public long getNextSequence(TypeDescriptor typeDescriptor, Session session) {
// check if there is an id in the cache
ConcurrentLinkedQueue cachedIds =
(ConcurrentLinkedQueue) this.typeDescriptorToIdCache.get(typeDescriptor);
if (null == cachedIds) {
typeDescriptorToIdCache.putIfAbsent(typeDescriptor, new ConcurrentLinkedQueue());
cachedIds = (ConcurrentLinkedQueue) this.typeDescriptorToIdCache.get(typeDescriptor);
}
Number cachedId = (Number) cachedIds.poll();
if (cachedId == null) {
synchronized (cachedIds) {
cachedId = (Number) cachedIds.poll();
if (cachedId == null) {
List newIds = this.getNextSequenceImpl(typeDescriptor, session);
Assert.condition(0 < newIds.size());
// reserve first for own use
cachedId = (Number) newIds.remove(0);
cachedIds.addAll(newIds);
}
}
}
if (trace.isDebugEnabled()) {
trace.debug("returning unique ID: " + cachedId.longValue());
}
return cachedId.longValue();
}
/**
* 执行统计查询语句，语句的执行结果必须只返回一个数值
*
* @param sql
* @param params
* @return
* @throws DBException
*/
public long stat(String sql, Object... params) throws SQLException {
printIn(sql);
printIn("params length:" + params.length);
for (int i = 0; i < params.length; i++) {
printIn("params" + i + ":" + params[i]);
}
Number num = (Number) queryRunner.query(getConnection(), sql, scalarHandler, params);
return (num != null) ? num.longValue() : -1;
}