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request_operations.hpp
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1 /***************************************************************************
2  * foxxll/io/request_operations.hpp
3  *
4  * Part of FOXXLL. See http://foxxll.org
5  *
6  * Copyright (C) 2002 Roman Dementiev <[email protected]>
7  * Copyright (C) 2008, 2009 Andreas Beckmann <[email protected]>
8  * Copyright (C) 2009 Johannes Singler <[email protected]>
9  *
10  * Distributed under the Boost Software License, Version 1.0.
11  * (See accompanying file LICENSE_1_0.txt or copy at
12  * http://www.boost.org/LICENSE_1_0.txt)
13  **************************************************************************/
14 
15 #ifndef FOXXLL_IO_REQUEST_OPERATIONS_HEADER
16 #define FOXXLL_IO_REQUEST_OPERATIONS_HEADER
17 
19 #include <foxxll/io/iostats.hpp>
20 #include <foxxll/io/request.hpp>
21 
22 namespace foxxll {
23 
24 //! \addtogroup foxxll_reqlayer
25 //! \{
26 
27 //! Collection of functions to track statuses of a number of requests.
28 
29 //! Suspends calling thread until \b all given requests are completed.
30 //! \param reqs_begin begin of request sequence to wait for
31 //! \param reqs_end end of request sequence to wait for
32 template <class RequestIterator>
33 void wait_all(RequestIterator reqs_begin, RequestIterator reqs_end)
34 {
35  for ( ; reqs_begin != reqs_end; ++reqs_begin)
36  (request_ptr(*reqs_begin))->wait();
37 }
38 
39 //! Suspends calling thread until \b all given requests are completed.
40 //! \param req_array array of request_ptr objects
41 //! \param count size of req_array
42 static inline void wait_all(request_ptr req_array[], size_t count)
43 {
44  wait_all(req_array, req_array + count);
45 }
46 
47 //! Cancel requests.
48 //! The specified requests are canceled unless already being processed.
49 //! However, cancelation cannot be guaranteed.
50 //! Cancelled requests must still be waited for in order to ensure correct
51 //! operation.
52 //! \param reqs_begin begin of request sequence
53 //! \param reqs_end end of request sequence
54 //! \return number of request canceled
55 template <class RequestIterator>
56 typename std::iterator_traits<RequestIterator>::difference_type
57 cancel_all(RequestIterator reqs_begin, RequestIterator reqs_end)
58 {
59  typename std::iterator_traits<RequestIterator>::difference_type num_canceled = 0;
60  while (reqs_begin != reqs_end)
61  {
62  if ((request_ptr(*reqs_begin))->cancel())
63  ++num_canceled;
64  ++reqs_begin;
65  }
66  return num_canceled;
67 }
68 
69 //! Polls requests.
70 //! \param reqs_begin begin of request sequence to poll
71 //! \param reqs_end end of request sequence to poll
72 //! \return \c true if any of requests is completed, then index contains valid value, otherwise \c false
73 template <class RequestIterator>
74 RequestIterator poll_any(RequestIterator reqs_begin, RequestIterator reqs_end)
75 {
76  while (reqs_begin != reqs_end)
77  {
78  if ((request_ptr(*reqs_begin))->poll())
79  return reqs_begin;
80 
81  ++reqs_begin;
82  }
83  return reqs_end;
84 }
85 
86 //! Polls requests.
87 //! \param req_array array of request_ptr objects
88 //! \param count size of req_array
89 //! \param index contains index of the \b first completed request if any
90 //! \return \c true if any of requests is completed, then index contains valid value, otherwise \c false
91 static inline
92 bool poll_any(request_ptr req_array[], size_t count, size_t& index)
93 {
94  request_ptr* res = poll_any(req_array, req_array + count);
95  index = static_cast<size_t>(res - req_array);
96  return res != (req_array + count);
97 }
98 
99 //! Suspends calling thread until \b any of requests is completed.
100 //! \param reqs_begin begin of request sequence to wait for
101 //! \param reqs_end end of request sequence to wait for
102 //! \return index in req_array pointing to the \b first completed request
103 template <class RequestIterator>
104 RequestIterator wait_any(RequestIterator reqs_begin, RequestIterator reqs_end)
105 {
107 
108  onoff_switch sw;
109 
110  RequestIterator cur = reqs_begin, result = reqs_end;
111 
112  for ( ; cur != reqs_end; cur++)
113  {
114  if ((request_ptr(*cur))->add_waiter(&sw))
115  {
116  // request is already done, no waiter was added to the request
117  result = cur;
118 
119  if (cur != reqs_begin)
120  {
121  while (--cur != reqs_begin)
122  (request_ptr(*cur))->delete_waiter(&sw);
123 
124  (request_ptr(*cur))->delete_waiter(&sw);
125  }
126 
127  (request_ptr(*result))->check_errors();
128 
129  return result;
130  }
131  }
132 
133  sw.wait_for_on();
134 
135  for (cur = reqs_begin; cur != reqs_end; cur++)
136  {
137  (request_ptr(*cur))->delete_waiter(&sw);
138  if (result == reqs_end && (request_ptr(*cur))->poll())
139  result = cur;
140  }
141 
142  return result;
143 }
144 
145 //! Suspends calling thread until \b any of requests is completed.
146 //! \param req_array array of \c request_ptr objects
147 //! \param count size of req_array
148 //! \return index in req_array pointing to the \b first completed request
149 static inline
150 size_t wait_any(request_ptr req_array[], size_t count)
151 {
152  return static_cast<size_t>(wait_any(req_array, req_array + count) - req_array);
153 }
154 
155 //! \}
156 
157 } // namespace foxxll
158 
159 #endif // !FOXXLL_IO_REQUEST_OPERATIONS_HEADER
160 
161 /**************************************************************************/
void wait_for_on()
wait for switch to turn ON
std::iterator_traits< RequestIterator >::difference_type cancel_all(RequestIterator reqs_begin, RequestIterator reqs_end)
tlx::counting_ptr< request > request_ptr
A reference counting pointer for request.
Definition: request.hpp:43
void wait_all(RequestIterator reqs_begin, RequestIterator reqs_end)
Collection of functions to track statuses of a number of requests.
High-performance smart pointer used as a wrapping reference counting pointer.
RequestIterator wait_any(RequestIterator reqs_begin, RequestIterator reqs_end)
RequestIterator poll_any(RequestIterator reqs_begin, RequestIterator reqs_end)