/usr/include/asio/detail/win_iocp_io_service.hpp is in libasio-dev 1.4.1-3ubuntu2.
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// 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 ASIO_DETAIL_WIN_IOCP_IO_SERVICE_HPP
#define ASIO_DETAIL_WIN_IOCP_IO_SERVICE_HPP
#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
#include "asio/detail/push_options.hpp"
#include "asio/detail/win_iocp_io_service_fwd.hpp"
#if defined(ASIO_HAS_IOCP)
#include "asio/detail/push_options.hpp"
#include <limits>
#include <boost/throw_exception.hpp>
#include "asio/detail/pop_options.hpp"
#include "asio/io_service.hpp"
#include "asio/system_error.hpp"
#include "asio/detail/call_stack.hpp"
#include "asio/detail/handler_alloc_helpers.hpp"
#include "asio/detail/handler_invoke_helpers.hpp"
#include "asio/detail/service_base.hpp"
#include "asio/detail/socket_types.hpp"
#include "asio/detail/timer_queue.hpp"
#include "asio/detail/mutex.hpp"
namespace asio {
namespace detail {
class win_iocp_io_service
: public 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(asio::io_service& io_service)
: 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();
asio::system_error e(
asio::error_code(last_error,
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.
asio::error_code register_handle(
HANDLE handle, asio::error_code& ec)
{
if (::CreateIoCompletionPort(handle, iocp_.handle, 0, 0) == 0)
{
DWORD last_error = ::GetLastError();
ec = asio::error_code(last_error,
asio::error::get_system_category());
}
else
{
ec = asio::error_code();
}
return ec;
}
// Run the event loop until stopped or no more work.
size_t run(asio::error_code& ec)
{
if (::InterlockedExchangeAdd(&outstanding_work_, 0) == 0)
{
ec = asio::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(asio::error_code& ec)
{
if (::InterlockedExchangeAdd(&outstanding_work_, 0) == 0)
{
ec = asio::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(asio::error_code& ec)
{
if (::InterlockedExchangeAdd(&outstanding_work_, 0) == 0)
{
ec = asio::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(asio::error_code& ec)
{
if (::InterlockedExchangeAdd(&outstanding_work_, 0) == 0)
{
ec = asio::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();
asio::system_error e(
asio::error_code(last_error,
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))
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();
asio::system_error e(
asio::error_code(last_error,
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();
asio::system_error e(
asio::error_code(last_error,
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)
{
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)
{
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;
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;
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, asio::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)
{
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
{
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 = asio::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 = asio::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 = asio::error_code(last_error,
asio::error::get_system_category());
return 0;
}
ec = asio::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.
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
#endif // defined(ASIO_HAS_IOCP)
#include "asio/detail/pop_options.hpp"
#endif // ASIO_DETAIL_WIN_IOCP_IO_SERVICE_HPP
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