### What problem were solved in this pull request?

Issue Number: close #152 

Problem:
增加gitpod 开发说明

### What is changed and how it works?

### Other information

### What problem were solved in this pull request?

Issue Number: close #89 close #154 

Problem:
how_to_build 文档中描述的编译内容缺少了benchmark，并且步骤过于繁琐。

### What is changed and how it works?
使用build.sh为基础描述构建文档。

### Other information

### What problem were solved in this pull request?

Issue Number: close #155 close #135 

Problem:
实现了简单的事务处理。
当前支持并发事务数据.

### What is changed and how it works?
- 支持两种事务模式：Vacuous和MVCC。
  Vacuous 事务模式算是没有事务，它的事务接口什么都不做。
MVCC 是多版本并发控制(Multi-Version Concurrency
Control)，使用多个版本保留记录数据。启动miniob时增加运行时选项 -t mvcc可以选择mvcc。

- MVCC：简单模式的多版本并发控制。
  当前miniob仅包含insert和delete操作，因此数据最多包含两个版本，并且不需要在record中保留版本链表信息；
  不支持持久化；
  没有做垃圾回收；
  遗留一个BUG：在提交时没有保证提交的数据一次性对外可见；
  使用简单的写写冲突策略：检测到要修改的数据当前有人在修改，就回退

- 编译MINIOB时使用 -DCONCURRENCY=ON 才会支持并发
支持各个模块并发处理，包括buffer pool、bplus、record
manager。如果编译时没有使用CONCURRENCY选项，则保持原样，不支持并发，保持系统的简单性。

- 编译时增加 -DDEBUG=ON 还会增加并发调试日志与严格的运行时检测(ASSERT语句)
- 当前版本代码中包含了bplus tree和record manager的并发测试，参考benchmark目录下的代码。

### Other information

### What problem were solved in this pull request?

Issue Number: close #159 

Problem:
common链接库编译了两次

### What is changed and how it works?
删除common_static，将common直接改成static链接库

### What problem were solved in this pull request?
github build action adds support for mac system
close #157 
Problem:

### What is changed and how it works?
added ci/cd support for Mac 

Fix problem:
1. the buffer pool and b tree is not thread safe;
2. github/workflow/build does not work

### What is changed and how it works?
1. thread-safe buffer pool
- I use a mutex in buffer pool and take a lock in buffer pool operations
such as allocate frame, dispose frame;
- The frame is locked while updating/reading the content of frame;
- Frame manager take a lock when allocate/free pages.

2. thread-safe b+tree
- Crabing protocol is used to support concurrent

3. github/workflow/build
- update the submodules;
- create a build script and run build.sh in build.yaml

logical plan & physical plan;
explain;
yacc rewrite;
join operator(nested loop join);
simple rewrite rules;
fix some issues of mysql protocol;

增加License、CODE_OF_CONDUCT、NOTICE和CONTRIBUTING文件
Co-authored-by: wangyunlai <hnwyllmm@126.com>

优化Docker开发环境：
- docker镜像使用zsh；
- 自动初始化vscode开发调试配置环境；
- 容器中开启ssh服务，方便远程开发；
- 可以在构建镜像时clone自己的代码；
- 提供了丰富详细的使用文档。

tested by mariadb ( Ver 15.1 Distrib 5.5.65-MariaDB, for Linux (x86_64) using readline 5.1)
but failed with obclient

如果使用readline，可以记录历史命令

* add comments for select-meta

Update problem specification for select-meta.

add cmake_prefix_path

add deps prefix

update googletest

update googletest