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         }
  34         if ( nullptr == owner_) {
  35             owner_ = active_ctx;
  36             return;
  37         }
  38         BOOST_ASSERT( ! active_ctx->wait_is_linked() );
  39         active_ctx->wait_link( wait_queue_);
  40         // suspend this fiber
  41         active_ctx->suspend( lk);
  42         BOOST_ASSERT( ! active_ctx->wait_is_linked() );
  43     }
  44 }
  45
  46 bool
  47 mutex::try_lock() {
  48     context * active_ctx = context::active();
  49     detail::spinlock_lock lk{ wait_queue_splk_ };
  50     if ( BOOST_UNLIKELY( active_ctx == owner_) ) {
  51         throw lock_error{
  52                 std::make_error_code( std::errc::resource_deadlock_would_occur),
  53                 "boost fiber: a deadlock is detected" };
  54     }
  55     if ( nullptr == owner_) {
  56         owner_ = active_ctx;
  57     }
  58     lk.unlock();
  59     // let other fiber release the lock
  60     active_ctx->yield();
  61     return active_ctx == owner_;
  62 }
  63
  64 void
  65 mutex::unlock() {
  66     context * active_ctx = context::active();
  67     detail::spinlock_lock lk{ wait_queue_splk_ };
  68     if ( BOOST_UNLIKELY( active_ctx != owner_) ) {
  69         throw lock_error{
  70                 std::make_error_code( std::errc::operation_not_permitted),
  71                 "boost fiber: no  privilege to perform the operation" };
  72     }
  73     owner_ = nullptr;
  74     if ( ! wait_queue_.empty() ) {
  75         context * ctx = & wait_queue_.front();
  76         wait_queue_.pop_front();
  77         active_ctx->schedule( ctx);
  78     }
  79 }
  80
  81 }}
  82
  83 #ifdef BOOST_HAS_ABI_HEADERS
  84 #  include BOOST_ABI_SUFFIX
  85 #endif