This commit adds ability to check status of cached file descriptor to
make sure that it can be reused. We inspect last modification time
and number of hard links. If last modification is changed from the
last validation time, or number of hard links gets 0, we don't reuse
file descriptor. We also capped upper limit of the cached file
descriptors. If the limit is reached, we will close file descriptor
which is least recently used, and its usecount is 0.
To make use cache fd more robust manner (e.g. among several
connections), eviction of cached file descriptor now takes place using
timer. The timer is started when there is no handler (no
connections). The timeout value is hard-coded and 2 seconds.
Compile with BoringSSL except for neverbleed and libnghttp2_asio. The
former uses ENGINE and RSA_METHOD, and they are quite different
between OpenSSL and BoringSSL. The latter uses boost::asio, which
calls OpenSSL functions deleted in BoringSSL.
Implement fd caching for static files. The response body for such as
404 was dynamically generated previously, but now it is written in
temporally file and its fd is cached. Currently, cache is reference
counted and expired when count becomes 0. This makes caching is not
effective other than "busy" period, but we don't need this feature if
we are not busy.
Previously nghttp2_session_send() and nghttp2_session_mem_send() did
not send 24 bytes client magic byte string (MAGIC). We made
nghttp2_session_recv() and nghttp2_session_mem_recv() process MAGIC by
default, so it is natural to make library send MAGIC as well. This
commit makes nghttp2_session_send() and nghttp2_session_mem_send()
send MAGIC. This commit also replace "connection preface" with
"client magic", since we call MAGIC as "connection preface" but it is
just a part of connection preface. NGHTTP2_CLIENT_CONNECTION_PREFACE
macro was replaced with NGHTTP2_CLIENT_MAGIC. The already deprecated
NGHTTP2_CLIENT_CONNECTION_HEADER macro was removed permanently.
nghttp2_option_set_no_recv_client_preface() was renamed as
nghttp2_option_set_no_recv_client_magic(). NGHTTP2_ERR_BAD_PREFACE
was renamed as NGHTTP2_ERR_BAD_CLIENT_MAGIC.
Tatsuhiro Tsujikawa