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use memcpy() instead of memmove() if data doesn't overlap
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Andrea Guzzo committed Apr 13, 2014
1 parent ed353ca commit e6ba756
Showing 1 changed file with 6 additions and 6 deletions.
12 changes: 6 additions & 6 deletions src/iomux.c
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Original file line number Diff line number Diff line change
Expand Up @@ -883,19 +883,19 @@ iomux_run(iomux_t *iomux, struct timeval *tv_default)
continue;

if (len) {
memmove(iomux->connections[i]->outbuf + iomux->connections[i]->outlen, data, len);
memcpy(iomux->connections[i]->outbuf + iomux->connections[i]->outlen, data, len);
iomux->connections[i]->outlen += len;
memcpy(&iomux->events[n], &iomux->connections[i]->event, 2 * sizeof(struct kevent));
n += 2;
} else {
memmove(&iomux->events[n], &iomux->connections[i]->event, sizeof(struct kevent));
memcpy(&iomux->events[n], &iomux->connections[i]->event, sizeof(struct kevent));
n++;
}
} else if (iomux->connections[i]->outlen) {
memmove(&iomux->events[n], &iomux->connections[i]->event, 2 * sizeof(struct kevent));
memcpy(&iomux->events[n], &iomux->connections[i]->event, 2 * sizeof(struct kevent));
n += 2;
} else {
memmove(&iomux->events[n], &iomux->connections[i]->event, sizeof(struct kevent));
memcpy(&iomux->events[n], &iomux->connections[i]->event, sizeof(struct kevent));
n++;
}
}
Expand Down Expand Up @@ -986,7 +986,7 @@ iomux_run(iomux_t *iomux, struct timeval *tv_default)
continue;

if (len) {
memmove(iomux->connections[i]->outbuf + iomux->connections[i]->outlen, data, len);
memcpy(iomux->connections[i]->outbuf + iomux->connections[i]->outlen, data, len);
iomux->connections[i]->outlen += len;
}
}
Expand Down Expand Up @@ -1098,7 +1098,7 @@ iomux_run(iomux_t *iomux, struct timeval *tv_default)
continue;

if (len) {
memmove(iomux->connections[fd]->outbuf + iomux->connections[fd]->outlen, data, len);
memcpy(iomux->connections[fd]->outbuf + iomux->connections[fd]->outlen, data, len);
iomux->connections[fd]->outlen += len;
}
}
Expand Down

2 comments on commit e6ba756

@dgryski
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Benchmark please :P. I'm of the camp that you should just always use memmove and let libc have the three asm instructions to determine if the blocks overlap and which implementation to dispatch to. Having a single code path is also simpler.

@xant
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@xant xant commented on e6ba756 Apr 13, 2014

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well they don't overlap there... memmove was used in the previous implementation and I just left it there.
For what it's doing sounds more natural to use memcpy() instead of memmove() ... performances are exactly the same from what I've seen
(AKA: it's irrelevant)

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