boost/asio/detail/win_iocp_io_service.hpp
// // win_iocp_io_service.hpp // ~~~~~~~~~~~~~~~~~~~~~~~ // // Copyright (c) 2003-2008 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_DETAIL_WIN_IOCP_IO_SERVICE_HPP #define BOOST_ASIO_DETAIL_WIN_IOCP_IO_SERVICE_HPP #if defined(_MSC_VER) && (_MSC_VER >= 1200) # pragma once #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) #include <boost/asio/detail/push_options.hpp> #include <boost/asio/detail/win_iocp_io_service_fwd.hpp> #if defined(BOOST_ASIO_HAS_IOCP) #include <boost/asio/detail/push_options.hpp> #include <limits> #include <boost/throw_exception.hpp> #include <boost/system/system_error.hpp> #include <boost/asio/detail/pop_options.hpp> #include <boost/asio/io_service.hpp> #include <boost/asio/detail/call_stack.hpp> #include <boost/asio/detail/handler_alloc_helpers.hpp> #include <boost/asio/detail/handler_invoke_helpers.hpp> #include <boost/asio/detail/service_base.hpp> #include <boost/asio/detail/socket_types.hpp> #include <boost/asio/detail/timer_queue.hpp> #include <boost/asio/detail/mutex.hpp> namespace boost { namespace asio { namespace detail { class win_iocp_io_service : public boost::asio::detail::service_base<win_iocp_io_service> { public: // Base class for all operations. A function pointer is used instead of // virtual functions to avoid the associated overhead. // // This class inherits from OVERLAPPED so that we can downcast to get back to // the operation pointer from the LPOVERLAPPED out parameter of // GetQueuedCompletionStatus. class operation : public OVERLAPPED { public: typedef void (*invoke_func_type)(operation*, DWORD, size_t); typedef void (*destroy_func_type)(operation*); operation(win_iocp_io_service& iocp_service, invoke_func_type invoke_func, destroy_func_type destroy_func) : outstanding_operations_(&iocp_service.outstanding_operations_), invoke_func_(invoke_func), destroy_func_(destroy_func) { Internal = 0; InternalHigh = 0; Offset = 0; OffsetHigh = 0; hEvent = 0; ::InterlockedIncrement(outstanding_operations_); } void do_completion(DWORD last_error, size_t bytes_transferred) { invoke_func_(this, last_error, bytes_transferred); } void destroy() { destroy_func_(this); } protected: // Prevent deletion through this type. ~operation() { ::InterlockedDecrement(outstanding_operations_); } private: long* outstanding_operations_; invoke_func_type invoke_func_; destroy_func_type destroy_func_; }; // Constructor. win_iocp_io_service(boost::asio::io_service& io_service) : boost::asio::detail::service_base<win_iocp_io_service>(io_service), iocp_(), outstanding_work_(0), outstanding_operations_(0), stopped_(0), shutdown_(0), timer_thread_(0), timer_interrupt_issued_(false) { } void init(size_t concurrency_hint) { iocp_.handle = ::CreateIoCompletionPort(INVALID_HANDLE_VALUE, 0, 0, static_cast<DWORD>((std::min<size_t>)(concurrency_hint, DWORD(~0)))); if (!iocp_.handle) { DWORD last_error = ::GetLastError(); boost::system::system_error e( boost::system::error_code(last_error, boost::asio::error::get_system_category()), "iocp"); boost::throw_exception(e); } } // Destroy all user-defined handler objects owned by the service. void shutdown_service() { ::InterlockedExchange(&shutdown_, 1); while (::InterlockedExchangeAdd(&outstanding_operations_, 0) > 0) { DWORD bytes_transferred = 0; #if (WINVER < 0x0500) DWORD completion_key = 0; #else DWORD_PTR completion_key = 0; #endif LPOVERLAPPED overlapped = 0; ::GetQueuedCompletionStatus(iocp_.handle, &bytes_transferred, &completion_key, &overlapped, INFINITE); if (overlapped) static_cast<operation*>(overlapped)->destroy(); } for (std::size_t i = 0; i < timer_queues_.size(); ++i) timer_queues_[i]->destroy_timers(); timer_queues_.clear(); } // Initialise the task. Nothing to do here. void init_task() { } // Register a handle with the IO completion port. boost::system::error_code register_handle( HANDLE handle, boost::system::error_code& ec) { if (::CreateIoCompletionPort(handle, iocp_.handle, 0, 0) == 0) { DWORD last_error = ::GetLastError(); ec = boost::system::error_code(last_error, boost::asio::error::get_system_category()); } else { ec = boost::system::error_code(); } return ec; } // Run the event loop until stopped or no more work. size_t run(boost::system::error_code& ec) { if (::InterlockedExchangeAdd(&outstanding_work_, 0) == 0) { ec = boost::system::error_code(); return 0; } call_stack<win_iocp_io_service>::context ctx(this); size_t n = 0; while (do_one(true, ec)) if (n != (std::numeric_limits<size_t>::max)()) ++n; return n; } // Run until stopped or one operation is performed. size_t run_one(boost::system::error_code& ec) { if (::InterlockedExchangeAdd(&outstanding_work_, 0) == 0) { ec = boost::system::error_code(); return 0; } call_stack<win_iocp_io_service>::context ctx(this); return do_one(true, ec); } // Poll for operations without blocking. size_t poll(boost::system::error_code& ec) { if (::InterlockedExchangeAdd(&outstanding_work_, 0) == 0) { ec = boost::system::error_code(); return 0; } call_stack<win_iocp_io_service>::context ctx(this); size_t n = 0; while (do_one(false, ec)) if (n != (std::numeric_limits<size_t>::max)()) ++n; return n; } // Poll for one operation without blocking. size_t poll_one(boost::system::error_code& ec) { if (::InterlockedExchangeAdd(&outstanding_work_, 0) == 0) { ec = boost::system::error_code(); return 0; } call_stack<win_iocp_io_service>::context ctx(this); return do_one(false, ec); } // Stop the event processing loop. void stop() { if (::InterlockedExchange(&stopped_, 1) == 0) { if (!::PostQueuedCompletionStatus(iocp_.handle, 0, 0, 0)) { DWORD last_error = ::GetLastError(); boost::system::system_error e( boost::system::error_code(last_error, boost::asio::error::get_system_category()), "pqcs"); boost::throw_exception(e); } } } // Reset in preparation for a subsequent run invocation. void reset() { ::InterlockedExchange(&stopped_, 0); } // Notify that some work has started. void work_started() { ::InterlockedIncrement(&outstanding_work_); } // Notify that some work has finished. void work_finished() { if (::InterlockedDecrement(&outstanding_work_) == 0) stop(); } // Request invocation of the given handler. template <typename Handler> void dispatch(Handler handler) { if (call_stack<win_iocp_io_service>::contains(this)) boost_asio_handler_invoke_helpers::invoke(handler, &handler); else post(handler); } // Request invocation of the given handler and return immediately. template <typename Handler> void post(Handler handler) { // If the service has been shut down we silently discard the handler. if (::InterlockedExchangeAdd(&shutdown_, 0) != 0) return; // Allocate and construct an operation to wrap the handler. typedef handler_operation<Handler> value_type; typedef handler_alloc_traits<Handler, value_type> alloc_traits; raw_handler_ptr<alloc_traits> raw_ptr(handler); handler_ptr<alloc_traits> ptr(raw_ptr, *this, handler); // Enqueue the operation on the I/O completion port. if (!::PostQueuedCompletionStatus(iocp_.handle, 0, 0, ptr.get())) { DWORD last_error = ::GetLastError(); boost::system::system_error e( boost::system::error_code(last_error, boost::asio::error::get_system_category()), "pqcs"); boost::throw_exception(e); } // Operation has been successfully posted. ptr.release(); } // Request invocation of the given OVERLAPPED-derived operation. void post_completion(operation* op, DWORD op_last_error, DWORD bytes_transferred) { // Enqueue the operation on the I/O completion port. if (!::PostQueuedCompletionStatus(iocp_.handle, bytes_transferred, op_last_error, op)) { DWORD last_error = ::GetLastError(); boost::system::system_error e( boost::system::error_code(last_error, boost::asio::error::get_system_category()), "pqcs"); boost::throw_exception(e); } } // Add a new timer queue to the service. template <typename Time_Traits> void add_timer_queue(timer_queue<Time_Traits>& timer_queue) { boost::asio::detail::mutex::scoped_lock lock(timer_mutex_); timer_queues_.push_back(&timer_queue); } // Remove a timer queue from the service. template <typename Time_Traits> void remove_timer_queue(timer_queue<Time_Traits>& timer_queue) { boost::asio::detail::mutex::scoped_lock lock(timer_mutex_); for (std::size_t i = 0; i < timer_queues_.size(); ++i) { if (timer_queues_[i] == &timer_queue) { timer_queues_.erase(timer_queues_.begin() + i); return; } } } // Schedule a timer in the given timer queue to expire at the specified // absolute time. The handler object will be invoked when the timer expires. template <typename Time_Traits, typename Handler> void schedule_timer(timer_queue<Time_Traits>& timer_queue, const typename Time_Traits::time_type& time, Handler handler, void* token) { // If the service has been shut down we silently discard the timer. if (::InterlockedExchangeAdd(&shutdown_, 0) != 0) return; boost::asio::detail::mutex::scoped_lock lock(timer_mutex_); if (timer_queue.enqueue_timer(time, handler, token)) { if (!timer_interrupt_issued_) { timer_interrupt_issued_ = true; lock.unlock(); ::PostQueuedCompletionStatus(iocp_.handle, 0, steal_timer_dispatching, 0); } } } // Cancel the timer associated with the given token. Returns the number of // handlers that have been posted or dispatched. template <typename Time_Traits> std::size_t cancel_timer(timer_queue<Time_Traits>& timer_queue, void* token) { // If the service has been shut down we silently ignore the cancellation. if (::InterlockedExchangeAdd(&shutdown_, 0) != 0) return 0; boost::asio::detail::mutex::scoped_lock lock(timer_mutex_); std::size_t n = timer_queue.cancel_timer(token); if (n > 0 && !timer_interrupt_issued_) { timer_interrupt_issued_ = true; lock.unlock(); ::PostQueuedCompletionStatus(iocp_.handle, 0, steal_timer_dispatching, 0); } return n; } private: // Dequeues at most one operation from the I/O completion port, and then // executes it. Returns the number of operations that were dequeued (i.e. // either 0 or 1). size_t do_one(bool block, boost::system::error_code& ec) { long this_thread_id = static_cast<long>(::GetCurrentThreadId()); for (;;) { // Try to acquire responsibility for dispatching timers. bool dispatching_timers = (::InterlockedCompareExchange( &timer_thread_, this_thread_id, 0) == 0); // Calculate timeout for GetQueuedCompletionStatus call. DWORD timeout = max_timeout; if (dispatching_timers) { boost::asio::detail::mutex::scoped_lock lock(timer_mutex_); timer_interrupt_issued_ = false; timeout = get_timeout(); } // Get the next operation from the queue. DWORD bytes_transferred = 0; #if (WINVER < 0x0500) DWORD completion_key = 0; #else DWORD_PTR completion_key = 0; #endif LPOVERLAPPED overlapped = 0; ::SetLastError(0); BOOL ok = ::GetQueuedCompletionStatus(iocp_.handle, &bytes_transferred, &completion_key, &overlapped, block ? timeout : 0); DWORD last_error = ::GetLastError(); // Dispatch any pending timers. if (dispatching_timers) { try { boost::asio::detail::mutex::scoped_lock lock(timer_mutex_); timer_queues_copy_ = timer_queues_; for (std::size_t i = 0; i < timer_queues_copy_.size(); ++i) { timer_queues_copy_[i]->dispatch_timers(); timer_queues_copy_[i]->dispatch_cancellations(); timer_queues_copy_[i]->complete_timers(); } } catch (...) { // Transfer responsibility for dispatching timers to another thread. if (::InterlockedCompareExchange(&timer_thread_, 0, this_thread_id) == this_thread_id) { ::PostQueuedCompletionStatus(iocp_.handle, 0, transfer_timer_dispatching, 0); } throw; } } if (!ok && overlapped == 0) { if (block && last_error == WAIT_TIMEOUT) { // Relinquish responsibility for dispatching timers. if (dispatching_timers) { ::InterlockedCompareExchange(&timer_thread_, 0, this_thread_id); } continue; } // Transfer responsibility for dispatching timers to another thread. if (dispatching_timers && ::InterlockedCompareExchange( &timer_thread_, 0, this_thread_id) == this_thread_id) { ::PostQueuedCompletionStatus(iocp_.handle, 0, transfer_timer_dispatching, 0); } ec = boost::system::error_code(); return 0; } else if (overlapped) { // We may have been passed a last_error value in the completion_key. if (last_error == 0) { last_error = completion_key; } // Transfer responsibility for dispatching timers to another thread. if (dispatching_timers && ::InterlockedCompareExchange( &timer_thread_, 0, this_thread_id) == this_thread_id) { ::PostQueuedCompletionStatus(iocp_.handle, 0, transfer_timer_dispatching, 0); } // Ensure that the io_service does not exit due to running out of work // while we make the upcall. auto_work work(*this); // Dispatch the operation. operation* op = static_cast<operation*>(overlapped); op->do_completion(last_error, bytes_transferred); ec = boost::system::error_code(); return 1; } else if (completion_key == transfer_timer_dispatching) { // Woken up to try to acquire responsibility for dispatching timers. ::InterlockedCompareExchange(&timer_thread_, 0, this_thread_id); } else if (completion_key == steal_timer_dispatching) { // Woken up to steal responsibility for dispatching timers. ::InterlockedExchange(&timer_thread_, 0); } else { // Relinquish responsibility for dispatching timers. If the io_service // is not being stopped then the thread will get an opportunity to // reacquire timer responsibility on the next loop iteration. if (dispatching_timers) { ::InterlockedCompareExchange(&timer_thread_, 0, this_thread_id); } // The stopped_ flag is always checked to ensure that any leftover // interrupts from a previous run invocation are ignored. if (::InterlockedExchangeAdd(&stopped_, 0) != 0) { // Wake up next thread that is blocked on GetQueuedCompletionStatus. if (!::PostQueuedCompletionStatus(iocp_.handle, 0, 0, 0)) { last_error = ::GetLastError(); ec = boost::system::error_code(last_error, boost::asio::error::get_system_category()); return 0; } ec = boost::system::error_code(); return 0; } } } } // Check if all timer queues are empty. bool all_timer_queues_are_empty() const { for (std::size_t i = 0; i < timer_queues_.size(); ++i) if (!timer_queues_[i]->empty()) return false; return true; } // Get the timeout value for the GetQueuedCompletionStatus call. The timeout // value is returned as a number of milliseconds. We will wait no longer than // 1000 milliseconds. DWORD get_timeout() { if (all_timer_queues_are_empty()) return max_timeout; boost::posix_time::time_duration minimum_wait_duration = boost::posix_time::milliseconds(max_timeout); for (std::size_t i = 0; i < timer_queues_.size(); ++i) { boost::posix_time::time_duration wait_duration = timer_queues_[i]->wait_duration(); if (wait_duration < minimum_wait_duration) minimum_wait_duration = wait_duration; } if (minimum_wait_duration > boost::posix_time::time_duration()) { int milliseconds = minimum_wait_duration.total_milliseconds(); return static_cast<DWORD>(milliseconds > 0 ? milliseconds : 1); } else { return 0; } } struct auto_work { auto_work(win_iocp_io_service& io_service) : io_service_(io_service) { io_service_.work_started(); } ~auto_work() { io_service_.work_finished(); } private: win_iocp_io_service& io_service_; }; template <typename Handler> struct handler_operation : public operation { handler_operation(win_iocp_io_service& io_service, Handler handler) : operation(io_service, &handler_operation<Handler>::do_completion_impl, &handler_operation<Handler>::destroy_impl), io_service_(io_service), handler_(handler) { io_service_.work_started(); } ~handler_operation() { io_service_.work_finished(); } private: // Prevent copying and assignment. handler_operation(const handler_operation&); void operator=(const handler_operation&); static void do_completion_impl(operation* op, DWORD, size_t) { // Take ownership of the operation object. typedef handler_operation<Handler> op_type; op_type* handler_op(static_cast<op_type*>(op)); typedef handler_alloc_traits<Handler, op_type> alloc_traits; handler_ptr<alloc_traits> ptr(handler_op->handler_, handler_op); // Make a copy of the handler so that the memory can be deallocated before // the upcall is made. Handler handler(handler_op->handler_); // Free the memory associated with the handler. ptr.reset(); // Make the upcall. boost_asio_handler_invoke_helpers::invoke(handler, &handler); } static void destroy_impl(operation* op) { // Take ownership of the operation object. typedef handler_operation<Handler> op_type; op_type* handler_op(static_cast<op_type*>(op)); typedef handler_alloc_traits<Handler, op_type> alloc_traits; handler_ptr<alloc_traits> ptr(handler_op->handler_, handler_op); // A sub-object of the handler may be the true owner of the memory // associated with the handler. Consequently, a local copy of the handler // is required to ensure that any owning sub-object remains valid until // after we have deallocated the memory here. Handler handler(handler_op->handler_); (void)handler; // Free the memory associated with the handler. ptr.reset(); } win_iocp_io_service& io_service_; Handler handler_; }; // The IO completion port used for queueing operations. struct iocp_holder { HANDLE handle; iocp_holder() : handle(0) {} ~iocp_holder() { if (handle) ::CloseHandle(handle); } } iocp_; // The count of unfinished work. long outstanding_work_; // The count of unfinished operations. long outstanding_operations_; friend class operation; // Flag to indicate whether the event loop has been stopped. long stopped_; // Flag to indicate whether the service has been shut down. long shutdown_; enum { // Maximum GetQueuedCompletionStatus timeout, in milliseconds. max_timeout = 500, // Completion key value to indicate that responsibility for dispatching // timers is being cooperatively transferred from one thread to another. transfer_timer_dispatching = 1, // Completion key value to indicate that responsibility for dispatching // timers should be stolen from another thread. steal_timer_dispatching = 2 }; // The thread that's currently in charge of dispatching timers. long timer_thread_; // Mutex for protecting access to the timer queues. mutex timer_mutex_; // Whether a thread has been interrupted to process a new timeout. bool timer_interrupt_issued_; // The timer queues. std::vector<timer_queue_base*> timer_queues_; // A copy of the timer queues, used when dispatching, cancelling and cleaning // up timers. The copy is stored as a class data member to avoid unnecessary // memory allocation. std::vector<timer_queue_base*> timer_queues_copy_; }; } // namespace detail } // namespace asio } // namespace boost #endif // defined(BOOST_ASIO_HAS_IOCP) #include <boost/asio/detail/pop_options.hpp> #endif // BOOST_ASIO_DETAIL_WIN_IOCP_IO_SERVICE_HPP