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Implement N4508: shared_mutex. Reviewed as http://reviews.llvm.org/D10480

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git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@241067 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Marshall Clow
2015-06-30 14:04:14 +00:00
parent f3c8fb22ec
commit abadb458d0
10 changed files with 439 additions and 26 deletions
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113
include/shared_mutex
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@@ -19,6 +19,29 @@
namespace std
{
class shared_mutex // C++17
{
public:
shared_mutex();
~shared_mutex();
shared_mutex(const shared_mutex&) = delete;
shared_mutex& operator=(const shared_mutex&) = delete;
// Exclusive ownership
void lock(); // blocking
bool try_lock();
void unlock();
// Shared ownership
void lock_shared(); // blocking
bool try_lock_shared();
void unlock_shared();
typedef implementation-defined native_handle_type; // See 30.2.3
native_handle_type native_handle(); // See 30.2.3
};
class shared_timed_mutex
{
public:
@@ -118,7 +141,7 @@ template <class Mutex>
_LIBCPP_BEGIN_NAMESPACE_STD
class _LIBCPP_TYPE_VIS shared_timed_mutex
struct _LIBCPP_TYPE_VIS __shared_mutex_base
{
mutex __mut_;
condition_variable __gate1_;
@@ -127,6 +150,58 @@ class _LIBCPP_TYPE_VIS shared_timed_mutex
static const unsigned __write_entered_ = 1U << (sizeof(unsigned)*__CHAR_BIT__ - 1);
static const unsigned __n_readers_ = ~__write_entered_;
__shared_mutex_base();
_LIBCPP_INLINE_VISIBILITY ~__shared_mutex_base() = default;
__shared_mutex_base(const __shared_mutex_base&) = delete;
__shared_mutex_base& operator=(const __shared_mutex_base&) = delete;
// Exclusive ownership
void lock(); // blocking
bool try_lock();
void unlock();
// Shared ownership
void lock_shared(); // blocking
bool try_lock_shared();
void unlock_shared();
// typedef implementation-defined native_handle_type; // See 30.2.3
// native_handle_type native_handle(); // See 30.2.3
};
#if _LIBCPP_STD_VER > 14
class _LIBCPP_TYPE_VIS shared_mutex
{
__shared_mutex_base __base;
public:
shared_mutex() : __base() {}
_LIBCPP_INLINE_VISIBILITY ~shared_mutex() = default;
shared_mutex(const shared_mutex&) = delete;
shared_mutex& operator=(const shared_mutex&) = delete;
// Exclusive ownership
_LIBCPP_INLINE_VISIBILITY void lock() { return __base.lock(); }
_LIBCPP_INLINE_VISIBILITY bool try_lock() { return __base.try_lock(); }
_LIBCPP_INLINE_VISIBILITY void unlock() { return __base.unlock(); }
// Shared ownership
_LIBCPP_INLINE_VISIBILITY void lock_shared() { return __base.lock_shared(); }
_LIBCPP_INLINE_VISIBILITY bool try_lock_shared() { return __base.try_lock_shared(); }
_LIBCPP_INLINE_VISIBILITY void unlock_shared() { return __base.unlock_shared(); }
// typedef __shared_mutex_base::native_handle_type native_handle_type;
// _LIBCPP_INLINE_VISIBILITY native_handle_type native_handle() { return __base::unlock_shared(); }
};
#endif
class _LIBCPP_TYPE_VIS shared_timed_mutex
{
__shared_mutex_base __base;
public:
shared_timed_mutex();
_LIBCPP_INLINE_VISIBILITY ~shared_timed_mutex() = default;
@@ -170,30 +245,30 @@ bool
shared_timed_mutex::try_lock_until(
const chrono::time_point<_Clock, _Duration>& __abs_time)
{
unique_lock<mutex> __lk(__mut_);
if (__state_ & __write_entered_)
unique_lock<mutex> __lk(__base.__mut_);
if (__base.__state_ & __base.__write_entered_)
{
while (true)
{
cv_status __status = __gate1_.wait_until(__lk, __abs_time);
if ((__state_ & __write_entered_) == 0)
cv_status __status = __base.__gate1_.wait_until(__lk, __abs_time);
if ((__base.__state_ & __base.__write_entered_) == 0)
break;
if (__status == cv_status::timeout)
return false;
}
}
__state_ |= __write_entered_;
if (__state_ & __n_readers_)
__base.__state_ |= __base.__write_entered_;
if (__base.__state_ & __base.__n_readers_)
{
while (true)
{
cv_status __status = __gate2_.wait_until(__lk, __abs_time);
if ((__state_ & __n_readers_) == 0)
cv_status __status = __base.__gate2_.wait_until(__lk, __abs_time);
if ((__base.__state_ & __base.__n_readers_) == 0)
break;
if (__status == cv_status::timeout)
{
__state_ &= ~__write_entered_;
__gate1_.notify_all();
__base.__state_ &= ~__base.__write_entered_;
__base.__gate1_.notify_all();
return false;
}
}
@@ -206,22 +281,22 @@ bool
shared_timed_mutex::try_lock_shared_until(
const chrono::time_point<_Clock, _Duration>& __abs_time)
{
unique_lock<mutex> __lk(__mut_);
if ((__state_ & __write_entered_) || (__state_ & __n_readers_) == __n_readers_)
unique_lock<mutex> __lk(__base.__mut_);
if ((__base.__state_ & __base.__write_entered_) || (__base.__state_ & __base.__n_readers_) == __base.__n_readers_)
{
while (true)
{
cv_status status = __gate1_.wait_until(__lk, __abs_time);
if ((__state_ & __write_entered_) == 0 &&
(__state_ & __n_readers_) < __n_readers_)
cv_status status = __base.__gate1_.wait_until(__lk, __abs_time);
if ((__base.__state_ & __base.__write_entered_) == 0 &&
(__base.__state_ & __base.__n_readers_) < __base.__n_readers_)
break;
if (status == cv_status::timeout)
return false;
}
}
unsigned __num_readers = (__state_ & __n_readers_) + 1;
__state_ &= ~__n_readers_;
__state_ |= __num_readers;
unsigned __num_readers = (__base.__state_ & __base.__n_readers_) + 1;
__base.__state_ &= ~__base.__n_readers_;
__base.__state_ |= __num_readers;
return true;
}