hello experts, Please, can anynobody give me an example of circular queue from real life. i mean in real life where do we use a circular queue. what are its computer implementations ?
Waiting..
Thanks.
TheTechGuy.
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> in real life where do we use a circular queue
How about .... a wall clock? You got 60sec in a queue, second hand indicates current position in queue. Same for the 60 minutes, and minute hand.
> what are its computer implementations ?
The computer simulates the clock's queue through applied math. Ramifications: try handling that one where every so often they want you to add a second to the clock this year, but not last year or next.
In real life?
Think about your bills, on a monthly basis.
Pay the ISP
Pay the rent
Pay the alimony
Pay the mortgage
Pay the credit-card
.....
And the next month, same thing, same order...
Sure, occasionally things get added to or removed from the merry-go-round, but it's still just a re-adjusted sequence.
If you haven't had much practice in this area, you could pay a few of my bills for a while if you like - just so you get to understand the concept 'K?
...Bill
Oh - you wanted computer implications?
The bank's computer seems to handle each of these operations with alarming precision - but I think it's on some kind of commission. Often it amuses itself by sending me a bogus letter saying I'm out of funds - but i think it's just doing that to keep the mailman in a job.
Concurrent machines - or is that Perkin-Elmer. Interdata maybe - shows his age... :(
have list-handling inbuilt into their instruction set. ATL adds to the top-of-list, ABL to bottom, and RxL removed from the x position IIRC - it's been a while!
I believe other machines are normally fed macros to perform these tasks.
...Bill
Business Accounts
Answer for Membership
by: _nn_Posted on 2003-08-25 at 03:52:56ID: 9215219
Every time you need a FIFO (First In First Out) buffer, it's smarter to use a circular buffer, because you avoid lengthy memory move operations :
Let's assume :
you've read "abcdefghij" from your COM port
[abcdefghij--------------]
now another thread wants to process the content byte per byte. You have to
* read one byte
[-bcdefghij--------------]
* move the entire buffer one byte to the left
[bcdefghij---------------]
That's slooooooooooooow and dumb.
Instead, use 2 pointers : one for reading, one for writing.
v
[abcdefghij--------------]
^
You never move the memory, you just update pointers (or array indexes). One must be careful with the implementation, i.e. :
- deal properly with overflows
- threads synchronization
but there are tons of freely available examples, just google a bit : "circular buffer queue" should get you tons of hits.
A real life example ? The kernel of our product is a console application. There are contexts threads associated with "lines" (this is a telephony application). Each of these lines has a debug output which is buffered in a FIFO, so that I can display at runtime the latest output of each of these "lines". Size of the buffers is limited. What algo did I use ? A circular buffer of course. In this case, they are a bit special though, since after a while, they are always full (oldest entries get overwritten by the newest ones). But it does the job I want : it tells me what are the latest events on each line.