lock_queue_entry_t Class Reference

A lock request entry in a lock queue. More...

#include <lock_bucket.h>

Public Member Functions
uint32_t	get_observed_release_version () const
const okvl_mode &	get_requested_mode () const
const okvl_mode &	get_granted_mode () const

Private Member Functions
	lock_queue_entry_t (xct_t &xct, smthread_t &thr, xct_lock_info_t &li, const okvl_mode &granted_mode, const okvl_mode &requested_mode)

Private Attributes
xct_t &	_xct
	owning xct. More...
smthread_t &	_thr
	owning thread. More...
xct_lock_info_t &	_li
xct_lock_entry_t *	_xct_entry
lock_queue_entry_t *	_prev
lock_queue_entry_t *	_next
uint64_t	_observed_release_version
okvl_mode	_granted_mode
okvl_mode	_requested_mode

Friends
class	lock_queue_t
class	lock_core_m
ostream &	operator<< (ostream &o, const lock_queue_entry_t &r)

Detailed Description

A lock request entry in a lock queue.

All fields except _prev and _next, which are protected by L in the usual way, of this class have unusual access protections:

For any thread but this->_thr:

read a field: must have read access to L write a field: forbidden

For the thread this->_thr:

read a field: always legal write a field: must have write access to L

where L is the _requests_latch latch of the lock_queue_t we belong to if any. It is believed that this provides complete protection (e.g., no stale reads).

The primary reason for these relaxed rules is to allow release_duration to avoid needing to find and take L in read mode just to see if a lock needs to be released.

Constructor & Destructor Documentation

lock_queue_entry_t()

lock_queue_entry_t::lock_queue_entry_t ( xct_t &  xct, smthread_t &  thr, xct_lock_info_t &  li, const okvl_mode &  granted_mode, const okvl_mode &  requested_mode  )

inlineprivate

Member Function Documentation

get_granted_mode()

const okvl_mode& lock_queue_entry_t::get_granted_mode ( ) const

inline

get_observed_release_version()

uint32_t lock_queue_entry_t::get_observed_release_version ( ) const

inline

get_requested_mode()

const okvl_mode& lock_queue_entry_t::get_requested_mode ( ) const

inline

Friends And Related Function Documentation

lock_core_m

friend class lock_core_m

friend

lock_queue_t

friend class lock_queue_t

friend

operator<<

ostream& operator<< ( ostream &  o, const lock_queue_entry_t &  r  )

friend

Requires holding a read latch for queue._requests_latch where queue is the lock_queue_t that r belongs to.

Member Data Documentation

_granted_mode

okvl_mode lock_queue_entry_t::_granted_mode

private

_li

xct_lock_info_t& lock_queue_entry_t::_li

private

_next

lock_queue_entry_t* lock_queue_entry_t::_next

private

_observed_release_version

uint64_t lock_queue_entry_t::_observed_release_version

private

The _release_version of the lock queue when this lock's _wait_map is last updated. When we check deadlocks, we tentatively ignore other lock requests whose observed_release_version is older than _release_version of the lock queue to prevent false detections. 0 if this lock is not waiting. This is NOT protected by latch because this is used only opportunistically.

_prev

lock_queue_entry_t* lock_queue_entry_t::_prev

private

_requested_mode

okvl_mode lock_queue_entry_t::_requested_mode

private

_thr

smthread_t& lock_queue_entry_t::_thr

private

owning thread.

_xct

xct_t& lock_queue_entry_t::_xct

private

owning xct.

_xct_entry

xct_lock_entry_t* lock_queue_entry_t::_xct_entry

private

---

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

• src/sm/lock_bucket.h