George Cristea

我在一个生产系统中实现了一个有向无环图，用于读/写比率大于1的授权,000. Additionally, the most frequent operation was to get the ancestors for a node. 我将数据结构从“使用有理数到键嵌套集”扩展到实现有向无环图. The data structures described by the paper are multi-way trees. 子树中的节点值在由子树根值及其右侧兄弟节点定义的间隔内具有编码.

Work Done:
• Introduced a root node to handle cases not covered by the original paper (e.g., when a node doesn't exist in the system).
•转换数据结构，以允许有向无环图的表示，并检测和防止引入循环. 代码使用几个多路树来表示从根节点到叶节点的多条路径，每个子树都存储为MongoDB文档.
• To ensure data consistency I used Redis locking for document updates. The reason for using Redis has to do with MongoDB concurrency model.
• Using the continued fractions encoding, 我能够确保根据MongoDB查询的数量，在恒定的时间内执行读取操作.

I designed and implemented a cloud management system that supports multiple cloud providers, both public and private. 私有云基于OpenStack，而公共云提供商是AWS、GCP和Azure. The system offers the ability to audit cloud accounts, provision new cloud accounts, and is integrated with a corporate finance system.

它是使用AWS简单工作流服务实现的，每个提供商都有几个工作流. The back-end was implemented using Node.js and PostgreSQL.

A Cassandra NoSQL storage system was trying to use a hard-coded set of ciphers. 但是，在主机上没有安装所有密码的情况下，服务器无法创建SSL套接字，因此我为此创建了一个修复程序.

我为一个由大约20个节点组成的Cassandra集群实现了一个备份管理器. 备份管理器使用分布式锁将执行备份的节点数量限制为一次只有一个.

分布式锁在Cassandra中使用keyspace实现，其中执行备份的节点将写入其身份. 存储在keyspace中的值具有较长的过期时间，以确保在出现节点故障时继续进行备份.

I implemented an Erlang port to interface with a Berkeley DB High Availability C library. The Berkeley DB HA offers full replication of data from the master to slave nodes.

Erlang端口驱动程序运行与Erlang VM相同的进程，它跟踪哪个节点是主节点. 所有的读操作都来自本地Berkeley DB存储，而写操作则通过Erlang的本地远程过程调用转发到主服务器.

I designed and implemented an engine for calculating the order total, taxes, discounts, and shipping charges. The library's C++ code was generated by a compiler from field dependency declarations. The compiler extracted semantic information from the input (e.g., the price to be displayed should include taxes for EU countries).