Range<AsyncIO::Op**> AsyncIO::doWait(size_t minRequests, size_t maxRequests) {
io_event events[pending_];
int count;
do {
// Wait forever
count = io_getevents(ctx_, minRequests, maxRequests, events, nullptr);
} while (count == -EINTR);
checkKernelError(count, "AsyncIO: io_getevents failed");
DCHECK_GE(count, minRequests); // the man page says so
DCHECK_LE(count, pending_);
completed_.clear();
if (count == 0) {
return folly::Range<Op**>();
}
for (size_t i = 0; i < count; ++i) {
DCHECK(events[i].obj);
Op* op = boost::intrusive::get_parent_from_member(
events[i].obj, &AsyncIOOp::iocb_);
--pending_;
op->complete(events[i].res);
completed_.push_back(op);
}
return folly::Range<Op**>(&completed_.front(), count);
}
Range<AsyncIO::Op**> AsyncIO::doWait(size_t minRequests, size_t maxRequests) {
io_event events[maxRequests];
size_t count = 0;
do {
int ret;
do {
// GOTCHA: io_getevents() may returns less than min_nr results if
// interrupted after some events have been read (if before, -EINTR
// is returned).
ret = io_getevents(ctx_,
minRequests - count,
maxRequests - count,
events + count,
/* timeout */ nullptr); // wait forever
} while (ret == -EINTR);
// Check as may not be able to recover without leaking events.
CHECK_GE(ret, 0)
<< "AsyncIO: io_getevents failed with error " << errnoStr(-ret);
count += ret;
} while (count < minRequests);
DCHECK_LE(count, maxRequests);
completed_.clear();
if (count == 0) {
return folly::Range<Op**>();
}
for (size_t i = 0; i < count; ++i) {
DCHECK(events[i].obj);
Op* op = boost::intrusive::get_parent_from_member(
events[i].obj, &AsyncIOOp::iocb_);
decrementPending();
op->complete(events[i].res);
completed_.push_back(op);
}
return folly::Range<Op**>(&completed_.front(), count);
}