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net: use Sock::WaitMany() instead of CConnman::SocketEvents()
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Rename `GenerateSelectSet()` to `GenerateWaitSockets()` and adapt it to
generate a wait data suitable for `Sock::WaitMany()`. Then call it from
`CConnman::SocketHandler()` and feed the generated data to
`Sock::WaitMany()`.

This way `CConnman::SocketHandler()` can be unit tested because
`Sock::WaitMany()` is mockable, so the usage of real sockets can be
avoided.

Resolves bitcoin#21744
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@vasild
vasild committed Aug 30, 2021
1 parent 7bdf64f commit e04d850
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Showing 2 changed files with 22 additions and 147 deletions.
152 changes: 20 additions & 132 deletions src/net.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1327,10 +1327,12 @@ bool CConnman::InactivityCheck(const CNode& node) const
return false;
}

bool CConnman::GenerateSelectSet(const std::vector<CNode*>& nodes, std::set<SOCKET> &recv_set, std::set<SOCKET> &send_set, std::set<SOCKET> &error_set)
Sock::WaitData CConnman::GenerateWaitSockets(const std::vector<CNode*>& nodes)
{
Sock::WaitData what;

for (const ListenSocket& hListenSocket : vhListenSocket) {
recv_set.insert(hListenSocket.sock->Get());
what.emplace(hListenSocket.sock, Sock::WaitEvents{Sock::RECV, 0});
}

for (CNode* pnode : nodes) {
Expand All @@ -1357,143 +1359,29 @@ bool CConnman::GenerateSelectSet(const std::vector<CNode*>& nodes, std::set<SOCK
continue;
}

error_set.insert(pnode->m_sock->Get());
Sock::Event requested{0};
if (select_send) {
send_set.insert(pnode->m_sock->Get());
continue;
}
if (select_recv) {
recv_set.insert(pnode->m_sock->Get());
}
}

return !recv_set.empty() || !send_set.empty() || !error_set.empty();
}

#ifdef USE_POLL
void CConnman::SocketEvents(const std::vector<CNode*>& nodes, std::set<SOCKET> &recv_set, std::set<SOCKET> &send_set, std::set<SOCKET> &error_set)
{
std::set<SOCKET> recv_select_set, send_select_set, error_select_set;
if (!GenerateSelectSet(nodes, recv_select_set, send_select_set, error_select_set)) {
interruptNet.sleep_for(std::chrono::milliseconds(SELECT_TIMEOUT_MILLISECONDS));
return;
}

std::unordered_map<SOCKET, struct pollfd> pollfds;
for (SOCKET socket_id : recv_select_set) {
pollfds[socket_id].fd = socket_id;
pollfds[socket_id].events |= POLLIN;
}

for (SOCKET socket_id : send_select_set) {
pollfds[socket_id].fd = socket_id;
pollfds[socket_id].events |= POLLOUT;
}

for (SOCKET socket_id : error_select_set) {
pollfds[socket_id].fd = socket_id;
// These flags are ignored, but we set them for clarity
pollfds[socket_id].events |= POLLERR|POLLHUP;
}

std::vector<struct pollfd> vpollfds;
vpollfds.reserve(pollfds.size());
for (auto it : pollfds) {
vpollfds.push_back(std::move(it.second));
}

if (poll(vpollfds.data(), vpollfds.size(), SELECT_TIMEOUT_MILLISECONDS) < 0) return;

if (interruptNet) return;

for (struct pollfd pollfd_entry : vpollfds) {
if (pollfd_entry.revents & POLLIN) recv_set.insert(pollfd_entry.fd);
if (pollfd_entry.revents & POLLOUT) send_set.insert(pollfd_entry.fd);
if (pollfd_entry.revents & (POLLERR|POLLHUP)) error_set.insert(pollfd_entry.fd);
}
}
#else
void CConnman::SocketEvents(const std::vector<CNode*>& nodes, std::set<SOCKET> &recv_set, std::set<SOCKET> &send_set, std::set<SOCKET> &error_set)
{
std::set<SOCKET> recv_select_set, send_select_set, error_select_set;
if (!GenerateSelectSet(nodes, recv_select_set, send_select_set, error_select_set)) {
interruptNet.sleep_for(std::chrono::milliseconds(SELECT_TIMEOUT_MILLISECONDS));
return;
}

//
// Find which sockets have data to receive
//
struct timeval timeout;
timeout.tv_sec = 0;
timeout.tv_usec = SELECT_TIMEOUT_MILLISECONDS * 1000; // frequency to poll pnode->vSend

fd_set fdsetRecv;
fd_set fdsetSend;
fd_set fdsetError;
FD_ZERO(&fdsetRecv);
FD_ZERO(&fdsetSend);
FD_ZERO(&fdsetError);
SOCKET hSocketMax = 0;

for (SOCKET hSocket : recv_select_set) {
FD_SET(hSocket, &fdsetRecv);
hSocketMax = std::max(hSocketMax, hSocket);
}

for (SOCKET hSocket : send_select_set) {
FD_SET(hSocket, &fdsetSend);
hSocketMax = std::max(hSocketMax, hSocket);
}

for (SOCKET hSocket : error_select_set) {
FD_SET(hSocket, &fdsetError);
hSocketMax = std::max(hSocketMax, hSocket);
}

int nSelect = select(hSocketMax + 1, &fdsetRecv, &fdsetSend, &fdsetError, &timeout);

if (interruptNet)
return;

if (nSelect == SOCKET_ERROR)
{
int nErr = WSAGetLastError();
LogPrintf("socket select error %s\n", NetworkErrorString(nErr));
for (unsigned int i = 0; i <= hSocketMax; i++)
FD_SET(i, &fdsetRecv);
FD_ZERO(&fdsetSend);
FD_ZERO(&fdsetError);
if (!interruptNet.sleep_for(std::chrono::milliseconds(SELECT_TIMEOUT_MILLISECONDS)))
return;
}

for (SOCKET hSocket : recv_select_set) {
if (FD_ISSET(hSocket, &fdsetRecv)) {
recv_set.insert(hSocket);
requested = Sock::SEND;
} else if (select_recv) {
requested = Sock::RECV;
}
}

for (SOCKET hSocket : send_select_set) {
if (FD_ISSET(hSocket, &fdsetSend)) {
send_set.insert(hSocket);
}
what.emplace(pnode->m_sock, Sock::WaitEvents{requested, 0});
}

for (SOCKET hSocket : error_select_set) {
if (FD_ISSET(hSocket, &fdsetError)) {
error_set.insert(hSocket);
}
}
return what;
}
#endif

void CConnman::SocketHandler()
{
const NodesSnapshot snap{*this, false};

std::set<SOCKET> recv_set, send_set, error_set;
SocketEvents(snap.Nodes(), recv_set, send_set, error_set);
const auto timeout = std::chrono::milliseconds(SELECT_TIMEOUT_MILLISECONDS);

auto what = GenerateWaitSockets(snap.Nodes());
if (what.empty() || !what.begin()->first->WaitMany(timeout, what)) {
interruptNet.sleep_for(timeout);
}

if (interruptNet) return;

Expand All @@ -1508,7 +1396,7 @@ void CConnman::SocketHandler()
//
for (const ListenSocket& hListenSocket : vhListenSocket)
{
if (hListenSocket.sock->Get() != INVALID_SOCKET && recv_set.count(hListenSocket.sock->Get()) > 0) {
if (hListenSocket.sock->Get() != INVALID_SOCKET && what[hListenSocket.sock].occurred & Sock::RECV) {
AcceptConnection(hListenSocket);
}
}
Expand All @@ -1531,9 +1419,9 @@ void CConnman::SocketHandler()
if (!pnode->m_sock) {
continue;
}
recvSet = recv_set.count(pnode->m_sock->Get()) > 0;
sendSet = send_set.count(pnode->m_sock->Get()) > 0;
errorSet = error_set.count(pnode->m_sock->Get()) > 0;
recvSet = what[pnode->m_sock].occurred & Sock::RECV;
sendSet = what[pnode->m_sock].occurred & Sock::SEND;
errorSet = what[pnode->m_sock].occurred & Sock::ERR;
}
if (recvSet || errorSet)
{
Expand Down
17 changes: 2 additions & 15 deletions src/net.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1002,22 +1002,9 @@ class CConnman
/**
* Generate a collection of sockets that we want to be checked for readiness for IO.
* @param[in] nodes Select from these nodes' sockets.
* @param[out] recv_set Sockets to check for read readiness.
* @param[out] send_set Sockets to check for write readiness.
* @param[out] error_set Sockets to check for errors.
* @return true if at least one socket is to be checked (the returned set is not empty)
* @return sockets to check for readiness
*/
bool GenerateSelectSet(const std::vector<CNode*>& nodes, std::set<SOCKET> &recv_set, std::set<SOCKET> &send_set, std::set<SOCKET> &error_set);

/**
* Check which sockets are ready for IO.
* @param[in] nodes Select from these nodes' sockets.
* @param[out] recv_set Sockets which are ready for read.
* @param[out] send_set Sockets which are ready for write.
* @param[out] error_set Sockets which have errors.
* This calls `GenerateSelectSet()` to gather a list of sockets to check.
*/
void SocketEvents(const std::vector<CNode*>& nodes, std::set<SOCKET> &recv_set, std::set<SOCKET> &send_set, std::set<SOCKET> &error_set);
Sock::WaitData GenerateWaitSockets(const std::vector<CNode*>& nodes);

void SocketHandler();
void ThreadSocketHandler();
Expand Down

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