void Buffer::ensureWritableBytes(size_t len)
{
if (writableBytes() < len)
{
makeSpace(len);
}
assert(writableBytes() >= len);
}
ssize_t Buffer::readFd(int fd, int* savedErrno)
{
// saved an ioctl()/FIONREAD call to tell how much to read
char extrabuf[65536];
struct iovec vec[2];
const size_t writable = writableBytes();
vec[0].iov_base = begin()+writerIndex_;
vec[0].iov_len = writable;
vec[1].iov_base = extrabuf;
vec[1].iov_len = sizeof extrabuf;
// when there is enough space in this buffer, don't read into extrabuf.
// when extrabuf is used, we read 128k-1 bytes at most.
const int iovcnt = (writable < sizeof extrabuf) ? 2 : 1;
const ssize_t n = sockets::readv(fd, vec, iovcnt);
if (n < 0)
{
*savedErrno = errno;
}
else if (implicit_cast<size_t>(n) <= writable)
{
writerIndex_ += n;
}
else
{
writerIndex_ = buffer_.size();
append(extrabuf, n - writable);
}
// if (n == writable + sizeof extrabuf)
// {
// goto line_30;
// }
return n;
}
Buffer::Buffer()
: readerIndex_(kCheapPrepend),
writerIndex_(kCheapPrepend)
{
buffer_.assign(kInitialSize+kCheapPrepend,0);
assert(readableBytes() == 0);
assert(writableBytes() == kInitialSize);
assert(prependableBytes() == kCheapPrepend);
}
void Buffer::makeSpace(size_t len)
{
if (writableBytes() + prependableBytes() < len + kCheapPrepend)
{
// FIXME: move readable data
buffer_.resize(writerIndex_+len+kCheapPrepend,0);
}
else
{
// move readable data to the front, make space inside buffer
assert(kCheapPrepend < readerIndex_);
size_t readable = readableBytes();
std::copy(begin()+readerIndex_,
begin()+writerIndex_,
begin()+kCheapPrepend);
readerIndex_ = kCheapPrepend;
writerIndex_ = readerIndex_ + readable;
assert(readable == readableBytes());
}
}
