locksys::Latches::Unique_sharded_rw_lock Class Reference

A helper wrapper around Shared_rw_lock which simplifies: More...

Public Member Functions
	Unique_sharded_rw_lock ()
	~Unique_sharded_rw_lock ()
bool	try_x_lock (ut::Location location)
bool	is_x_blocked_by_our_s ()
	Checks if there is a thread requesting an x-latch waiting for our thread to release its s-latch. More...
void	x_lock (ut::Location location)
void	x_unlock ()
void	s_lock (ut::Location location)
void	s_unlock ()
bool	x_own () const
bool	s_own () const

Private Attributes
Sharded_rw_lock	rw_lock
	The actual rw_lock implementation doing the heavy lifting. More...

Static Private Attributes
static constexpr size_t	NOT_IN_USE = std::numeric_limits<size_t>::max()
	The value used for m_shard_id to indicate that current thread did not s-latch any of the rw_lock's shards. More...
static thread_local size_t	m_shard_id {NOT_IN_USE}
	The id of the rw_lock's shard which this thread has s-latched, or NOT_IN_USE if it has not s-latched any. More...

Detailed Description

A helper wrapper around Shared_rw_lock which simplifies:

• lifecycle by providing constructor and destructor, and
• s-latching and s-unlatching by keeping track of the shard id used for spreading the contention. There must be at most one instance of this class (the one in the lock_sys), as it uses thread_local-s to remember which shard of sharded rw lock was used by this thread to perform s-latching (so, hypothetical other instances would share this field, overwriting it and leading to errors).

Constructor & Destructor Documentation

Unique_sharded_rw_lock()

locksys::Latches::Unique_sharded_rw_lock::Unique_sharded_rw_lock

(

)

~Unique_sharded_rw_lock()

locksys::Latches::Unique_sharded_rw_lock::~Unique_sharded_rw_lock

(

)

Member Function Documentation

is_x_blocked_by_our_s()

bool locksys::Latches::Unique_sharded_rw_lock::is_x_blocked_by_our_s ( )

inline

Checks if there is a thread requesting an x-latch waiting for our thread to release its s-latch.

Must be called while holding an s-latch.

Returns

true iff there is an x-latcher blocked by our s-latch.

s_lock()

void locksys::Latches::Unique_sharded_rw_lock::s_lock ( ut::Location  location )

inline

s_own()

bool locksys::Latches::Unique_sharded_rw_lock::s_own ( ) const

inline

s_unlock()

void locksys::Latches::Unique_sharded_rw_lock::s_unlock ( )

inline

try_x_lock()

bool locksys::Latches::Unique_sharded_rw_lock::try_x_lock ( ut::Location  location )

inline

x_lock()

void locksys::Latches::Unique_sharded_rw_lock::x_lock ( ut::Location  location )

inline

x_own()

bool locksys::Latches::Unique_sharded_rw_lock::x_own ( ) const

inline

x_unlock()

void locksys::Latches::Unique_sharded_rw_lock::x_unlock ( )

inline

Member Data Documentation

m_shard_id

thread_local size_t locksys::Latches::Unique_sharded_rw_lock::m_shard_id {NOT_IN_USE}

staticprivate

The id of the rw_lock's shard which this thread has s-latched, or NOT_IN_USE if it has not s-latched any.

NOT_IN_USE

constexpr size_t locksys::Latches::Unique_sharded_rw_lock::NOT_IN_USE = std::numeric_limits<size_t>::max()

staticconstexprprivate

The value used for m_shard_id to indicate that current thread did not s-latch any of the rw_lock's shards.

rw_lock

Sharded_rw_lock locksys::Latches::Unique_sharded_rw_lock::rw_lock

private

The actual rw_lock implementation doing the heavy lifting.

---

The documentation for this class was generated from the following files:

• storage/innobase/include/lock0latches.h
• storage/innobase/lock/lock0latches.cc