Writeset_trx_dependency_tracker Class Reference

Generate logical timestamps for MTS using WRITESET binlog transaction dependency tracking algorithm. More...

#include <rpl_trx_tracking.h>

Public Member Functions
	Writeset_trx_dependency_tracker (ulong max_history_size)
void	get_dependency (THD *thd, int64 &sequence_number, int64 &commit_parent)
	Main function that gets the dependencies using the WRITESET tracker. More...
void	rotate (int64 start)

Public Attributes
std::atomic< ulong >	m_opt_max_history_size

Private Types
using	Writeset_history = ankerl::unordered_dense::map< uint64, int64 >

Private Attributes
int64	m_writeset_history_start
Writeset_history	m_writeset_history

Detailed Description

Generate logical timestamps for MTS using WRITESET binlog transaction dependency tracking algorithm.

Tracks dependencies based on the set of rows updated. Any two transactions that change disjoint sets of rows, are said concurrent and non-contending.

Member Typedef Documentation

Writeset_history

using Writeset_trx_dependency_tracker::Writeset_history = ankerl::unordered_dense::map<uint64, int64>

private

Constructor & Destructor Documentation

Writeset_trx_dependency_tracker()

Writeset_trx_dependency_tracker::Writeset_trx_dependency_tracker ( ulong  max_history_size )

inline

Member Function Documentation

get_dependency()

void Writeset_trx_dependency_tracker::get_dependency	(	THD *	thd,
		int64 &	sequence_number,
		int64 &	commit_parent
	)

Main function that gets the dependencies using the WRITESET tracker.

Get the writeset dependencies of a transaction.

Parameters

[in]	thd	THD of the caller.
[in,out]	sequence_number	sequence_number initialized and returned.
[in,out]	commit_parent	commit_parent to be returned.

This takes the commit_parent that must be previously set using Commit_order_trx_dependency_tracker and tries to make the commit_parent as low as possible, using the writesets of each transaction. The commit_parent returned depends on how many row hashes are stored in the writeset_history, which is cleared once it reaches the user-defined maximum.

Parameters

[in]	thd	Current THD from which to extract trx context.
[in,out]	sequence_number	Sequence number of current transaction.
[in,out]	commit_parent	Commit_parent of current transaction, pre-filled with the commit_parent calculated by Commit_order_trx_dependency_tracker to use when the writeset commit_parent is not valid.

rotate()

void Writeset_trx_dependency_tracker::rotate

(

int64

start

)

Member Data Documentation

m_opt_max_history_size

std::atomic<ulong> Writeset_trx_dependency_tracker::m_opt_max_history_size

m_writeset_history

Writeset_history Writeset_trx_dependency_tracker::m_writeset_history

private

m_writeset_history_start

int64 Writeset_trx_dependency_tracker::m_writeset_history_start

private

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

• sql/rpl_trx_tracking.h
• sql/rpl_trx_tracking.cc