ceph/src/boost/boost/asio/detail/strand_service.hpp

   1 //
   2 // detail/strand_service.hpp
   3 // ~~~~~~~~~~~~~~~~~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
   6 //
   7 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   8 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   9 //
  10
  11 #ifndef BOOST_ASIO_DETAIL_STRAND_SERVICE_HPP
  12 #define BOOST_ASIO_DETAIL_STRAND_SERVICE_HPP
  13
  14 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
  15 # pragma once
  16 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
  17
  18 #include <boost/asio/detail/config.hpp>
  19 #include <boost/asio/io_context.hpp>
  20 #include <boost/asio/detail/mutex.hpp>
  21 #include <boost/asio/detail/op_queue.hpp>
  22 #include <boost/asio/detail/operation.hpp>
  23 #include <boost/asio/detail/scoped_ptr.hpp>
  24
  25 #include <boost/asio/detail/push_options.hpp>
  26
  27 namespace boost {
  28 namespace asio {
  29 namespace detail {
  30
  31 // Default service implementation for a strand.
  32 class strand_service
  33   : public boost::asio::detail::service_base<strand_service>
  34 {
  35 private:
  36   // Helper class to re-post the strand on exit.
  37   struct on_do_complete_exit;
  38
  39   // Helper class to re-post the strand on exit.
  40   struct on_dispatch_exit;
  41
  42 public:
  43
  44   // The underlying implementation of a strand.
  45   class strand_impl
  46     : public operation
  47   {
  48   public:
  49     strand_impl();
  50
  51   private:
  52     // Only this service will have access to the internal values.
  53     friend class strand_service;
  54     friend struct on_do_complete_exit;
  55     friend struct on_dispatch_exit;
  56
  57     // Mutex to protect access to internal data.
  58     boost::asio::detail::mutex mutex_;
  59
  60     // Indicates whether the strand is currently "locked" by a handler. This
  61     // means that there is a handler upcall in progress, or that the strand
  62     // itself has been scheduled in order to invoke some pending handlers.
  63     bool locked_;
  64
  65     // The handlers that are waiting on the strand but should not be run until
  66     // after the next time the strand is scheduled. This queue must only be
  67     // modified while the mutex is locked.
  68     op_queue<operation> waiting_queue_;
  69
  70     // The handlers that are ready to be run. Logically speaking, these are the
  71     // handlers that hold the strand's lock. The ready queue is only modified
  72     // from within the strand and so may be accessed without locking the mutex.
  73     op_queue<operation> ready_queue_;
  74   };
  75
  76   typedef strand_impl* implementation_type;
  77
  78   // Construct a new strand service for the specified io_context.
  79   BOOST_ASIO_DECL explicit strand_service(boost::asio::io_context& io_context);
  80
  81   // Destroy all user-defined handler objects owned by the service.
  82   BOOST_ASIO_DECL void shutdown();
  83
  84   // Construct a new strand implementation.
  85   BOOST_ASIO_DECL void construct(implementation_type& impl);
  86
  87   // Request the io_context to invoke the given handler.
  88   template <typename Handler>
  89   void dispatch(implementation_type& impl, Handler& handler);
  90
  91   // Request the io_context to invoke the given handler and return immediately.
  92   template <typename Handler>
  93   void post(implementation_type& impl, Handler& handler);
  94
  95   // Determine whether the strand is running in the current thread.
  96   BOOST_ASIO_DECL bool running_in_this_thread(
  97       const implementation_type& impl) const;
  98
  99 private:
 100   // Helper function to dispatch a handler. Returns true if the handler should
 101   // be dispatched immediately.
 102   BOOST_ASIO_DECL bool do_dispatch(implementation_type& impl, operation* op);
 103
 104   // Helper fiunction to post a handler.
 105   BOOST_ASIO_DECL void do_post(implementation_type& impl,
 106       operation* op, bool is_continuation);
 107
 108   BOOST_ASIO_DECL static void do_complete(void* owner,
 109       operation* base, const boost::system::error_code& ec,
 110       std::size_t bytes_transferred);
 111
 112   // The io_context implementation used to post completions.
 113   io_context_impl& io_context_;
 114
 115   // Mutex to protect access to the array of implementations.
 116   boost::asio::detail::mutex mutex_;
 117
 118   // Number of implementations shared between all strand objects.
 119 #if defined(BOOST_ASIO_STRAND_IMPLEMENTATIONS)
 120   enum { num_implementations = BOOST_ASIO_STRAND_IMPLEMENTATIONS };
 121 #else // defined(BOOST_ASIO_STRAND_IMPLEMENTATIONS)
 122   enum { num_implementations = 193 };
 123 #endif // defined(BOOST_ASIO_STRAND_IMPLEMENTATIONS)
 124
 125   // Pool of implementations.
 126   scoped_ptr<strand_impl> implementations_[num_implementations];
 127
 128   // Extra value used when hashing to prevent recycled memory locations from
 129   // getting the same strand implementation.
 130   std::size_t salt_;
 131 };
 132
 133 } // namespace detail
 134 } // namespace asio
 135 } // namespace boost
 136
 137 #include <boost/asio/detail/pop_options.hpp>
 138
 139 #include <boost/asio/detail/impl/strand_service.hpp>
 140 #if defined(BOOST_ASIO_HEADER_ONLY)
 141 # include <boost/asio/detail/impl/strand_service.ipp>
 142 #endif // defined(BOOST_ASIO_HEADER_ONLY)
 143
 144 #endif // BOOST_ASIO_DETAIL_STRAND_SERVICE_HPP