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

   1 //
   2 // detail/strand_executor_service.hpp
   3 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2019 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_EXECUTOR_SERVICE_HPP
  12 #define BOOST_ASIO_DETAIL_STRAND_EXECUTOR_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/detail/atomic_count.hpp>
  20 #include <boost/asio/detail/executor_op.hpp>
  21 #include <boost/asio/detail/memory.hpp>
  22 #include <boost/asio/detail/mutex.hpp>
  23 #include <boost/asio/detail/op_queue.hpp>
  24 #include <boost/asio/detail/scheduler_operation.hpp>
  25 #include <boost/asio/detail/scoped_ptr.hpp>
  26 #include <boost/asio/execution_context.hpp>
  27
  28 #include <boost/asio/detail/push_options.hpp>
  29
  30 namespace boost {
  31 namespace asio {
  32 namespace detail {
  33
  34 // Default service implementation for a strand.
  35 class strand_executor_service
  36   : public execution_context_service_base<strand_executor_service>
  37 {
  38 public:
  39   // The underlying implementation of a strand.
  40   class strand_impl
  41   {
  42   public:
  43     BOOST_ASIO_DECL ~strand_impl();
  44
  45   private:
  46     friend class strand_executor_service;
  47
  48     // Mutex to protect access to internal data.
  49     mutex* mutex_;
  50
  51     // Indicates whether the strand is currently "locked" by a handler. This
  52     // means that there is a handler upcall in progress, or that the strand
  53     // itself has been scheduled in order to invoke some pending handlers.
  54     bool locked_;
  55
  56     // Indicates that the strand has been shut down and will accept no further
  57     // handlers.
  58     bool shutdown_;
  59
  60     // The handlers that are waiting on the strand but should not be run until
  61     // after the next time the strand is scheduled. This queue must only be
  62     // modified while the mutex is locked.
  63     op_queue<scheduler_operation> waiting_queue_;
  64
  65     // The handlers that are ready to be run. Logically speaking, these are the
  66     // handlers that hold the strand's lock. The ready queue is only modified
  67     // from within the strand and so may be accessed without locking the mutex.
  68     op_queue<scheduler_operation> ready_queue_;
  69
  70     // Pointers to adjacent handle implementations in linked list.
  71     strand_impl* next_;
  72     strand_impl* prev_;
  73
  74     // The strand service in where the implementation is held.
  75     strand_executor_service* service_;
  76   };
  77
  78   typedef shared_ptr<strand_impl> implementation_type;
  79
  80   // Construct a new strand service for the specified context.
  81   BOOST_ASIO_DECL explicit strand_executor_service(execution_context& context);
  82
  83   // Destroy all user-defined handler objects owned by the service.
  84   BOOST_ASIO_DECL void shutdown();
  85
  86   // Create a new strand_executor implementation.
  87   BOOST_ASIO_DECL implementation_type create_implementation();
  88
  89   // Request invocation of the given function.
  90   template <typename Executor, typename Function, typename Allocator>
  91   static void dispatch(const implementation_type& impl, Executor& ex,
  92       BOOST_ASIO_MOVE_ARG(Function) function, const Allocator& a);
  93
  94   // Request invocation of the given function and return immediately.
  95   template <typename Executor, typename Function, typename Allocator>
  96   static void post(const implementation_type& impl, Executor& ex,
  97       BOOST_ASIO_MOVE_ARG(Function) function, const Allocator& a);
  98
  99   // Request invocation of the given function and return immediately.
 100   template <typename Executor, typename Function, typename Allocator>
 101   static void defer(const implementation_type& impl, Executor& ex,
 102       BOOST_ASIO_MOVE_ARG(Function) function, const Allocator& a);
 103
 104   // Determine whether the strand is running in the current thread.
 105   BOOST_ASIO_DECL static bool running_in_this_thread(
 106       const implementation_type& impl);
 107
 108 private:
 109   friend class strand_impl;
 110   template <typename Executor> class invoker;
 111
 112   // Adds a function to the strand. Returns true if it acquires the lock.
 113   BOOST_ASIO_DECL static bool enqueue(const implementation_type& impl,
 114       scheduler_operation* op);
 115
 116   // Mutex to protect access to the service-wide state.
 117   mutex mutex_;
 118
 119   // Number of mutexes shared between all strand objects.
 120   enum { num_mutexes = 193 };
 121
 122   // Pool of mutexes.
 123   scoped_ptr<mutex> mutexes_[num_mutexes];
 124
 125   // Extra value used when hashing to prevent recycled memory locations from
 126   // getting the same mutex.
 127   std::size_t salt_;
 128
 129   // The head of a linked list of all implementations.
 130   strand_impl* impl_list_;
 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_executor_service.hpp>
 140 #if defined(BOOST_ASIO_HEADER_ONLY)
 141 # include <boost/asio/detail/impl/strand_executor_service.ipp>
 142 #endif // defined(BOOST_ASIO_HEADER_ONLY)
 143
 144 #endif // BOOST_ASIO_DETAIL_STRAND_EXECUTOR_SERVICE_HPP