public void updateRecord(MetaRecord rec) {
try {
long ts = System.currentTimeMillis();
putRecord(rec, ts);
String node = ZKUtil.joinZNode(H2MetaTableTracker.NODE_NAME, Integer.toString(rec.getId()));
// setData会异步触发所有机器(包括本机)上的H2MetaTableTracker.nodeDataChanged
// 然后触发下列调用:
// =>org.h2.engine.Database.updateDatabaseObject(int)
// =>org.h2.engine.Database.update(Session, DbObject)
// =>org.h2.engine.Database.addMeta0(Session, DbObject, boolean)
// =>又到此方法
// 所以会造成循环
synchronized (this) { // 避免setData后立刻触发nodeDataChanged，此时IdVersion还未更新
ZKUtil.setData(watcher, node, Bytes.toBytes(ts));
// setData后watch不见了，所以要继续watch，监听其他人对此node的修改
// ZKUtil.watchAndCheckExists(watcher, node);
Stat stat = new Stat();
ZKUtil.getDataAndWatch(watcher, node, stat);
// 这里记录下id的最新版本，触发nodeDataChanged时再检查一下是否版本一样，
// 如果不大于这里的版本那么就不再执行updateDatabaseObject操作
tracker.updateIdVersion(rec.getId(), stat.getVersion());
}
} catch (Exception e) {
throw new RuntimeException(e);
}
}
public void addRecord(MetaRecord rec) {
try {
putRecord(rec, System.currentTimeMillis());
String node = ZKUtil.joinZNode(H2MetaTableTracker.NODE_NAME, Integer.toString(rec.getId()));
ZKUtil.createAndWatch(watcher, node, EMPTY_BYTE_ARRAY);
tracker.updateIdVersion(rec.getId(), 0);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
public void loadMetaRecords(List<MetaRecord> records) throws Exception {
MetaRecord rec;
for (Result r : table.getScanner(new Scan())) {
if (r.isEmpty()) continue;
rec = getMetaRecord(r);
records.add(rec);
if (!tracker.contains(rec.getId()))
ZKUtil.createNodeIfNotExistsAndWatch(
watcher,
ZKUtil.joinZNode(H2MetaTableTracker.NODE_NAME, Integer.toString(rec.getId())),
EMPTY_BYTE_ARRAY);
}
}
private void putRecord(MetaRecord rec, long ts) throws Exception {
Put put = new Put(Bytes.toBytes(rec.getId()));
put.add(FAMILY, OBJECT_TYPE, ts, Bytes.toBytes(rec.getObjectType()));
put.add(FAMILY, SQL, ts, Bytes.toBytes(rec.getSQL()));
// System.out.println("addRecord id: " + rec.getId() + ", sql=" + rec.getSQL());
table.put(put);
}