Bad request from cache server

[medic0803]

Describe the bug
The cache server send the wrong format of http request which lead to http 400 bad request

[medic0803]

Reason: Readlines() freezed the whole process, change it to readline(), everything run smoothly

[medic0803]

The http connection has successfully completed with the full header of http request, but the new issue is that the read data cannot be written into the tempfile and send back to client

[medic0803]

On the one hand recv() hangs due to the socket would block itself. Since I set the timeout it could break itself, on the other hand, when we get the big file, it would be cut into small block, so we have to enlarge the buffer size. Everything run smoothly now.