Sharding branch, doc: https://github.com/Qihoo360/Atlas/wiki/Atlas-Sharding

New features:

1. sql parser 增加"show variables"语法支持

Bug fix:

1. 修复配置文件groupid指定不连续导致的bug.

New features:

1. Add ‘select/add/remove pwd(or enpwd)' command in admin interface, use this command to set the config option: pwds.
2. 'save config' command can save the pwds to the config file.
3. add ‘select version’ command in admin interface, use this command to show the version of Atlas.
4. log the forbidden SQLs and client ip to the log file.
5. close the inactive client connections after wait-timeout seconds.

Bug fix:

1. fix the bug of no checking the length of token which may lead Atlas crash.

New features:

1. Add 'save config' command in admin interface, use this command can save the master/slave infomation to the config file.
2. Add 'add/remove client' command in admin interface, use this command can set the config option: client-ips.
3. Adjust the strategy of forwarding result, avoid using too large memory.
4. When the parent process restart the child process, the child process will reload the config file.
5. The master thread only process the requests from admin port, do not process the requests from work port.
6. Add config option:'sql-log-slow' for recording slow logs.
7. Use jemalloc library to optimize memory management.
8. Support utf8mb4 charset.
9. Support prepare statement limited, supporting java, python, PHP(PDO mode).

Bug fix:

1. Fix the bug of multiple clients connect admin port, Atlas will crash.
2. Fix the bug of strategy of load balance leading read/write spliting failure.
3. Fix the bug of parsing the handshaking packet error, when the count of mysql connection reach the ceiling.
4. Fix the bug of analyzing the sql token error, Atlas will quit.

New features:

1. Support multiple MySQL clients: MySQL Workbench, Navicat and SQLyog.
2. The master can be a slave for reading.
3. Forbid the update sqls that have no 'where' condition.
4. Add the informations about server port and client port in sql log.
5. Remove the config options: admin-lua-script and instance.
6. Each thread has a connection pool to backend.

Bug fix:

1. Fix bug of the config option:charset doesn't work
2. Fix bug of update/delete operate in sharding.

1. change backend state from unknown to down when connect fails
2. send COM_SET_OPTION to slave
3. remove uuid and connected_clients in admin.lua

fix bug of set character_[client|results|connection]

1. support long connection
2. remove min-idle-connections
3. SQL log can be closed
4. remove the mode restriction of config file
5. fix space bug in admin.lua
6. remove chassis_private->cons and con_mutex
7. remove is_insert_id
8. mysql-proxyd reports error info when startup fails
9. check_state doesn't change the state of backends to down
10. check_state doesn't check the DBs whose state is UP
11. Atlas destructs the connection when a client which in transaction state exits