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Improve polling for available file descriptors #2365

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Improve polling for available file descriptors #2365

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57 changes: 24 additions & 33 deletions utilities/xmlrpcpp/src/XmlRpcServer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -30,26 +30,6 @@ XmlRpcServer::XmlRpcServer()
_accept_error(false),
_accept_retry_time_sec(0.0)
{
#if !defined(_WINDOWS)
struct rlimit limit = { .rlim_cur = 0, .rlim_max = 0 };
unsigned int max_files = 1024;

if(getrlimit(RLIMIT_NOFILE, &limit) == 0) {
max_files = limit.rlim_max;
if( limit.rlim_max == RLIM_INFINITY ) {
max_files = 0;
}
} else {
XmlRpcUtil::error("Could not get open file limit: %s", strerror(errno));
}
pollfds.resize(max_files);
for(unsigned int i=0; i<max_files; i++) {
// Set up file descriptor query for all events.
pollfds[i].fd = i;
pollfds[i].events = POLLIN | POLLPRI | POLLOUT;
}
#endif

// Ask dispatch not to close this socket if it becomes unreadable.
setKeepOpen(true);
}
Expand Down Expand Up @@ -233,13 +213,31 @@ bool XmlRpcServer::enoughFreeFDs() {
if( limit.rlim_max == RLIM_INFINITY ) {
return true;
}
} else {
// The man page for getrlimit says that it can fail if the requested
// resource is invalid or the second argument is invalid. I'm not sure
// either of these can actually fail in this code, but it's better to
// check.
XmlRpcUtil::error("XmlRpcServer::enoughFreeFDs: Could not get open file "
"limit, getrlimit() failed: %s", strerror(errno));
return false;
}

// Poll the available file descriptors.
// The POSIX specification guarantees that rlim_cur will always be less or
// equal to the process's initial rlim_max, so we don't need an additional
// bounds check here.
if(poll(&pollfds[0], limit.rlim_cur, 1) >= 0) {
for(rlim_t i=0; i<limit.rlim_cur; i++) {
// List of all file descriptors, used for counting open files.
pollfds.resize(limit.rlim_cur > FREE_FD_BUFFER ? FREE_FD_BUFFER : limit.rlim_cur);

// Poll the available file descriptors.
// The POSIX specification guarantees that rlim_cur will always be less or
// equal to the process's initial rlim_max, so we don't need an additional
// bounds check here.
for(unsigned long long offset=0; offset<limit.rlim_cur; offset += FREE_FD_BUFFER) {
for(unsigned int i=0; i<pollfds.size(); i++) {
// Set up file descriptor query for all events.
pollfds[i].fd = i + offset;
pollfds[i].events = POLLIN | POLLPRI | POLLOUT;
}
if(poll(&pollfds[0], pollfds.size(), 1) >= 0) {
for(rlim_t i=0; i<pollfds.size(); i++) {
if(pollfds[i].revents & POLLNVAL) {
free_fds++;
}
Expand All @@ -254,13 +252,6 @@ bool XmlRpcServer::enoughFreeFDs() {
XmlRpcUtil::error("XmlRpcServer::enoughFreeFDs: poll() failed: %s",
strerror(errno));
}
} else {
// The man page for getrlimit says that it can fail if the requested
// resource is invalid or the second argument is invalid. I'm not sure
// either of these can actually fail in this code, but it's better to
// check.
XmlRpcUtil::error("XmlRpcServer::enoughFreeFDs: Could not get open file "
"limit, getrlimit() failed: %s", strerror(errno));
}

return false;
Expand Down