When transferring 500 downloads in parallel with a c-ares enabled build only

to find that it crashed miserably, and this was due to some select()isms left
in the code. This was due to API restrictions in c-ares 1.3.x, but with the
upcoming c-ares 1.4.0 this is no longer the case so now libcurl runs much
better with c-ares and the multi interface with > 1024 file descriptors in
use.
This commit is contained in:
Daniel Stenberg 2007-05-31 11:34:32 +00:00
parent 713c9f8602
commit 4c663ba9a8
8 changed files with 92 additions and 263 deletions

10
CHANGES
View File

@ -10,6 +10,16 @@ Daniel S (31 May 2007)
- Feng Tu made (lib)curl support "upload" resuming work for file:// URLs.
Daniel S (30 May 2007)
- I modified the 10-at-a-time.c example to transfer 500 downloads in parallel
with a c-ares enabled build only to find that it crashed miserably, and this
was due to some select()isms left in the code. This was due to API
restrictions in c-ares 1.3.x, but with the upcoming c-ares 1.4.0 this is no
longer the case so now libcurl runs much better with c-ares and the multi
interface with > 1024 file descriptors in use.
Extra note: starting now we require c-ares 1.4.0 for asynchronous name
resolves.
- Added CURLMOPT_MAXCONNECTS which is a curl_multi_setopt() option for setting
the maximum size of the connection cache maximum size of the multi handle.

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@ -19,6 +19,7 @@ This release includes the following changes:
o SFTP now supports quote commands before a transfer
o CURLMOPT_MAXCONNECTS added to curl_multi_setopt()
o upload resume works for file:// URLs
o asynchronous name resolves now require c-ares 1.4.0 or later
This release includes the following bugfixes:

View File

@ -2050,10 +2050,10 @@ fi
dnl set variable for use in automakefile(s)
AM_CONDITIONAL(USE_MANUAL, test x"$USE_MANUAL" = x1)
AC_MSG_CHECKING([whether to enable ares])
AC_MSG_CHECKING([whether to enable c-ares])
AC_ARG_ENABLE(ares,
AC_HELP_STRING([--enable-ares=PATH],[Enable ares for name lookups])
AC_HELP_STRING([--disable-ares],[Disable ares for name lookups]),
AC_HELP_STRING([--enable-ares=PATH],[Enable c-ares for name lookups])
AC_HELP_STRING([--disable-ares],[Disable c-ares for name lookups]),
[ case "$enableval" in
no)
AC_MSG_RESULT(no)
@ -2061,10 +2061,10 @@ AC_HELP_STRING([--disable-ares],[Disable ares for name lookups]),
*) AC_MSG_RESULT(yes)
if test "x$IPV6_ENABLED" = "x1"; then
AC_MSG_NOTICE([ares may not work properly with ipv6])
AC_MSG_NOTICE([c-ares may not work properly with ipv6])
fi
AC_DEFINE(USE_ARES, 1, [Define if you want to enable ares support])
AC_DEFINE(USE_ARES, 1, [Define if you want to enable c-ares support])
dnl substitute HAVE_ARES for curl-config and similar
HAVE_ARES="1"
AC_SUBST(HAVE_ARES)
@ -2109,7 +2109,8 @@ void curl_domalloc() { }
int main(void)
{
ares_channel channel;
ares_cancel(channel);
ares_cancel(channel); /* added in 1.2.0 */
ares_process_fd(channel, 0, 0); /* added in 1.4.0 */
return 0;
}
],

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@ -12,8 +12,7 @@ c-ares:
http://daniel.haxx.se/projects/c-ares/
NOTE
The latest libcurl version requires c-ares 1.3.2 or later to work
flawlessly.
The latest libcurl version requires c-ares 1.4.0 or later.
Once upon the time libcurl built fine with the "original" ares. That is no
longer true. You need to use c-ares.

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@ -420,11 +420,14 @@ CURLcode curl_easy_perform(CURL *easy)
timeout.tv_sec = 1;
timeout.tv_usec = 0;
/* get file descriptors from the transfers */
/* Old deprecated style: get file descriptors from the transfers */
curl_multi_fdset(multi, &fdread, &fdwrite, &fdexcep, &maxfd);
rc = Curl_select(maxfd+1, &fdread, &fdwrite, &fdexcep, &timeout);
/* The way is to extract the sockets and wait for them without using
select. This whole alternative version should probably rather use the
curl_multi_socket() approach. */
if(rc == -1)
/* select error */
break;

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@ -125,6 +125,69 @@ int Curl_resolv_getsock(struct connectdata *conn,
return max;
}
/*
* ares_waitperform()
*
* 1) Ask ares what sockets it currently plays with, then
* 2) wait for the timeout period to check for action on ares' sockets.
* 3) tell ares to act on all the sockets marked as "with action"
*
* return number of sockets it worked on
*/
static int ares_waitperform(struct connectdata *conn, int timeout_ms)
{
struct SessionHandle *data = conn->data;
int nfds;
int bitmask;
int socks[ARES_GETSOCK_MAXNUM];
struct pollfd pfd[ARES_GETSOCK_MAXNUM];
int m;
int i;
int num;
bitmask = ares_getsock(data->state.areschannel, socks, ARES_GETSOCK_MAXNUM);
for(i=0; i < ARES_GETSOCK_MAXNUM; i++) {
pfd[i].events = 0;
m=0;
if(ARES_GETSOCK_READABLE(bitmask, i)) {
pfd[i].fd = socks[i];
pfd[i].events |= POLLRDNORM|POLLIN;
m=1;
}
if(ARES_GETSOCK_WRITABLE(bitmask, i)) {
pfd[i].fd = socks[i];
pfd[i].events |= POLLWRNORM|POLLOUT;
m=1;
}
pfd[i].revents=0;
if(!m)
break;
}
num = i;
if(num)
nfds = Curl_poll(pfd, num, timeout_ms);
else
nfds = 0;
if(!nfds)
/* Call ares_process() unconditonally here, even if we simply timed out
above, as otherwise the ares name resolve won't timeout! */
ares_process_fd(data->state.areschannel, ARES_SOCKET_BAD, ARES_SOCKET_BAD);
else {
/* move through the descriptors and ask for processing on them */
for(i=0; i < num; i++)
ares_process_fd(data->state.areschannel,
pfd[i].revents & (POLLRDNORM|POLLIN)?
pfd[i].fd:ARES_SOCKET_BAD,
pfd[i].revents & (POLLWRNORM|POLLOUT)?
pfd[i].fd:ARES_SOCKET_BAD);
}
return nfds;
}
/*
* Curl_is_resolved() is called repeatedly to check if a previous name resolve
* request has completed. It should also make sure to time-out if the
@ -135,25 +198,12 @@ int Curl_resolv_getsock(struct connectdata *conn,
CURLcode Curl_is_resolved(struct connectdata *conn,
struct Curl_dns_entry **dns)
{
fd_set read_fds, write_fds;
struct timeval tv={0,0};
struct SessionHandle *data = conn->data;
int nfds;
FD_ZERO(&read_fds);
FD_ZERO(&write_fds);
nfds = ares_fds(data->state.areschannel, &read_fds, &write_fds);
(void)Curl_select(nfds, &read_fds, &write_fds, NULL,
(struct timeval *)&tv);
/* Call ares_process() unconditonally here, even if we simply timed out
above, as otherwise the ares name resolve won't timeout! */
ares_process(data->state.areschannel, &read_fds, &write_fds);
*dns = NULL;
ares_waitperform(conn, 0);
if(conn->async.done) {
/* we're done, kill the ares handle */
if(!conn->async.dns) {
@ -194,28 +244,18 @@ CURLcode Curl_wait_for_resolv(struct connectdata *conn,
/* Wait for the name resolve query to complete. */
while (1) {
int nfds=0;
fd_set read_fds, write_fds;
struct timeval *tvp, tv, store;
int count;
struct timeval now = Curl_tvnow();
long timediff;
store.tv_sec = (int)timeout/1000;
store.tv_usec = (timeout%1000)*1000;
FD_ZERO(&read_fds);
FD_ZERO(&write_fds);
nfds = ares_fds(data->state.areschannel, &read_fds, &write_fds);
if (nfds == 0)
/* no file descriptors means we're done waiting */
break;
tvp = ares_timeout(data->state.areschannel, &store, &tv);
count = Curl_select(nfds, &read_fds, &write_fds, NULL, tvp);
if ((count < 0) && (SOCKERRNO != EINVAL))
break;
ares_process(data->state.areschannel, &read_fds, &write_fds);
if(!ares_waitperform(conn, tv.tv_sec * 1000 + tv.tv_usec/1000))
/* no sockets to wait on, get out of the loop */
break;
timediff = Curl_tvdiff(Curl_tvnow(), now); /* spent time */
timeout -= timediff?timediff:1; /* always deduct at least 1 */

View File

@ -482,227 +482,6 @@ int Curl_poll(struct pollfd ufds[], unsigned int nfds, int timeout_ms)
return r;
}
/*
* This is a wrapper around select(). It uses poll() when a fine
* poll() is available, in order to avoid limits with FD_SETSIZE,
* otherwise select() is used. An error is returned if select() is
* being used and a the number of file descriptors is larger than
* FD_SETSIZE. A NULL timeout pointer makes this function wait
* indefinitely, unles no valid file descriptor is given, when this
* happens the NULL timeout is ignored and the function times out
* immediately. When compiled with CURL_ACKNOWLEDGE_EINTR defined,
* EINTR condition is honored and function might exit early without
* awaiting timeout, otherwise EINTR will be ignored.
*
* Return values:
* -1 = system call error or nfds > FD_SETSIZE
* 0 = timeout
* N = number of file descriptors kept in file descriptor sets.
*/
int Curl_select(int nfds,
fd_set *fds_read, fd_set *fds_write, fd_set *fds_excep,
struct timeval *timeout)
{
struct timeval initial_tv;
int timeout_ms;
int pending_ms = 0;
int error;
int r;
#ifdef HAVE_POLL_FINE
struct pollfd small_fds[SMALL_POLLNFDS];
struct pollfd *poll_fds;
int ix;
int fd;
int poll_nfds = 0;
#else
struct timeval pending_tv;
struct timeval *ptimeout;
#endif
int ret = 0;
if ((nfds < 0) ||
((nfds > 0) && (!fds_read && !fds_write && !fds_excep))) {
SET_SOCKERRNO(EINVAL);
return -1;
}
if (timeout) {
if ((timeout->tv_sec < 0) ||
(timeout->tv_usec < 0) ||
(timeout->tv_usec >= 1000000)) {
SET_SOCKERRNO(EINVAL);
return -1;
}
timeout_ms = (int)(timeout->tv_sec * 1000) +
(int)(timeout->tv_usec / 1000);
}
else {
timeout_ms = -1;
}
if ((!nfds) || (!fds_read && !fds_write && !fds_excep)) {
r = wait_ms(timeout_ms);
return r;
}
/* Avoid initial timestamp, avoid gettimeofday() call, when elapsed
time in this function does not need to be measured. This happens
when function is called with a zero timeout in the timeval struct
referenced argument or when a NULL pointer is received as timeval
reference indicating a blocking call should be performed. */
if (timeout_ms > 0) {
pending_ms = timeout_ms;
initial_tv = curlx_tvnow();
}
#ifdef HAVE_POLL_FINE
if (fds_read || fds_write || fds_excep) {
fd = nfds;
while (fd--) {
if ((fds_read && (0 != FD_ISSET(fd, fds_read))) ||
(fds_write && (0 != FD_ISSET(fd, fds_write))) ||
(fds_excep && (0 != FD_ISSET(fd, fds_excep))))
poll_nfds++;
}
}
if (!poll_nfds)
poll_fds = NULL;
else if (poll_nfds <= SMALL_POLLNFDS)
poll_fds = small_fds;
else {
poll_fds = malloc(poll_nfds * sizeof(struct pollfd));
if (!poll_fds) {
SET_SOCKERRNO(ENOBUFS);
return -1;
}
}
if (poll_fds) {
int events;
ix = 0;
fd = nfds;
while (fd--) {
events = 0;
if (fds_read && (0 != FD_ISSET(fd, fds_read)))
events |= (POLLRDNORM|POLLIN);
if (fds_write && (0 != FD_ISSET(fd, fds_write)))
events |= (POLLWRNORM|POLLOUT);
if (fds_excep && (0 != FD_ISSET(fd, fds_excep)))
events |= (POLLRDBAND|POLLPRI);
if (events) {
poll_fds[ix].events = events;
poll_fds[ix].fd = fd;
poll_fds[ix].revents = 0;
ix++;
if(ix == poll_nfds)
/* since we know this is the total amount of descriptors with
interesting actions, we can skip the rest of the loop at this
point */
break;
}
}
}
do {
if (timeout_ms < 0)
pending_ms = -1;
else if (!timeout_ms)
pending_ms = 0;
r = poll(poll_fds, poll_nfds, pending_ms);
if (r != -1)
break;
error = SOCKERRNO;
if ((error == EINVAL) || error_is_EINTR)
break;
if (timeout_ms > 0) {
pending_ms = timeout_ms - elapsed_ms;
if (pending_ms <= 0)
break;
}
} while (r == -1);
if (r < 0)
ret = -1;
if (r > 0) {
ix = poll_nfds;
while (ix--) {
if (poll_fds[ix].revents & POLLNVAL) {
SET_SOCKERRNO(EBADF);
ret = -1;
break;
}
}
}
if (!ret) {
ix = poll_nfds;
while (ix--) {
if (fds_read && (0 != FD_ISSET(poll_fds[ix].fd, fds_read))) {
if (0 == (poll_fds[ix].revents & (POLLRDNORM|POLLERR|POLLHUP|POLLIN)))
FD_CLR(poll_fds[ix].fd, fds_read);
else
ret++;
}
if (fds_write && (0 != FD_ISSET(poll_fds[ix].fd, fds_write))) {
if (0 == (poll_fds[ix].revents & (POLLWRNORM|POLLERR|POLLHUP|POLLOUT)))
FD_CLR(poll_fds[ix].fd, fds_write);
else
ret++;
}
if (fds_excep && (0 != FD_ISSET(poll_fds[ix].fd, fds_excep))) {
if (0 == (poll_fds[ix].revents & (POLLRDBAND|POLLERR|POLLHUP|POLLPRI)))
FD_CLR(poll_fds[ix].fd, fds_excep);
else
ret++;
}
}
}
if (poll_fds && (poll_nfds > SMALL_POLLNFDS))
free(poll_fds);
#else /* HAVE_POLL_FINE */
VERIFY_NFDS(nfds);
ptimeout = (timeout_ms < 0) ? NULL : &pending_tv;
do {
if (timeout_ms > 0) {
pending_tv.tv_sec = pending_ms / 1000;
pending_tv.tv_usec = (pending_ms % 1000) * 1000;
}
else if (!timeout_ms) {
pending_tv.tv_sec = 0;
pending_tv.tv_usec = 0;
}
r = select(nfds, fds_read, fds_write, fds_excep, ptimeout);
if (r != -1)
break;
error = SOCKERRNO;
if ((error == EINVAL) || (error == EBADF) || error_is_EINTR)
break;
if (timeout_ms > 0) {
pending_ms = timeout_ms - elapsed_ms;
if (pending_ms <= 0)
break;
}
} while (r == -1);
if (r < 0)
ret = -1;
else
ret = r;
#endif /* HAVE_POLL_FINE */
return ret;
}
#ifdef TPF
/*
* This is a replacement for select() on the TPF platform.

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@ -81,10 +81,6 @@ int Curl_socket_ready(curl_socket_t readfd, curl_socket_t writefd,
int Curl_poll(struct pollfd ufds[], unsigned int nfds, int timeout_ms);
int Curl_select(int nfds,
fd_set *fds_read, fd_set *fds_write, fd_set *fds_excep,
struct timeval *timeout);
#ifdef TPF
int tpf_select_libcurl(int maxfds, fd_set* reads, fd_set* writes,
fd_set* excepts, struct timeval* tv);