olahol / cpp-csp Goto Github PK

Is it possible to add support for the "timed waiting"?

So, I like the brevity and convenience...unfortunately, it's got several significant bugs in it.

1. FIFO is not preserved: suppose A then B put on a channel, and block. The reader gets. A's value gets read, but whether it's A or B that gets notified is up to chance. PLUS (or maybe instead), since when A/B check their status, there's still an item on the queue, neither actually unblocks. (Maybe the order thing would start to actually matter once you got more than two writers.)
2. notify_one vs notify_all: Some test code I wrote triggered a bug where a writer and reader were asleep at the same time on a channel, and writer wrote, and rather than the reader waking up and checking its condition, the other writer woke up, noted its condition still false, and went back to sleep. Replacing both of the notify_ones with notify_alls seemed to fix that particular deadlock.
3. Maybe not a bug, but it looks like select just busy-waits, continually checking if any channel has stuff. This probably WORKS, and is EASY, but should perhaps be noted?

You could look at https://github.com/tidwall/Safe - I remember that library working pretty well for me, and it might make good reference.