Author: Smita Vijayakumar
2015/5/23

Build Instructions:
-------------------
   exoredis_server binary is provided along with the source code. This is the
   most recent binary. Alternately, the binary may be compile by running make
   inside the source directory.

Please read the Limitations section that captures the current limitations.

Through the developer's mind
-----------------------------

This was what was thought when making this project:
1. Implement simple TCP Server at port EXOREDIS_SERVER_TCP_PORT
2. Test telnet echoes a server response for the telnet request (connection 
   request and special request)
3. Implement REDIS protocol at server
4. Repeat step 2.

Limitations:
-------------
1. Only one client may connect to this server for now.
2. .exordb file format is slightly different. Only length-key-value make up the
   entries for now.
3. No buffering of requests. For now one request is followed by response, in
   that order.
4. LOAD: DB file contents are loaded into hash table during startup.
5. READ: When a read occurs, the hash table is looked up. A hit returns the
   value. A miss writes a new entry into hash table.
6. WRITE: Write always writes the value of the key into the hash table, or
   updates it. This also depends on optional flags (NX or XX).
7. SAVE (Or Program Exit): Write contents of the hash table to the file. 
   Replace exisiting file with the new DB file written.
8. Spaces are considered valid characters in value, so trailing spaces in value
   are not pruned.
9. ZADD does not strip or match quotes (""). They are considered a part of the
   string, unlike the original protocol that matches and strips the quotes. 
   Hence, the length in such cases will be more than that reported by REDIS.
   If desired, the strings can be specified without the quotes.
10. When no DB file exists, do a touch on the file and provide input

Sample UT Logs:
---------------
On the server do:

make clean; make; touch dbfile; ./exoredis_server dbfile

Sample logs on client:
root@smita-virtual-machine:/home/smita/exoredis# telnet localhost 15000
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
GET str
$0
SET str newstring
+OK 
GEt str
$9
newstring
SAVE
+OK 
ZADD set 3 "three"
:1
ZADD set 2 "two"
:1
ZADD set 4 "four"
:1
ZRANGE set 0 2 withscores
*6
$5
"two"
$1
2
$7
"three"
$1
3
$6
"four"
$1
4
SAVE
+OK