Mercurial > hg > nginx
comparison src/event/ngx_event.h @ 7583:efd71d49bde0
Events: available bytes calculation via ioctl(FIONREAD).
This makes it possible to avoid looping for a long time while working
with a fast enough peer when data are added to the socket buffer faster
than we are able to read and process them (ticket #1431). This is
basically what we already do on FreeBSD with kqueue, where information
about the number of bytes in the socket buffer is returned by
the kevent() call.
With other event methods rev->available is now set to -1 when the socket
is ready for reading. Later in ngx_recv() and ngx_recv_chain(), if
full buffer is received, real number of bytes in the socket buffer is
retrieved using ioctl(FIONREAD). Reading more than this number of bytes
ensures that even with edge-triggered event methods the event will be
triggered again, so it is safe to stop processing of the socket and
switch to other connections.
Using ioctl(FIONREAD) only after reading a full buffer is an optimization.
With this approach we only call ioctl(FIONREAD) when there are at least
two recv()/readv() calls.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Thu, 17 Oct 2019 16:02:19 +0300 |
parents | 4698cede59ff |
children | ec2e6893caaa 45db1b5c1706 |
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7582:70749256af79 | 7583:efd71d49bde0 |
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89 * read: bytes to read when event is ready | 89 * read: bytes to read when event is ready |
90 * or lowat when event is set with NGX_LOWAT_EVENT flag | 90 * or lowat when event is set with NGX_LOWAT_EVENT flag |
91 * write: available space in buffer when event is ready | 91 * write: available space in buffer when event is ready |
92 * or lowat when event is set with NGX_LOWAT_EVENT flag | 92 * or lowat when event is set with NGX_LOWAT_EVENT flag |
93 * | 93 * |
94 * epoll with EPOLLRDHUP: | |
95 * accept: 1 if accept many, 0 otherwise | |
96 * read: 1 if there can be data to read, 0 otherwise | |
97 * | |
98 * iocp: TODO | 94 * iocp: TODO |
99 * | 95 * |
100 * otherwise: | 96 * otherwise: |
101 * accept: 1 if accept many, 0 otherwise | 97 * accept: 1 if accept many, 0 otherwise |
98 * read: bytes to read when event is ready, -1 if not known | |
102 */ | 99 */ |
103 | 100 |
104 #if (NGX_HAVE_KQUEUE) || (NGX_HAVE_IOCP) | |
105 int available; | 101 int available; |
106 #else | |
107 unsigned available:1; | |
108 #endif | |
109 | 102 |
110 ngx_event_handler_pt handler; | 103 ngx_event_handler_pt handler; |
111 | 104 |
112 | 105 |
113 #if (NGX_HAVE_IOCP) | 106 #if (NGX_HAVE_IOCP) |