protected EntryPosition findStartPositionInternal(ErosaConnection connection) {
MysqlConnection mysqlConnection = (MysqlConnection) connection;
LogPosition logPosition = logPositionManager.getLatestIndexBy(destination);
if (logPosition == null) { // 找不到历史成功记录
EntryPosition entryPosition = null;
if (masterInfo != null
&& mysqlConnection.getConnector().getAddress().equals(masterInfo.getAddress())) {
entryPosition = masterPosition;
} else if (standbyInfo != null
&& mysqlConnection.getConnector().getAddress().equals(standbyInfo.getAddress())) {
entryPosition = standbyPosition;
}
if (entryPosition == null) {
entryPosition = findEndPosition(mysqlConnection); // 默认从当前最后一个位置进行消费
}
// 判断一下是否需要按时间订阅
if (StringUtils.isEmpty(entryPosition.getJournalName())) {
// 如果没有指定binlogName，尝试按照timestamp进行查找
if (entryPosition.getTimestamp() != null && entryPosition.getTimestamp() > 0L) {
logger.warn(
"prepare to find start position {}:{}:{}",
new Object[] {"", "", entryPosition.getTimestamp()});
return findByStartTimeStamp(mysqlConnection, entryPosition.getTimestamp());
} else {
logger.warn("prepare to find start position just show master status");
return findEndPosition(mysqlConnection); // 默认从当前最后一个位置进行消费
}
} else {
if (entryPosition.getPosition() != null && entryPosition.getPosition() > 0L) {
// 如果指定binlogName + offest，直接返回
logger.warn(
"prepare to find start position {}:{}:{}",
new Object[] {entryPosition.getJournalName(), entryPosition.getPosition(), ""});
return entryPosition;
} else {
EntryPosition specificLogFilePosition = null;
if (entryPosition.getTimestamp() != null && entryPosition.getTimestamp() > 0L) {
// 如果指定binlogName + timestamp，但没有指定对应的offest，尝试根据时间找一下offest
EntryPosition endPosition = findEndPosition(mysqlConnection);
if (endPosition != null) {
logger.warn(
"prepare to find start position {}:{}:{}",
new Object[] {entryPosition.getJournalName(), "", entryPosition.getTimestamp()});
specificLogFilePosition =
findAsPerTimestampInSpecificLogFile(
mysqlConnection,
entryPosition.getTimestamp(),
endPosition,
entryPosition.getJournalName());
}
}
if (specificLogFilePosition == null) {
// position不存在，从文件头开始
entryPosition.setPosition(BINLOG_START_OFFEST);
return entryPosition;
} else {
return specificLogFilePosition;
}
}
}
} else {
if (logPosition
.getIdentity()
.getSourceAddress()
.equals(mysqlConnection.getConnector().getAddress())) {
logger.warn("prepare to find start position just last position");
return logPosition.getPostion();
} else {
// 针对切换的情况，考虑回退时间
long newStartTimestamp =
logPosition.getPostion().getTimestamp() - fallbackIntervalInSeconds * 1000;
logger.warn(
"prepare to find start position by switch {}:{}:{}",
new Object[] {"", "", logPosition.getPostion().getTimestamp()});
return findByStartTimeStamp(mysqlConnection, newStartTimestamp);
}
}
}
