Mercurial > gnulib
changeset 29999:032e4bdcd522
microoptimization of lib/poll.c
2008-08-06 Paolo Bonzini <bonzini@gnu.org>
* lib/poll.c (poll): Avoid division when timeout is 0, cache
_SC_OPEN_MAX, avoid repeated access to errno. Check for nfd < 0.
| author | Paolo Bonzini <bonzini@gnu.org> |
|---|---|
| date | Wed, 06 Aug 2008 10:27:53 +0200 |
| parents | b6424a5300bb |
| children | 9e66ce7a81a8 |
| files | ChangeLog lib/poll.c |
| diffstat | 2 files changed, 25 insertions(+), 10 deletions(-) [+] |
line wrap: on
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--- a/ChangeLog Wed Aug 06 09:40:32 2008 +0200 +++ b/ChangeLog Wed Aug 06 10:27:53 2008 +0200 @@ -1,3 +1,8 @@ +2008-08-06 Paolo Bonzini <bonzini@gnu.org> + + * lib/poll.c (poll): Avoid division when timeout is 0, cache + _SC_OPEN_MAX, avoid repeated access to errno. Check for nfd < 0. + 2008-08-06 Jim Meyering <meyering@redhat.com> * modules/inet_pton (License): Relicense under LGPLv2+.
--- a/lib/poll.c Wed Aug 06 09:40:32 2008 +0200 +++ b/lib/poll.c Wed Aug 06 10:27:53 2008 +0200 @@ -55,19 +55,25 @@ int timeout; { fd_set rfds, wfds, efds; - struct timeval tv, *ptv; + struct timeval tv = { 0, 0 }; + struct timeval *ptv; int maxfd, rc; nfds_t i; #ifdef _SC_OPEN_MAX - if (nfd > sysconf (_SC_OPEN_MAX)) + static int sc_open_max = -1; + + if (nfd < 0 + || (nfd > sc_open_max + && (sc_open_max != -1 + || nfd > (sc_open_max = sysconf (_SC_OPEN_MAX))))) { errno = EINVAL; return -1; } #else /* !_SC_OPEN_MAX */ #ifdef OPEN_MAX - if (nfd > OPEN_MAX) + if (nfd < 0 || nfd > OPEN_MAX) { errno = EINVAL; return -1; @@ -84,10 +90,11 @@ } /* convert timeout number into a timeval structure */ - ptv = &tv; - if (timeout >= 0) + if (timeout == 0) + ptv = &tv; + else if (timeout > 0) { - /* return immediately or after timeout */ + ptv = &tv; ptv->tv_sec = timeout / 1000; ptv->tv_usec = (timeout % 1000) * 1000; } @@ -155,6 +162,7 @@ if (FD_ISSET (pfd[i].fd, &rfds)) { int r; + int socket_errno; #if defined __MACH__ && defined __APPLE__ /* There is a bug in Mac OS X that causes it to ignore MSG_PEEK @@ -162,23 +170,25 @@ connected socket, a server socket, or something else using a 0-byte recv, and use ioctl(2) to detect POLLHUP. */ r = recv (pfd[i].fd, NULL, 0, MSG_PEEK); - if (r == 0 || errno == ENOTSOCK) + socket_errno = (r < 0) ? errno : 0; + if (r == 0 || socket_errno == ENOTSOCK) ioctl(pfd[i].fd, FIONREAD, &r); #else char data[64]; r = recv (pfd[i].fd, data, sizeof (data), MSG_PEEK); + socket_errno = (r < 0) ? errno : 0; #endif if (r == 0) happened |= POLLHUP; /* If the event happened on an unconnected server socket, that's fine. */ - else if (r > 0 || ( /* (r == -1) && */ errno == ENOTCONN)) + else if (r > 0 || ( /* (r == -1) && */ socket_errno == ENOTCONN)) happened |= (POLLIN | POLLRDNORM) & sought; /* Distinguish hung-up sockets from other errors. */ - else if (errno == ESHUTDOWN || errno == ECONNRESET - || errno == ECONNABORTED || errno == ENETRESET) + else if (socket_errno == ESHUTDOWN || socket_errno == ECONNRESET + || socket_errno == ECONNABORTED || socket_errno == ENETRESET) happened |= POLLHUP; else