这里ToWriteBytes>10240有什么意义

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ssize_t HttpConn::write(int* saveErrno) {
ssize_t len = -1;
do {
len = writev(fd_, iov_, iovCnt_);
if(len <= 0) {
saveErrno = errno;
break;
}
if(iov_[0].iov_len + iov_[1].iov_len == 0) { break; } / 传输结束 /
else if(static_cast<size_t>(len) > iov_[0].iov_len) {
iov_[1].iov_base = (uint8_t) iov_[1].iov_base + (len - iov_[0].iov_len);
iov_[1].iov_len -= (len - iov_[0].iov_len);
if(iov_[0].iov_len) {
writeBuff_.RetrieveAll();
iov_[0].iov_len = 0;
}
}
else {
iov_[0].iov_base = (uint8_t*)iov_[0].iov_base + len;
iov_[0].iov_len -= len;
writeBuff_.Retrieve(len);
}
} while(isET || ToWriteBytes() > 10240);
return len;
`}```