2pc 优化

数据存储

数据

//data_key1_ver3 --> {state:deleted, value:value22}
data_key1_commit_ts --> {state:update, value:value2}
data_key1_start_ts --> {state:update, value:value2}
data_key1_commit_ts_old --> {state:insert, value:value2}

锁

lock_key --> {}

事务链

trans_commit_ts --> {type:commited, beginTrans:start_ts, transList:[id0, id1/*参与者列表*/]}
//trans_commit_ts --> {type:prepared, beginTrans:start_ts}
trans_start_ts --> {type:begin, commitTrans:commit_ts}

流程

start_ts = getTS()
begin(start_ts)   //  trans_start_ts --> {type:begin, }
value = get(key, start_ts) 
value2 += value
update(key, value2, start_ts)   // data_key_start_st --> {state:ok, value:value}
                                // trans_start_ts --> {type:begin, keys:[key, ] }
commit_ts = getTS()
commit(commit_ts)   // data_key_commit_ts --> {state:ok, value:value,  }
                    // trans_commit_ts --> {type:prepared-->commited, beginTrans:start_ts, transList:[id0, id1/*参与者列表*/]}

访问

begin(start_ts)

增加记录 trans_start_ts --> {type:begin, }

get(key, start_ts)

搜索data_key_start_ts, SeekToPrev, 
loop key, ver, value
    1, 如果ver是start_ts, 返回value
    2, 通过ver查找事务trans_ver, 然后trans_ver的事务状态是commited, 返回value, 事务状态为commited或者abort则等待
    3, 返回not found

update(key, value2, start_ts)

增加记录data_key_start_st --> {state:ok, value:value}
trans_start_ts --> {type:begin, keys:[key, ] }中keys增加key

commit(commit_ts)

prepare:参与者:写trans_commit_ts --> {type:prepared, beginTrans:start_ts, transList:[id0, id1/*参与者列表*/]},
                trans_start_ts --> {type:begin, commitTrans:commit_ts}, 
        参与者:写data_key_commit_ts --> {state:ok, value:value,  }(*~~这里代价高~~*), 返回
    协调者:如果所有节点prepare返回成功, 则返回client成功, 异步通知transList:id0成功prepared
    参与者:transList:id0异步收集其他参与者状态, 都prepared后, 或者收到协调者通知prepared, 通知其他参与者commited

rollback(commit_ts)

prepare:参与者:写trans_commit_ts --> {type:abort, beginTrans:start_ts, transList:[id0, id1/*参与者列表*/]},
                    trans_start_ts --> {type:begin, commitTrans:commit_ts}, 返回

清理数据

死锁检测