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

   1 //
   2 // detail/strand_executor_service.hpp
   3 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2022 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/detail/type_traits.hpp>
  27 #include <boost/asio/execution.hpp>
  28 #include <boost/asio/execution_context.hpp>
  29
  30 #include <boost/asio/detail/push_options.hpp>
  31
  32 namespace boost {
  33 namespace asio {
  34 namespace detail {
  35
  36 // Default service implementation for a strand.
  37 class strand_executor_service
  38   : public execution_context_service_base<strand_executor_service>
  39 {
  40 public:
  41   // The underlying implementation of a strand.
  42   class strand_impl
  43   {
  44   public:
  45     BOOST_ASIO_DECL ~strand_impl();
  46
  47   private:
  48     friend class strand_executor_service;
  49
  50     // Mutex to protect access to internal data.
  51     mutex* mutex_;
  52
  53     // Indicates whether the strand is currently "locked" by a handler. This
  54     // means that there is a handler upcall in progress, or that the strand
  55     // itself has been scheduled in order to invoke some pending handlers.
  56     bool locked_;
  57
  58     // Indicates that the strand has been shut down and will accept no further
  59     // handlers.
  60     bool shutdown_;
  61
  62     // The handlers that are waiting on the strand but should not be run until
  63     // after the next time the strand is scheduled. This queue must only be
  64     // modified while the mutex is locked.
  65     op_queue<scheduler_operation> waiting_queue_;
  66
  67     // The handlers that are ready to be run. Logically speaking, these are the
  68     // handlers that hold the strand's lock. The ready queue is only modified
  69     // from within the strand and so may be accessed without locking the mutex.
  70     op_queue<scheduler_operation> ready_queue_;
  71
  72     // Pointers to adjacent handle implementations in linked list.
  73     strand_impl* next_;
  74     strand_impl* prev_;
  75
  76     // The strand service in where the implementation is held.
  77     strand_executor_service* service_;
  78   };
  79
  80   typedef shared_ptr<strand_impl> implementation_type;
  81
  82   // Construct a new strand service for the specified context.
  83   BOOST_ASIO_DECL explicit strand_executor_service(execution_context& context);
  84
  85   // Destroy all user-defined handler objects owned by the service.
  86   BOOST_ASIO_DECL void shutdown();
  87
  88   // Create a new strand_executor implementation.
  89   BOOST_ASIO_DECL implementation_type create_implementation();
  90
  91   // Request invocation of the given function.
  92   template <typename Executor, typename Function>
  93   static void execute(const implementation_type& impl, Executor& ex,
  94       BOOST_ASIO_MOVE_ARG(Function) function,
  95       typename enable_if<
  96         can_query<Executor, execution::allocator_t<void> >::value
  97       >::type* = 0);
  98
  99   // Request invocation of the given function.
 100   template <typename Executor, typename Function>
 101   static void execute(const implementation_type& impl, Executor& ex,
 102       BOOST_ASIO_MOVE_ARG(Function) function,
 103       typename enable_if<
 104         !can_query<Executor, execution::allocator_t<void> >::value
 105       >::type* = 0);
 106
 107   // Request invocation of the given function.
 108   template <typename Executor, typename Function, typename Allocator>
 109   static void dispatch(const implementation_type& impl, Executor& ex,
 110       BOOST_ASIO_MOVE_ARG(Function) function, const Allocator& a);
 111
 112   // Request invocation of the given function and return immediately.
 113   template <typename Executor, typename Function, typename Allocator>
 114   static void post(const implementation_type& impl, Executor& ex,
 115       BOOST_ASIO_MOVE_ARG(Function) function, const Allocator& a);
 116
 117   // Request invocation of the given function and return immediately.
 118   template <typename Executor, typename Function, typename Allocator>
 119   static void defer(const implementation_type& impl, Executor& ex,
 120       BOOST_ASIO_MOVE_ARG(Function) function, const Allocator& a);
 121
 122   // Determine whether the strand is running in the current thread.
 123   BOOST_ASIO_DECL static bool running_in_this_thread(
 124       const implementation_type& impl);
 125
 126 private:
 127   friend class strand_impl;
 128   template <typename F, typename Allocator> class allocator_binder;
 129   template <typename Executor, typename = void> class invoker;
 130
 131   // Adds a function to the strand. Returns true if it acquires the lock.
 132   BOOST_ASIO_DECL static bool enqueue(const implementation_type& impl,
 133       scheduler_operation* op);
 134
 135   // Transfers waiting handlers to the ready queue. Returns true if one or more
 136   // handlers were transferred.
 137   BOOST_ASIO_DECL static bool push_waiting_to_ready(implementation_type& impl);
 138
 139   // Invokes all ready-to-run handlers.
 140   BOOST_ASIO_DECL static void run_ready_handlers(implementation_type& impl);
 141
 142   // Helper function to request invocation of the given function.
 143   template <typename Executor, typename Function, typename Allocator>
 144   static void do_execute(const implementation_type& impl, Executor& ex,
 145       BOOST_ASIO_MOVE_ARG(Function) function, const Allocator& a);
 146
 147   // Mutex to protect access to the service-wide state.
 148   mutex mutex_;
 149
 150   // Number of mutexes shared between all strand objects.
 151   enum { num_mutexes = 193 };
 152
 153   // Pool of mutexes.
 154   scoped_ptr<mutex> mutexes_[num_mutexes];
 155
 156   // Extra value used when hashing to prevent recycled memory locations from
 157   // getting the same mutex.
 158   std::size_t salt_;
 159
 160   // The head of a linked list of all implementations.
 161   strand_impl* impl_list_;
 162 };
 163
 164 } // namespace detail
 165 } // namespace asio
 166 } // namespace boost
 167
 168 #include <boost/asio/detail/pop_options.hpp>
 169
 170 #include <boost/asio/detail/impl/strand_executor_service.hpp>
 171 #if defined(BOOST_ASIO_HEADER_ONLY)
 172 # include <boost/asio/detail/impl/strand_executor_service.ipp>
 173 #endif // defined(BOOST_ASIO_HEADER_ONLY)
 174
 175 #endif // BOOST_ASIO_DETAIL_STRAND_EXECUTOR_SERVICE_HPP