// Request the io_service to invoke the given handler.
/**
* This function is used to ask the io_service to execute the given handler.
*
* The io_service guarantees that the handler will only be called in a thread
* in which the run(), run_one(), poll() or poll_one() member functions is
* currently being invoked. The handler may be executed inside this function
* if the guarantee can be met.
*
* @param handler The handler to be called. The io_service will make
* a copy of the handler object as required. The function signature of the
* handler must be: @code void handler(); @endcode
*
* @note This function throws an exception only if:
*
* @li the handler's @c asio_handler_allocate function; or
*
* @li the handler's copy constructor
*
* throws an exception.
*/
template <typename CompletionHandler>
BOOST_ASIO_INITFN_RESULT_TYPE(CompletionHandler, void ())
dispatch(BOOST_ASIO_MOVE_ARG(CompletionHandler) handler);
/// Request the io_service to invoke the given handler and return immediately.
/**
* This function is used to ask the io_service to execute the given handler,
* but without allowing the io_service to call the handler from inside this
* function.
*
* The io_service guarantees that the handler will only be called in a thread
* in which the run(), run_one(), poll() or poll_one() member functions is
* currently being invoked.
*
* @param handler The handler to be called. The io_service will make
* a copy of the handler object as required. The function signature of the
* handler must be: @code void handler(); @endcode
*
* @note This function throws an exception only if:
*
* @li the handler's @c asio_handler_allocate function; or
*
* @li the handler's copy constructor
*
* throws an exception.
*/
template <typename CompletionHandler>
BOOST_ASIO_INITFN_RESULT_TYPE(CompletionHandler, void ())
post(BOOST_ASIO_MOVE_ARG(CompletionHandler) handler);
/// Create a new handler that automatically dispatches the wrapped handler
/// on the io_service.
/**
* This function is used to create a new handler function object that, when
* invoked, will automatically pass the wrapped handler to the io_service
* object's dispatch function.
*
* @param handler The handler to be wrapped. The io_service will make a copy
* of the handler object as required. The function signature of the handler
* must be: @code void handler(A1 a1, ... An an); @endcode
*
* @return A function object that, when invoked, passes the wrapped handler to
* the io_service object's dispatch function. Given a function object with the
* signature:
* @code R f(A1 a1, ... An an); @endcode
* If this function object is passed to the wrap function like so:
* @code io_service.wrap(f); @endcode
* then the return value is a function object with the signature
* @code void g(A1 a1, ... An an); @endcode
* that, when invoked, executes code equivalent to:
* @code io_service.dispatch(boost::bind(f, a1, ... an)); @endcode
*/
template <typename Handler>
#if defined(GENERATING_DOCUMENTATION)
unspecified
#else
detail::wrapped_handler<io_service&, Handler>
#endif
wrap(Handler handler);
/// Fork-related event notifications.
enum fork_event
{
/// Notify the io_service that the process is about to fork.
fork_prepare,
/// Notify the io_service that the process has forked and is the parent.
fork_parent,
/// Notify the io_service that the process has forked and is the child.
fork_child
};
/// Notify the io_service of a fork-related event.
/**
* This function is used to inform the io_service that the process is about
* to fork, or has just forked. This allows the io_service, and the services
* it contains, to perform any necessary housekeeping to ensure correct
* operation following a fork.
*
* This function must not be called while any other io_service function, or
* any function on an I/O object associated with the io_service, is being
* called in another thread. It is, however, safe to call this function from
* within a completion handler, provided no other thread is accessing the
* io_service.
*
* @param event A fork-related event.
*
* @throws boost::system::system_error Thrown on failure. If the notification
* fails the io_service object should no longer be used and should be
* destroyed.
*
* @par Example
* The following code illustrates how to incorporate the notify_fork()
* function:
* @code my_io_service.notify_fork(boost::asio::io_service::fork_prepare);
* if (fork() == 0)
* {
* // This is the child process.
* my_io_service.notify_fork(boost::asio::io_service::fork_child);
* }
* else
* {
* // This is the parent process.
* my_io_service.notify_fork(boost::asio::io_service::fork_parent);
* } @endcode
*
* @note For each service object @c svc in the io_service set, performs
* <tt>svc->fork_service();</tt>. When processing the fork_prepare event,
* services are visited in reverse order of the beginning of service object
* lifetime. Otherwise, services are visited in order of the beginning of
* service object lifetime.
*/
BOOST_ASIO_DECL void notify_fork(boost::asio::io_service::fork_event event);
/// Obtain the service object corresponding to the given type.
/**
* This function is used to locate a service object that corresponds to
* the given service type. If there is no existing implementation of the
* service, then the io_service will create a new instance of the service.
*
* @param ios The io_service object that owns the service.
*
* @return The service interface implementing the specified service type.
* Ownership of the service interface is not transferred to the caller.
*/
template <typename Service>
friend Service& use_service(io_service& ios);
/// Add a service object to the io_service.
/**
* This function is used to add a service to the io_service.
*
* @param ios The io_service object that owns the service.
*
* @param svc The service object. On success, ownership of the service object
* is transferred to the io_service. When the io_service object is destroyed,
* it will destroy the service object by performing:
* @code delete static_cast<io_service::service*>(svc) @endcode
*
* @throws boost::asio::service_already_exists Thrown if a service of the
* given type is already present in the io_service.
*
* @throws boost::asio::invalid_service_owner Thrown if the service's owning
* io_service is not the io_service object specified by the ios parameter.
*/
template <typename Service>
friend void add_service(io_service& ios, Service* svc);
/// Determine if an io_service contains a specified service type.
/**
* This function is used to determine whether the io_service contains a
* service object corresponding to the given service type.
*
* @param ios The io_service object that owns the service.
*
* @return A boolean indicating whether the io_service contains the service.
*/
template <typename Service>
friend bool has_service(io_service& ios);
private:
#if defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
detail::winsock_init<> init_;
#elif defined(__sun) || defined(__QNX__) || defined(__hpux) || defined(_AIX) \
|| defined(__osf__)
detail::signal_init<> init_;
#endif
// The service registry.
boost::asio::detail::service_registry* service_registry_;
// The implementation.
impl_type& impl_;
};
/// Class to inform the io_service when it has work to do.
/**
* The work class is used to inform the io_service when work starts and
* finishes. This ensures that the io_service object's run() function will not
* exit while work is underway, and that it does exit when there is no
* unfinished work remaining.
*
* The work class is copy-constructible so that it may be used as a data member
* in a handler class. It is not assignable.
*/
class io_service::work
{
public:
/// Constructor notifies the io_service that work is starting.
/**
* The constructor is used to inform the io_service that some work has begun.
* This ensures that the io_service object's run() function will not exit
* while the work is underway.
*/
explicit work(boost::asio::io_service& io_service);
/// Copy constructor notifies the io_service that work is starting.
/**
* The constructor is used to inform the io_service that some work has begun.
* This ensures that the io_service object's run() function will not exit
* while the work is underway.
*/
work(const work& other);
/// Destructor notifies the io_service that the work is complete.
/**
* The destructor is used to inform the io_service that some work has
* finished. Once the count of unfinished work reaches zero, the io_service
* object's run() function is permitted to exit.
*/
~work();
/// Get the io_service associated with the work.
boost::asio::io_service& get_io_service();
private:
// Prevent assignment.
void operator=(const work& other);
// The io_service implementation.
detail::io_service_impl& io_service_impl_;
};
/// Class used to uniquely identify a service.
class io_service::id
: private noncopyable
{
public:
/// Constructor.
id() {}
};
/// Base class for all io_service services.
class io_service::service
: private noncopyable
{
public:
/// Get the io_service object that owns the service.
boost::asio::io_service& get_io_service();
protected:
/// Constructor.
/**
* @param owner The io_service object that owns the service.
*/
BOOST_ASIO_DECL service(boost::asio::io_service& owner);
/// Destructor.
BOOST_ASIO_DECL virtual ~service();
private:
/// Destroy all user-defined handler objects owned by the service.
virtual void shutdown_service() = 0;
/// Handle notification of a fork-related event to perform any necessary
/// housekeeping.
/**
* This function is not a pure virtual so that services only have to
* implement it if necessary. The default implementation does nothing.
*/
BOOST_ASIO_DECL virtual void fork_service(
boost::asio::io_service::fork_event event);
friend class boost::asio::detail::service_registry;
struct key
{
key() : type_info_(0), id_(0) {}
const std::type_info* type_info_;
const boost::asio::io_service::id* id_;
} key_;
boost::asio::io_service& owner_;
service* next_;
};
/// Exception thrown when trying to add a duplicate service to an io_service.
class service_already_exists
: public std::logic_error
{
public:
BOOST_ASIO_DECL service_already_exists();
};
/// Exception thrown when trying to add a service object to an io_service where
/// the service has a different owner.
class invalid_service_owner
: public std::logic_error
{
public:
BOOST_ASIO_DECL invalid_service_owner();
};
namespace detail {
// Special derived service id type to keep classes header-file only.
template <typename Type>
class service_id
: public boost::asio::io_service::id
{
};
// Special service base class to keep classes header-file only.
template <typename Type>
class service_base
: public boost::asio::io_service::service
{
public:
static boost::asio::detail::service_id<Type> id;
// Constructor.
service_base(boost::asio::io_service& io_service)
: boost::asio::io_service::service(io_service)
{
}
};
template <typename Type>
boost::asio::detail::service_id<Type> service_base<Type>::id;
} // namespace detail
} // namespace asio
} // namespace boost
#include <boost/asio/detail/pop_options.hpp>
#include <boost/asio/impl/io_service.hpp>
#if defined(BOOST_ASIO_HEADER_ONLY)
# include <boost/asio/impl/io_service.ipp>
#endif // defined(BOOST_ASIO_HEADER_ONLY)
#endif // BOOST_ASIO_IO_SERVICE_HPP