SauronDB

An extended fork of SimpleDB (http://www.cs.bc.edu/~sciore/simpledb/).

Meet The Team

Team Member	Unity Id
Dustin Lambright	dalambri
Guanxu Yu	gyu9
Darshan Bhandari	dbhanda
Leonard Kerr	lwkerr
Yuchen Sun	ysun34

Files Changed - Add these on your own, lads!

SimpleDB.java

initFileLogAndBufferMgr() method

• Updated such that the buffermanager is initialized before the log manager so that the log manager can use the buffer manager to pin blocks.

LogMgr.java

Changed all methods to now use buffers from the buffer manager instead of pages.

printLogPageBuffer() method

• This is the optional print method to view the changes made to the pinned block

LogFormatter.java

This is a new class which implements PageFormatter to satisfy the need for a PageFormatter in the pinNew method. This is essentially an empty class.

Buffer.java

Add two private variables in Buffer class

• Add private long lastAccessTime and secLastAccessTime to record last/second last access time of a buffer.

getContents() method

• This is a wrapper method to get the contents of the pinned block for the printLogPageBuffer() method

updateAccessTime()

• Update access time of buffer when buffer is pinned

getLastAccessTime()

• Get last access time of a buffer

getSecLastAccessTime()

• Get second last access time of a buffer

resetAccessTime()

• Reset last/second last access time to infinity when a buffer is chosen to replace

BasicBufferMgr.java

BasicBufferMgr()

• This is the constructor of BasicBufferMgr class. Since we changed the bufferpoll into map, so we changed how bufferpool initialized at constructor.

flushAll() method

• Rewrite this method to fit map structure

pin() method

• Rewrite this method to fit map structure and update buffer access time

pinNew() method

• Rewrite this method to fit map structure and update buffer access time

containsMapping() method

• Used for testing

getMapping() method

• Used for testing

findExistingBuffer(Block blk) method

• Returns the buffer that the map maps the specified block to.

chooseUnpinnedBuffer() method

• Returns the buffer that is unpinned. Change function to work with map
• Choose replacing buffer based on LRU (K=2) policy

LRU2() method

• LRU (K=2) policy, take a list of candidate buffers, return chosen one by LRU

How to run the test scenarios

Log Manager:

• in lines DUZN and DUZN of LogMgr.java we have hard-coded print statements for the pinned block to prove functionality before and after flush. If you want to avoid these statements, feel free to comment them out.

• We've written TestLogMgr to show the use of pinned blocks. If you run TestLogMgr many times, you will see that the block pinned to the buffer increases (Displayed like so: Buffer number pinned to the log block: 14)

Buffer Manager:

• In TestBufferMgr.java file, we already setup testcase for Buffer Manager. And also we add comments and hard-code print statements to indicate what our testcase looks like. You just need to run it and see the result.