mcs_rwlock Class Reference

Inherits w_pthread_lock_t.

Inheritance diagram for mcs_rwlock:

[legend]Collaboration diagram for mcs_rwlock:

[legend]List of all members.

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Detailed Description

"Shore read-write lock:: many-reader/one-writer spin lock

This read-write lock is implemented around a queue-based lock. It is the basis for latches in the storage manager.

Use this to protect data structures that get constantly hammered by short reads, and less frequently (but still often) by short writes.

"Short" is the key word here, since this is spin-based.

Definition at line 91 of file srwlock.h.

Public Types
enum	rwmode_t
Public Member Functions
	mcs_rwlock ()
	~mcs_rwlock ()
rwmode_t	mode () const
	Return the mode in which this lock is held by anyone.
bool	is_locked () const
	True if locked in any mode.
int	num_holders () const
	1 if held in write mode, else it's the number of readers
bool	has_reader () const
	True iff has one or more readers.
bool	has_writer () const
	True iff has a writer (never more than 1).
bool	attempt_read ()
	True if success.
void	acquire_read ()
	Wait (spin) until acquired.
void	release_read ()
	This thread had better hold the lock in read mode.
bool	attempt_write ()
	True if success.
void	acquire_write ()
	Wait (spin) until acquired.
void	release_write ()
	This thread had better hold the lock in write mode.
bool	attempt_upgrade ()
	Try to upgrade from READ to WRITE mode. Fail if any other threads are waiting.
void	downgrade ()
	Atomically downgrade the lock from WRITE to READ mode.

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

• src/sthread/srwlock.h
• src/sthread/srwlock.cpp

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