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| author | dim <dim@FreeBSD.org> | 2014-03-05 19:30:36 +0000 |
|---|---|---|
| committer | dim <dim@FreeBSD.org> | 2014-03-05 19:30:36 +0000 |
| commit | 22ca1336dcfb663d86a6892dbe1e48eee20bb6db (patch) | |
| tree | 72f4bceef54682e8e577b4ddd08c0ad24ea08ff6 /contrib/libc++/src/shared_mutex.cpp | |
| parent | a5552de0b34d11a40bdc1d8e53fa44a923b6b1a8 (diff) | |
| download | FreeBSD-src-22ca1336dcfb663d86a6892dbe1e48eee20bb6db.zip FreeBSD-src-22ca1336dcfb663d86a6892dbe1e48eee20bb6db.tar.gz | |
MFC r261283:
Import libc++ 3.4 release. This contains a lot of bugfixes, and some
preliminary support for C++1y.
MFC r261604:
HEAD is not buildable for the past day. Commit a 'quick fix' in order to permit
buildworld to complete.
Reviewed by: theraven
MFC r261608:
Apply a cleaner solution for the sign warnings that can occur when
compiling libc++'s <locale> header with -Wsystem-headers on.
This has also been submitted upstream.
Reported by: asomers
MFC r261801:
An ABI incompatibility crept into the libc++ 3.4 import in r261283. It
was caused by upstream libc++ commit r194536, which aimed to make the
headers more standards-compliant, by making std::pair's copy constructor
trivial. Unfortunately, this could cause certain C++ applications using
shared libraries built against the previous version of libc++ to crash.
Fix the ABI incompatibility by making std::pair's copy constructor
non-trivial again.
Please note: Any C++ applications or shared libraries built with libc++
between r261283 and this revision should be recompiled.
Reported by: stefanf
Diffstat (limited to 'contrib/libc++/src/shared_mutex.cpp')
| -rw-r--r-- | contrib/libc++/src/shared_mutex.cpp | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/contrib/libc++/src/shared_mutex.cpp b/contrib/libc++/src/shared_mutex.cpp new file mode 100644 index 0000000..5fb22e4 --- /dev/null +++ b/contrib/libc++/src/shared_mutex.cpp @@ -0,0 +1,101 @@ +//===---------------------- shared_mutex.cpp ------------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is dual licensed under the MIT and the University of Illinois Open +// Source Licenses. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +#define _LIBCPP_BUILDING_SHARED_MUTEX +#include "shared_mutex" + +_LIBCPP_BEGIN_NAMESPACE_STD + +shared_mutex::shared_mutex() + : __state_(0) +{ +} + +// Exclusive ownership + +void +shared_mutex::lock() +{ + unique_lock<mutex> lk(__mut_); + while (__state_ & __write_entered_) + __gate1_.wait(lk); + __state_ |= __write_entered_; + while (__state_ & __n_readers_) + __gate2_.wait(lk); +} + +bool +shared_mutex::try_lock() +{ + unique_lock<mutex> lk(__mut_); + if (__state_ == 0) + { + __state_ = __write_entered_; + return true; + } + return false; +} + +void +shared_mutex::unlock() +{ + lock_guard<mutex> _(__mut_); + __state_ = 0; + __gate1_.notify_all(); +} + +// Shared ownership + +void +shared_mutex::lock_shared() +{ + unique_lock<mutex> lk(__mut_); + while ((__state_ & __write_entered_) || (__state_ & __n_readers_) == __n_readers_) + __gate1_.wait(lk); + unsigned num_readers = (__state_ & __n_readers_) + 1; + __state_ &= ~__n_readers_; + __state_ |= num_readers; +} + +bool +shared_mutex::try_lock_shared() +{ + unique_lock<mutex> lk(__mut_); + unsigned num_readers = __state_ & __n_readers_; + if (!(__state_ & __write_entered_) && num_readers != __n_readers_) + { + ++num_readers; + __state_ &= ~__n_readers_; + __state_ |= num_readers; + return true; + } + return false; +} + +void +shared_mutex::unlock_shared() +{ + lock_guard<mutex> _(__mut_); + unsigned num_readers = (__state_ & __n_readers_) - 1; + __state_ &= ~__n_readers_; + __state_ |= num_readers; + if (__state_ & __write_entered_) + { + if (num_readers == 0) + __gate2_.notify_one(); + } + else + { + if (num_readers == __n_readers_ - 1) + __gate1_.notify_one(); + } +} + + +_LIBCPP_END_NAMESPACE_STD |
