Extend task 1 so that it now supports a memory buffer of limited size. Provide the same functionality as task 1 except now make the server work with a limited buffer size.

Like task 1, the server is the only thread that can access the buffer directly.

1. Allow user to specify a 2nd command line argument which specifies the buffer size in terms of the number of pages. Let that number be B.

2. The server reads the first B pages from the init_buffer_pages.dat file into the buffer. It then copies all the pages into a store file. You can organize the store file anyway you want as long as it stores all pages including those not in memory. I recommend that you use a binary file to do this since that allows you to do random seeks on the file. Assume all pages have a fixed size of 4096 characters.

3. When a page request for a non-buffer resident page occurs one page that is currently in the buffer must be evicted from memory to make room for the newly requested page to be loaded from the store file. The page replacement policy you need to implement is the least recently used (LRU) policy. Please read page 489 of the textbook for an explanation of the LRU policy.

4. Once a page to be evicted has been chosen then the program must decide whether it should be flushed to the store file or discarded.
a) If the page has been dirtied (modified) since its last load from disk then it should be flush to the store file on disk.
b) Otherwise it should be discarded without flushing to the store file.

5 The server needs to keep a log of the sequence of page evictions (pages either discarded or flushed to disk) in a log file called "server_log.dat". The entries in the log file are in the order that they were evicted. Looking at this file I will be able to tell if you have implemented the LRU page-replacement policy correctly.

The server_log.dat file should be in the following format:


...
...

For example:

20 abscde
10 KJlkljf
29 jjkjkKKH