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Do not count free FDs in userland. #1928

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Do not count free FDs in userland. #1928

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5 changes: 0 additions & 5 deletions utilities/xmlrpcpp/include/xmlrpcpp/XmlRpcServer.h
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Original file line number Diff line number Diff line change
Expand Up @@ -96,9 +96,6 @@ namespace XmlRpc {
//! Create a new connection object for processing requests from a specific client.
virtual XmlRpcServerConnection* createConnection(int socket);

//! Count number of free file descriptors
int countFreeFDs();

// Whether the introspection API is supported by this server
bool _introspectionEnabled;

Expand All @@ -123,8 +120,6 @@ namespace XmlRpc {
// Retry time for accept.
double _accept_retry_time_sec;

// Minimum number of free file descriptors before rejecting clients.
static const int FREE_FD_BUFFER;
#ifndef _WINDOWS
// List of all file descriptors, used for counting open files.
std::vector<struct pollfd> pollfds;
Expand Down
61 changes: 3 additions & 58 deletions utilities/xmlrpcpp/src/XmlRpcServer.cpp
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Expand Up @@ -19,7 +19,6 @@

using namespace XmlRpc;

const int XmlRpcServer::FREE_FD_BUFFER = 32;
const double XmlRpcServer::ACCEPT_RETRY_INTERVAL_SEC = 1.0;

XmlRpcServer::XmlRpcServer()
Expand Down Expand Up @@ -191,17 +190,15 @@ XmlRpcServer::acceptConnection()
{
//this->close();
XmlRpcUtil::error("XmlRpcServer::acceptConnection: Could not accept connection (%s).", XmlRpcSocket::getErrorMsg().c_str());
if (XmlRpcSocket::getError() == EMFILE) {
XmlRpcUtil::error("XmlRpcServer::acceptConnection: there is not enough free file descriptors.");
}

// Note that there was an accept error; retry in 1 second
_accept_error = true;
_accept_retry_time_sec = _disp.getTime() + ACCEPT_RETRY_INTERVAL_SEC;
return 0; // Stop monitoring this FD
}
else if( countFreeFDs() < FREE_FD_BUFFER )
{
XmlRpcSocket::close(s);
XmlRpcUtil::error("XmlRpcServer::acceptConnection: Rejecting client, not enough free file descriptors");
}
else if ( ! XmlRpcSocket::setNonBlocking(s))
{
XmlRpcSocket::close(s);
Expand All @@ -216,58 +213,6 @@ XmlRpcServer::acceptConnection()
return XmlRpcDispatch::ReadableEvent; // Continue to monitor this fd
}

int XmlRpcServer::countFreeFDs() {
// NOTE(austin): this function is not free, but in a few small tests it only
// takes about 1.2mS when querying 50k file descriptors.
//
// If the underlying system calls here fail, this will print an error and
// return 0

#if !defined(_WINDOWS)
int free_fds = 0;

struct rlimit limit = { .rlim_cur = 0, .rlim_max = 0 };

// Get the current soft limit on the number of file descriptors.
if(getrlimit(RLIMIT_NOFILE, &limit) == 0) {
// If we have infinite file descriptors, always return FREE_FD_BUFFER so
// that we never hit the low-water mark.
if( limit.rlim_max == RLIM_INFINITY ) {
return FREE_FD_BUFFER;
}

// 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 additonal
// bounds check here.
if(poll(&pollfds[0], limit.rlim_cur, 1) >= 0) {
for(rlim_t i=0; i<limit.rlim_cur; i++) {
if(pollfds[i].revents & POLLNVAL) {
free_fds++;
}
}
} else {
// poll() may fail if interrupted, if the pollfds array is a bad pointer,
// if nfds exceeds RLIMIT_NOFILE, or if the system is out of memory.
XmlRpcUtil::error("XmlRpcServer::countFreeFDs: 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::countFreeFDs: Could not get open file "
"limit, getrlimit() failed: %s", strerror(errno));
}

return free_fds;
#else
return FREE_FD_BUFFER;
#endif
}


// Create a new connection object for processing requests from a specific client.
XmlRpcServerConnection*
XmlRpcServer::createConnection(int s)
Expand Down