On Wednesday, 1 July 2020 at 07:52:28 UTC, AB wrote:
Hello. I am unsure how to proceed about printing progress in my
program.
Suppose the program is processing a very big file and is
iterating the file's bytes using a for loop. The processing
takes several minutes and I want a progress percentage be
printed every 2 seconds in this manner:
Progress: 0.40%
Progress: 3.20%
Progress: 5.73%
Is it a good idea to std.concurrency.spawn a new thread and
pass to it
cast(float)i * 100 / fileSize
somehow? If not, what's a better way to do this?
This example code shows my situation:
MmFile input = new MmFile(/* ... */);
ulong fileSize = input.length;
for (ulong i = 0; i < fileSize; ++i)
{
// ...
}
Thanks in advance.
If doing the update in the same thread that does the processing
is somehow not an option, this works for me:
import std.concurrency;
import std.stdio;
import core.thread;
import core.time;
void main() {
ulong filesize = 1234;
ulong i = 0;
Tid progress = spawn((shared const(ulong)* p, ulong f){
while (!receiveTimeout(2000.msecs, (int i){ })) {
writeln(*p, "/", f, ": ", *p*100.0/f, "%");
}
}, cast(shared)&i, filesize);
for (; i < filesize; ++i) {
// Process
}
progress.send(0); // Stop
}
There's a cast to shared there which may be suboptimal, but since
the progress thread is only reading it, I would say it's ok.
--
Simen
