I have found pseudo code on how to implement a circular buffer.
// Producer.
while (true) {
/* produce item v */
while ((in+1)%n == out)
/* Wait. */;
b[in] = v;
in = (in + 1) % n
}
// Consumer.
while (true) {
while (in == out)
/* Wait. */;
w = b[out];
out = (out + 1) % n;
/* Consume item w. */
}
What I don't understand is the "Consume item w." comment, because I think that with w = b[out]; we are consuming w, aren't we?
With
w = b[out];
You only grab a copy of the item to be consumed. With
out = (out + 1) % n;
You advance the index of the item to be consumed, thereby preventing it from being referenced again.
In a manner, multiple calls to w = b[out]; don't actually consume the buffer's slot, it just accesses it; while out = (out + 1) % n; prevents further access of that item. Preventing further access of the buffer item is the strongest definition of the term "consume the item" that I can think of.
these two lines are both part of consuming process:
w = b[out];
out = (out + 1) % n;
The first extract the value and the second increment the out index. The comment refers to the previously two lines.
/* produce item v */ we need to assign v to a random number or something like that.. i thought we need a different process for ` /* Consume item w. */ `
Yes, because then it's out of the buffer, which the following row says is empty. Then we can process w.
