ceph/src/boost/libs/fiber/src/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/mutex.hpp"
   8
   9 #include <algorithm>
  10 #include <functional>
  11 #include <system_error>
  12
  13 #include "boost/fiber/exceptions.hpp"
  14 #include "boost/fiber/scheduler.hpp"
  15
  16 #ifdef BOOST_HAS_ABI_HEADERS
  17 #  include BOOST_ABI_PREFIX
  18 #endif
  19
  20 namespace boost {
  21 namespace fibers {
  22
  23 void
  24 mutex::lock() {
  25     while ( true) {
  26         context * active_ctx = context::active();
  27         // store this fiber in order to be notified later
  28         detail::spinlock_lock lk{ wait_queue_splk_ };
  29         if ( BOOST_UNLIKELY( active_ctx == owner_) ) {
  30             throw lock_error{
  31                     std::make_error_code( std::errc::resource_deadlock_would_occur),
  32                     "boost fiber: a deadlock is detected" };
  33         } else if ( nullptr == owner_) {
  34             owner_ = active_ctx;
  35             return;
  36         }
  37         BOOST_ASSERT( ! active_ctx->wait_is_linked() );
  38         active_ctx->wait_link( wait_queue_);
  39         // suspend this fiber
  40         active_ctx->suspend( lk);
  41         BOOST_ASSERT( ! active_ctx->wait_is_linked() );
  42     }
  43 }
  44
  45 bool
  46 mutex::try_lock() {
  47     context * active_ctx = context::active();
  48     detail::spinlock_lock lk{ wait_queue_splk_ };
  49     if ( BOOST_UNLIKELY( active_ctx == owner_) ) {
  50         throw lock_error{
  51                 std::make_error_code( std::errc::resource_deadlock_would_occur),
  52                 "boost fiber: a deadlock is detected" };
  53     } else if ( nullptr == owner_) {
  54         owner_ = active_ctx;
  55     }
  56     lk.unlock();
  57     // let other fiber release the lock
  58     active_ctx->yield();
  59     return active_ctx == owner_;
  60 }
  61
  62 void
  63 mutex::unlock() {
  64     context * active_ctx = context::active();
  65     detail::spinlock_lock lk{ wait_queue_splk_ };
  66     if ( BOOST_UNLIKELY( active_ctx != owner_) ) {
  67         throw lock_error{
  68                 std::make_error_code( std::errc::operation_not_permitted),
  69                 "boost fiber: no  privilege to perform the operation" };
  70     }
  71     owner_ = nullptr;
  72     if ( ! wait_queue_.empty() ) {
  73         context * ctx = & wait_queue_.front();
  74         wait_queue_.pop_front();
  75         active_ctx->schedule( ctx);
  76     }
  77 }
  78
  79 }}
  80
  81 #ifdef BOOST_HAS_ABI_HEADERS
  82 #  include BOOST_ABI_SUFFIX
  83 #endif