ceph/src/boost/libs/fiber/src/recursive_mutex.cpp

   1
   2 //          Copyright Oliver Kowalke 2013.
   3 // Distributed under the Boost Software License, Version 1.0.
   4 //    (See accompanying file LICENSE_1_0.txt or copy at
   5 //          http://www.boost.org/LICENSE_1_0.txt)
   6
   7 #include "boost/fiber/recursive_mutex.hpp"
   8
   9 #include <algorithm>
  10 #include <functional>
  11
  12 #include "boost/fiber/exceptions.hpp"
  13 #include "boost/fiber/scheduler.hpp"
  14
  15 #ifdef BOOST_HAS_ABI_HEADERS
  16 #  include BOOST_ABI_PREFIX
  17 #endif
  18
  19 namespace boost {
  20 namespace fibers {
  21
  22 void
  23 recursive_mutex::lock() {
  24     while ( true) {
  25         context * active_ctx = context::active();
  26         // store this fiber in order to be notified later
  27         detail::spinlock_lock lk{ wait_queue_splk_ };
  28         if ( active_ctx == owner_) {
  29             ++count_;
  30             return;
  31         } else if ( nullptr == owner_) {
  32             owner_ = active_ctx;
  33             count_ = 1;
  34             return;
  35         }
  36         BOOST_ASSERT( ! active_ctx->wait_is_linked() );
  37         active_ctx->wait_link( wait_queue_);
  38         // suspend this fiber
  39         active_ctx->suspend( lk);
  40         BOOST_ASSERT( ! active_ctx->wait_is_linked() );
  41     }
  42 }
  43
  44 bool
  45 recursive_mutex::try_lock() noexcept {
  46     context * active_ctx = context::active();
  47     detail::spinlock_lock lk{ wait_queue_splk_ };
  48     if ( nullptr == owner_) {
  49         owner_ = active_ctx;
  50         count_ = 1;
  51     } else if ( active_ctx == owner_) {
  52         ++count_;
  53     }
  54     lk.unlock();
  55     // let other fiber release the lock
  56     context::active()->yield();
  57     return active_ctx == owner_;
  58 }
  59
  60 void
  61 recursive_mutex::unlock() {
  62     context * active_ctx = context::active();
  63     detail::spinlock_lock lk( wait_queue_splk_);
  64     if ( BOOST_UNLIKELY( active_ctx != owner_) ) {
  65         throw lock_error(
  66                 std::make_error_code( std::errc::operation_not_permitted),
  67                 "boost fiber: no  privilege to perform the operation");
  68     }
  69     if ( 0 == --count_) {
  70         owner_ = nullptr;
  71         if ( ! wait_queue_.empty() ) {
  72             context * ctx = & wait_queue_.front();
  73             wait_queue_.pop_front();
  74             active_ctx->schedule( ctx);
  75         }
  76     }
  77 }
  78
  79 }}
  80
  81 #ifdef BOOST_HAS_ABI_HEADERS
  82 #  include BOOST_ABI_SUFFIX
  83 #endif