Update demo to use process identifier for entry name
Remove unused countEntries()
Add void, static, and const

Add void and const to the function parameters.
Add static to the global variables.
Add find() with region locking and close database atexit()
Update {lock,unlock}DB to region locking
Update addP() to region locking
Update removeP() to region locking and add print_region() function
Fix unlockDB to use F_SETLCK command and F_UNLCK type

Update lseeks to use lock start and whence fields
Fix removeDB deadlock

removeP releases RDLCK and yields if it cannot acquire WRLCK
lockDB attempts the lock a fixed number of times before returning.
addP calls fcntl directly using F_SETLKW instead of calling lockDB
Update getP() to region locking

Add lockDBW(), comments, and perror messages