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perf: remove libtransmission::Buffer.vecs() (#4401) 

Its two calls to evbuffer_peek() used 3.5% of CPU use (measured with perf
when built with RelWithDebInfo). I added vecs() so that libtransmsision
could send noncontiguous buffers via utp_writev(); but in my testing, all
the buffers being sent are contiguous and so this is unnecessary work.
This commit is contained in:
Charles Kerr 2022-12-18 12:09:02 -06:00 committed by GitHub
parent cc4141c619
commit 28b12f091f
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2 changed files with 6 additions and 18 deletions
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12
libtransmission/peer-socket.cc
View File

@ -80,19 +80,19 @@ size_t tr_peer_socket::try_write(Buffer& buf, size_t max, tr_error** error) cons
#ifdef WITH_UTP #ifdef WITH_UTP
if (is_utp()) if (is_utp())
{ {
auto iov = buf.vecs(max); auto [data, datalen] = buf.pullup();
errno = 0; errno = 0;
auto const n = utp_writev(handle.utp, reinterpret_cast<struct utp_iovec*>(std::data(iov)), std::size(iov)); auto const n_written = utp_write(handle.utp, data, std::min(datalen, max));
auto const error_code = errno; auto const error_code = errno;
if (n > 0) if (n_written > 0)
{ {
buf.drain(n); buf.drain(n_written);
return static_cast<size_t>(n); return static_cast<size_t>(n_written);
} }
if (n < 0 && error_code != 0) if (n_written < 0 && error_code != 0)
{ {
tr_error_set(error, error_code, tr_strerror(error_code)); tr_error_set(error, error_code, tr_strerror(error_code));
} }

12
libtransmission/tr-buffer.h
View File

@ -158,18 +158,6 @@ public:
return evbuffer_get_length(buf_.get()) == 0; return evbuffer_get_length(buf_.get()) == 0;
} }
[[nodiscard]] auto vecs(size_t n_bytes) const
{
auto chains = std::vector<Iovec>(evbuffer_peek(buf_.get(), n_bytes, nullptr, nullptr, 0));
evbuffer_peek(buf_.get(), n_bytes, nullptr, std::data(chains), std::size(chains));
return chains;
}
[[nodiscard]] auto vecs() const
{
return vecs(size());
}
[[nodiscard]] auto begin() noexcept [[nodiscard]] auto begin() noexcept
{ {
return Iterator{ buf_.get(), 0U }; return Iterator{ buf_.get(), 0U };